CN106987285A - A kind of method that multi phase state prepares high alcohol bio-fuel - Google Patents

Abstract

The invention discloses a method for preparing high-level monoalcohol biofuels in a multiphase state. In the method, a sugar alcohol aqueous solution with a concentration of 5-30wt% and hydrogen flow into a fixed-bed reactor in parallel. Under the condition that the pressure is 2-10MPa and the liquid space velocity is 1.0-10.0h ^-1 , under the synergy of Ru-MoOx/AC or Ru-MoOx/CNT multifunctional catalyst, the selectivity of sugar alcohol in the multiphase state Deoxygenation to prepare high-grade monoalcohol biofuels with pentanol and hexanol as the main components; the conversion rate of sugar alcohols reaches 99%, and the selectivity of high-grade monools in biofuels reaches more than 80%, with simple process, green and low carbon, and mild conversion conditions , low hydrogen consumption, high energy utilization efficiency and high added value of the product, etc., are easy to industrialized production, and the obtained pentanol and hexanol are important chemical raw materials, solvents and additives.

Description

A method for preparing high-level monoalcohol biofuels in a multiphase state

Technical field:

The invention relates to the technical field of low-carbon biofuels, in particular to a method for preparing high-level monoalcohol biofuels in a multiphase state.

Background technique:

Biomass is the only carbon resource in renewable energy that can produce liquid fuels and chemicals. Lignocellulosic biomass resources such as agricultural and forestry wastes are very rich, which can be converted into various products such as alcohols, ethers and hydrocarbons through gasification synthesis technology, but the carbon chain distribution of products obtained by gasification Fischer-Tropsch synthesis technology is wide, and the production The crude oil still needs to be distilled and cut to separate different fractions, the technical route is long, and it is difficult to be economical on a small scale. Lignocellulose can be hydrolyzed and fermented to produce fuel ethanol, but ethanol fermentation strains have not yet achieved efficient conversion of five-carbon sugars, and the energy consumption of ethanol distillation and purification remains high. At present, the cost of cellulosic fuel ethanol is still relatively high. Due to the need for waterproof and anti-corrosion, ethanol gasoline has increased costs in blending, storage and transportation, sales and after-sales service. Ethanol gasoline is easy to absorb water, has low calorific value, and insufficient power for vehicles burning ethanol gasoline, which hinders the application of ethanol gasoline, and the prospect is not optimistic. Therefore, exploring a new way to efficiently convert biomass into bioliquid fuels is one of the research hotspots at home and abroad.

In recent years, sugar alcohols have been obtained from biomass through hydrolysis and hydrogenation, and then hydrogen, liquid alkanes and chemicals can be synthesized through catalytic hydrogenation and aqueous phase reforming technologies. Huber et al. (Angew Chem Int Ed, 2004, 43:1549) prepared a Pt/Al ₂ O ₃ -SiO ₂ catalyst, which can effectively control the selective synthesis of C1-C6 alkanes by aqueous phase reforming of sorbitol, at 225 ℃, 3.96MPa, the total selectivity of alkanes can reach 58-89%, and the selectivity of n-pentane and n-hexane is 21% and 40% respectively. Chinese patent CN 101550350A discloses a preparation method of biogasoline and a catalyst preparation process, which is characterized in that sorbitol is used as a raw material, a supported noble metal Pt/HZSM-5 catalyst is used, and a miniature slurry bed is used for high-pressure hydrogenation reaction, which can Higher selectivity to obtain liquid alkane products. However, the water-phase catalytic conversion of biomass to alkanes needs to remove all the oxygen atoms in the sugar alcohol molecules. This process not only consumes a lot of hydrogen, but also has a low mass yield of sugar alcohols converted into alkanes. The conversion temperature of this process is relatively high. The energy consumption is large, and the overall efficiency still needs to be improved.

