WO2008111941A2 - Procédé et système pour production de butanol - Google Patents

Procédé et système pour production de butanol Download PDF

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WO2008111941A2
WO2008111941A2 PCT/US2007/006645 US2007006645W WO2008111941A2 WO 2008111941 A2 WO2008111941 A2 WO 2008111941A2 US 2007006645 W US2007006645 W US 2007006645W WO 2008111941 A2 WO2008111941 A2 WO 2008111941A2
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butanol
produce
product mixture
acetone
mixture
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WO2008111941A3 (fr
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Fangxiao Yang
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    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
    • C12P7/00—Preparation of oxygen-containing organic compounds
    • C12P7/62—Carboxylic acid esters

Definitions

  • This invention relates to a process for eliminating unpleasant odors associated with butanol production by fermentation.
  • the invention relates to a process for converting short chain organic acids to their corresponding alkyl esters which then remain in the product stream as oxygenation agents for a butanol fuel.
  • Butanol is in several ways more similar to gasoline than it is to erhanol. Butanol can, therefore, be used as fuel in internal combustion engines. Butanol has been demonstrated to work in some vehicles designed for use with gasoline without any modification. It can be produced from biomass as well as fossil fuels. Sometimes butanol from fermentation is called biobutanol to reflect its origin, although it has the same chemical properties as butanol produced from petroleum. Butanol is currently an industrial commodity and manufactured primarily from petroleum, with a market of 370 million gallons per year at a selling price of about $3.75 per gallon. (WWW domain: butanol.com)
  • Butanol has higher energy content (at 110,000 Btu per gallon) than ethanol (at 84,000 Btu per gallon), whereas gasoline contains about 115,000 Btu's per gallon. Butanol is six times less "evaporative" than ethanol and 13.5 times less evaporative than gasoline. This characteristic makes it safer to use as a fuel oxygenate in Arizona, California and other "warmer” states, thereby eliminating the need for special blends during the summer and winter months.
  • fuel oxygenates are chemicals containing oxygen that are added to fuels, especially gasoline, to make them burn more efficiently. Adding oxygenates to gasoline boosts the gasoline's octane level and reduces atmospheric pollution associated with automobile emissions.
  • butanol As an alternative fuel because of the historically low yields and low concentrations of butanol that are produced through Acetone- Butanol-Ethanol (ABE) fermentation compared to those of ethanol; that is, for each bushel of corn fermented, one obtains 1.3 gallons of butanol, 0.7 gallon of acetone and 0.13 gallon of ethanol with concentrations of 1-2 percent by weight.
  • ABE Acetone- Butanol-Ethanol
  • Clostridia acetobutylicum also known as the Weizmann organism
  • Clostridia acetobutylicum also known as the Weizmann organism
  • Weizmann patented the process using this bacteria to produce acetone from starch in 1919 (U.S. Patent No. 1,315,585) and England approached the young microbiologist and asked for the rights to make acetone for cordite. Up until the 1920s acetone was the product sought, but for every pound of acetone fermented, two pounds of butanol were formed.
  • the process also creates a recoverable amount of hydrogen (H 2 ) gas and a number of other by-products: acetic, lactic and propionic acids, acetone, isopropanol and ethanol.
  • H 2 hydrogen
  • a growing automotive paint industry turned the market around, and by 1927 butanol was primary target product and acetone became the byproduct.
  • butanol by fermentation declined from the 1940s through the 1950s, primarily because the price of butanol produced from petrochemicals dropped below that of butanol produced from starch and sugar substrates such as corn and molasses.
  • the overhead of the labor intensive batch fermentation system combined with low yields contributed to the situation.
  • Commercial fermentation-derived acetone and butanol production basically ceased in the late 1950s.
  • butyric, propionic, lactic and acetic acids are first produced by C. acetobutylicum (in an acidogenesis stage) and the culture pH drops. Then, the culture undergoes a metabolic shift (in a solventogenesis stage) and butanol, acetone, isopropanol and ethanol are formed (Fond, O., G. Matta-Ammouri, H. Petitdemange, and J. M. Engasser, The role of acids on the production of acetone and butanol by Clostridium acetobutylicum. Applied Microbiology Biotechnology 22: 195-200, 1985). Increasing butyric acid concentration to greater than 2 grams per liter (g/L) and decreasing the pH to less than 5 usually are required for the induction of a metabolic shift from acidogenesis stage to solventogenesis stage.
  • g/L grams per liter
  • butanol yield from glucose is low, typically at about 15 percent weight by weight (w/w) and rarely exceeds 25 percent.
  • the production of butanol is limited by severe product inhibition.
  • Butanol at a concentration of 1.0 - 2.0 percent can significantly inhibit cell growth, causing the fermentation to cease. Consequently, butanol concentration in conventional ABE fermentations is usually lower than about 1.3 percent. (WWW domain: butanol.com/)
  • Butanol production and ethanol production differ primarily in the characteristics of the fermentation process rather than in starting materials.
