WO2009091978A2 - Synthèse non catalytique et traitement utilisant un plasma à pression atmosphérique - Google Patents

Synthèse non catalytique et traitement utilisant un plasma à pression atmosphérique Download PDF

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Publication number
WO2009091978A2
WO2009091978A2 PCT/US2009/031249 US2009031249W WO2009091978A2 WO 2009091978 A2 WO2009091978 A2 WO 2009091978A2 US 2009031249 W US2009031249 W US 2009031249W WO 2009091978 A2 WO2009091978 A2 WO 2009091978A2
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Prior art keywords
plasma
cellulosic material
plasma flame
species
nitrogen
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WO2009091978A3 (fr
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Jerome J. Cuomo
Matthew R. King
Christopher J. Oldham
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North Carolina State University
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North Carolina State University
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/48—Generating plasma using an arc
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H2240/00—Testing
    • H05H2240/10—Testing at atmospheric pressure
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H2245/00—Applications of plasma devices
    • H05H2245/10—Treatment of gases
    • H05H2245/15—Ambient air; Ozonisers

Definitions

  • This invention relates to the synthesis of chemistries utilizing atmospheric-pressure plasma.
  • the invention also relates to the use of atmospheric-pressure plasma in the processing of biomass such as cellulosic material to produce sugars and the fermentation of such sugars to produce alcohols and other chemicals.
  • Plasma may generally be described as a volume of highly-energetic ionized gas composed of electrons, ions and neutral molecules. Plasma is typically generated by application of an electrical field to a background gas, although some types of plasmas may be generated by chemical means or very high temperatures.
  • the electrical field may be constant (direct current or DC) or alternating (alternating current or AC, and particularly radio frequency or RF).
  • Atmospheric-pressure (AP) plasma is generated without the requirement of a sealed vacuum environment and thus may be utilized in a broad range of process environments.
  • AP atmospheric-pressure
  • dielectric barrier discharges corona discharges, plasma arcs, microplasmas, inductively coupled plasmas, laser- assisted plasmas, thermal plasmas, plasma torches
  • gases e.g. He, Ne, Ar, O 2 , N 2 , air, H 2 , H 2 O, CO 2 , CH 4 .
  • He, Ne, Ar, O 2 , N 2 , air, H 2 , H 2 O, CO 2 , CH 4 gases
  • the parameters of the plasma discharge are chosen based on the application of interest. Choosing an application governs the boundaries in which the plasma operates, such as the appropriate temperature, pressure, and energy ranges, current-voltage regime, frequency range, gap size, and gas compositions, as well as the type of chemical species produced by the discharge.
  • syngas is a gas mixture containing carbon monoxide (CO) and diatomic hydrogen (H 2 ). Syngas may be utilized as a fuel or as an intermediate product in the synthesis of other chemical products such as hydrogen gas, ammonia and methanol. Syngas is typically produced from natural gas (methane, CH 4 ) via the well-known steam reforming reaction: [010] CH 4 + H 2 O ⁇ CO + 3H 2 .
  • the steam reforming reaction is endothermic, occurring at high temperatures (700- 1100 0 C) and thus requiring a large input of heat energy.
  • the heat energy is typically provided by an external source of hot gas that heats tubes in which the reaction takes place.
  • a nickel catalyst is utilized.
  • ammonia As another example, the Haber (or Haber-Bosch) process is widely utilized to produce ammonia (NH 3 ), which in turn is widely utilized for various purposes as well as a precursor chemical species for other products.
  • ammonia is often supplied as a source of nitrogen for use in the production of electronic and electro-mechanical devices and sensors, micro-scale analytical instruments, coatings for tools and other articles, etc.
  • ammonia is often oxidized to produce nitrates and nitrites to produce various products such as munitions, fertilizer (ammonium nitrate, NH 4 NO 3 ) and acids (most notably nitric acid, HNO 3 ).
  • Many ammonia-derived chemicals are produced by the megaton each year.
  • the cost, catalysts, and energy requirements of producing and supplying hydrogen gas as a feedstock for the Haber process is, in and of itself, significant.
  • the hydrogen gas must be obtained from methane or natural gas utilizing heterogeneous catalysis. Multiple process steps are required, including steam reforming, secondary reforming, water gas shift reaction, methanation, and carbon dioxide removal. Various process steps may require sulfur scrubbing to prevent sulfur from poisoning the required catalyts, and reactions with zinc oxide (ZnO), steam and potassium carbonate.
  • Catalysts employed at different stages include nickel oxide; a mixture of iron, chiOmium and copper; and a mixture of copper, zinc and aluminum.
  • Methane not converted by steam reforming may be subjected to secondary reforming reactions for further conversion as follows: PATENT Docket No. NS08001 WO
  • ammonia produced according to the Haber process is in turn utilized as a feedstock in the Ostwald process to produce nitric acid (HNO 3 ).
  • HNO 3 nitric acid
  • ammonia is oxidized by heating with diatomic oxygen gas (O 2 ) in the presence of a platinum/rhodium catalyst to produce nitric oxide and water. Pressure ranges from 4-10 atmospheres, and temperature is about 900 0 C.
  • the nitric oxide is then oxidized using diatomic oxygen, which produces nitrogen dioxide (NO 2 ).
  • the oxidation reactions are as follows:
  • Ammonia produced according to the Haber process may also be utilized to produce ammonium nitrate according to the following acid base reaction with nitric acid:
  • Syngas may also be utilized to produce methanol (CH 3 OH).
  • the carbon monoxide and hydrogen react on a catalyst at a pressure of 50-100 atmospheres and a temperature of 250
  • the catalyst is a mixture of copper, zinc oxide and alumina.
  • the reaction is as follows: PATENT Docket No. NS08001 WO
  • Chlorine dioxide has important applications such as disinfecting municipal water supplies and bleaching wood pulp. Chlorine dioxide, however, has a tendency to explosively decompose into chorine and oxygen. Consequently, the costs associated with the safe handling of chlorine dioxide are high, and it is preferable that chlorine dioxide be synthesized on site where it is to be utilized.
  • Cellulosic materials including lignocellulosic materials, biomass, etc., occur abundantly in nature and constitute a significant source of sugars from which alcohols and other industrial chemicals may be derived.
  • Cellulose, hemicellulose, and lignin are three primary components of cellulosic materials.
  • Cellulose forms the primary structural component of plant cell walls.
  • the secondary cell wall of green plants contains lignin as well as cellulose.
  • Lignocellulose (cellulose and lignin) such as wood is the most common terrestrial biopolymer, by some accounts comprising approximately 50% of the biomass in the world. Cellulose holds particular interest because it can be processed to yield glucose monomers.
  • Glucose can be converted to fuel-grade alcohols such as ethanol (CH 3 CH 2 OH, or C 2 H 6 O) by fermentation (i.e., bioethanol). Rendering bioethanol commercially available is considered to be a viable way for reducing the environmental effects of and dependence on fossil fuels. Accordingly, cellulosic materials are considered to be an important potential renewable source — particularly a domestic source of alternative fuels — and thus the efficient PATENT Docket No. NS08001 WO conversion of cellulosic components to alcohols, particularly ethanol, is the subject of ongoing research.
  • Cellulose and hemicellulose are carbohydrate polymers.
  • Cellulose is a long-chain polysaccharide carbohydrate of ⁇ glucose monomers, which may be chemically represented as (C 6 Hi O Os) n . More specifically, cellulose is a polymer of D-glucose (C 6 Hi 2 O 6 ) with ⁇ [1 ⁇ 4] linkages (glycosidic bonds) between each of the about 500 to 10,000 glucose units.
  • Cellulose is a straight-chain polymer that exhibits a rod-like conformation, unlike starch which exhibits coiling. Cellulose constitutes about 35-60% by weight of typical cellulosic materials.
  • Hemicellulose is a non-cellulosic, heteropolymer polysaccharide of primarily D-xylose (C 5 H 10 O 5 ) and other pentoses and some hexoses with ⁇ [1 ⁇ 4] linkages. Hemicellulose may be found as a branched polymer of glucose or xylose, substituted with arabinose, xylose, galactose, fucose, mannose, glucose, or glucuronic acid. The molecular weights of hemicellulose polymers are usually lower than that of cellulose, and hemicellulose polymers have a weak undifferentiated structure compared to crystalline cellulose.
  • Hemicellulose binds with pectin (a heterosaccharide) to cellulose to form a network of cross-linked fibers that serves as the structural backbone of plant cell walls.
  • Hemicellulose constitutes about 20-35% by weight of typical cellulosic materials.
  • Lignin may be characterized as a complex, cross-linked, random, amorphous, three-dimensional polyphenolic polymer that typically is based on variously substituted p-hydroxyphenlypropane units. Lignin generally permeates the matrix of cellulose fibers and largely fills in the interstices between the cellular structures (cellulose, hemicellulose and pectin components) of the cellulosic material.
  • lignin appears to be more intimately cross-linked or otherwise associated with hemicellulose than with the distinct crystalline phase of cellulose. Lignin constitutes about 10-30% by weight of typical cellulosic materials.
  • Cellulosic materials are converted to alcohols by releasing the component sugars of the cellulosic materials, and fermenting the sugars to alcohols.
  • the carbohydrate polymers of cellulosic materials are typically depolymerized (degraded or broken down) into fermentable monomeric sugars by hydrolysis.
  • Component sugars may include six-carbon sugars (hexoses) such as glucose, galactose, and mannose, and five-carbon sugars (pentoses) such as xylose and arabinose. Both chemical and enzymatic hydrolytic processes have been utilized.
  • Chemical hydrolysis typically entails the use of an acid such as sulfuric acid as a catalyst.
  • an acid such as sulfuric acid as a catalyst.
  • microcrystalline cellulose is relatively resistant to typical acid hydrolysis, amorphous cellulose is less resistant, hemicellulose (which is also amorphous) is even less resistant, and lignin is highly resistant but may be dissolved by certain organic solvents.
  • Acid hydrolysis utilizes either concentrated acids or diluted acids. Acid hydrolysis generally is around 10-40% efficient in terms of sugar recovery, depending on process conditions. Concentrated acid hydrolysis involves short reaction times, but requires a large amount of expensive acid(s), corrosion-resistant equipment, and energy-demanding means for recycling the acid. Moreover, concentrated acid hydrolysis requires significant control over the reaction to avoid degrading the desired sugars and forming toxic byproducts.
  • Dilute acid hydrolysis is a lower cost process involving a relatively low consumption of acid(s), but requires longer reaction times and results in a decreased glucose yield as compared to concentrated acid hydrolysis.
  • dilute acid hydrolysis requires high temperatures to attain acceptable rates of conversion of cellulose to sugar monomers. High temperatures require a high input of energy, promote equipment corrosion, and increase the rates of hemicellulose-derived sugar decomposition.
  • the products of decomposing hemicellulose may include furfural and hydroxymethylfurfual. It is known that sugar decomposition products can inhibit the subsequent fermentation process.
  • a two-stage acid hydrolysis process has been employed.