Invention content:

The purpose of the present invention is to provide a method for preparing high-level monohydric alcohol biofuels in a heterogeneous state. At a relatively low conversion temperature, the oxygen atom in the sugar alcohol molecule is selectively removed, and pentyl alcohol and hexanol are used for directional production. The high-grade monoalcohol biofuel as the main component has the advantages of mild conversion conditions, low hydrogen consumption, high energy utilization efficiency and high added value of the product.

The present invention is achieved through the following technical solutions:

A method for preparing high-level monoalcohol biofuels in a multiphase state, the method uses a concentration of 5-30wt% sugar alcohol aqueous solution and hydrogen to flow into a fixed-bed reactor at a temperature of 140-300 ° C and a hydrogen pressure of 2- Under the conditions of 10MPa and liquid space velocity of 1.0-10.0h ^-1 , under the synergistic effect of Ru-MoOx/AC or Ru-MoOx/CNT multifunctional catalysts, the selective deoxygenation of sugar alcohols in a heterogeneous state prepared pentyl Alcohol and hexanol are high-level monohydric alcohol biofuels as the main components; the aqueous sugar alcohol solution is the hydrolyzed sugar solution (mainly composed of glucose and xylose) of starchy and lignocellulosic biomass or the hydrolyzed sugar solution after hydrogenation Polyhydric alcohol (main component is sorbitol and xylitol) aqueous solution; The method comprises the following steps:

1) Fill the Ru-MoOx/AC or Ru-MoOx/CNT multifunctional catalyst in the constant temperature zone of the reaction tube of the fixed bed reactor, and replace the hydrogen at room temperature until the air in the fixed bed reactor is completely replaced by hydrogen;

2) Introduce hydrogen, and at the same time, the fixed-bed reactor is raised from normal temperature to 350°C at a rate of 5°C/min and kept at 350°C for 3-5 hours until the Ru-MoOx/AC or Ru-MoOx/CNT multifunctional catalyst is fully reduction;

3) Reduce the temperature of the fixed-bed reactor to the set reaction temperature of 140-300°C, and flow the aqueous solution of sugar alcohol with a concentration of 5-30wt% and hydrogen into the fixed-bed reactor at a volume flow ratio of 1:50-1:200 , control the liquid space velocity of 1.0-10.0h ^-1 and the hydrogen pressure of 2-10MPa, so that the aqueous solution of sugar alcohol in the fixed-bed reactor can be evaporated and condensed repeatedly in a multiphase state in Ru-MoOx/AC or Ru-MoOx /CNT catalyst surface selective deoxygenation reaction into pentanol and hexanol;

4) The gas-liquid mixture discharged from the outlet of the fixed-bed reactor is condensed under high pressure at 2-10MPa, and separated into liquid products and non-condensable gas products. The liquid products are separated into oil phase and water phase, and the oil phase is pentanol and hexanol. The mixture; the water phase is used in the hydrolysis process to prepare the hydrolyzed sugar alcohol liquid, and the gas phase is mainly excess hydrogen that has not participated in the reaction, which is pressurized by the circulating compressor and then enters the fixed-bed reactor for recycling.

Step 1) Replace hydrogen at room temperature until the air in the fixed-bed reactor is completely replaced by hydrogen. The specific steps are as follows: pass hydrogen into the fixed-bed reactor at room temperature and stop adding hydrogen until the total pressure of the reactor reaches 0.3 MPa. Stand still for 1 -After 10 minutes, the fixed-bed reactor was exhausted to normal pressure, and so on until the air in the fixed-bed reactor was completely replaced by hydrogen.

The preparation method of described Ru-MoOx/AC catalyst is as follows: coconut shell activated carbon adopts nitric acid to soak 12 hours, then adopts deionized water to clean, soaks and cleans repeatedly 3 times, fully removes the salt in coconut shell activated carbon; Coconut shell activated carbon was loaded with 30wt% MoO ₂ , and after drying, 3wt% Ru was loaded twice to prepare Ru-MoOx/AC catalyst.