  • the feedstocks are essentially the same: energy crops such as sugar beets, sugar cane, corn grain, wheat and cassava as well as agricultural byproducts such as straw and corn stalks.
  • energy crops such as sugar beets, sugar cane, corn grain, wheat and cassava as well as agricultural byproducts such as straw and corn stalks.
  • existing bioethanol plants can be cost-effectively retrofitted to perform biobutanol production.
  • the Weizmann organism Regardless of the feedstock, the Weizmann organism also dies when the butanol content rises to 7 percent.
  • Saccharomyces yeasts used in the fermentation of sugars into ethanol die when the ethanol content of their feedstock reaches 14 percent.
  • Specialized strains of so-called turbo yeast can tolerate ethanol concentrations up to 16 percent ethanol (WWW domain: running_on_alcohol.tripod.com).
  • WWW domain running_on_alcohol.tripod.com
  • ordinary Saccharomyces yeasts can be modified to improve their ethanol resistance, scientists may yet one day produce a strain of the Weizmann organism with a butanol resistance higher than the natural boundary of 7 percent. This would be further favor butanol production over ethanol production.
  • butanol Before butanol can be used as regular fuel for automobiles, one major issue has to be addressed: its odor.
  • the odor of butanol produced by the ABE process is very unpleasant (a pungent, putrid odor) due to residual amounts of butyric, acetic and other short chain carboxylic acids.
  • octane rating relates to antiknock properties of gasoline.
  • Lead has now been eliminated from gasoline for environmental reasons.
  • gasoline sold in the United States has been blended with 5 to 15 percent methyl-tertiary-butyl-ether (MTBE) or ethyl tertiary - butyl ether (ETBE), an oxygenate, in order to raise the octane rating and to reduce environmentally harmful exhaust emissions.
  • MTBE methyl-tertiary-butyl-ether
  • ETBE ethyl tertiary - butyl ether
  • MTBE is itself a pollutant, having an objectionable odor and taste and has been classified as a potential human carcinogen.
  • gasoline storage tanks have developed leaks.
  • MTBE is highly soluble in water and is low in biodegradability.
  • MTBE features a trinary carbon bond which is difficult for natural organisms, such as bacteria, to break down. Consequently, MTBE has polluted the groundwater in many communities.
  • Several states, including California, are phasing out the use of MTBE. This phase out will result in an eventual ban. Actually, all ethers are difficult for natural microorganism to digest but esters are very biodegradable.
  • ETBE has long been recognized as a suitable blending cosolvent for hydrous ethanol in gasoline stocks (see U.S. Patent Nos. 4,207,076 and 5,449,839). There has previously been some interest in the use of ETBE as a lead free octane booster for gasoline.
  • ETBE can be blended into a fuel gasoline at about a 10 to 20 volume percent level, usually nearer 9 to 12 percent, in which the fuel comprises about 70 to 84 percent gasoline and 5 to 20 percent of 95 percent ethanol, i.e. grain alcohol.
  • ETBE solubilizes grain alcohol in gasoline in all proportions, thereby allowing wide latitude application requesting for the precise amount of ethanol which can be blended with gasoline.
  • U.S. Patent No. 4,487,832 discloses a process for producing n-butyl butyrate by passing a fermentation medium containing solvent-producing cells of C. acetobutylicum through a bed of activated carbon, followed by desorbing the n-butyl butyrate from the carbon.
  • the inventors claim that n-butyl butyrate is formed only as the fermentation medium passes slowly through the carbon column.
  • Experiments performed by the applicant have shown that that the formation of n-butyl butyrate does not occur on the carbon column in the absence of the microorganism, that is, that n-butyl butyrate can be only formed with the microorganism and activated carbon present at the same time.
  • esters have been used to produce fruity aromas in food products. Therefore, many attempts to intensify ester flavors have been made. Microbial esterases from yeast and fungi are known to contribute to ester formation. Discoveries have included a method in which alcohol is added to oils and fats containing volatile fatty acids, a method in which a lipase derived from Rhizopus chinensis or from Candida cylindracea is employed to produce an ester compound and a method in which the flavor is intensified by the addition of lipase derived from Rizopus delemar, Aspergillus niger or Candida cylindracea to fruit juice. Esterase from animal tissues such as the liver, kidney, heart or other organ from pig, cow, horse and goat also have also the capability of synthesizing fruity esters (US Patent No. 6,242,015 Bl).
  • the purpose of the invention is to eliminate the unpleasant odor associated with butanol produced by fermentation.
  • the process produces organic acid alkyl esters that remain in the final product stream as oxygenate agents for resulting butanol fuel.
  • the present invention provides a process for the production of short chain carboxylic acid alkyl esters from products produced by the acetone, butanol and ethanol (ABE) fermentation process.
  • the esters preferably remain in the final product (butanol fuel) stream as deodorizing agents for the alcohol fuel and serve as oxygenates or oxygen additives for the fuel.