  • the first stage is carried out under relatively mild conditions to release sugars as a result of hydrolysis of the hemicellulose, and the second stage is carried out under relatively harsher conditions to hydrolyze the cellulose fraction.
  • the first stage enables the second stage to proceed under the harsher conditions without decomposing the hemicellulose into undesired byproducts, but the glucose yield is still unacceptably low (e.g., 50%).
  • Fermentation of hydrolyzate sugars involves the use of digesting or metabolizing agents such as yeast.
  • yeast readily metabolizes glucose, which is the predominant hydrolyzate of many types of cellulosic materials.
  • Yeast cannot metabolize other hydrolyzates such as xylose, and thus other organisms such as certain species of bacteria (e.g., Zymonmonas sp. and E. col ⁇ ) have been employed for this purpose, including organisms genetically PATENT Docket No. NS0800 IWO engineered to consume a specific type of hydrolyzate such as xylose.
  • the stoichiometric expressions for the conversion of glucose and xylose into ethanol are, respectively: [042] C 6 Hi 2 O 6 ⁇ 2C 2 H 6 O + 2CO 2 and [043] 3C 5 H 10 O 5 ⁇ 5C 2 H 6 O + 5CO 2 .
  • the resulting alcohols may be separated (e.g., distilled) and purified according to any suitable processes. Residual components of the fermentation process may include lignin, unreacted cellulose and hemicellulose, ash, enzymes, microorganisms, etc.
  • cellulose Due to its crystalline structure, cellulose is generally water-insoluble and resistant to depolymerization. The highly packed and crystalline structure of cellulose also means that the surface area available for hydrolytic and fermentative activity is low. Moreover, as noted above, the presence of hemicellulose and lignin impedes hydrolysis of the cellulose. As a result, the efficiency and costs associated with the conversion of cellulosic material into alcohols are less than desirable.
  • various pre-treatment methods have been proposed that endeavor to disrupt the cellulose-hemicellulose-lignin complex, expose the cellulose, and/or modify the pores of the matrix, and thereby make the cellulose more available for hydrolysis such as by allowing enzymes to penetrate into the fibers of the matrix. As in the case of hydrolytic process steps, some of these pre-treatment methods entail the use of acids such as H 2 SO 4 or HCl. Many of these pre-treatment methods require high pressures, temperatures and energy inputs, and are costly.
  • AP plasma apparatus Various configurations of AP plasma apparatus were operated to generate plasmas effective to degrade cellulosic materials, either in combination with acids or pretreatments or as a complete substitution for PATENT Docket No NS08001WO acid hydrolysis and pietreatments
  • the AP plasma may be utilized to conduct an in situ acid treatment, in which AP plasma is utilized to synthesize acid directly within the structure of cellulosic materials
  • a method for synthesizing a chemistry A plasma flame is ignited m a chamber at atmospheiic pressure in the presence of a gas including a plurality of gas-phase components, by applying a periodic signal to at least one of a pair of electrodes in the chamber
  • the plasma flame includes a thermal core m a gap between the electrodes and a non-equilibrium region adjacent to the thermal core
  • a synthesis reaction is conducted by reacting at least one component of the gas with either another component of the gas or with a precursor component introduced in the chamber separately from the gas
  • the synthesis reaction is conducted for a first period of time After the first period of time, a post-discharge reaction region including energetic species of the gas is created in the chamber, by ceasing application of the periodic signal such that the plasma flame is extinguished For a second period of time after the plasma flame has been extinguished, the synthesis reaction is conducted in the post-discharge reaction region The steps taken during
  • the plurality of gas-phase components includes oxygen and mtrogen, igniting the plasma flame produces energetic oxygen species from the oxygen, energetic nitrogen species from the mtrogen, and energetic nitrogen oxides from both, and conducting the synthesis reaction mcludes combining nitrogen and oxygen from the energetic species to form nitrogen dioxide
  • the reaction products are combined with water to produce nitric acid This step may take place in the reaction chamber, m a secondary chamber or holding device, or at any location not inherently connected to the chamber [051]
  • a method is provided for synthesizing syngas including carbon monoxide and diatomic hydrogen
  • a plasma flame is ignited in a chamber at atmospheric pressure, by applying a periodic signal to at least one of a pair of electrodes in the PATENT Docket No. NS0800 IWO chamber.
  • the plasma flame includes a thermal core in a gap between the electrodes and a non- equilibrium region adjacent to the thermal core.
  • a mixture of a hydrocarbon and water is flowed toward the plasma flame. Species of the hydrocarbon and water energized by the plasma flame are reacted to form syngas.
  • a method for synthesizing ammonia is provided.
  • a plasma flame is ignited in a chamber at atmospheric pressure, by applying a periodic signal to at least one of a pair of electrodes in the chamber.
  • the plasma flame includes a thermal core in a gap between the electrodes and a non-equilibrium region adjacent to the thermal core. Nitrogen species and hydrogen species, obtained from a hydrogen source not limited to diatomic hydrogen gas, energized by the plasma flame are reacted to form ammonia.
  • a method for synthesizing chlorine dioxide is provided.
  • a plasma flame is ignited in a chamber at atmospheric pressure, by applying a periodic signal to at least one of a pair of electrodes in the chamber.
  • the plasma flame includes a thermal core in a gap between the electrodes and a non-equilibrium region adjacent to the thermal core. Chlorine species and oxygen species, energized by the plasma flame are reacted to form ammonia.
  • a method for synthesizing methanol.
  • a plasma flame is ignited in a chamber at atmospheric pressure, by applying a periodic signal to at least one of a pair of electrodes in the chamber.
  • the plasma flame includes a thermal core in a gap between the electrodes and a non-equilibrium region adjacent to the thermal core.
  • a hydrogen source, carbon source, and/or oxygen source is flowed toward the plasma flame. Carbon-, hydrogen-, and/or oxygen-containing species and are reacted with the species energized by the plasma flame to form methanol.
  • a method for synthesizing ammonium nitrate by reacting ammonia and nitric acid are provided.
  • the ammonia, nitric acid, or both, are produced by operating a plasma flame.
  • a method for treating a cellulosic material.
  • the method includes operating a plasma flame to synthesize nitrogen dioxide and exposing the cellulosic material to the nitrogen dioxide.
  • the method further includes subjecting the cellulosic material to an atmospheric-pressure plasma.
  • the atmospheric-pressure plasma to which the cellulosic material is subjected may be the plasma flame utilized to synthesize the nitrogen dioxide.
  • the atmospheric-pressure plasma to which the cellulosic material is subjected may be a separate plasma distinct from the plasma flame utilized to synthesize the nitrogen dioxide.
  • This separate plasma may be of the same type as the plasma flame or may be a different type of plasma.
  • the separate plasma may be operated (i.e., ignited and maintained) in the same chamber as the plasma flame utilized to synthesize the nitrogen dioxide, or the separate plasma may be operated in a separate chamber.
  • nitric acid is formed within the cellulosic material by reacting the nitrogen dioxide with hydrogen species supplied by a gas or by the cellulosic material.
  • the cellulosic material is degraded by exposing the cellulosic material to the nitric acid.
  • one or more components of the plasma-treated cellulosic material are fermented. Fermenting may produce, for example, an organic compound such as, for example, an alcohol.
  • a method for treating a cellulosic material.
  • the cellulosic material is subjected to an atmospheric-pressure plasma to produce a plasma-treated cellulosic material.
  • One or more components of the plasma-treated cellulosic material is subjected to an acid hydrolysis process to produce a hydrolyzed cellulosic material, by operating a plasma flame to synthesize nitrogen dioxide and exposing the cellulosic material to the nitrogen dioxide, forming nitric acid within the cellulosic material by reacting the nitrogen dioxide with hydrogen species supplied by a gas or by the cellulosic material (i.e. part of the cellulosic material itself or the water inherently contained within its structure), and degrading the cellulosic material by exposing the cellulosic material to the nitric acid.
  • a method for treating a cellulosic material.
  • the cellulosic material is subjected to a first degradation process to produce a first degradation-processed cellulosic material.
  • One or more components of the first degradation- processed cellulosic material are subjected to an atmospheric-pressure plasma to produce a plasma-treated cellulosic material.
  • One or more components of the plasma-treated cellulosic PATENT Docket No. NS08001WO material are subjected to a second degradation process to produce a second degradation- processed cellulosic material.
  • Subjecting the cellulosic material to at least one of the first and second degradation processes includes operating a plasma flame to synthesize nitrogen dioxide and exposing the cellulosic material to the nitrogen dioxide, forming nitric acid within the cellulosic material by reacting the nitrogen dioxide with hydrogen species supplied by a gas or by the cellulosic material, and degrading the cellulosic material by exposing the cellulosic material to the nitric acid.
  • a method for treating a cellulosic material.
  • the cellulosic material is subjected to a pretreatment process.
  • the cellulosic material is subjected to an atmospheric-pressure plasma.
  • the cellulosic material is subjected to a degradation process.
  • Subjecting the cellulosic material to at least one of the pretreatment process and the degradation process includes operating a plasma flame to synthesize nitrogen dioxide and exposing the cellulosic material to the nitrogen dioxide, forming nitric acid within the cellulosic material by reacting the nitrogen dioxide with hydrogen species supplied by a gas or by the cellulosic material (i.e. part of the cellulosic material itself or the water inherently contained within its structure), and degrading the cellulosic material by exposing the cellulosic material to the nitric acid.
  • a method for treating a cellulosic material.
  • a plasma flame is operated to produce nitrogen dioxide, the nitrogen dioxide is liquefied or solidified, and the cellulosic material is exposed to the liquefied or solidified nitrogen dioxide.
  • a method for treating a cellulosic material.
  • a plasma flame is operated to produce nitrogen dioxide. Water is reacted with the nitrogen dioxide to produce nitric acid. The nitric acid is liquefied. The cellulosic material is exposed to the liquefied nitric acid.
  • Figure 1 is a schematic diagram illustrating an example of an atmospheric-pressure (AP) plasma apparatus provided in accordance with one or more implementations taught in the present disclosure.
  • AP atmospheric-pressure
  • Figure 2 is a plot of ignition and stabilized I-V characteristics for a plasma flame discharge according to one or more implementations taught in the present disclosure.
  • Figure 3 is a plot of curves indicating absorbance of NO 2 as a function of wavelength, as the reaction time of air in a plasma flame discharge increases, according to one or more implementations taught in the present disclosure.
  • Figure 4 is a plot of absorbance of NO 2 at 435.4 run as a function of time for various electrode materials, according to one or more implementations taught in the present disclosure.
  • Figure 5 is a plot indicating nitrogen dioxide concentration as a function of time for a gas mixing ratio of IN: 10 subjected to a plasma flame discharge and for different times at which the plasma flame discharge was turned off, according to one or more implementations taught in the present disclosure.
  • Figure 6 is a plot indicating nitrogen dioxide concentration as a function of time for a gas mixing ratio of 1N:4O subjected to a plasma flame discharge and for different times at which the plasma flame discharge was turned off, according to one or more implementations taught in the present disclosure.
