A method for producing biofuel

Abstract

The present invention provides a method for producing bio-jet fuel, which belongs to the technical field of bio-oil products, and includes the following steps: S1, producing hydrogen and fermentation liquid by fermentation of mixed bacteria containing clostridium, and collecting hydrogen for standby use; S2, putting a porous ZnO carrier into an impregnation solution containing Cu, Rh and phosphotungstic acid, impregnating, drying, calcining, and obtaining a Cu-Rh-phosphotungstic acid supported catalyst; S3, putting restaurant waste oil, Cu-Rh-phosphotungstic acid supported catalyst and methanol into a high-temperature and high-pressure reactor, ventilating, introducing the hydrogen collected in step S1, reacting, and obtaining bio-jet fuel. The technical solution of the present invention realizes the ability to improve the production efficiency of preparing bio-jet fuel from bio-oil without the need for liquefied hydrogen and with cheap and readily available raw materials.

Description

Technical Field

[0001] The present invention relates to the technical field of bio-oil products, and in particular to a method for producing bio-jet fuel. Background Art

[0002] Biojet fuel is a type of aviation fuel made from renewable resources. The development and use of biojet fuel has important environmental significance because it can emit less carbon dioxide than traditional petroleum-based jet fuel over its entire life cycle, which helps airlines reduce greenhouse gas emissions and is in line with the global aviation industry's goal of reducing carbon emissions and addressing climate change.

[0003] Although biojet fuel has significant advantages in reducing carbon emissions in the aviation industry, there are still some problems that hinder its wider application. One of the primary problems is the high production cost, which is mainly because the raw materials required for biojet fuel are mainly animal and plant oils, which are usually more expensive than traditional petroleum raw materials. Therefore, finding a more economical source of raw materials is one of the key research directions to improve the competitiveness of biojet fuel in the future.

[0004] Secondly, the production process of biojet fuel involves hydrogenation reaction, which requires a large amount of hydrogen. Hydrogen is not only expensive, but also difficult to become liquid. There is a risk of flammability and explosion during transportation, which is also a technical problem that needs to be solved urgently in the industry.

[0005] In addition, the existing bio-jet fuel production process mainly obtains products by hydrogenating animal and plant oils or their derivatives. These products are mainly straight-chain alkanes of C15~C18, while the main components of ideal bio-jet fuel should be alkanes in the range of C9~C16, which makes the content of bio-jet fuel in the hydrogenated product low. In order to increase the content of bio-jet fuel in production, the product needs to be further cracked or isomerized. In this process, the selection and optimization of catalysts are crucial. However, the current existing technology mainly focuses on improving the activity of the hydrodeoxygenation process, and lacks efficient catalysts that can simultaneously catalyze hydrodeoxygenation and cracking or isomerization. This not only limits the output of bio-jet fuel, but also shortens the service life of the catalyst, thereby increasing the total cost of industrial production, so it is necessary to conduct in-depth research and improvement.

[0006] Finally, in the process of preparing bio-jet fuel through hydrogenation reaction, there will be crude glycerol as a by-product that is not completely consumed, which makes the production efficiency of bio-jet fuel low. Further research is needed to further utilize the by-product to improve the overall yield.

[0007] Therefore, it is necessary to provide a method for producing bio-jet fuel to solve the problems existing in the above-mentioned prior art. Summary of the invention

[0008] In view of this, the present invention provides a method for producing bio-jet fuel, which can improve the production efficiency of preparing bio-jet fuel from bio-oil without the need for liquefied hydrogen and with cheap and readily available raw materials.

[0009] To achieve the above object, the present invention provides a method for producing bio-jet fuel, comprising the following steps:

[0010] Step S1: Producing hydrogen and fermentation liquid by fermentation of mixed bacteria containing Clostridium, and collecting hydrogen for later use;

[0011] Step S2: placing the porous ZnO carrier into an impregnation solution containing Cu, Rh and phosphotungstic acid, performing impregnation, drying and calcination to obtain a Cu-Rh-phosphotungstic acid supported catalyst;

[0012] Step S3: Put the waste cooking oil, Cu-Rh-phosphotungstic acid supported catalyst and methanol into a high temperature and high pressure reactor, ventilate, introduce the hydrogen collected in step S1, react and produce biojet fuel.

[0013] The present invention produces hydrogen through methanol under high temperature and high pressure reaction conditions, but carbon dioxide is produced in the process of hydrogenation of methanol under high temperature and high pressure, and by-products such as crude glycerol are produced in the production process of bio-jet fuel. Therefore, mixed bacteria containing Clostridium are used to consume carbon dioxide and by-products through fermentation to prepare hydrogen, and further provide the required hydrogen for the hydrogenation reaction in the production process of bio-jet fuel. This method replaces the traditional method of directly using high-pressure gaseous or low-temperature liquid hydrogen tanks to supply hydrogen, which not only effectively avoids the flammable and explosive risks caused by impact or wear that may be encountered during transportation, but also significantly reduces production costs, and realizes the recycling of by-products in the production process of bio-jet fuel, thereby improving the yield of bio-jet fuel.