  • the process also leads to a simplified separation and purification process for ABE fermentation, because ethanol is consumed as co-substrate during ester production.
  • One of the objects of preferred embodiments of the invention is the production of esters with an immobilized enzyme lipase (or substances containing this enzyme) used as a catalyst, with the esterification products being used as additives for butanol fuel.
  • the ester production process is preferably carried out in a packed bed column reactor of solid immobilized lipase particles and is preferably operated in a counter current flow mode.
  • the esters produced by the present invention are preferably the products of reactions between alcohols and carboxylic acids which are the products of the ABE fermentation process.
  • Another object of preferred embodiments of the present invention is to provide a continuous conversion of ABE fermentation residuals, e.g., butyric acid and other short chain organic acids, to their corresponding alkyl esters.
  • a further object of preferred embodiments of the invention is to provide in-situ de-odorizing of the final products of the ABE process and make these final products acceptable for consumer use.
  • Another object of preferred embodiments of the invention is to use solid acid as catalyst for the esterification reaction between organic acids and ethanol or other short chain alcohols to produce fruity flavor esters.
  • Preferred solid acids include DowexTM Monosphere DR-2030 strong acid cation exchange resin, DowexTM Monosphere 650C strong acid cation exchange resin, zeolite, and sulfated zirconia.
  • the preferred reactor is packed bed for the process but a continuous stirred tank reactor may be used for enhanced mass transfer.
  • Another object of preferred embodiments of the invention is to use a combination of solid acid and immobilized lipase as a catalyst for the esterification reaction.
  • Solid acid is preferably used as primary catalyst for the reaction and a packed enzyme column is preferably in the final polishing process. Incompletely converted organic acids from the effluent of solid acid reactor are preferably converted to corresponding esters in the enzyme reactor.
  • Another object of preferred embodiments of the invention is to use an integrated approach that takes advantage of each process step, e.g., the rapid conversion of unpleasantly smelling carboxylic acids from ABE fermentation into alkyl esters catalyzed by solid acids or lipase enzymes, with the product, esters, remaining in the final product stream, resulting, therefore, in a simplified separation process.
  • the substrates for such reactions are alcohols and organic acids.
  • the following alcohols may be used: methanol, ethanol, propanol, isopropanol, butanol, isobutanol, amyl alcohol, isoamyl alcohol, phenetyl alcohol and hexanol.
  • organic acids may be used: formic acid, acetic acid, butyric acid, isobutyric acid, folic acid, isofolic acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, lactic acid, malic acid, citric acid, tartric acid, pyruvic acid, levulinic acid, gluconic acid, and phenylacetic acid.
  • esters during the enzyme reaction requires the presence of at least one alcohol and at least one organic acid, but if these components are produced during the process then no addition of them is required. Addition of alcohols and organic acids is not necessary in case of ABE fermentation processes in which alcohols and organic acids are produced.
  • the enzyme which possesses ester-synthesizing activity generally tends towards hydrolysis in solutions having low alcohol concentrations, and is considered to be poor in the production of esters. It has been shown that an enzyme substance having such ester-synthesizing activity in a 0.5 percent alcohol solution can so adequately produce esters. Therefore, a product mixture from an ABE fermentation process is preferably dehydrated to a certain degree. Solvent extraction is one of many methods that may be used to achieve that goal. Water removal is preferred in any case for butanol and some esters to be used as final products for fuel.
  • the invention is a process for producing carboxylic acid alkyl esters for de-odorizing an acetone-butanol-ethanol fermentation product mixture and oxygenating a butanol fuel derived from the acetone-butanol-ethanol fermentation product mixture, said process comprising: introducing the acetone-butanol-ethanol fermentation product mixture to a solvent extraction reactor containing an organic solvent to produce an organic solvent phase comprising butanol, ethanol and a plurality of short-chain organic acids; introducing said organic solvent phase to an esterification reactor at a controlled rate to produce an esterified product mixture containing a deodorizing agent, said esterification reactor being selected from the group consisting of: (1) a first single stage reactor comprising an enzymatic packed bed reactor containing an immobilized enzyme that catalyzes esterification reactions, (2) a second single stage reactor comprising a solid acid packed bed reactor, a solid acid fluidized bed reactor, a solid acid continuous stirred tank reactor or a solid acid sonic
  • said immobilized enzyme is a lipase that is derived from a microorganism or an animal tissue.
  • said deodorizing agent comprises a plurality short-chain carboxylic acid alkyl esters in an amount of at least 20 ⁇ mol per gram of the butanol fuel, and at least 80 percent of said plurality of short-chain carboxylic acid alkyl esters is butyric ethyl ester (ethyl butyrate).
  • said organic solvent phase has an alcohol concentration that is in the range from about 0.1 percent to about 20 percent.
  • said esterification reaction is carried out in an enzymatic packed bed reactor at a temperature in the range of 10 0 C to about 60 0 C and during a residence time in the range of about 0.2 hours to about 1 hour.