  • Figure 7 is a plot indicating nitrogen dioxide concentration as a function of time for a gas mixing ratio of 4N:1O subjected to a plasma flame discharge and for different times at which the plasma flame discharge was turned off, according to one or more implementations taught in the present disclosure.
  • Figure 8 is a plot of absorbance as a function of time for plasma flame discharge- synthesized nitrogen dioxide, according to one or more implementations taught in the present disclosure.
  • Figure 9 is a plot of curves indicating the temperature of a background gas in an AP plasma reactor as a function of time for different plasma "on" times, according to one or more implementations taught in the present disclosure.
  • Figure 10 is a plot of curves indicating nitrogen dioxide concentration as a function of time for a plasma "on" time of 10 minutes, and background gas temperature as a function of time, according to one or more implementations taught in the present disclosure.
  • Figure 11 is a plot of curves indicating intensity as a function of wavelength for an
  • O 2 emission band according to one or more implementations taught in the present disclosure.
  • Figure 12 is a plot of curves indicating intensity as a function of wavelength for an atomic O emission band, according to one or more implementations taught in the present disclosure.
  • Figure 13 is a plot of curves indicating reaction rates as a function of reactant temperature for various reactions that may be initiated by the plasma flame discharge according to one or more implementations taught in the present disclosure.
  • Figure 14 is a plot of partial pressures of various species as a function of time, including syngas synthesized by plasma flame discharge, according to one or more implementations taught in the present disclosure.
  • Figure 15 is a flow diagram illustrating an example of a method for synthesizing a chemistry by plasma flame discharge according to one or more implementations taught in the present disclosure.
  • Figure 16 is a flow diagram illustrating an example of another method for synthesizing a chemistry by plasma flame discharge according to one or more implementations taught in the present disclosure.
  • Figure 17 is a flow diagram illustrating an example of a method for treating cellulosic material according to one or more implementations taught in the present disclosure.
  • Figure 18 is a flow diagram illustrating an example of another method for treating cellulosic material according to one or more other implementations taught in the present disclosure.
  • Figure 19 is a flow diagram illustrating an example of another method for treating cellulosic material according to one or more other implementations taught in the present disclosure.
  • Figure 20 is a flow diagram illustrating an example of another method for treating cellulosic material according to one or more other implementations taught in the present disclosure.
  • Figure 21 is a schematic diagram illustrating another example of an AP plasma apparatus provided in accordance with one or more implementations taught in the present disclosure.
  • Figure 22 is a schematic diagram illustrating another example of an AP plasma apparatus provided in accordance with one or more implementations taught in the present disclosure.
  • air is intended to encompass not only ambient air but also a mixture including O 2 and N 2 in any ratio suitable or desired for a particular implementation of the presently disclosed subject matter.
  • Additional gases may also be included in the air or mixture for such purposes as cooling, material transport or flow, conducting a particular type of synthesis, dilution, modification of pH, modification of polarity or volatility, etc.
  • Additional gases may include, for example, noble or inert gases, reactive gases, water vapor, etc.
  • the "atmospheric" or “ambient” is intended to take into account the fact that atmospheric pressure varies according to geographic location and ambient temperature, and thus is not restricted to conditions occurring precisely at sea level. Moreover, the term “atmospheric pressure” is not limited to the exact value of 760 Torr but may range from, for example, about 10 to about 1000 Ton”. Accordingly, as used herein, the term “atmospheric” encompasses the term “near atmospheric.” PATENT Docket No. NS08001 WO
  • AC signal (or “AC current,” “AC voltage,” “AC power,” etc.) is intended to also encompass a pulsed DC signal.
  • AC encompasses any suitable periodic waveform, including not only sinusoidal but also square, sawtooth, pulsed, and the like.
  • Devices, circuitry, hardware and/or software utilized to generate AC and pulsed DC power, with various waveform configurations, are readily known to persons skilled in the art.
  • chemistry refers to one or more chemical compounds, or one or more types of chemical compounds, depending on the particular synthesis contemplated.
  • chemistry may refer to nitrogen dioxide, i.e., one or more molecules of NO 2 .
  • chemistry may refer to syngas, i.e., a mixture of one or more molecules ofH 2 and one or more molecules of CO.
  • AP plasma is employed in direct, non-catalytic processes for the production of various chemistries that may be utilized in a wide variety of applications and/or as basic chemical building blocks in the synthesis of other high-value chemistries.
  • the synthesis of such chemistries conventionally require complex process steps that utilize high energy inputs, high temperatures, high pressures and expensive catalysts.
  • such chemistries may now be synthesized by techniques entailing the application of AP plasma in a manner that simplifies and reduces the cost of synthesis.
  • AP plasma-driven synthesis as taught herein occurs at low (atmospheric) pressure, without the use of catalysts, through the use of a unique type of plasma flame discharge.
  • Most discharges are characterized as being either completely thermal or completely non-thermal. Discharges which do contain both thermal and non-thermal components have temporal and spatial variations such that the thermal and non-thermal regions do not exist simultaneously.
  • the plasma flame discharge disclosed herein is unique in that, during stable operation, this plasma flame discharge simultaneously and continuously exhibits two distinct regions or zones: a core sustained at thermal equilibrium and a non-thermal, non-equilibrium region. Atomic species and other active species form within the thermal region and react to form new compounds as they diffuse outward into cooler regions.
  • ambient air or, as noted above, a mixture of oxygen and nitrogen in controlled concentrations
  • the ambient air is subjected to the novel "plasma flame" discharge generated in the reactor.
  • the plasma flame discharge taught herein is unique in the atmospheric plasma domain due to its mode of operation and the resultant products when using air as the reaction gas.
  • Thermal plasmas typically fall into two categories, thermal and non-thermal (alternatively, equilibrium and non-equilibrium).
  • thermal plasmas Two hallmarks of thermal plasmas are the massive amounts of current (tens or hundreds of amps) and power (kilowatts to tens of kilowatts) utilized to sustain the discharge.
  • Thermal plasmas as the name implies, are extremely hot and are utilized, for example, in welding applications. Since most of the energy in these discharges is converted to heat, little in the way of chemical activity can be seen.
  • Nonthermal plasmas on the other hand, have some chemical reactivity.
  • the plasma flame discharge disclosed herein is novel in that, unlike thermal discharges, it is driven using low power and current; and, in contrast to nonthermal discharges which use low power and low current, the plasma flame discharge is highly energetic and highly reactive.
  • the temperature of the plasma flame discharge is high enough to produce high energy active species in large quantities (to an extent which is not feasible in purely non-thermal discharges), but low enough to avoid complete thermalization of the discharge. This is accomplished by simultaneously sustaining a thermal core and a non- equilibrium region.
  • the plasma flame discharge is ignited by applying AC (or, as noted above, pulsed DC) power to two bare metallic electrodes provided in the reactor chamber that are PATENT Docket No. NS0800 IWO separated by a gas gap.
  • the electrical current associated with this plasma flame discharge is on the order of hundreds of milliamps (as one example, 0.1 A or thereabouts) as opposed to tens or hundreds of amps. Also, the voltage is significantly higher than many thermal plasmas (as one example, 1000 V or thereabouts).
  • the plasma flame discharge is very energetic, with a core gas temperature of approximately 3000K as determined from OH rotational band emission. These are surprising characteristics as most types of artificially produced plasmas at this energy level require an input power on the order of kilowatts.
  • the plasma flame discharge taught herein only requires an input power of, as one example, 100 W or thereabouts.
  • the plasma flame is quiescent and uniform with no electrical instabilities.
  • the frequency of the AC signal applied to ignite the plasma flame may range, for example, from about 120 to about 160 kHz.
  • a frequency of about 158 IcHz has been found particularly effective for generating the quiescent plasma flame from which chemistries such as nitrogen dioxide may be synthesized.
  • the operating parameters needed for coupling or impedance matching may depend on the particular electronics utilized for operating the plasma reactor, and thus no limitation is placed on such operating parameters as regards the broad aspects of the invention.
  • a pulsed DC signal may be substituted for a true AC signal, and thus the signal applied to the electrode(s) may be characterized generally as a periodic signal.
  • the periodic signal is applied at a power ranging from about 20 to 500 W, at a current ranging from about 0.025 to 0.5 A, and at a voltage ranging from about 600 to 6000 V.
  • the periodic signal is applied at a power ranging from about 50 to 150 W.
  • An AC signal may also be cycled on or off to likewise alternate the plasma flame discharge between operating and extinguished stages.
  • the thermal core of the plasma flame discharge produces highly energetic species which then migrate to the non-equilibrium region of the discharge.
  • the types of energetic species specifically produced in thermal core depend on the gas or gases present in the reaction PATENT Docket No. NS0800 IWO chamber. Additional energetic species may be produced in the non-equilibrium region, which may depend also on the composition of any background gas present outside the discharge as well as the composition of any precursor gas that may be added to the reaction chamber to synthesize a desired compound. Compounds may be synthesized directly in the highly reactive non-equilibrium region, but also may be synthesized outside of the discharge, or both. The region of the reaction chamber outside of the discharge in many implementations is much cooler than the discharge itself. Controlling the ratio between the plasma temperature and the ambient gas temperature directs pertinent reactions toward formation of a desired intermediate or final product.
  • the synthesis of a desired chemistry may depend strongly on the temperature conditions within the reaction chamber.
  • the temperature of the plasma flame discharge and the region of the reaction chamber outside of the discharge may be controlled as desired.
  • the temperature of the plasma flame discharge may be controlled, for example, by controlling the temperature of the gas provided to the electrodes for striking the plasma flame, by controlling the operating parameters of the periodic signal applied to the electrodes (e.g., current, voltage, frequency, etc.) and/or by controlling the plasma density (i.e. controlling the number of electrons and ions in a given volume).
  • the temperature of the plasma flame discharge may be controlled through selection of the material comprising the electrodes, and/or by externally heating the electrodes.
  • the temperature of the region of the reaction chamber outside of the discharge may be controlled by, for example, heating the reaction chamber by any suitable means (e.g., resistive or inductive heater, circulation of a fluidic heat transfer medium, etc.), heating a gas that is flowed into the chamber separately from the gas utilized to ignite the discharge (for example, a precursor gas introduced to provide one or more desired reactants.
  • Control of the plasma flame discharge may include control of the temperature gradient between the thermal core and the non-equilibrium region.
  • Control of the plasma flame discharge may also include control of the volumetric ratio of the plasma flame, which is defined in the present disclosure as the ratio of the volume of the thermal core to the volume of the non- equilibrium region.
  • the volumetric ratio of the plasma flame may PATENT Docket No. NS0800 IWO range from 1:3 to 1: 100.
  • the volumetric ratio of the plasma flame may be controlled by, for example, controlling the operating parameters of the periodic signal applied to the electrodes, and may also depend on the properties (e.g., composition, temperature, etc.) of the gas utilized to ignite the discharge.
  • the volumetric ratio can also be controlled by changing the plasma density by any means known to those familiar in the art. This may include, for example, adding electrons or ions to the plasma (e.g. promoting thermionic emission from the electrodes) and/or changing the lifetime of electrons and ions in the plasma (e.g. supplying an external magnetic field which sustains the electrons and ions).