[0014] The invention prepares a catalyst for producing bio-jet fuel by one-step hydrogenation reaction. A loaded catalyst is prepared by using porous ZnO as a carrier, wherein the porous structure provides more reaction sites for the catalyst, enhances the catalytic activity, and increases the specific surface area. ZnO has high thermal stability and is suitable for high-temperature reaction environments, which solves the shortcomings of small specific surface area, inconvenience in reuse, and easy deactivation at high temperatures of general catalysts. The porous ZnO carrier is then immersed in an impregnation solution containing Cu, Rh, and phosphotungstic acid to load Cu, Rh, and phosphotungstic acid. The Cu and Rh bimetallic is loaded by impregnation, so that the formed Cu-Rh alloy and partially oxidized Cu can improve the activity of in-situ hydrogenation and deoxygenation and provide metal sites. The oxygen-containing compounds in the bio-oil are firstly hydrogenated and deoxygenated at the metal sites to generate alkane compound components. Subsequently, more acid sites are provided by impregnating tungsten phosphate. Under the synergistic effect of the metal sites and the acid sites, the alkane components undergo cracking and isomerization reactions, thereby generating more alkanes within the range of jet fuel.

[0015] The present invention uses waste cooking oil as a raw material for preparing bio-jet fuel, thereby realizing the recycling of resources, reducing waste oil waste and environmental pollution, and lowering raw material costs. It also helps to reduce dependence on fossil fuels, promote the development of renewable energy, and facilitate the realization of sustainable development goals.

[0016] Optionally, the clostridia contained in the clostridia mixed bacteria in step S1 include Clostridium pasteurianum, Clostridium beijerinckii, and Clostridium butyricum; in step S1, the clostridium mixed bacteria are expanded and cultured and then mixed with bio-jet fuel by-products in a closed fermentation tank for fermentation to obtain a fermentation liquid, and the hydrogen produced in the fermentation tank is collected.

[0017] Optionally, the molar ratio of Clostridium pasteurianum, Clostridium beijerinckii and Clostridium butyricum is 1:1:1; the expansion culture time is 3 days, the expansion culture temperature is 35°C, and the expansion culture process is carried out at a rotation speed of 180r / min; the fermentation time is 2 days, the fermentation temperature is 35°C, and the fermentation process is carried out at a rotation speed of 180r / min.

[0018] Optionally, the mixed Clostridium-containing bacteria also include anaerobic methanophiles and Propionibacterium; the fermentation liquid is centrifuged and the supernatant is discarded, washed with deionized water, dried to constant weight at 105°C, extracted with a mixed solution of chloroform and methanol, and then added with 3% sulfuric acid solution and heated at 105°C to extract to obtain microbial oil; in step S3, the microbial oil, acidified oil, vegetable oil and catering waste oil are put into a high-temperature and high-pressure reactor.

[0019] In the process of clostridial fermentation to produce hydrogen, byproducts such as methane and acetic acid are produced. The purpose of the clostridial mixed bacteria also including anaerobic methanogens and propionibacteria is to consume the byproducts methane and acetic acid produced by Clostridium pasteurianum, Clostridium beijerinckii and Clostridium butyricum in the process of fermentation to produce hydrogen. The anaerobic methanogens use methane as a carbon source to convert it into carbon dioxide and water, while releasing energy. This process not only reduces the emission of methane, but also promotes its own growth through metabolic activities. The propionibacteria further metabolize the acetic acid through the fermentation process to produce fatty acids. Finally, microbial oils are obtained through extraction and acid heating to achieve endogenous recycling. In this process, the acidic condition is conducive to separating oils from the mixed phase, improving the purity and efficiency of the extraction, and further improving the overall utilization rate to increase the yield of bio-jet fuel.

[0020] Optionally, the ratio of the sum of the molar fractions of Clostridium pasteurianum, Clostridium beijerinckii and Clostridium butyricum to the molar fractions of anaerobic methanophiles and Propionibacterium is 1:(2~4):(2~4); the volume ratio of chloroform to methanol in the mixed solution of chloroform and methanol is 2:1; the volume ratio of the mixed solution of chloroform and methanol to 3% sulfuric acid solution is 1:(0.1~0.2).

[0021] The ratio of the sum of the molar fractions of Clostridium pasteurianum, Clostridium beijerinckii and Clostridium butyricum to the molar fractions of anaerobic methanogens and propionibacteria used in the present invention is 1:(2-4):(2-4), which is the best for hydrogen production by mixed bacteria containing Clostridium and extraction of microbial oils. Too low a ratio of anaerobic methanogens to propionibacteria will affect the conversion rate of fatty acids.

[0022] Optionally, in step S2, the porous ZnO carrier is prepared by uniformly mixing a zinc nitrate solution and a hexadecyltrimethylammonium bromide solution, adding 25% NH3·H2O to form a gel, standing and heat-treating at 80°C, and then calcining at 400°C; wherein the volume ratio of the zinc nitrate solution to the hexadecyltrimethylammonium bromide is 20:1, and the standing time is 24 hours.

[0023] Optionally, in step S2, the porous ZnO carrier is immersed in a copper nitrate solution and mixed, after immersing for 5 hours, the impregnated carrier is dried in a 60°C oven, immersed in a rhodium chloride solution and mixed, immersed for 5 hours, dried in a 60°C oven, immersed in a phosphotungstic acid solution and mixed, immersed for 5 hours, and then calcined at 400°C for 2 hours to obtain a Cu-Rh-phosphotungstic acid supported catalyst; wherein the mass ratio of the porous ZnO carrier to the volume fractions of the copper nitrate solution, the rhodium chloride solution, and the phosphotungstic acid solution is 1:2:2:2.