The preparation method of the Ru-MoOx/CNT catalyst is as follows: the multi-walled carbon nanotubes are soaked in nitric acid for 12 hours, then washed with deionized water, soaked and cleaned repeatedly for 3 times, and the metal components in the multi-walled carbon nanotubes are fully removed ; Then load 30wt% MoO ₂ on the treated multi-walled carbon nanotubes, and load 2wt% Ru twice after drying to prepare Ru-MoOx/CNT catalyst.

The beneficial effects of the present invention are as follows: the present invention selectively removes the oxygen atoms in sugar alcohol molecules at a relatively low conversion temperature, and directionally produces high-grade monoalcohol biofuels with pentanol and hexanol as main components, sugar The alcohol conversion rate reaches 99%, and the selectivity of higher monohydric alcohols in biofuels reaches more than 80%. It has the advantages of simple process, green and low carbon, mild conversion conditions, low hydrogen consumption, high energy utilization efficiency and high added value of products, and is easy for industrial production. , the obtained pentanol and hexanol are important chemical raw materials, solvents and additives, which can be widely used in organic synthesis, coatings, fine chemical additives, etc., and can also be added to motor gasoline and diesel in a high proportion. Compared with ethanol gasoline , has obvious advantages in waterproof, corrosion, calorific value and engine power, etc., and is suitable for power equipment on all ordinary commercial gasoline and diesel vehicles and ships.

detailed description:

The following is a further description of the present invention, rather than a limitation of the present invention.

Example 1:

Coconut shell activated carbon is soaked in nitric acid for 12 hours, and then washed with deionized water. Repeated soaking and cleaning 3 times to fully remove the salt in coconut shell activated carbon. Then, 30wt% MoO ₂ was loaded on the treated coconut shell activated carbon, and 3wt% Ru was loaded for the second time after drying to prepare Ru-MoOx/AC catalyst.

Fill 300g of multifunctional catalyst Ru-MoOx/AC in the constant temperature zone of the reaction tube of the fixed-bed reactor, pass hydrogen into the fixed-bed reactor at room temperature, stop adding hydrogen until the total pressure of the reactor reaches 0.3MPa, and let it stand for 1 - After 10 minutes, the fixed-bed reactor is exhausted to normal pressure, and the air is repeatedly inflated and exhausted 3-5 times until the air in the fixed-bed reactor is completely replaced by hydrogen;

Continue to feed hydrogen into the fixed-bed reactor, and at the same time, the fixed-bed reactor is raised from normal temperature to 350°C at a rate of 5°C/min and kept at 350°C for 5 hours until the catalyst is fully reduced;

Lower the temperature of the fixed-bed reactor to the reaction temperature of 300°C, the concentration of 20wt% sugar alcohol aqueous solution and hydrogen flow into the fixed-bed reactor at a volume flow ratio of 1:50, strictly control the liquid space velocity of 1.5h ^-1 and keep the hydrogen pressure constant Carry out the selective deoxygenation reaction of sugar alcohol in multiphase state at 8.5-8.7MPa;

The product discharged from the outlet of the fixed bed reactor is condensed under 8.0MPa high pressure, and then separated into liquid product and non-condensable gas product. The liquid product is separated into oil phase and water phase, and the oil phase is a mixture of pentanol and hexanol. up to 82.5%. The water phase is used in the hydrolysis process to prepare the hydrolyzed sugar alcohol liquid, and the gas phase is mainly excess hydrogen that has not participated in the reaction, which is pressurized by the circulating compressor and then enters the fixed-bed reactor for recycling. The high-grade monoalcohol biofuel is collected from the bottom of the gas-liquid separator, and the remaining hydrogen is discharged from the top of the gas-liquid separator, pressurized by the circulating compressor, and then enters the fixed-bed reactor for recycling.

Example 2:

Coconut shell activated carbon is soaked in nitric acid for 12 hours, and then washed with deionized water. Repeated soaking and cleaning 3 times to fully remove the salt in coconut shell activated carbon. Then, 30wt% MoO ₂ was loaded on the treated coconut shell activated carbon, and 3wt% Ru was loaded for the second time after drying to prepare Ru-MoOx/AC catalyst.