  • the ratio of the volume of the plasma flame discharge to the volume of the interior of the reaction chamber may also be controlled by controlling the size (volume) of the discharge. In various implementations, the ratio of the volume of the plasma flame discharge to the volume of the interior of the reaction chamber may range from 1: 10 to 1: 10,000.
  • the ratio of the volume of the plasma flame discharge to the volume of the interior of the reaction chamber may also be controlled by, for example, controlling the operating parameters of the periodic signal and may also depend on the properties of the gas utilized to ignite the discharge. Depending on the product being synthesized, one or more of the foregoing conditions may play a significant role in directing the desired reactions appropriately.
  • All or part of a desired synthesis reaction may occur in a second reaction chamber (or enclosure, compartment, etc.) or in more than one additional reaction chamber, separate from the first reaction chamber in which the plasma flame discharge is operated.
  • the second reaction chamber may selectively communicate with the first reaction chamber by any suitable means such as, for example, baffles, valves, etc.
  • the first reaction chamber may initially be fluidly isolated from the second reaction chamber while the discharge in the first reaction chamber is being maintained. After a period of time during which energetic species are produced by the discharge, an isolation or sealing device (e.g., baffle, valve, etc.) may then be opened to enable energetic species, and possibly products already synthesized in the first reaction chamber, to flow into the second reaction chamber.
  • an isolation or sealing device e.g., baffle, valve, etc.
  • the second reaction chamber may provide a contained area that is held at a different temperature than the first reaction chamber to enable a desired synthesis reaction to proceed.
  • one or more precursor materials may be provided in the second reaction chamber for reaction with PATENT Docket No. NS08001 WO intermediate components produced in the first reaction chamber.
  • the second reaction chamber (or one or more additional reaction chambers) may also include electrodes for producing a plasma flame discharge of the type disclosed herein, or may be configured to produce different types of plasmas such as, for example, plasma arcs, corona discharges, microplasmas, dielectric barrier discharges, glow discharges, and gliding arcs.
  • the same reaction chamber may include more than one set of electrodes for igniting more than one plasma flame discharge.
  • a flow of energetic species, gases, partially or wholly synthesized products, and the like, may be established from one discharge to another in this same chamber.
  • FIG. 1 is a schematic illustration of an example of an AP plasma system or apparatus 100 according to one implementation.
  • the AP plasma system 100 includes a reactor enclosure 102 that may include a lid or other means (not shown) for alternately opening and closing off the interior space of the enclosure 102.
  • the reactor enclosure 102 is a nearly cylindrical acrylic structure having a height of 45 cm, a diameter of 14 cm, and a wall thickness of 3 mm.
  • Two bare metallic electrodes 104 and 106 extend into the interior space of the enclosure 102 in any parallel or non-parallel orientation that results in a gap 108 being defined between the respective distal tips of the electrodes 104 and 106.
  • each electrode 104 and 106 is cylindrical with a flat cross-section and the dimension of the gap 108 between the electrode tips is one inch.
  • An AC high- voltage power supply 110 is coupled to one of the electrodes 104 and the other electrode 106 is coupled to a suitable ground 112.
  • the power supply 110 is manufactured by AP Solutions, Inc., Cary, NC, as model designation DBD-5000. This particular power supply 110 was operated at 1-1.2 IcV, 50-80 niA, 158 kHz, and a phase angle of 8° or less in many of the experiments conducted in accordance with the present disclosure.
  • the AP plasma system 100 In operation, the AP plasma system 100 generates the above-noted unique plasma flame discharge 114 that extends into a discharge zone 118 within the interior space of the enclosure 102. As noted above, the plasma flame discharge 114 includes two distinct regions or zones: a thermal core 122 and a non-thermal, non-equilibrium region 124. PATENT Docket No. NS0800 IWO
  • analytical instrumentation provided with the AP plasma system 100 included a high-voltage probe 132 communicating with the output side of the power supply 110 and the corresponding electrode 104, a current probe 134 communicating with the grounded electrode 106, and an oscilloscope 136 for monitoring the various electrical characteristics of the power input (e.g., voltage, current, frequency, etc.).
  • the analytical instrumentation included an optical detection system utilized for measuring absorbance values of, and thereby identifying, gas-phase components synthesized in the plasma flame discharge 114 and the discharge zone 118 of the enclosure 102.
  • the optical detection system included a 150-W fluorescent (halogen) light source 142 operated at its lowest power level to transmit incident light signals into the discharge zone 118 via a fiber-optic line 144 and 25-cm collimating lens 146, and a monochromator 152 receiving attenuated light signals from the discharge zone 118 via a fiber-optic line 154 and 0.55-cm collimating lens 156.
  • the optical data were processed in a CPU 158 communicating with the monochromator 152.
  • absorbance values as a function of wavelength e.g., 400-700 nm
  • the AP plasma flame generated between the two electrodes is reacted with ambient air.
  • the energy of the applied AP plasma flame enables the reformation of air into nitrogen dioxide.
  • the presence of nitrogen dioxide is visually observable as a significant brown-colored gas emanating from the AP plasma flame.
  • the plasma-driven synthesis of nitrogen dioxide from air is enhanced by first subjecting the air to the AP plasma flame and then turning off the AP plasma flame after a designated period of time. After the AP plasma flame is turned off, the reaction kinetics proceed predominantly in the direction of the desired synthesis for another designated period of time. In one example, the AP plasma flame is left "on" for about five minutes.
  • the durations of time during which synthesis of a given chemistry occurs via the activated plasma flame discharge and the post-discharge reaction zone, respectively may be greater or less than 5 minutes.
  • the optimal time durations may vaiy for different chemistries.
  • synthesis may occur over several cycles alternating between the active discharge and the post-discharge reaction zone.
  • the AP plasma flame is activated for 5 min utilizing a power input of 60-70 Watts in an enclosure volume of about 5.9 liters.
  • the process produces 0.055 moles of nitrogen dioxide. This typically requires a high activation energy because of the large bond energies associated with N 2 and O 2 .
  • FIG. 2 illustrates the current-voltage (I-V) characteristics of the AP plasma flame discharge during ignition and stabilization according to one experiment.
  • the current curve is designated 202 and the voltage curve is designated 204.
  • the data were obtained by setting a 50- mA trigger on the digital oscilloscope in a 2-ns window. That is, a 50-mA current spike within a 2 ns window causes the oscilloscope to collect a single set of data over a given time frame. Based on the graph, the breakdown voltage of this discharge configuration is approximately 9 kV. In practice this value can be as low as 6 kV, and it is very dependent on the gap height. Concurrent with a 5A current spike, the voltage drops precipitously.
  • FIG. 1 illustrates the optical absorption of the gas within the enclosure as a function of wavelength according to one experiment. Each set of data points was taken at 30-second intervals over the course of 10 minutes. It can be seen that as the reaction time is increased, a compound is produced that absorbs in the visible range. This compound is assumed to be NO 2 , a coiTosive brown gas, given that other potential reaction products (e.g.
  • Figure 4 is also illustrative of the rate of synthesis of nitrogen dioxide while the plasma discharge is turned on and while the plasma discharge is turned off. From 0 to about 3 min the absorption increases at a rate of about 0.2 AU/min, at which point the rate decreases by about 40% from about 3 to 4.5 min. At 4.5 min, the plasma discharge is turned off and the absorbance is measured for another 5 minutes. Following the point at which the plasma is turned off, the absorbance increases at a rate of 0.55 AU/min until a saturation point is reached around 5.5-6 min. It can be seen that after the plasma flame is turned off, the reaction proceeds rapidly and preferentially in the desired direction.
  • Figures 5-7 show that the reaction kinetics entailing the synthesis of nitrogen dioxide, as discussed above in conjunction with Figure 4, follow similar curves at different plasma off times and different nitrogen/oxygen ratios. In particular, in each case the rate of synthesis jumps immediately following the turning off of the plasma.
  • Figure 5 illustrates the concentration of as-synthesized nitrogen dioxide as a function of time.
  • the input gas had a nitrogen/oxygen ratio of 1:1 PATENT Docket No NS08001WO and the plasma was turned off at different times 30 sec (curve 502), 1 mm (curve 504), 2 mm
  • Figuie 6 illustrates the concentiation of as-synthesized nitiogen dioxide as a function of time
  • the input gas had a nitrogen/oxygen ratio of 1 4 and the plasma was turned off at different times 30 sec (curve 602), 1 mm (curve 604), 2 mm
  • Figuie 7 illustrates the concentration of as-synthesized nitiogen dioxide as a function of time
  • the input gas had a nitrogen/oxygen ratio of 4 1 and the plasma was turned off at different times 30 sec (curve 702), 1 mm (curve 704), 2 mm
  • Figure 8 illustrates absorbance of NO 2 at 435 nm as a function of time similar to
  • FIG. 5-7 A plasma flame as described above was utilized to synthesize nitrogen dioxide m a quartz enclosure The plasma flame was turned off at 120 seconds The absorbance curve, obtained from 5 -second data acquisition intervals, is similar to those illustrated in Figures 5-7
  • Figure 9 includes plots of the temperature of the background (or "ambient") gas (i e , not the gas in the plasma) as a function of time for diffeient plasma "on" times
  • the information piovided in Figure 9 may be correlated with nitrogen dioxide concentration vs time plots such as Figures 5-7 to demonstrate the relationship between temperatuie and nitrogen dioxide synthesis
  • Figure 10 includes a plot of nitrogen dioxide concentration as a function of time for a plasma turn-off time of 10 minutes, along with a plot of background gas temperature as a function of time for the same experiment Figure 10 further demonstrates the relationship between temperature and nitrogen dioxide synthesis
  • Figures 11 and 12 show examples of species activated in the plasma flame discharge and available for synthesis of a desired product such as nitrogen dioxide Specifically, Figure 11 plots the mtensity (in arbitrary units) as a function of wavelength (in nm) for an O 2 emission band at different N O ratios Likewise, Figure 12 plots the intensity (m arbitrary units) as a function of wavelength (in nm) for an atomic O emission band at different N O ratios A spectrometer was utilized to take these measuiements, which are representative of active O 2 and
  • Figure 13 includes plots of reaction rates as a function of reactant temperature for various reactions that may be initiated by the plasma flame discharge. This is based on theoretical kinetic calculations for these reactions. Figure 13 demonstrates how active species are formed in the thermal core of the plasma flame discharge. Once the active species cool off outside the plasma flame discharge, they form nitrogen dioxide.
  • nitrogen dioxide produced according to the present disclosure may be utilized to produce various other chemistries, as well as to treat biomass.
  • the nitrogen dioxide may be utilized for etching materials such as metals as is needed in the fabrication of microelectronics and other fields of microfabrication.
  • the above- described processes may also be utilized to produce excited states useful for catalytic reactions, a few non-limiting examples being CH 3 and NO x .
  • the nitrogen dioxide produced as described by way of example above may then be utilized to produce, for example, nitric acid (HNO 3 ).