[0024] Optionally, in step S3, after adding the Cu-Rh-phosphotungstic acid supported catalyst, the air in the high-temperature and high-pressure reactor and the pipeline is purged with nitrogen, methanol is added and the hydrogen collected in the closed fermentation tank is introduced to carry out a one-step hydrogenation reaction under stirring to produce bio-jet fuel; wherein the high-temperature and high-pressure reaction conditions are a temperature of 250~400°C, a pressure of 2~5MPa, a stirring rate of 550rpm, and a stirring time of 3.5~7h.

[0025] Optionally, the biojet fuel comprises the following raw materials in parts by weight: 1-4 parts of methanol, 1-4 parts of hydrogen collected in step S1, 10-40 parts of waste cooking oil, and 0.7-1.6 parts of Cu-Rh-phosphotungstic acid supported catalyst.

[0026] Optionally, the biojet fuel also includes the following raw materials in parts by weight: 1 to 20 parts of acidified oil, 4 to 15 parts of vegetable oil, and 15 to 65 parts of microbial oil.

[0027] The above technical solution of the present invention includes at least the following beneficial effects:

[0028] The present invention produces hydrogen from methanol and uses mixed bacteria containing Clostridium to ferment and prepare hydrogen for use in the hydrogenation reaction for preparing bio-jet fuel. This method replaces the traditional method of directly using high-pressure gaseous or low-temperature liquid hydrogen tanks to supply hydrogen, which not only effectively avoids the risk of flammability and explosion caused by impact or wear and tear that may be encountered during transportation, but also significantly reduces production costs.

[0029] The present invention obtains a Cu-Rh-phosphotungstic acid supported catalyst by using porous ZnO as a carrier to impregnate an impregnation solution containing Cu, Rh and phosphotungstic acid, thereby increasing the specific surface area of ​​the porous ZnO structure, providing more reaction sites for the catalyst, and enhancing the catalytic activity. In addition, Cu and Rh bimetallic materials are impregnated to increase the activity of in-situ hydrogenation and deoxygenation and provide metal sites. More acid sites are provided by impregnating tungsten phosphate, so that oxygen-containing compounds in biological oils and fats are hydrogenated and deoxygenated at the metal sites to generate alkane compound components. Subsequently, under the synergistic effect of the metal sites and the acid sites, the alkane components undergo cracking and isomerization reactions, thereby generating more alkanes within the range of aviation kerosene fuel, and improving production efficiency.

[0030] The present invention uses waste cooking oil as the raw material for preparing bio-jet fuel, which can realize the recycling of resources, reduce waste oil waste and environmental pollution, and reduce raw material costs. At the same time, it helps to reduce dependence on fossil fuels, promote the development of renewable energy, and promote the realization of sustainable development goals. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a graph showing the effect of different catalysts on the yield of bio-jet fuel;

[0032] Figure 2 This is a graph showing the impact of different hydrogen supply modes on the yield of bio-jet fuel. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described in combination with the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0034] Preparation

[0035] Activated culture medium: Take 40 parts of glucose, 40 parts of yeast extract, 8 parts of magnesium sulfate, 12 parts of dipotassium hydrogen phosphate and 8 parts of L-cysteine ​​hydrochloride by mass, add 1000 parts of deionized water, mix well, sterilize at 121°C for 20 minutes, and obtain the activated culture medium.

[0036] Seed culture medium: Take 4.5 parts of yeast extract, 30 parts of peptone, 30 parts of beef extract, 20 parts of glucose, 3 parts of starch, 15 parts of sodium acetate and 1.5 parts of L-cysteine ​​by mass, add 1000 parts of deionized water, mix well, add appropriate amount of HCl and / or NaOH to adjust the initial pH of the seed culture medium to pH 7.0±0.2, and then sterilize at 121°C for 20 min to obtain the seed culture medium.

[0037] Example 1

[0038] In terms of molar proportions, 5 parts of Clostridium pasteurianum solution, 5 parts of Clostridium beijerinckii solution, 5 parts of Clostridium butyricum solution, 30 parts of anaerobic methanophilic bacteria solution, and 45 parts of Propionibacterium solution were inoculated into the activated culture solution, and cultured in a constant temperature shaker at a temperature of 35°C and a speed of 180 r / min for 2 days to obtain the activated mixed bacteria containing Clostridium. The activated mixed bacteria containing Clostridium were inoculated into the seed culture medium at an inoculation rate of 5%, and cultured in a constant temperature shaker at a temperature of 35°C and a speed of 180 r / min for 3 days to obtain the expanded culture mixed bacteria containing Clostridium for later use.

[0039] By volume, 50 parts of the mixed bacteria containing Clostridium after the expanded culture, 50 parts of the byproduct gas of bio-jet fuel and crude glycerol were put into a closed fermentation tank, and cultured at a temperature of 35°C and a speed of 180r / min for 2 days to obtain the fermentation liquid. The hydrogen produced during the period was collected for the subsequent preparation of bio-jet fuel. The fermentation liquid was centrifuged to discard the supernatant, and then the wet cells were washed with deionized water and dried to constant weight at 105°C. The extraction was carried out with a mixed solution of 100 parts of chloroform and methanol as the extractant, in which the volume ratio of chloroform to methanol was 2:1, and 10 parts of 3% sulfuric acid solution were added and heated at 105°C to extract the microbial oil.