Fill 300g of multifunctional catalyst Ru-MoOx/AC in the constant temperature zone of the reaction tube of the fixed-bed reactor, pass hydrogen into the fixed-bed reactor at room temperature, stop adding hydrogen until the total pressure of the reactor reaches 0.3MPa, and let it stand for 1 - After 10 minutes, the fixed-bed reactor is exhausted to normal pressure, and the air is repeatedly inflated and exhausted 3-5 times until the air in the fixed-bed reactor is completely replaced by hydrogen;

Continue to feed hydrogen into the fixed-bed reactor, and at the same time, the fixed-bed reactor is raised from normal temperature to 350°C at a rate of 5°C/min and kept at 350°C for 5 hours until the catalyst is fully reduced;

Lower the temperature of the fixed bed reactor to the reaction temperature of 240°C, the concentration of 15wt% sugar alcohol aqueous solution and hydrogen flow into the fixed bed reactor at a volume flow ratio of 1:100, strictly control the liquid space velocity of 1.5h ^-1 and keep the hydrogen pressure constant Carry out the selective deoxygenation reaction of sugar alcohol in multiphase state at 3.4-3.6MPa;

The product discharged from the outlet of the fixed-bed reactor is condensed under high pressure at 3.0MPa, and then separated into liquid product and non-condensable gas product. The liquid product is separated into oil phase and water phase, and the oil phase is a mixture of pentanol and hexanol. Up to 86.8%. The water phase is used in the hydrolysis process to prepare the hydrolyzed sugar alcohol liquid, and the gas phase is mainly excess hydrogen that has not participated in the reaction, which is pressurized by the circulating compressor and then enters the fixed-bed reactor for recycling. The high-grade monoalcohol biofuel is collected from the bottom of the gas-liquid separator, and the remaining hydrogen is discharged from the top of the gas-liquid separator, pressurized by the circulating compressor, and then enters the fixed-bed reactor for recycling.

Example 3:

The multi-walled carbon nanotubes were soaked in nitric acid for 12 hours, and then washed with deionized water. The soaking and washing were repeated three times to fully remove the metal components in the multi-walled carbon nanotubes. Then, 30wt% MoO ₂ is loaded on the treated multi-walled carbon nanotubes, and 2wt% Ru is loaded for the second time after drying to prepare a Ru-MoOx/CNT catalyst.

Fill 300g of multifunctional catalyst Ru-MoOx/CNT in the constant temperature zone of the reaction tube of the fixed bed reactor, pass hydrogen into the fixed bed reactor at room temperature, stop adding hydrogen until the total pressure of the reactor reaches 0.3MPa, and let it stand for 1 - After 10 minutes, the fixed-bed reactor is exhausted to normal pressure, and the air is repeatedly inflated and exhausted 3-5 times until the air in the fixed-bed reactor is completely replaced by hydrogen;

Continue to feed hydrogen into the fixed-bed reactor, and at the same time, the fixed-bed reactor is raised from normal temperature to 350°C at a rate of 5°C/min and kept at 350°C for 5 hours until the catalyst is fully reduced;

Lower the temperature of the fixed bed reactor to the reaction temperature of 220°C, the concentration of 20wt% sugar alcohol aqueous solution and hydrogen flow into the fixed bed reactor at a volume flow ratio of 1:100, and keep the liquid space velocity at 6.0h ^-1 and the pressure constant at 2.3 -2.5MPa for selective deoxygenation of sugar alcohols in a heterogeneous state;

The product discharged from the outlet of the fixed bed reactor is condensed under 2.0MPa high pressure and separated into liquid product and non-condensable gas product. The liquid product is separated into oil phase and water phase. The oil phase is a mixture of pentanol and hexanol. Selectivity up to 81.7%. The water phase is used in the hydrolysis process to prepare the hydrolyzed sugar alcohol liquid, and the gas phase is mainly excess hydrogen that has not participated in the reaction, which is pressurized by the circulating compressor and then enters the fixed-bed reactor for recycling. The high-grade monoalcohol biofuel is collected from the bottom of the gas-liquid separator, and the remaining hydrogen is discharged from the top of the gas-liquid separator, pressurized by the circulating compressor, and then enters the fixed-bed reactor for recycling.