  • nitric acid HNO 3
  • 0.055 mol nitrogen dioxide may be employed to produce 0.055 mol nitric acid.
  • the AP plasma process may be carried out to replace the first two oxidation stages of the Ostwald process described earlier in this disclosure. In lieu of the foregoing two stages, the AP plasma process produces the nitrogen dioxide directly and non-catalytically from ambient air. The nitrogen dioxide output from the AP plasma process is then easily synthesized to nitric acid by carrying out reaction with water, or water and air, also described earlier.
  • the AP plasma flame as described above is utilized to produce syngas.
  • the system described above and illustrated in Figure 1 was modified to enable methane to be bubbled through water.
  • the resulting gases are flowed through the reactor enclosure and encounter the plasma flame generated between the two electrodes.
  • Figure 14 illustrates the acquisition of partial pressure data as a function of time (minutes) resulting from production of syngas as just described above. In Figure 14, the process proceeds from right to left.
  • the data were acquired by flowing the product gases from the PATENT Docket No. NS0800 IWO enclosure to a residual gas analyzer (RGA), which in this case was a mass spectrometer.
  • RAA residual gas analyzer
  • the production of syngas resulting from the applied AP plasma flame can be observed by the increase in partial pressures of carbon monoxide and diatomic hydrogen gas after the plasma was turned on, at a frequency of 158 kHz.
  • the processes utilizing the above-described AP plasma flame may be extended to the production of ammonia (NH 3 ) by the direct reaction of N 2 + H 2 , or N 2 with some other hydrogen source, without requiring catalysts; the production of methanol (CH 3 OH) by the reaction of CH 4 + CO 2 without requiring catalysts; the production of chlorine dioxide (ClO 2 ) by reacting chlorine and oxygen species excited by the plasma flame, the production of biofuels by atmospheric plasma processing of fats and glycerin; and the synthesis of carbon nanotubes using methane (CH 4 ).
  • Ammonia may be produced, for example, by flowing a hydrogen source toward the plasma flame discharge to produce hydrogen, and by flowing a nitrogen source into the reaction chamber. Nitrogen species and hydrogen species energized by the discharge may then be combined to synthesize ammonia. Methanol may be synthesized by energized carbon, oxygen and hydrogen species. Ammonia and nitric acid produced according to the present disclosure may be combined to form ammonium nitrate (NH 4 NO 3 ). Either or both of the ammonia and nitric acid may be provided through synthesis driven by the plasma flame.
  • FIG. 15 is a flow diagram 1500 illustrating an example of a method for synthesizing a chemistry.
  • the flow diagram 1500 may also represent an apparatus or system capable of performing the illustrated method.
  • the method begins at the starting point 1502.
  • a plasma flame as described above is generated in an AP environment.
  • one or more components of a gas or gases of appropriate composition are reacted with each other in the reaction chamber, as for example air in the case of nitrogen dioxide as described above, or are reacted with other components added to or entrained in the gas or gases as for example in the case of syngas, methanol, etc. as described above.
  • post-synthesis processing may be performed at block 1510.
  • the chemistry synthesized at block 1506 may serve as an intermediate product that is then utilized to PATENT Docket No. NS0800 IWO synthesize another chemistry. Examples are described above, such as utilizing nitrogen dioxide to produce nitric acid, utilizing syngas to produce ammonia or methanol, etc. The method ends at the ending point 1512.
  • FIG. 16 is a flow diagram 1600 illustrating another example of a method for synthesizing a chemistry.
  • the flow diagram 1600 may also represent an apparatus or system capable of performing the illustrated method.
  • the method begins at the starting point 1602.
  • a plasma flame as described above is generated in an AP environment.
  • the plasma flame is utilized to synthesize a desired chemistry.
  • the plasma flame is turned off after a desired period of time to generate a post-discharge reaction zone as described above.
  • synthesis of the chemistry continues in the post-discharge reaction zone.
  • the plasma flame may be cycled on and off in desired time intervals to perform the synthesis in alternating environments of plasma flame discharge and post-discharge reaction zone. This cycling may facilitate the scaling up of the production yield of the chemistiy being synthesized. For instance, after each iteration and prior to re-igniting the plasma flame, the chemistry synthesized in the last iteration may be routed from the reactor to a suitable collection designation. The method ends at the ending point 1614. [0139] U.S. Patent App. Pub. No.
  • the nitrogen dioxide along with activated plasma species penetrate the structure of the cellulosic feedstock.
  • Hydrogen species supplied from air in the reactor enclosure (e.g., water vapor) and/or from the cellulosic material itself (e.g., from the structure itself or the water inherent in the material), react with the nitrogen dioxide to form nitric acid that is immediately available for reaction with the structure of the cellulosic material.
  • an aspect of implementations for treating cellulosic material is directed to a novel in situ acid hydrolysis technique, or "acid-on-demand" technique, that is initiated by the plasma flame as described above.
  • cellulosic material or other biomass is treated by atmospheric-pressure (AP) plasma.
  • AP plasma atmospheric-pressure
  • the treatment by AP plasma is employed as a substitute for conventionally known degradation or depolymerization processes such as acid hydrolysis and enzymatic hydrolysis. That is, the treatment by AP plasma is in some implementations sufficient to activate, expose, and/or even release or produce fermentable sugars from the cellulosic material.
  • the treatment by atmospheric plasma is utilized to improve or enhance other processes for converting the cellulosic material to sugars (e.g., hydrolysis), including processes for converting the cellulosic material to fermentable sugars followed by converting the sugars to alcohols as well as other industrial chemicals.
  • AP plasma treatment is less harsh or rigorous in terms of its effects on cellulosic material and the process conditions required. Accordingly, the AP plasma treatment of cellulosic materials may be characterized as a "soft" degradation technique (e.g., soft depolymerization, soft hydrolysis, etc.).
  • the treatment by AP plasma renders the cellulosic material more susceptible or accessible to methods for breaking down the cellulosic material into constituent sugars — such as glucose in the case of cellulose, and xylose PATENT Docket No. NS08001 WO and/or other pentoses in the case of most hemicelluloses — such methods including chemical hydrolysis and enzymatic hydrolysis.
  • the treatment by AP plasma renders fermentation techniques for producing chemicals of interest (e.g., ethanol) more effective, including techniques entailing co-fermentation of more than one type of sugar and techniques entailing simultaneous depolymerization and fermentation.
  • the treatment by AP plasma facilitates not only the extraction of sugars but also the conversion of the hydrolyzate sugars into ethanol and/or other alcohols and chemicals of interest.
  • the treatment by AP plasma is a low-cost, low-energy (e.g., low-temperature, low electrical demand) alternative to conventional treatments.
  • AP plasma treatment enables the conversion of cellulosic material to sugars or further to alcohols or other chemicals to be performed as a continuous process.
  • the AP plasma treatment may be configured to initiate a new technique of acid hydrolysis via in situ synthesis of nitric acid.
  • the technique is also characterized herein as acid-on-demand.
  • AP plasma in accordance with the invention degrades the coating (e.g., lignin) protecting the cellulose and opens up the cellulose-hemicellulose-lignin complex by enlarging spatial features existing in the complex and/or creating new spatial features, thereby creating greater access to internal structures of value, i.e., saccharide components. It is also believed that the AP plasma treatment prevents further interference from secondary protective coatings such as lignin and other binders in biomass material.
  • coating e.g., lignin
  • the AP plasma disrupts at least some of the bonds or linkages existing within the complex, including bonds between the cellulose, hemicellulose and lignin (e.g., delignification) and/or at least some of the bonds or linkages existing within one or more individual components of the cellulose, hemicellulose and lignin.
  • the treatment by AP plasma renders the cellulose component of the cellulosic material more amenable to hydrolytic cleavage or other types of depolymerization and, more generally, increases both the chemical and biochemical reactivity of the cellulose.
  • the AP plasma-treated cellulosic material provides greater surface area available for hydrolyzing, PATENT Docket No. NS0800 IWO solubilizing and fermenting activity, and greater access and contact with hydrolyzing, solubilizing and fermenting agents, thereby improving the efficiency of yield as well as the effectiveness and rates of reaction.
  • an AP plasma flame may be configured to synthesize nitrogen dioxide, which subsequently is combined with hydrogen species to synthesize nitric acid directly at reaction sites within the structural matrix of the cellulosic material.
  • the nitric acid may contribute to a form of acid hydrolysis that breaks down bonds or linkages within the cellulosic structure.
  • nitrogen dioxide or nitric acid synthesized with the use of the AP plasma flame as described above may then be liquefied by cooling and/or compression.
  • Cellulosic material or other biomass may be treated by exposing the cellulosic material to the liquefied nitrogen dioxide or nitric acid such as by, for example, dipping the cellulosic material in a container of liquefied nitrogen dioxide or nitric acid, placing the cellulosic material in a container with liquefied nitrogen dioxide or nitric acid and allowing the nitrogen dioxide or nitric acid to migrate into the cellulosic material via liquefaction, evaporation, diffusion, capillary action, etc.
  • the liquefied nitrogen dioxide or nitric acid such as by, for example, dipping the cellulosic material in a container of liquefied nitrogen dioxide or nitric acid, placing the cellulosic material in a container with liquefied nitrogen dioxide or nitric acid and allowing the nitrogen dioxide or nitric acid to migrate into the cellulosic material via liquefaction, evaporation, diffusion, capillary action, etc.
  • Figures 17 - 20 illustrate examples of methods for treating cellulosic material. In some implementations, such methods may be practiced for at least partially converting the cellulosic materials into sugars. In other implementations, such methods may be practiced for at least partially converting the sugars into alcohols, such as ethanol, or other desired chemicals. [0146] Figure 17 is a flow diagram 1700 illustrating an example of a method for treating cellulosic material.
  • the treatment of the cellulosic material by AP plasma according to the method may, in and of itself, result in degradation of at least some of the biopolymeric components of the cellulosic material such that monomelic sugars are released (or oligomeric compounds readily convertible to monomeric sugars).
  • the AP plasma treatment may be performed in conjunction with enzymatic treatment for producing alcohols or other desired chemicals, or may be directly followed by such enzymatic treatment.
  • the AP plasma treatment at least may result in conditioning the cellulosic material in a manner that optimizes or facilitates a subsequent degradation process such as, for example, hydrolysis.
  • the hydrolysis may be acid hydrolysis utilizing locally synthesized PATENT Docket No. NS08001 WO nitric acid via operation of a plasma flame in air as described above.
  • the flow diagram 1700 may also represent an apparatus or system capable of performing the illustrated method. [0147] The method begins at starting point 1702.
  • the starting point 1702 may be representative of any suitable preliminary steps that may be taken to prepare the cellulosic material for treatment by AP plasma. For instance, if the cellulosic material is initially provided in the form of large pieces of wood, the wood may be further comminuted into wood chips or sawdust.
  • the cellulosic material may be washed to remove dirt or other undesired substances.
  • the cellulosic material may be dried by any suitable means to remove moisture if desired.