[0040] By volume, 1.5 parts of hexadecyltrimethylammonium bromide were added to 30 parts of zinc nitrate solution to control the morphology and porosity of the final product, and the mixture was stirred evenly to obtain a transparent solution. 12 parts of 25% NH3·H2O were slowly added to the prepared solution to perform hydrolysis and polycondensation reactions to form a sol. The gel was placed in a sealed container, allowed to stand at room temperature for 24 hours, and then placed in an oven for heat treatment at 80°C to remove the solvent and form a dry gel. Then, high-temperature calcination is carried out at 400°C for 2h to remove organic components and form a porous ZnO carrier, and then step-by-step impregnation is carried out. 50 parts of the prepared porous ZnO carrier are immersed in 100 parts of copper nitrate solution, mixed and evenly immersed for 5h, and then dried in an oven at 60°C. Then, they are immersed in 100 parts of rhodium chloride solution, mixed and evenly immersed for 5h, and then dried in an oven at 60°C. Finally, they are immersed in 100 parts of phosphotungstic acid solution, mixed and evenly immersed for 5h, and then calcined at 400°C for 2h to finally obtain a Cu-Rh-phosphotungstic acid supported catalyst.

[0041] According to weight, 10 parts of catering waste oil, 1 part of acidified oil, 4 parts of soybean oil, 65 parts of prepared microbial oil, and 0.7 parts of Cu-Rh-phosphotungstic acid supported catalyst were added, the air in the reactor and pipeline was purged with nitrogen, 1 part of methanol was added and 4 parts of hydrogen collected in closed fermentation tanks were introduced, stirred and mixed, and then a one-step hydrogenation reaction was carried out. The reaction conditions were temperature 250°C, pressure 2MPa, stirring rate 550rpm, and the reaction was carried out for 4h to prepare biojet fuel.

[0042] Example 2

[0043] In terms of molar proportions, 5 parts of Clostridium pasteurianum solution, 5 parts of Clostridium beijerinckii solution, 5 parts of Clostridium butyricum solution, 45 parts of anaerobic methanophilic bacteria solution, and 45 parts of Propionibacterium solution were inoculated into the activated culture solution, and cultured in a constant temperature shaker at a temperature of 35°C and a speed of 180 r / min for 2 days to obtain the activated mixed bacteria containing Clostridium. The activated mixed bacteria containing Clostridium were inoculated into the seed culture medium at an inoculation rate of 5%, and cultured in a constant temperature shaker at a temperature of 35°C and a speed of 180 r / min for 3 days to obtain the expanded culture mixed bacteria containing Clostridium for later use.

[0044] By volume, 50 parts of the mixed bacteria containing Clostridium after the expanded culture, 50 parts of the byproduct gas of bio-jet fuel and crude glycerol were put into a closed fermentation tank, cultured at a temperature of 35°C and a speed of 180r / min for 2 days to obtain the fermentation liquid, and the hydrogen produced during the collection period was used for the subsequent preparation of bio-jet fuel. The fermentation liquid was centrifuged to discard the supernatant, and then the wet cells were washed with deionized water and dried to constant weight at 105°C. The extraction was carried out with a mixed solution of 100 parts of chloroform and methanol as the extractant, wherein the volume ratio of chloroform to methanol was 2:1, and 20 parts of 3% sulfuric acid solution were added and heated at 105°C to extract the microbial oil.

[0045] By volume, 1.5 parts of hexadecyltrimethylammonium bromide were added to 30 parts of zinc nitrate solution to control the morphology and porosity of the final product, and the mixture was stirred evenly to obtain a transparent solution. 12 parts of 25% NH3·H2O were slowly added to the prepared solution to perform hydrolysis and polycondensation reactions to form a sol. The gel was placed in a sealed container, allowed to stand at room temperature for 24 hours, and then placed in an oven for heat treatment at 80°C to remove the solvent and form a dry gel. Then, high-temperature calcination is carried out at 400°C for 2h to remove organic components and form a porous ZnO carrier, and then step-by-step impregnation is carried out. 50 parts of the prepared porous ZnO carrier are immersed in 100 parts of copper nitrate solution, mixed and evenly immersed for 5h, and then dried in an oven at 60°C. Then, they are immersed in 100 parts of rhodium chloride solution, mixed and evenly immersed for 5h, and then dried in an oven at 60°C. Finally, they are immersed in 100 parts of phosphotungstic acid solution, mixed and evenly immersed for 5h, and then calcined at 400°C for 2h to finally obtain a Cu-Rh-phosphotungstic acid supported catalyst.

[0046] According to weight, 30 parts of catering waste oil, 15 parts of acidified oil, 5 parts of corn oil, 35 parts of prepared microbial oil, and 1.6 parts of Cu-Rh-phosphotungstic acid supported catalyst were added, and the air in the high-temperature and high-pressure reactor and pipelines was purged with nitrogen. 3 parts of methanol were added and the hydrogen collected in 2 closed fermentation tanks was introduced and stirred to mix well, and then a one-step hydrogenation reaction was carried out. The reaction conditions were temperature 250°C, pressure 2MPa, stirring rate 550rpm, and the reaction was carried out for 4h to prepare bio-jet fuel.