Claims (3)

1. A method for preparing high-level monohydric alcohol biofuels in a multiphase state is characterized in that, the method is that the sugar alcohol aqueous solution of 5-30wt% and hydrogen flow into the fixed-bed reactor with a concentration of 5-30wt%, and the temperature is 140-300 ℃ , under the conditions of hydrogen pressure of 2-10MPa and liquid space velocity of 1.0-10.0h ^-1 , under the synergistic effect of Ru-MoOx/AC or Ru-MoOx/CNT multifunctional catalysts, sugar alcohols are in a multi-phase state Selective deoxygenation to prepare higher monohydric alcohol biofuels with pentanol and hexanol as the main components; the sugar alcohol aqueous solution is the hydrolyzed sugar solution of starch and lignocellulosic biomass or the polyol aqueous solution after hydrogenation of the hydrolyzed sugar solution ; the method includes the following steps: 1) Fill the Ru-MoOx/AC or Ru-MoOx/CNT multifunctional catalyst in the constant temperature zone of the reaction tube of the fixed bed reactor, and replace the hydrogen at room temperature until the air in the fixed bed reactor is completely replaced by hydrogen; 2) Introduce hydrogen, and at the same time, the fixed-bed reactor is raised from normal temperature to 350°C at a rate of 5°C/min and kept at 350°C for 3-5 hours until the Ru-MoOx/AC or Ru-MoOx/CNT multifunctional catalyst is fully reduction; 3) Reduce the temperature of the fixed-bed reactor to the set reaction temperature of 140-300°C, and flow the aqueous solution of sugar alcohol with a concentration of 5-30wt% and hydrogen into the fixed-bed reactor at a volume flow ratio of 1:50-1:200 , control the liquid space velocity of 1.0-10.0h ^-1 and the hydrogen pressure of 2-10MPa, so that the aqueous solution of sugar alcohol in the fixed-bed reactor can be evaporated and condensed repeatedly in a multiphase state in Ru-MoOx/AC or Ru-MoOx /CNT catalyst surface selective deoxygenation reaction into pentanol and hexanol; 4) The gas-liquid mixture discharged from the outlet of the fixed-bed reactor is condensed under high pressure at 2-10MPa, and separated into liquid products and non-condensable gas products. The liquid products are separated into oil phase and water phase, and the oil phase is pentanol and hexanol. The mixture; the water phase is used in the hydrolysis process to prepare the hydrolyzed sugar alcohol liquid, and the gas phase is mainly excess hydrogen that has not participated in the reaction, which is pressurized by the circulating compressor and then enters the fixed-bed reactor for recycling. 2. the multiphase state according to claim 1 prepares the method for advanced monohydric alcohol biofuel, is characterized in that, the preparation method of described Ru-MoOx/AC catalyst is as follows: coconut shell activated carbon adopts nitric acid to soak for 12 hours, then uses Ion water washing, repeated soaking and washing 3 times to remove the salt in coconut shell activated carbon; then loaded 30wt% MoO ₂ on the treated coconut shell activated carbon, and loaded 3wt% Ru twice after drying to prepare Ru-MoOx/AC catalyst. 3. the multiphase state according to claim 1 prepares the method for advanced monohydric alcohol biofuel, is characterized in that, the preparation method of described Ru-MoOx/CNT catalyst is as follows: multi-wall carbon nanotube adopts nitric acid to soak for 12 hours, then Washing with deionized water, repeated soaking and washing 3 times, to remove the metal components in the multi-walled carbon nanotubes; then load 30wt% MoO ₂ on the treated multi-walled carbon nanotubes, and load 2wt% Ru for the second time after drying, Prepared Ru-MoOx/CNT catalyst.