  • the cellulosic material 1704 (raw feedstock, or feedstock prepared such as by the afore-mentioned preliminary steps) is introduced to an apparatus for generating an AP plasma (AP plasma apparatus).
  • the AP plasma apparatus may be adapted for either batch processing or continuous processing, and therefore the term "introduced" is used to indicate any manner by which the cellulosic material 1704 is exposed to the AP plasma such as, for example, loading or feeding the cellulosic material 1704 into the AP plasma, apparatus directing an AP plasma plume or jet toward the cellulosic material, etc.
  • the AP plasma apparatus is operated to generate and maintain a suitable AP plasma, thereby subjecting the cellulosic material 1704 to the AP plasma.
  • AP plasma apparatus or systems are described above with reference to Figure 1, and in above-cited U.S. Patent App. Pub. No. 2008/0006536.
  • the plasma flame discharge generated by the apparatus illustrated in Figure 1 of the present disclosure may be utilized in accordance with the operating parameters described in conjunction with Figure 1.
  • the same apparatus may also be utilized to generate plasma discharges for use in AP plasma treatment steps that do not entail the synthesis of nitrogen dioxide.
  • the same plasma flame may be utilized for these non-synthesis steps, or alternatively the apparatus may be configured to generate the above-described plasma discharge as well as other types of plasmas such as those described in U.S. Pat. App. Pub. No. 2008/0006536.
  • the apparatus utilized for generating acid locally in the cellulosic material may be separate from the apparatus utilized for treating the cellulosic material in accordance with the subject matter disclosed in U.S. Pat. App. Pub. No. 2008/0006536. PATENT Docket No. NS08001 WO
  • the plasma may be an ionized gas stream or cloud generated in, for example, a radio frequency (RF), direct current (DC), pulsed DC, asymmetrical pulsed, or alternating current (AC) electromagnetic field, or by microwave energy.
  • RF radio frequency
  • DC direct current
  • AC alternating current
  • U.S. Pat. App. Pub. No. 2008/0006536 additionally describes examples of a parallel plate dielectric barrier discharge (DBD) apparatus, a drop-tube DBD apparatus, a fluidized-bed apparatus, a liquid-bath apparatus, and a plasma-jet apparatus.
  • DBD parallel plate dielectric barrier discharge
  • the input current for the generation of a suitable plasma may typically range from about 30 to about 300 mA, although the invention is not limited to this range.
  • the voltage applied to the plasma may typically range from about 500 to about 50,000 V, although the invention is not limited to this range.
  • the working frequency of the plasma may typically range from about 0.050 to about 150 kHz, although the invention is not limited to this range.
  • the power density of the plasma may typically range from about 0.1 to about 500 W/cm 3 , although the invention is not limited to this range. Any suitable working gases for the AP plasma may be utilized.
  • working gases include, but are not limited to, air, oxygen, hydrogen, helium, water-saturated helium, neon, argon, hydrogen, nitrogen, xenon, carbon dioxide, SF 6 , CF 4 , NH 3 , and combinations of two or more of the foregoing.
  • Flow rates may typically range from about 100 to about 50,000 standard cubic centimeters per minute (seem), although the invention is not limited to this range.
  • the particular species of the AP plasma that serve an active role in altering the structure or chemistry of the cellulosic material to attain the beneficial effects described herein will generally depend on the type of working gases employed.
  • active species of the plasma may include, but are not limited to, oxygen radicals, hydroxide radicals, monatomic nitrogen, NO x , and ozone.
  • Other liquid or vapor precursors may also be added to the AP plasma environment. This may be for the generation of specific chemical species to be used as a reactant in the production of other desired chemistries, for the purpose of synthesizing such chemical species as the desired product, or both. Examples of such compounds are glycerol, industrial wastes, and hazardous materials, although the invention is not limited to these compounds.
  • the temperature in the chamber of the apparatus containing the AP plasma may range from about 25 to about 700 0 C, although the invention is not limited to this range.
  • the duration of the AP plasma treatment may range from about 1 to about 30 minutes, although the invention is not limited to this range.
  • the treatment of the cellulosic material 1704 by AP plasma at block 1706 results in an AP plasma-treated cellulosic material 1708.
  • the plasma- treated cellulosic material 1708 may include oligosaccharide and/or monosaccharide species released from components of the cellulosic material (cellulose and/or hemicellulose) as a result of the AP plasma treatment 1706, as well as residual polysaccharide species, lignin and other components of the cellulosic material not appreciably affected by the AP plasma treatment 1706.
  • the AP plasma treatment may have the effect of removing lignin or at least disrupting the structure of lignin and its bonds so as to reduce interference of the lignin with the treatment of the cellulose.
  • the released monosaccharide species may include hexose sugars such as, for example, glucose, galactose and/or mannose, and/or pentose sugars such as, for example, xylose and/or arabinose, and/or other monosaccharides.
  • the sugars may be recovered and separated from the plasma-treated cellulosic material 1708 by any suitable means such as, for example, cyclone separation, centrifugation, decanting, filtration, washing, etc. If desired, the sugars may then be subjected to any suitable purification and/or refinement processes as necessary to provide commercial-grade sugars. In the case where sugars are the intended end product, the method ends at 1714.
  • the sugars (particularly the monosaccharides) produced or released as a result of the AP plasma treatment 1706 are microbially fermentable and hence may be utilized as a fermentation medium to produce desired alcohols and/or any other desired chemicals or organic compounds such as various ketones and organic acids. Accordingly, in other implementations, as illustrated in Figure 17, the process may continue by subjecting AP plasma treatment-derived sugars to any suitable fermentation processing 1710 to produce a fermentation product 1712 that includes alcohols such as ethanol or other chemicals.
  • the fermentation process 1710 may entail the use of any microorganisms capable of converting the sugars (e.g., oligosaccharides, monosaccharides, and the like) into the desired alcohols or other chemicals.
  • any suitable ethanologenic strains of microorganisms may be employed.
  • more than one fermentation step may be required, depending on the desired chemical(s) to be produced (e.g., ethanol, xylitol, etc.), the type(s) of sugars to be fermented PATENT Docket No. NS0800 IWO
  • fermentation processes may be carried out in the same reaction vessel or in different reaction vessels.
  • fermentation may be carried out as a batch process or as a continuous process.
  • fermentation of different types of components of the plasma-treated cellulosic material 1708 may be carried out sequentially or simultaneously.
  • the fermentation process 1710 may be preceded by any suitable pre-conditioning steps deemed necessary in preparation for fermentation, such as neutralization or other pH adjustment, removal of any components deemed to act as fermentation inhibitors, and the like.
  • the fermentation product 1712 may be subjected to any suitable post-fermentation processes as needed, such as distillation and/or adsorption to separate the desired alcohols or other chemicals from the fermentation medium and concentrate and purify the alcohols or other chemicals for commercially-acceptable uses.
  • residual materials such as lignin may be recovered for utilization as an energy source, as appreciated by persons skilled in the art.
  • Figure 17 may also represent an example of an apparatus or system 1700 for treating cellulosic material.
  • block 1706 may be considered as depicting a means for subjecting cellulosic material to AP plasma.
  • An example of such means is a plasma- generating apparatus or system and associated components and materials required for its operation. Specific examples of plasma-generating apparatus or systems are described elsewhere in this disclosure and are illustrated in Figure 17 as well as in above-cited U.S. Patent App. Pub. No. 2008/0006536.
  • Block 1710 may be considered as depicting a means for fermenting plasma-treated cellulosic material.
  • the apparatus or system 1700 may be configured for continuous processing or batch processing, or partially for continuous processing and partially for batch processing. Accordingly, in the context of an apparatus or system 1700 for treating cellulosic material, one or more of the arrows shown in Figure 1 may represent physical components (e.g., pipes, conduits, containers, or the like) employed for holding the cellulosic material being processed or transporting the PATENT Docket No. NS08001 WO cellulosic material from one location or device to another, or may otherwise represent the direction of process flow between locations or devices of the apparatus or system 1700.
  • physical components e.g., pipes, conduits, containers, or the like
  • the AP plasma treatment 1706 does not necessarily entail subjecting the cellulosic material the plasma itself. Instead, a plasma flame as described above may be utilized to synthesize nitrogen dioxide, and the cellulosic material is exposed to the nitrogen dioxide for treatment.
  • the AP plasma treatment 1706 includes both subjecting the cellulosic material to an atmospheric-pressure plasma and exposing the cellulosic material to nitrogen dioxide synthesized via a plasma flame.
  • the atmospheric- pressure plasma to which the cellulosic material is subjected may be the plasma flame utilized to synthesize the nitrogen dioxide.
  • the atmospheric-pressure plasma to which the cellulosic material is subjected may be a separate plasma distinct from the plasma flame utilized to synthesize the nitrogen dioxide. This separate plasma may be of the same type as the plasma flame or may be a different type of plasma.
  • the separate plasma may be operated (i.e., ignited and maintained) in the same chamber as the plasma flame utilized to synthesize the nitrogen dioxide, or the separate plasma may be operated in a separate chamber.
  • Figure 18 is a flow diagram 1800 illustrating another example of a method for treating cellulosic material.
  • the flow diagram 1800 may also represent an apparatus or system capable of performing the illustrated method.
  • the method begins at the starting point 1802.
  • the starting point 1802 may be representative of any suitable preliminary steps taken to prepare the cellulosic material for treatment by AP plasma.
  • the raw or prepared cellulosic material 1804 is introduced to an AP plasma apparatus.
  • the AP plasma apparatus is operated to generate and maintain a suitable AP plasma that interacts with the cellulosic material 1804.
  • the process conditions (pressure, temperature, duration, etc.) of the AP plasma treatment 1806 may be the same as or similar to those described above for the method illustrated in Figure 17.
  • the treatment of the cellulosic material 1804 by AP plasma at block 1806 results in an AP plasma-treated cellulosic material 1808.
  • the plasma-treated cellulosic material 1808 may include oligosaccharide and/or monosaccharide species released PATENT Docket No. NS08001 WO from components of the cellulosic material (cellulose and/or hemicellulose) as a result of the AP plasma treatment 1806, as well as residual polysaccharide species and lignin not affected hy the AP plasma treatment 1806.
  • the released sugars may be recovered and separated from the plasma-treated cellulosic material 1808 by any suitable means and then subjected to further processing as necessary to provide commercial-grade sugars.
  • the released sugars may be recovered for subsequent fermentation.
  • the portion of the plasma-treated cellulosic material 1808 that has not been degraded by the AP plasma treatment step 1806 is nevertheless, as a result of the AP plasma treatment step 1806, optimally conditioned for subsequent degradation processing. Accordingly, at block 1812, the plasma-treated cellulosic material 1808 may then be subjected to any suitable cellulosic material degradation or depolymerization process.
  • the degradation process 1812 may be any process suitable for yielding desired sugars such that the sugars may then be subsequently processed for commercial consumption or fermented for producing alcohols or other chemicals. Examples of suitable degradation processes 1812 include, but are not limited to, acid hydrolysis processes and enzymatic hydrolysis processes.