  • said esterification reaction is carried out in a solid acid packed bed reactor and wherein solid acid is selected from the group consisting of: a strong acid cation exchange resin, a zeolite, and a sulfated zirconia.
  • said esterification reaction is carried out at a temperature in the range from about 65 0 C to about 150 0 C and during a residence time in the range of about 0.2 hours to about 1 hour.
  • said organic solvent is hexane.
  • the invention is a process discloses herein further comprising: introducing the acetone-butanol-ethanol fermentation product to a filtration unit for removal of biomass or cell debris before the acetone-butanol-ethanol fermentation product is introduced to said solvent extraction reactor.
  • the invention is a process for producing carboxylic acid alkyl esters for de-odorizing an acetone-butanol-ethanol fermentation product mixture and oxygenating a butanol fuel derived from the acetone-butanol-ethanol fermentation product mixture, said process comprising: introducing the acetone-butanol-ethanol fermentation product mixture to a solvent extraction reactor containing an organic solvent to produce an organic solvent phase comprising butanol and a plurality of short-chain organic acids; introducing said organic solvent phase to an esterification reactor at a controlled rate to produce an esterif ⁇ ed product mixture containing a deodorizing agent, said esterification reactor comprising an enzymatic packed bed reactor containing an immobilized enzyme that catalyzes esterification reactions; monitoring the organic acid content of said esterified product mixture and controlling said controlled rate to be the rate at which the weight of an unreacted portion of said plurality of short-chain acids does not exceed about 0.005 percent of the weight of said esterified product mixture;
  • the invention is a process for producing carboxylic acid alkyl esters for de-odorizing an acetone-butanol-ethanol fermentation product mixture and oxygenating a butanol fuel derived from the acetone-butanol-ethanol fermentation product mixture, said process comprising: a step for introducing the acetone-butanol-ethanol fermentation product mixture to a solvent extraction reactor containing an organic solvent to produce an organic solvent phase comprising butanol and a plurality of short-chain organic acids; a step for introducing said organic solvent phase to an esterif ⁇ cation reactor at a controlled rate to produce an esterified product mixture containing a deodorizing agent; a step for monitoring the organic acid content of said esterified product mixture and controlling said controlled rate to be the rate at which the weight of an unreacted portion of said plurality of short-chain acids does not exceed about 0.005 percent of the weight of said esterified product mixture; and a step for treating said esterified product mixture to remove residual water and said organic solvent and to
  • the invention is a system for producing carboxylic . acid alkyl esters for de-odorizing an acetone-butanol-ethanol fermentation product mixture and oxygenating a butanol fuel derived from the acetone-butanol-ethanol fermentation product mixture, said system comprising: means for processing the acetone-butanol-ethanol fermentation product mixture in a solvent extraction reactor containing an organic solvent to produce an organic solvent phase comprising butanol and a plurality of short-chain organic acids; means for processing said organic solvent phase in an esterif ⁇ cation reactor at a controlled rate to produce an esterified product mixture containing a deodorizing agent; means for monitoring the organic acid content of said esterified product mixture and controlling said controlled rate to be the rate at which the weight of an unreacted portion of said plurality of short-chain acids does not exceed about 0.005 percent of the weight of said esterified product mixture; and means for treating said esterified product mixture to remove residual water and said organic solvent and to produce the butanol
  • the invention is a system for producing carboxylic acid alkyl esters for de-odorizing an acetone-butanol-ethanol fermentation product mixture and oxygenating a butanol fuel derived from the acetone-butanol-ethanol fermentation product mixture, said system comprising: a solvent extraction reactor containing an organic solvent that is operative to treat the acetone-butanol-ethanol fermentation product mixture and to produce an organic solvent phase comprising butanol and a plurality of short-chain organic acids; an esterification reactor that is operative to treat said organic solvent phase at a controlled rate to produce an esterified product mixture containing a deodorizing agent; means for monitoring the organic acid content of said esterified product mixture and controlling said controlled rate to be the rate at which the weight of an unreacted portion of said plurality of short-chain acids does not exceed about 0.005 percent of the weight of said esterified product mixture; and means for treating said esterified product mixture to remove residual water and said organic solvent and to produce the butanol fuel.
  • the invention is a butanol fuel comprising: butanol; and a deodorizing agent that comprises a plurality short-chain carboxylic acid alkyl esters in an amount of at least 20 ⁇ mol per gram of the butanol fuel, with at least 80 percent of said plurality of short-chain carboxylic acid alkyl esters being butyric ethyl ester (ethyl butyrate).
  • the invention is a butanol fuel comprising: butanol; and a deodorizing agent that comprises a plurality short-chain carboxylic acid alkyl esters in an amount of at least 20 ⁇ mol per gram and less than 2 percent by weight of the butanol fuel.