[0047] Example 3

[0048] In terms of molar proportions, 5 parts of Clostridium pasteurianum solution, 5 parts of Clostridium beijerinckii solution, 5 parts of Clostridium butyricum solution, 45 parts of anaerobic methanophilic bacteria solution, and 60 parts of Propionibacterium solution were inoculated into the activated culture solution, and cultured in a constant temperature shaker at a temperature of 35°C and a speed of 180 r / min for 2 days to obtain the activated mixed bacteria containing Clostridium. The activated mixed bacteria containing Clostridium were inoculated into the seed culture medium at an inoculation rate of 5%, and cultured in a constant temperature shaker at a temperature of 35°C and a speed of 180 r / min for 3 days to obtain the expanded culture mixed bacteria containing Clostridium for later use.

[0049] By volume, 50 parts of the mixed bacteria containing Clostridium after the expanded culture, 50 parts of the byproduct gas of bio-jet fuel and crude glycerol were put into a closed fermentation tank, cultured at a temperature of 35°C and a speed of 180r / min for 2 days to obtain the fermentation liquid, and the hydrogen produced during the collection period was used for the subsequent preparation of bio-jet fuel. The fermentation liquid was centrifuged to discard the supernatant, and then the wet cells were washed with deionized water and dried to constant weight at 105°C. The extraction was carried out with a mixed solution of 100 parts of chloroform and methanol as the extractant, in which the volume ratio of chloroform to methanol was 2:1, and 15 parts of 3% sulfuric acid solution were added and heated at 105°C to extract the microbial oil.

[0050] By volume, 1.5 parts of hexadecyltrimethylammonium bromide were added to 30 parts of zinc nitrate solution to control the morphology and porosity of the final product, and the mixture was stirred evenly to obtain a transparent solution. 12 parts of 25% NH3·H2O were slowly added to the prepared solution to perform hydrolysis and polycondensation reactions to form a sol. The gel was placed in a sealed container, allowed to stand at room temperature for 24 hours, and then placed in an oven for heat treatment at 80°C to remove the solvent and form a dry gel. Then, high-temperature calcination is carried out at 400°C for 2h to remove organic components and form a porous ZnO carrier, and then step-by-step impregnation is carried out. 50 parts of the prepared porous ZnO carrier are immersed in 100 parts of copper nitrate solution, mixed and evenly immersed for 5h, and then dried in an oven at 60°C. Then, they are immersed in 100 parts of rhodium chloride solution, mixed and evenly immersed for 5h, and then dried in an oven at 60°C. Finally, they are immersed in 100 parts of phosphotungstic acid solution, mixed and evenly immersed for 5h, and then calcined at 400°C for 2h to finally obtain a Cu-Rh-phosphotungstic acid supported catalyst.

[0051] According to weight, 25 parts of catering waste oil, 10 parts of acidified oil, 5 parts of soybean oil, 45 parts of prepared microbial oil, and 1.2 parts of Cu-Rh-phosphotungstic acid supported catalyst were added, the air in the reactor and pipeline was purged with nitrogen, 2 parts of methanol were added and 3 parts of hydrogen collected in closed fermentation tanks were introduced, stirred and mixed, and then a one-step hydrogenation reaction was carried out. The reaction conditions were temperature 350°C, pressure 4.5MPa, stirring rate 550rpm, and reaction time 6h to prepare biojet fuel.

[0052] Example 4

[0053] In terms of molar proportions, 5 parts of Clostridium pasteurianum solution, 5 parts of Clostridium beijerinckii solution, 5 parts of Clostridium butyricum solution, 30 parts of anaerobic methanophilic bacteria solution, and 30 parts of Propionibacterium solution were inoculated into the activated culture solution, and cultured in a constant temperature shaker at a temperature of 35°C and a speed of 180 r / min for 2 days to obtain the activated mixed bacteria containing Clostridium. The activated mixed bacteria containing Clostridium were inoculated into the seed culture medium at an inoculation rate of 5%, and cultured in a constant temperature shaker at a temperature of 35°C and a speed of 180 r / min for 3 days to obtain the expanded culture mixed bacteria containing Clostridium for later use.

[0054] By volume, 50 parts of the mixed bacteria containing Clostridium after the expanded culture, 50 parts of the byproduct gas of bio-jet fuel and crude glycerol were put into a closed fermentation tank, and cultured at a temperature of 35°C and a speed of 180r / min for 2 days to obtain the fermentation liquid. The hydrogen produced during the period was collected for the subsequent preparation of bio-jet fuel. The fermentation liquid was centrifuged to discard the supernatant, and then the wet cells were washed with deionized water and dried to constant weight at 105°C. The extraction was carried out with a mixed solution of 100 parts of chloroform and methanol as the extractant, in which the volume ratio of chloroform to methanol was 2:1, and 10 parts of 3% sulfuric acid solution were added and heated at 105°C to extract the microbial oil.