  • Acid hydrolysis generally entails reacting the plasma-treated cellulosic material 1808 with water and employing a suitable acid or acidic compound as a catalyst.
  • suitable acids and acidic or acid-like compounds include, but are not limited to, mineral acids such as sulfuric acid, sulfurous acid, hydrochloric acid, hydrofluoric acid, phosphoric acid, formic acid and nitric acid, and acidic salts such as aluminum sulfate, ferric sulfate, ferrous sulfate, magnesium sulfate, ferric chloride, aluminum chloride, aluminum nitrate, and ferric nitrate.
  • Enzymatic hydrolysis generally entails reacting the plasma-treated cellulosic material 1808 with one or more appropriate carbohydrase enzymes such as various known cellulases and hemicellulases.
  • carbohydrase enzymes such as various known cellulases and hemicellulases.
  • a cellulase enzyme complex may be employed for the saccharification of the cellulose of the plasma-treated cellulosic material 1808 to yield glucose.
  • the degradation process 1812 entails reacting air in a plasma flame discharge to synthesize nitrogen dioxide.
  • the nitrogen dioxide reacts with PATENT Docket No. NS0800 IWO hydrogen to synthesize nitric acid. Synthesis of the nitric acid occurs before and/or after the nitrogen dioxide penetrates the cellulosic material.
  • processes represented by 1806 and 1812 may be earned out in separate AP plasma reactors or in the same reactor.
  • the process 1812 may be carried out prior to the process 1806.
  • the degradation process 1812 results in (at least partially) degraded cellulosic material 1814.
  • the degraded (or degradation-processed) cellulosic material 1814 may include oligosaccharide and/or monosaccharide species released from components of the cellulosic material (cellulose and/or hemicellulose) as well as residual polysaccharide species and lignin not affected by the degradation process 1812. Due to the preceding AP plasma treatment 1806, the degradation process 1812 may result in a much higher yield of monosaccharides than had the degradation process 1812 been carried out alone without the AP plasma treatment 1806 or had the degradation process 1812 been preceded by a conventional pre-treatment process.
  • the released sugars may be recovered and separated from the degraded cellulosic material 1814 by any suitable means and then subjected to further processing as necessary to provide commercial-grade sugars.
  • the method ends at 1820.
  • the process may continue by subjecting the sugars obtained from the degraded cellulosic material 1814 to any suitable fermentation processing 1816 to produce a fermentation product 1818.
  • the fermentation product 1818 may include alcohols such as ethanol and/or other desired chemicals. The method ends at 1820.
  • Figure 18 may also represent an example of an apparatus or system 1800 for treating cellulosic material.
  • block 1806 may be considered as depicting a means for subjecting cellulosic material to AP plasma. Examples of such means are referred to above in connection with the apparatus or system 1700 illustrated in Figure 17.
  • Block 1812 may be considered as depicting a means for degrading cellulosic material to produce sugars.
  • An example of such means is a plasma flame reactor as described and illustrated in Figure 1, or alternatively may be an apparatus configured for carrying out a conventional hydrolysis or other type of degradation technique.
  • the apparatus utilized to carry out the functions of blocks 1806 PATENT Docket No. NS0800 IWO and 1812 may be the same apparatus or two different reactors.
  • Block 1816 may be considered as depicting a means for fermenting plasma-treated cellulosic material as previously noted.
  • FIG 19 is a flow diagram 1900 illustrating another method for treating a cellulosic material.
  • the flow diagram 1900 may also represent an apparatus or system capable of performing the illustrated method. This example entails a two-stage degradation process that is enhanced by one or more AP plasma treatment steps.
  • the method begins at the starting point 1902.
  • Raw or prepared cellulosic material 1904 is subjected to a first-stage degradation process at block 1906, in which at least some of the components of the cellulosic material 1904 are degraded or depolymerized without the aid of AP plasma treatment.
  • the first-stage degradation process 1906 may entail dilute acid hydrolysis effected by localized synthesis of nitric acid as described above.
  • the first-stage degradation process 1906 may serve as a relatively mild process that acts on certain polysaccharide components of the cellulosic material 1904 that, due to their initial structure (e.g., degree of crystallinity or amorphousness) or accessibility (e.g., exposure, freedom from lignin binding, etc.), are readily degradable without the aid of a pre-treatment step.
  • the first-stage degradation process 1906 may serve as a pre- treatment process in and of itself, for example to break down the hemicellulose for removal, and/or more generally to at least partially disrupt the cellulose-hemicellulose-lignin complex, in preparation for hydrolyzing or otherwise degrading the cellulose (and particularly the crystalline phase) in a subsequent degradation step.
  • the first-stage degradation process 1906 produces (at least partially) degraded cellulosic material 1908, which may be a mixture of sugar solution and residual cellulosic material such as unreacted cellulose and lignin.
  • any suitable separation process may be performed to separate the sugar solution from the residual cellulosic material.
  • the sugars obtained at this stage may be processed for commercial use or, as indicated by line 1910 in Figure 19, recovered for subsequent fermentation.
  • the cellulosic material is subjected to AP plasma treatment as described elsewhere in this disclosure.
  • the process conditions (pressure, temperature, duration, etc.) of the AP plasma treatment 1912 may be the same as or similar to conditions described above.
  • the plasma-treated cellulosic material 1914 may include oligosaccharide and/or monosaccharide species released from components of the cellulosic material (cellulose and/or hemicellulose) as a result of the AP plasma treatment 1912, as well as residual polysaccharide species and lignin not affected by the AP plasma treatment 1912.
  • the released sugars may be recovered and separated from the plasma-treated cellulosic material 1914 by any suitable means and then subjected to further processing as necessary to provide commercial-grade sugars.
  • the released sugars may be recovered for subsequent fermentation.
  • the portion of the plasma-treated cellulosic material 1914 that has not yet been degraded at this stage is, as a result of the previous steps 1906 and 1912, optimally conditioned for subsequent degradation processing. Accordingly, at block 1918, the plasma-treated cellulosic material 1914 may then be subjected to a second-stage cellulose degradation or depolymerization process. To the extent that the cellulosic material undergoing the second-stage degradation 1918 was not degraded into sugars in the first-stage degradation process 1906 or AP plasma treatment process 1912 and hence is more difficult to degrade, the second-stage degradation process 1918 may be a more rigorous process in comparison to the first-stage degradation process 1906.
  • the second-stage degradation process 1918 may entail a plasma flame-initiated localized synthesis of nitric acid under more rigorous conditions, or alternatively may entail a conventional acid hydrolysis process in which a high concentration of acid is employed such as in a LOM (9.8% w/w) H 2 SO 4 solution.
  • the effectiveness of the AP treatment process 1912 may be such that the second-stage degradation process 1918 need not be more rigorous, or may even be less rigorous, than the first-stage degradation process 1906.
  • the second-stage degradation process 1918 may be an enzymatic process that employs enzymes (e.g., cellulases) specifically selected to hydrolyze the more difficultly hydrolyzable components of the cellulosic material such as crystalline cellulose.
  • enzymes e.g., cellulases
  • the processing of the plasma-treated cellulosic material 1914 by the second-stage degradation process 1918 yields further degradation-processed cellulosic material 1920 that includes sugars.
  • the sugars may be subjected to any post-degradation processes such as purification and refinement as necessary to provide commercial-grade sugar.
  • the process may continue by subjecting the sugars to any suitable fermentation process to produce alcohols or other desired chemicals.
  • any sugars produced from the first-stage degradation process 1906 and the AP plasma treatment process 1912 may likewise be fermented.
  • the sugars produced from the first-stage degradation process 1906 and/or the AP plasma treatment process 1912 may be combined with the sugars produced from the second-stage degradation process 1918, and all sugars co-fermented simultaneously.
  • the process illustrated in Figure 19 ends at 1924.
  • one or more AP plasma treatment steps may be combined with one or more degradation processes, as well as with "pre-treatment” processes traditionally associated with conventional degradation processes such as acid hydrolysis and enzymatic hydrolysis.
  • the pre-treatment process may be any chemical, biological, biochemical, physical, or physio-chemical process or processes now known or later developed that is effective in enhancing conventional degradation processes. Examples of pre-treatment processes include, but are not limited to, comminution, uncatalyzed steam explosion, hydrothermolysis, the addition of acids, bases, solvents, or ammonia, ammonia fiber/freeze explosion (AFEX), ammonia recycled percolation (ARP), etc.
  • the pre-treatment process entails the use of a plasma flame discharge to directly supply nitric acid to the cellulosic material as described above.
  • FIG 20 is a flow diagram 2000 illustrating another method for treating a cellulosic material.
  • the flow diagram 2000 may also represent an apparatus or system capable of performing the illustrated method.
  • the method begins at the starting point 2002.
  • Raw or prepared cellulosic material 2004 is introduced to a suitable AP plasma apparatus and subjected to a first-stage AP plasma treatment at block 2006, which yields plasma-treated cellulosic material 2008 as previously described.
  • the plasma-treated cellulosic material 2008 may include sugars as a result of the AP plasma treatment 2006, as well as residual polysaccharide species and lignin not affected by the AP plasma treatment 2006.
  • the released sugars may be recovered and separated from the plasma- treated cellulosic material 2008 by any suitable means and then subjected to further processing as necessary to provide commercial-grade sugars.
  • the sugars resulting from the first-stage AP plasma treatment 2006 may be recovered for subsequent fermentation.
  • the plasma-treated cellulosic material 2008 is subjected to any suitable pre-treatment process to enhance a subsequent degradation technique or techniques.
  • the pre-treatment process 2012 yields pre- treated cellulosic material 2014.
  • raw or prepared cellulosic material 2004 is subjected directly to the pre-treatment process 2012 without an intervening AP plasma treatment 2006.
  • the pre-treated cellulosic material 2014 is then subjected to a second-stage AP plasma treatment at block 2018, which yields further plasma-treated cellulosic material 2020.
  • the second-stage AP plasma treatment 2018 may serve to enhance the role of the pre-treatment step 2012 (and the first-stage AP plasma treatment 2006, if employed) in optimizing the cellulosic material for a subsequent degradation process or processes.
  • the pre-treatment step 2012 may be considered as enhancing the role of the first-stage AP plasma treatment 2006 and/or the second-stage AP plasma treatment 2018 in optimizing the cellulosic material for subsequent degradation.
  • the second-stage AP plasma treatment 2018 may yield sugars as a result of second-stage AP plasma treatment 2018. At this stage, if desired, these sugars may be recovered and separated from the plasma-treated cellulosic material 2020 by any suitable means and then subjected to further processing as necessary to provide commercial-grade sugars. Alternatively, as indicated by the process schematic line 2022 in Figure 20, the sugars resulting from the second-stage AP plasma treatment 2018 may be recovered for subsequent fermentation.
  • the plasma-treated cellulosic material 2020 is subjected to any suitable degradation process such as, for example, acid hydrolysis or enzymatic hydrolysis to break down remaining polysaccharide components of the plasma-treated cellulosic material 2020 into sugars.
  • Acid hydrolysis at this stage may be carried out by way of the in situ technique initiated by a plasma flame discharge as taught in the present disclosure.