  • the invention is a process for eliminating unpleasant odors associated with butanol production, the process comprising: mixing and sterilizing a carbohydrate feed and/or a sugar feed to produce a mixed and sterilized feedstock; performing acidogenesis fermentation on said mixed and sterilized feedstock to produce an first intermediate product that comprises at least one organic acid; performing solventogenesis fermentation on said intermediate product to produce a second intermediate product comprising said at least one organic acid, at least one alcohol, at least one ketone and water; using solvent extraction to extract at least some of said water from said second intermediate product to produce a solvent phase that comprises said at least one organic acid, said at least one alcohol and said at least one ketone; exposing said solvent phase to a solid acid and/or an immobilized lipase enzyme to catalyze an esterification reaction between said at least one organic acid and said at least one alcohol to produce a reaction product that comprises at least one ester and reaction water; exposing said reaction product to a molecular sieve to remove a first portion of said reaction
  • said performing acidogenesis fermentation step and said performing solventogenesis fermentation step are performed using Clostridia acetobutylicum.
  • said first intermediate product comprises butyric acid, propionic acid, lactic acid, and acetic acid.
  • said second intermediate product comprises butanol, acetone, iso- propanol and ethanol.
  • said using solvent extraction step is performed using hexane as a solvent.
  • said exposing said solvent phase step involves exposing said solvent phase to a solid acid that is selected from the group consisting of: a strong acid cation exchange resin, a zeolite, and a sulfated zirconia.
  • said exposing said solvent phase step is performed in a packed bed column reactor.
  • said packed bed column reactor is operated n a counter current flow mode.
  • the invention is a process for producing butanol comprising: fermenting a sterilized feedstock to produce an intermediate product that comprises a plurality of organic acids, a plurality of alcohols and water; removing at least some of the water from said intermediate product to produce a dehydrated mixture; exposing said dehydrated mixture to a solid acid and/or an immobilized lipase enzyme to produce a reaction product that comprises a plurality of esters and reaction water; and removing at least some of said reaction water from said reaction product.
  • the invention is a process for producing butanol comprising: removing at least some of the water from an aqueous solution comprising a plurality of organic acids, a plurality of alcohols and water to produce a dehydrated mixture; exposing said dehydrated mixture to a solid acid and/or an immobilized lipase enzyme to produce an esterification reaction product that comprises a plurality of esters and reaction water; and removing at least some of said reaction water from said reaction product.
  • the invention is a process for producing butanol comprising: a step for removing at least some of the water from an aqueous solution comprising a plurality of organic acids, a plurality of alcohols and water to produce a dehydrated mixture; a step for exposing said dehydrated mixture to a solid acid and/or an immobilized lipase enzyme to produce an esterification reaction product that comprises a plurality of esters and reaction water; and a step for removing at least some of said reaction water from said reaction product.
  • the invention is a system for producing butanol comprising: means for removing at least some of the water from an aqueous solution comprising a plurality of organic acids, a plurality of alcohols and water to produce a dehydrated mixture; means for exposing said dehydrated mixture to a solid acid and/or an immobilized lipase enzyme to produce an esterification reaction product that comprises a plurality of esters and reaction water; and means for removing at least some of said reaction water from said reaction product.
  • Fig. 1 is a schematic process flow diagram of a preferred embodiment of the invention.
  • Butanol production process 10 preferably includes six unit operations: feedstock preparation operation 12, two stage fermentation operation 14, filtration operation 15, solvent extraction operation 16, catalytic esterification operation 18, molecular sieve dehydration operation 20, distillation operation 22 and fuel (butanol mixture) delivery operation 24.
  • Catalytic esterification operation 18 involves conversion of short chain organic acids such acetic and butyric acids residual from two stage (ABE) fermentation operation 14 to their corresponding alkyl esters, which are used as butanol fuel additives and oxygenate agents.
  • the fruity flavoring esters also serve as de-odorizing agents for the fuel Since the reaction is an esterification reaction and one of the products is water, water is preferably removed from the process stream before feeding it to catalyzed esterification operation 18.
  • the water from fermentation operation 14 is preferably removed in any case in order to purify the final product (butanol) which is intended to be used as a vehicle fuel. Solvent extraction or other conventional methods of removing water from the butanol stream after ABE fermentation may be employed for such purpose.
  • the products produced by fermentation operation 14 are preferably separated from the culture media, i.e. microbial cell or cell debris, and other nutritional residue in filtration operation 15 and/or in solvent extraction operation 18. Water is also removed in solvent extraction operation 16 or another separation (dehydration) method is used.
  • the solvent mixture discharged from solvent extraction operation 16 contains only alcohols, ketones and organic acids and the enzymatic reactions that occur in catalytic esterif ⁇ cation operation 18 take place between alcohols and organic acids.
  • the products of enzyme catalyzed esterification operation 18 are esters and water. Water is removed from the product stream but the produced esters remain in the butanol fuel mixture as fuel additives.
  • the solvent phase of solvent extraction operation 16 containing alcohols, ketones and organic acids is preferably fed to a continuous enzyme packed bed reactor which provides sufficient residence time to achieve high conversion of organic acids, especially short chain carboxylic acids such as butyric acid, acetic acid or propionic acid.