[0055] By volume, 1.5 parts of hexadecyltrimethylammonium bromide were added to 30 parts of zinc nitrate solution to control the morphology and porosity of the final product, and the mixture was stirred evenly to obtain a transparent solution. 12 parts of 25% NH3·H2O were slowly added to the prepared solution to perform hydrolysis and polycondensation reactions to form a sol. The gel was placed in a sealed container, allowed to stand at room temperature for 24 hours, and then placed in an oven for heat treatment at 80°C to remove the solvent and form a dry gel. Then, high-temperature calcination is carried out at 400°C for 2h to remove organic components and form a porous ZnO carrier, and then step-by-step impregnation is carried out. 50 parts of the prepared porous ZnO carrier are immersed in 100 parts of copper nitrate solution, mixed and evenly immersed for 5h, and then dried in an oven at 60°C. Then, they are immersed in 100 parts of rhodium chloride solution, mixed and evenly immersed for 5h, and then dried in an oven at 60°C. Finally, they are immersed in 100 parts of phosphotungstic acid solution, mixed and evenly immersed for 5h, and then calcined at 400°C for 2h to finally obtain a Cu-Rh-phosphotungstic acid supported catalyst.

[0056] According to weight, 40 parts of catering waste oil, 15 parts of acidified oil, 15 parts of corn oil, 15 parts of prepared microbial oil, and 1.3 parts of Cu-Rh-phosphotungstic acid supported catalyst were added, and the air in the high-temperature and high-pressure reactor and pipelines was purged with nitrogen. 4 parts of methanol were added and 1 part of hydrogen collected in a closed fermentation tank was introduced, stirred and mixed, and then a one-step hydrogenation reaction was carried out. The reaction conditions were temperature 400°C, pressure 5MPa, stirring rate 550rpm, and the reaction time was 7h to prepare bio-jet fuel.

[0057] Example 5

[0058] In terms of molar proportions, 5 parts of Clostridium pasteurianum solution, 5 parts of Clostridium beijerinckii solution, 5 parts of Clostridium butyricum solution, 60 parts of anaerobic methanophilic bacteria solution, and 45 parts of Propionibacterium solution were inoculated into the activated culture solution prepared above, and cultured in a constant temperature shaker at a temperature of 35°C and a rotation speed of 180 r / min for 2 days to obtain an activated mixed cell containing Clostridium. The activated mixed cell containing Clostridium was inoculated into a seed culture medium at an inoculation rate of 5%, and cultured in a constant temperature shaker at a temperature of 35°C and a rotation speed of 180 r / min for 3 days to obtain an expanded culture mixed cell containing Clostridium for later use.

[0059] By volume, 50 parts of the mixed bacteria containing Clostridium after the expanded culture, 50 parts of the byproduct gas of bio-jet fuel and crude glycerol were put into a closed fermentation tank, cultured at a temperature of 35°C and a speed of 180r / min for 2 days to obtain the fermentation liquid, and the hydrogen produced during the collection period was used for the subsequent preparation of bio-jet fuel. The fermentation liquid was centrifuged to discard the supernatant, and then the wet cells were washed with deionized water and dried to constant weight at 105°C. The extraction was carried out with a mixed solution of 100 parts of chloroform and methanol as the extractant, wherein the volume ratio of chloroform to methanol was 2:1, and 20 parts of 3% sulfuric acid solution were added and heated at 105°C to extract the microbial oil.

[0060] By volume, 1.5 parts of hexadecyltrimethylammonium bromide were added to 30 parts of zinc nitrate solution to control the morphology and porosity of the final product, and the mixture was stirred evenly to obtain a transparent solution. 12 parts of 25% NH3·H2O were slowly added to the prepared solution to perform hydrolysis and polycondensation reactions to form a sol. The gel was placed in a sealed container, allowed to stand at room temperature for 24 hours, and then placed in an oven for heat treatment at 80°C to remove the solvent and form a dry gel. Then, high-temperature calcination is carried out at 400°C for 2h to remove organic components and form a porous ZnO carrier, and then step-by-step impregnation is carried out, 50 parts of the prepared porous ZnO carrier are immersed in 100 parts of copper nitrate solution, mixed and evenly immersed for 5h, and then dried in an oven at 60°C, and then immersed in 100 parts of rhodium chloride solution, mixed and evenly immersed for 5h, and then dried in an oven at 60°C, and finally immersed in 100 parts of phosphotungstic acid solution, mixed and evenly immersed for 5h, and then calcined at 400°C for 2h to finally obtain a Cu-Rh-phosphotungstic acid / ZuO supported catalyst.

[0061] According to weight, 20 parts of catering waste oil, 12 parts of acidified oil, 8 parts of corn oil, 25 parts of prepared microbial oil, and 1 part of Cu-Rh-phosphotungstic acid supported catalyst were added, and the air in the high-temperature and high-pressure reactor and pipelines was purged with nitrogen. 1 part of methanol was added and 4 parts of hydrogen collected in closed fermentation tanks were introduced, stirred and mixed, and then a one-step hydrogenation reaction was carried out. The reaction conditions were temperature 400°C, pressure 4MPa, stirring rate 550rpm, and the reaction time was 3.5h to prepare bio-jet fuel.