  • the degradation process 2024 yields a mixture 2026 of sugar solution and residual cellulosic material such as lignin.
  • the pre- treated cellulosic material 2014 is subjected directly to the degradation process 2024 without an intervening AP plasma treatment 2018.
  • any suitable separation process may be performed to separate the sugar solution from the residual cellulosic material.
  • the sugars obtained at this stage may be processed for commercial use.
  • the resulting sugars may be subjected any suitable fermentation process to produce a fermentation product 2032 that includes alcohols or other desired chemicals.
  • any sugars produced from the first-stage AP plasma treatment 2006 and/or the second-stage AP plasma treatment 2018 may likewise be fermented, together with or separately from the sugars derived from the degradation process 2024.
  • the process illustrated in Figure 20 ends at 2034.
  • any of the methods, apparatus and systems described by example above and illustrated by example in Figures 17 - 20, in implementations involving fermentation, may be adapted for separate hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), and/or simultaneous saccharification co-fe ⁇ nentation (SSCF).
  • SHF hydrolysis and fermentation
  • SSF simultaneous saccharification and fermentation
  • SSCF simultaneous saccharification co-fe ⁇ nentation
  • FIG. 21 is a schematic diagram illustrating an example of an atmospheric-pressure (AP) plasma apparatus 2100 adapted for continuous processing.
  • the apparatus 2100 includes two or more distinct reaction zones 2102, 2104, 2106, 2108. At least one of these reaction zones 2102, 2104, 2106, 2108 includes a set of electrodes 2114 and 2116 for generating a plasma flame discharge 2124 as described herein, and one or more inlets 2126 for supplying background gases for igniting the plasma flame discharge 2124 and/or precursor gases for driving a desired synthesis reaction.
  • One or more of the additional reaction zones 2102, 2104, 2106, 2108 may also include electrodes 2114 and 2124 for generating additional plasma flame discharges 2124.
  • One or more of the additional reaction zones 2102, 2104, 2106, 2108 may also include inlets 2126 for supplying background gases and/or precursor gases.
  • reaction zones 2102, 2104, 2106, 2108 may serve as post-discharge reaction zones into which active, metastable and/or neutral species from an active or recently active plasma area are conducted.
  • the reaction zones 2102, 2104, 2106, 2108 may be stacked vertically to produce a resultant upward process flow of gases that are subjected to multiple plasma flame discharges 2124, or alternatively may be arranged in series in another orientation such as horizontal.
  • An exhaust line 2128 may be provided at or near the top of the apparatus 2100 for collection of synthesized gas- phase products.
  • Another outlet line 2130 may be provided at a lower elevation to collect condensate products at a suitable receptacle 2132.
  • reaction zones 2102, 2104, 2106, 2108 may be defined, at least in part, by tapered inside surfaces 2134 that facilitate the collection and separation of condensate 2136 from the gas-phase components.
  • the apparatus 2100 illustrated in Figure 21 may be utilized to synthesize a wide variety of chemistries, such as those described earlier in this disclosure, on a continuous basis.
  • FIG 22 is a schematic diagram illustrating another example of an atmospheric- pressure (AP) plasma apparatus 2200 adapted for continuous processing.
  • This apparatus 2200 is particularly suitable for treating solid materials with gas-phase products synthesized by a plasma flame discharge as described earlier in the present disclosure.
  • biomass feedstock 2201 may be fed from a hopper 2202 onto a suitable conveying device 2204 such as may include an endless belt or chain. While the biomass 2201 is transported by the conveying device 2204 through a reaction chamber 2206, a separate reaction chamber 2208 containing one or more plasma flame discharge sources 2210 is utilized to produce nitrogen dioxide as described earlier in the present disclosure.
  • the as-produced nitrogen dioxide is flowed into the first reaction chamber 2206 as indicated by an arrow 2212 and into contact with the biomass 2201.
  • the nitrogen dioxide may be conducted in counterflow relation to the direction of transport of the biomass 2201 as in the illustrated example, but alternatively may be introduced by other pathways.
  • the nitrogen dioxide may be conducted in parallel or concurrent flow with the flow of biomass 2201, or in a mixed counterflow/ concurrent flow relative to the biomass 2201.
  • the nitrogen dioxide may be introduced into the first reaction chamber 2206 at several locations simultaneously by employing suitable means such as a gas distributor (not shown).
  • suitable means such as a gas distributor (not shown).
  • the nitrogen dioxide penetrates the cellular structure of the biomass 2201 as described earlier, combining PATENT Docket No.
  • NS08001WO with hydrogen species to form nitric acid that degrades the biomass 2201 in a direct, in situ fashion.
  • the treated biomass 2201 is then collected at a suitable reception site 2214.
  • Apparatus of the type illustrated in Figure 22 according to the present teachings, in which a plasma reaction zone operatively communicates with a distinct non-plasma or post-plasma reaction zone, may be referred to as a tandem reactor.
  • cellulosic material generally encompasses any cellulose- containing material, including lignocellulosic material and biomass, either living or existing as a waste product of industry or nature.
  • cellulosic material include, but are not limited to, the following: forestiy products, including forestry wastes, such as woods of various species of trees, including softwoods (e.g., gymnosperms such as conifers, pine, spruce, etc.), hardwoods (e.g., angiosperms such as maple, poplar, etc.), etc., including in the form of log slash, bark, trunks, stumps, branches, twigs, and the like, as well as grasses (e.g., angiosperms); agricultural products, including agricultural wastes, such as corn stover, com cobs, rice straw, orchard and vineyard trimmings, manure, etc.; biomass crops such as grasses (e.g., switch grass).
  • forestiy products including forestry wastes
  • wooden and non-wooden plant material may be in any form, including, but not limited to, stems, stalks, shrubs, foliage, leaves, bark, roots, shells, rinds, pods, nuts, husks, hulls, fibers, vines, straws, hay, grasses, bamboo, reeds, etc.
  • Wooden material may include heartwood (e.g., duramen) as well as outer wood (e.g., xylem).
  • the cellulosic material may be a mixture or combination of one or more of the foregoing items.
  • the term “degradation” generally encompasses any process that results in a molecule being broken down into simpler molecules, radicals, and/or charged species.
  • the term “degradation” may encompass the breaking down of a polymer into smaller polymers (e.g., oligomers, trimers, dimers, etc.) and/or monomers such as, for example, the breaking down of a cellulose into glucose units.
  • the term “degradation” may also encompass the breaking up or removal of physical and/or chemical bonds among different types PATENT Docket No. NS08001 WO of components of a complex material, and/or bonds internal to such components.
  • degradation may encompass the breaking up of bonds between cellulose, hemicellulose, and/or lignin, and/or the breaking down of polymeric cellulose or hemicellulose into component sugars.
  • degradation may also encompass the removal, in whole or in part, of a component from a complex material.
  • degradation may encompass the removal of at least some of the lignin from the complex, thereby providing greater access to the cellulose and hemicellulose components.
  • degradation may also encompass the alteration or modification of the structure of a biomaterial.
  • degradation may encompass the opening up of interstices, voids, recesses or pores (more generally, spatial features) existing within the structure of a complex of cellulose, hemicellulose and lignin, and/or the creation of new interstices, voids, recesses or pores in such material.
  • Degradation may entail physical, chemical, and/or biological work. Degradation may entail processes that are aided or unaided by catalytic activity.
  • the term "degradation” encompasses such terms as depolymerization, hydrolysis, dissociation, dissolution, disruption, delignification, removal of material, conversion of a complex material into simpler components, and release or extraction of components from a complex material.
  • starch is a water- insoluble, complex carbohydrate containing around 2500 glucose monomer units.
  • starches have the formula where "n" denotes the total number of glucose monomer units.
  • starch is a combination of the two polysaccharides amylose and amylopectin.
  • Amylose constitutes a straight chain of glucose units joined to one another by ⁇ - 1,4 linkages.
  • Amylopectin includes branches, with an ⁇ -1,6 linkage every 24-30 glucose units.
  • starch forms clusters of linked linear polymers, where the ⁇ -1,4 linked chains form columns of glucose units which branch regularly at the ⁇ -1,6 links.
  • a starch molecule as a result has a coiled conformation unlike a straight-chain cellulose molecule.
  • Starches can be digested by hydrolysis into simpler saccharide units.
  • the PATENT Docket No. NS0800 IWO hydrolysis may be catalyzed by enzymes known as amylases, which break the glycosidic bonds between the ⁇ -glucose components of the starch polysaccharide molecule.
  • the term “communicate” for example, a first component "communicates with” or “is in communication with” a second component
  • communicate for example, a first component "communicates with” or “is in communication with” a second component
  • communicate for example, a first component "communicates with” or “is in communication with” a second component
  • communicate is utilized in the present disclosure to indicate a structural, functional, mechanical, electrical, optical, magnetic, ionic or fluidic relationship between two or more components (or elements, features, or the like).
  • the fact that one component is said to communicate with a second component is not intended to exclude the possibility that additional components may be present between, and/or operatively associated or engaged with, the first and second components.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Chemical Or Physical Treatment Of Fibers (AREA)
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Abstract

L'invention concerne une décharge de flamme à plasma à pression atmosphérique utilisée pour synthétiser diverses chimies sans utiliser de catalyseur. Une décharge de flamme à plasma à pression atmosphérique est également utilisée pour traiter un matériau cellulosique.
PCT/US2009/031249 2008-01-16 2009-01-16 Synthèse non catalytique et traitement utilisant un plasma à pression atmosphérique Ceased WO2009091978A2 (fr)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI461113B (zh) * 2011-08-24 2014-11-11 Nat Univ Tsing Hua 常壓電漿噴射裝置
JP2018135239A (ja) * 2017-02-22 2018-08-30 大陽日酸株式会社 二酸化塩素ガスの製造方法
US12186728B2 (en) 2020-04-26 2025-01-07 Nitricity Inc. Systems and processes for producing fixed-nitrogen compounds

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JPS5532317A (en) * 1978-08-28 1980-03-07 Asahi Chemical Ind High frequency magnetic field coupling arc plasma reactor
US4472254A (en) * 1983-05-02 1984-09-18 Olin Corporation Electric plasma discharge combustion synthesis of chlorine dioxide
JP2000243742A (ja) * 1999-02-24 2000-09-08 Hitachi Chem Co Ltd プラズマ発生装置、そのチャンバー内壁保護部材及びその製造法、チャンバー内壁の保護方法並びにプラズマ処理方法
JP4041878B2 (ja) * 2002-05-14 2008-02-06 独立行政法人産業技術総合研究所 マイクロプラズマｃｖｄ装置

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI461113B (zh) * 2011-08-24 2014-11-11 Nat Univ Tsing Hua 常壓電漿噴射裝置
JP2018135239A (ja) * 2017-02-22 2018-08-30 大陽日酸株式会社 二酸化塩素ガスの製造方法
US12186728B2 (en) 2020-04-26 2025-01-07 Nitricity Inc. Systems and processes for producing fixed-nitrogen compounds

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