  • high conversion is meant a conversion of at least about 99.995 percent.
  • butanol production process 10 converts ethanol to organic acid ethyl ester. Therefore, both organic acid concentrations and the ethanol concentration are limited in the final ABE product mixture.
  • System 30 preferably carries out process 10 for butanol production and treatment of the final product mixture.
  • butanol production system 30 comprises feed mixer 34, feed pump 36, acidogenesis fermenter 38, solventogenesis fermenter 40, solvent extractor 42, setting tank 44, aqueous phase 46, hexane 48, hexane phase 50, immobilized lipase packed bed reactor, molecular sieve packed bed 54, distillation column 56 and transportation tank truck 58.
  • feed mixer 32 carbohydrate or sugar feed 32 produced in an upstream hydrolysis process (not shown) is mixed and sterilized and is then pumped to fermenters 38 and 40 by feed pump 36.
  • acidogenesis fermenter 38 sugar is converted to butyric acid and other organic acids.
  • solventogenesis fermenter 40 organic acids are converted to butanol, ethanol or acetone.
  • fermenters 38 and 40 carry out ABE fermentation and produce an ABE product mixture.
  • a person having ordinary skill in the art will know that a variety of fermenter configurations and methods of operation can be used to produce an ABE product mixture, a number of which fermenter configurations and methods of operation are disclosed in the U.S. patents incorporated by reference above.
  • filtration unit 41 is provided between fermenter 40 and solvent extractor 42 to remove biomass or cell debris.
  • solvent extractor 42 the organic materials present in the ABE product mixture are extracted into an organic (preferably, hexane) phase 50 and are therefore separated from water.
  • organic phase 50 preferably, hexane
  • settling tank 44 aqueous phase 46 is separated from organic phase 50 and aqueous phase 46 is returned to fermenter 40.
  • esterification reactor 52 where organic acids are reacted with ethanol or butanol, preferably in the presence of a catalyst, to form an esterified product mixture containing esters.
  • the catalyst for this step may be a solid acid or an immobilized enzyme or the combination of the two.
  • Esterification reactor 52 may be a packed bed, a continuous stirred tank, or a sonically agitated tank.
  • the esterified product mixture is introduced to dehydration reactor (preferably molecular sieve column) 54 where water produced during the esterification unit operation is removed from the esterified product mixture to produce a butanol-ester mixture.
  • dehydration reactor preferably molecular sieve column
  • a person having ordinary skill in the art will know that a variety of dehydration reactor configurations and methods of operation can be used to produce the butanol-ester product mixture, a number of which dehydration reactor configurations and methods of operation are disclosed in the U.S. patents and patent applications incorporated by reference above.
  • butanol-ester product mixture is then introduced to distillation column 56 where acetone and residual water are separated from the butanol-ester mixture to produce butanol fuel mixture 60.
  • water and acetone leave system 30 at this point in the process.
  • Butanol fuel mixture 60 is discharged to a final product receiving tank (e.g., transportation tank truck 58) which transports the butanol fuel mixture to its destination.
  • a final product receiving tank e.g., transportation tank truck 58
  • esterification reactor 52 is a packed bed column in which the medium is a solid acid, e.g., a dry acid catalyst or strong acid cation exchange resin, such as DowexTM Monosphere DR-2030, or an immobilized lipase enzyme.
  • Hexane phase 50 which comprises a solution of butanol, ethanol and short-chain organic acids, is preferably pumped through the bed of reactor 52 and the organic acids are converted into ethyl or butyl esters with the production of water.
  • reactor 52 is a packed bed filled with an immobilized lipase or other esterase enzyme.
  • a column with an aspect ratio of height to diameter of 5 to 12 is the preferred configuration.
  • an agitated vessel can be used as reactor 52.
  • the operating temperature can be as high as 65 degrees Centigrade ( 0 C) to promote the reaction rate, while the lipase catalyst requires only room temperature to achieve a reasonable reaction rate.
  • esterification reactor 52 i.e., esterified product mixture
  • esterified product mixture is preferably introduced into molecular sieve column 54 where water is adsorbed onto molecular sieve particles and the esterified product mixture is, therefore, dehydrated to produce a butanol-ester mixture.
  • the butanol-ester mixture is then fed to distillation column 56 where hexane is separated from the butanol-ester mixture.
  • the top stream is hexane (which is returned to solvent extracter 42) and the bottom is a water-free butanol fuel and is readily pumped to transportation tank truck 58.
  • a product of esterification reactions is water. This water tends to accumulate near the catalyst particles in esterification reactor 52. Too much water can cause catalyst deactivation, or drive the reverse reaction, hydrolysis. Water produced during esterification operation 18 is preferably removed to prevent deactivation of the esterification catalyst(s). Water-saturated solid acid or enzyme particles do not function effectively and water adsorption by these particles is preferably prevented.
  • the preferred strategy for removing water from esterification reactor 52 is to use excess ethanol and acetone, both are produced in the process. Preferably, ethanol is consumed by reaction with butyric acid and other organic acid. A small amount of acetone is expected, as was noted above.