[0062] Example 6

[0063] In terms of molar proportions, 5 parts of Clostridium pasteurianum solution, 5 parts of Clostridium beijerinckii solution, 5 parts of Clostridium butyricum solution, 60 parts of anaerobic methanophilic bacteria solution, and 60 parts of Propionibacterium solution were inoculated into the activated culture solution, and cultured in a constant temperature shaker at a temperature of 35°C and a speed of 180 r / min for 2 days to obtain the activated mixed bacteria containing Clostridium. The activated mixed bacteria containing Clostridium were inoculated into the seed culture medium at an inoculation rate of 5%, and cultured in a constant temperature shaker at a temperature of 35°C and a speed of 180 r / min for 3 days to obtain the expanded culture mixed bacteria containing Clostridium for later use.

[0064] By volume, 50 parts of the mixed bacteria containing Clostridium after the expanded culture, 50 parts of the byproduct gas of bio-jet fuel and crude glycerol were put into a closed fermentation tank, cultured at a temperature of 35°C and a speed of 180r / min for 2 days to obtain the fermentation liquid, and the hydrogen produced during the collection period was used for the subsequent preparation of bio-jet fuel. The fermentation liquid was centrifuged to discard the supernatant, and then the wet cells were washed with deionized water and dried to constant weight at 105°C. The extraction was carried out with a mixed solution of 100 parts of chloroform and methanol as the extractant, wherein the volume ratio of chloroform to methanol was 2:1, and 20 parts of 3% sulfuric acid solution were added and heated at 105°C to extract the microbial oil.

[0065] By volume, 1.5 parts of hexadecyltrimethylammonium bromide were added to 30 parts of zinc nitrate solution to control the morphology and porosity of the final product, and the mixture was stirred evenly to obtain a transparent solution. 12 parts of 25% NH3·H2O were slowly added to the prepared solution to perform hydrolysis and polycondensation reactions to form a sol. The gel was placed in a sealed container, allowed to stand at room temperature for 24 hours, and then placed in an oven for heat treatment at 80°C to remove the solvent and form a dry gel. Then, high-temperature calcination is carried out at 400°C for 2h to remove organic components and form a porous ZnO carrier, and then step-by-step impregnation is carried out. 50 parts of the prepared porous ZnO carrier are immersed in 100 parts of copper nitrate solution, mixed and evenly immersed for 5h, and then dried in an oven at 60°C. Then, they are immersed in 100 parts of rhodium chloride solution, mixed and evenly immersed for 5h, and then dried in an oven at 60°C. Finally, they are immersed in 100 parts of phosphotungstic acid solution, mixed and evenly immersed for 5h, and then calcined at 400°C for 2h to finally obtain a Cu-Rh-phosphotungstic acid supported catalyst.

[0066] According to weight, 20 parts of catering waste oil, 20 parts of acidified oil, 10 parts of sunflower oil, 35 parts of prepared microbial oil, and 1.1 parts of Cu-Rh-phosphotungstic acid supported catalyst were added, and the air in the high-temperature and high-pressure reactor and pipelines was purged with nitrogen. 2 parts of methanol were added and 3 parts of hydrogen collected in closed fermentation tanks were introduced, stirred and mixed, and then a one-step hydrogenation reaction was carried out. The reaction conditions were temperature 400°C, pressure 4MPa, stirring rate 550rpm, and the reaction time was 6.5h to prepare biojet fuel.

[0067] The present invention also carries out comparative examples and related tests.

[0068] Comparative Example 1

[0069] The steps are basically the same as those in Example 1, except that the catalyst used in the one-step hydrogenation reaction in the preparation of bio-jet fuel is replaced by a direct mixture of Cu, Rh, phosphotungstic acid, and ZnO, and the remaining raw materials and steps are consistent with those in Example 1, and finally bio-jet fuel is prepared.

[0070] Comparative Example 2

[0071] The steps are basically the same as those in Example 1, except that the catalyst used in the one-step hydrogenation reaction in the preparation of bio-jet fuel is replaced by Cu powder, and the remaining raw materials and steps are consistent with those in Example 1, and finally bio-jet fuel is prepared.

[0072] Comparative Example 3

[0073] By volume, 1.5 parts of hexadecyltrimethylammonium bromide were added to 30 parts of zinc nitrate solution to control the morphology and porosity of the final product, and the mixture was stirred evenly to obtain a transparent solution. 12 parts of 25% NH3·H2O were slowly added to the prepared solution to perform hydrolysis and polycondensation reactions to form a sol. The gel was placed in a sealed container, allowed to stand at room temperature for 24 hours, and then placed in an oven for heat treatment at 80°C to remove the solvent and form a dry gel. Then, high-temperature calcination is carried out at 400°C for 2h to remove organic components and form a porous ZnO carrier, and then step-by-step impregnation is carried out. 50 parts of the prepared porous ZnO carrier are immersed in 100 parts of copper nitrate solution, mixed and evenly immersed for 5h, and then dried in an oven at 60°C. Then, they are immersed in 100 parts of rhodium chloride solution, mixed and evenly immersed for 5h, and then dried in an oven at 60°C. Finally, they are immersed in 100 parts of phosphotungstic acid solution, mixed and evenly immersed for 5h, and then calcined at 400°C for 2h to finally obtain a Cu-Rh-phosphotungstic acid supported catalyst.