  • the effluent from the reactor 52 is continually monitored for the presence of organic acids by means of an automated caustic titration with a phenolphthalein indicator. The endpoint of the titration is detected spectrophotometrically.
  • a predetermined acid concentration is used as a feedback control of the rate of flow of hexane phase 50 into esterification reactor 52.
  • the organic acid content of the effluent stream of esterification reactor 52 i.e., esterified product mixture
  • Esterification reactor 52 is preferably operated at room temperature, i.e., about 20 to 25 0 C, if an enzyme packed bed is used, or about 65 0 C if a solid acid packed bed or stirred tank reactor is use.
  • room temperature i.e., about 20 to 25 0 C
  • a packed bed is the preferred reactor configuration because the immobilized enzyme particles are very fragile, and any agitation leads to particle fracture.
  • operation at room temperature reduces operational costs and prolongs enzyme stability.
  • a preferred residence time in immobilized lipase packed bed reactor 52 is between about 15 minutes to about 25 minutes, depending on the organic acid content of the feed. Typically a decrease in conversion rate is observed after 70 to 100 days of operation if no water is allowed to accumulate in the reactor.
  • Examples of enzyme catalysts that are preferred for use in esterification reactor 52 are are Lipase M® (Amano Pharmaceutical Co., Ltd., from Mucor javanicus), Palatase M® (Novozyme A/S, from Mucor miehe ⁇ ), Lipase F® (Amano Pharmaceutical Co., Ltd., from Rhizopus sp.), Talipase® (Tanabe Seiyaku Co., Ltd., from Rhizopus delemar), Neurase F® (Amano Pharmaceutical Co., Ltd., from Rhizopus niveus), Lipase MY® (Meito Sangyo Co., Ltd., from .
  • Candida cylindracea Lipase A® (Amano Pharmaceutical Co., Ltd., from Aspergillus niger), Lipase Au® (Shin Nihon Chemical Co., Ltd., from Arthrobacter ureafaciens), Lipase P® (Amano Pharmaceutical Co., Ltd., from Pseudomonas sp.), and Lipase SP® (Toyo Jozo Co., Ltd., from Chromobacterium viscosum).
  • Preferred commercially available enzyme preparations derived from animals include pancreatic Lipase 250® (Kyowa Solzyme Co., Ltd., from pig pancreas), Lipase 400® (Kyowa Hi Foods Co., Ltd., from sheep and goat pharynx), and Lipase 600® (Kyowa Hi Foods Co., Ltd., from cow pharynx).
  • the time required to reach this point is much longer than time required to reach the point of lost enzyme activity due to water saturation. Excess ethanol and acetone in the feed stream mixture, however, prevents water accumulation on enzyme particles. The symptom of the enzyme losing its activity is a decreasing conversion rate in the effluent stream.
  • This can be monitored using a device that is capable automated organic acid titration with an indicator and spectrophotometric detection of the endpoint.
  • the device is the titration meter from Fisher Scientific Company, Pittsburgh, PA.
  • the preferred operational conditions for solid acid catalyst reactor 52 are a temperature of about 65 0 C and a pressure of 100 pounds per square inch gauge (psig). Due to their robust physical nature, the reaction mixture with solid acid catalyst beads may be agitated and operation can be conducted at elevated temperature.
  • the catalytic esterification process may also occur in stages in a set of multiple reactors.
  • a solid acid catalytic reactor is used in the first stage to convert most of organic acid and in the second stage, a enzyme packed bed is used to convert the residual organic acid.
  • a heat exchanger is required between the solid acid reactor stage and the enzyme reactor stage to cool the effluent from the former reactor and maintain the feed in liquid form after it is de-pressurized.
  • scaling up of the reaction is preferably done in a straightforward manner for packed bed by applying the same residence time requirement for the volume of fluid to be processed, as long as the geometric constraint of the reactor aspect ratio remaining between 5:1 and 12:1 height to diameter (H/ D) is observed.
  • IU international unit
  • One international unit as used herein is defined as the potency of the enzyme activity which produces 1 micromole of ethyl butyrate in 1 minute, under the assay conditions described in the following method for determining ester-synthesizing activity.
  • Ester-synthesizing activity is determined by measuring the amount of ethyl butyrate produced with ethanol and butyric acid as the substrates.
  • the substrate solution is prepared by adding 0.5 percent by weight or 5 percent by weight ethanol and 2.6 percent by weight butyric acid to a 0.1M phosphate buffer solution (pH 6). The pH is adjusted to 6 using sodium hydroxide.
  • To 1.9 milliliters (ml) of the substrate solution is added 0.5 grams of immobilized lipase. The mixture is then placed on a rotator running at 60 revolutions per minute (rpm) at 30 0 C for 25 minutes, and 1 ml of acetone is added to stop the reaction.
  • aqueous ethyl ether containing 50 micromolar ( ⁇ M) ethyl caproate as the internal standard is added and mixed, and the mixture is allowed to stand for 10 minutes.
  • the upper layer liquid phase is then subjected to gas chromatography to determine the amount of ethyl butyrate produced.
  • the enzyme particles are added and the resulting mixture is used as the blank sample. The enzyme activity is expressed, defining the amount of enzyme which produces 1 ⁇ mol of ethyl butyrate in 1 minute under the conditions described above (0.5 percent ethanol concentration in the reaction system) as one international unit.
  • Ester hydrolysis activity is determined in the following manner, with reference to the method described in Methods in Enzymology, 77, 333 (1981).
  • the substrate solution is prepared by dissolving 18.1 mg ofp-nitrophenyl acetate in 1 ml of acetonitrile, and adding a Tris malate ' buffer (50 mM, pH 7.0) to make 100 ml solution. Then 0.5 gram of immobilized lipase is added to 1.8 ml of the substrate solution. The mixture is then placed on a rotator running at 60 rpm ' at 30 0 C for 10 minutes, followed by the addition of 1 ml of acetone to stop the reaction and the absorbance is measured at 405 nanometers (nm).
  • the amount of enzyme required to hydrolyze 1 ⁇ mol of /?-nitrophenyl acetate in 1 minute under the conditions described above, is defined as one unit.

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Abstract

L'invention concerne un appareil et un procédé pour convertir des acides acétiques, butyriques et d'autres acides carboxyliques à chaîne courte provenant du processus de fermentation d'acétone-butanol-éthanol (ABE) en leurs esters alkyliques correspondants présentant une odeur plaisante. De préférence, un acide fort et/ou une lipase immobilisée est utilisé(e) comme catalyseur dans un réacteur à lit tassé. Les esters produits restent dans le combustible butanol sous forme d'agents d'oxygénation ou d'additifs. Un processus de séparation et de purification simplifié pour la production de combustible butanol en résulte.
PCT/US2007/006645 2007-03-14 2007-03-14 Procédé et système pour production de butanol Ceased WO2008111941A2 (fr)

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NL2006984C2 (en) * 2011-06-22 2013-01-02 Univ Delft Tech A process for converting organic material.
US20130084613A1 (en) * 2009-02-11 2013-04-04 Xylceo Inc. Processing biomass
US9040263B2 (en) 2010-07-28 2015-05-26 Butamax Advanced Biofuels Llc Production of alcohol esters and in situ product removal during alcohol fermentation
US9175315B2 (en) 2010-06-18 2015-11-03 Butamax Advanced Biofuels Llc Production of alcohol esters and in situ product removal during alcohol fermentation
US9790444B2 (en) 2013-04-26 2017-10-17 The Regents Of The University Of California Methods to produce fuels
US9856427B2 (en) 2011-05-27 2018-01-02 The Regents Of The University Of California Method to convert fermentation mixture into fuels
US10106480B2 (en) 2014-10-29 2018-10-23 The Regents Of The University Of California Methods for producing fuels, gasoline additives, and lubricants using amine catalysts
US10138193B2 (en) 2014-10-29 2018-11-27 The Regents Of The University Of California Methods for producing fuels, gasoline additives, and lubricants using amine catalysts
US10207961B2 (en) 2014-03-24 2019-02-19 The Regents Of The University Of California Methods for producing cyclic and acyclic ketones

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ATE217900T1 (de) * 1995-06-08 2002-06-15 Kyowa Hakko Kogyo Kk Aromastoff

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US20130084613A1 (en) * 2009-02-11 2013-04-04 Xylceo Inc. Processing biomass
US20140302571A1 (en) * 2009-02-11 2014-10-09 Xyleco, Inc. Processing biomass
US9175315B2 (en) 2010-06-18 2015-11-03 Butamax Advanced Biofuels Llc Production of alcohol esters and in situ product removal during alcohol fermentation
US9040263B2 (en) 2010-07-28 2015-05-26 Butamax Advanced Biofuels Llc Production of alcohol esters and in situ product removal during alcohol fermentation
US9856427B2 (en) 2011-05-27 2018-01-02 The Regents Of The University Of California Method to convert fermentation mixture into fuels
NL2006984C2 (en) * 2011-06-22 2013-01-02 Univ Delft Tech A process for converting organic material.
US9790444B2 (en) 2013-04-26 2017-10-17 The Regents Of The University Of California Methods to produce fuels
US10207961B2 (en) 2014-03-24 2019-02-19 The Regents Of The University Of California Methods for producing cyclic and acyclic ketones
US10618856B2 (en) 2014-03-24 2020-04-14 The Regents Of The University Of California Methods for producing cyclic and acyclic ketones
US10106480B2 (en) 2014-10-29 2018-10-23 The Regents Of The University Of California Methods for producing fuels, gasoline additives, and lubricants using amine catalysts
US10138193B2 (en) 2014-10-29 2018-11-27 The Regents Of The University Of California Methods for producing fuels, gasoline additives, and lubricants using amine catalysts

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