[0074] According to weight, 75 parts of waste cooking oil, 1 part of acidified oil, 4 parts of soybean oil, and 0.7 parts of Cu-Rh-phosphotungstic acid supported catalyst were added, the air in the reactor and pipeline was purged with nitrogen, 5 parts of liquid hydrogen were added and stirred, and then a one-step hydrogenation reaction was carried out. The reaction conditions were temperature 250°C, pressure 2MPa, stirring rate 550rpm, and the reaction time was 4h to prepare biojet fuel.

[0075] Comparative Example 4

[0076] By volume, 1.5 parts of hexadecyltrimethylammonium bromide were added to 30 parts of zinc nitrate solution to control the morphology and porosity of the final product, and the mixture was stirred evenly to obtain a transparent solution. 12 parts of 25% NH3·H2O were slowly added to the prepared solution to perform hydrolysis and polycondensation reactions to form a sol. The gel was placed in a sealed container, allowed to stand at room temperature for 24 hours, and then placed in an oven for heat treatment at 80°C to remove the solvent and form a dry gel. Then, high-temperature calcination is carried out at 400°C for 2h to remove organic components and form a porous ZnO carrier, and then step-by-step impregnation is carried out. 50 parts of the prepared porous ZnO carrier are immersed in 100 parts of copper nitrate solution, mixed and evenly immersed for 5h, and then dried in an oven at 60°C. Then, they are immersed in 100 parts of rhodium chloride solution, mixed and evenly immersed for 5h, and then dried in an oven at 60°C. Finally, they are immersed in 100 parts of phosphotungstic acid solution, mixed and evenly immersed for 5h, and then calcined at 400°C for 2h to finally obtain a Cu-Rh-phosphotungstic acid supported catalyst.

[0077] According to weight, 75 parts of waste cooking oil, 1 part of acidified oil, 4 parts of soybean oil, and 0.7 parts of Cu-Rh-phosphotungstic acid supported catalyst were added, the air in the reactor and pipeline was purged with nitrogen, 5 parts of methanol were added and stirred, and then a one-step hydrogenation reaction was carried out. The reaction conditions were temperature 250°C, pressure 2MPa, stirring rate 550rpm, and the reaction was carried out for 4h to prepare biojet fuel.

[0078] The yield and related performance tests were conducted on the bio-jet fuel prepared in Examples 1 to 6 and Comparative Examples 1 to 4.

[0079] The bio-jet fuels prepared in Examples 1 to 6 and Comparative Examples 1 to 4 were subjected to product composition analysis and yield calculation (C9 to C16 hydrocarbon yield) according to GB / T32210-2015. The results are shown in Figure 1~Figure 2 .

[0080] Figure 1 The figure is a comparison chart of the bio-jet kerosene yield (C9-C16 hydrocarbon yield) in the product of the one-step hydrogenation reaction to produce bio-jet kerosene using the catalysts used in Comparative Examples 1 and 2 and the Cu-Rh-phosphotungstic acid supported catalyst prepared in Example 1. It can be seen from the figure that the yield of bio-jet kerosene in Example 1 can reach 70.12%. In Comparative Example 1, the Cu-Rh-phosphotungstic acid / ZuO supported catalyst is not used, but the yield of bio-jet kerosene after the one-step hydrogenation reaction is catalyzed by directly mixing Cu, Rh, phosphotungstic acid and ZuO components is only 41.27%. In Comparative Example 2, the Cu-Rh-phosphotungstic acid / ZuO supported catalyst is not used, but Cu powder is used to catalyze the one-step hydrogenation reaction, and its yield is only 38.22%. From the comparison of the results, it can be seen that the yield of bio-jet kerosene is significantly improved under the catalytic action of the Cu-Rh-phosphotungstic acid supported catalyst.

[0081] Figure 2A comparison chart of the bio-jet fuel yield (C9-C16 hydrocarbon yield) in the production of bio-jet fuel using liquid hydrogen or methanol to provide hydrogen in Comparative Examples 3 and 4 and the production of bio-jet fuel using methanol at high temperature and high pressure and fermentation of mixed Clostridium-containing bacteria to provide hydrogen in Example 1 is provided. It can be seen from the chart that the yield of bio-jet fuel in Example 1 can reach 70.12%, while that in Comparative Example 3 is only 37.51%, and that in Comparative Example 4 is only 28.23%, and the yields are significantly lower than those in Example 1.

[0082] The physical and chemical properties of the bio-jet fuels of Examples 1 to 6 and Comparative Examples 1 to 4 were measured, and relevant performance tests were conducted in accordance with the national standard GB / 6537-2018, requiring a density (20°C) of 775-830 kg / m 3 , freezing point ≤-47℃, flash point ≥38℃, kinematic viscosity (-20℃) ≤8mm 2 / s, net calorific value ≥42.8MJ / kg, the final test results are shown in Table 1.

[0083] Table 1: Test results of relevant properties of bio-jet fuel prepared in Examples 1 to 6 and Comparative Examples 1 to 4

[0084]

[0085] It can be seen from Table 1 that the supported catalysts used in Comparative Examples 1 and 2 have a greater impact on the density, freezing point, kinematic viscosity and net calorific value of the produced bio-jet fuel. Comparative Examples 3 and 4 use liquid hydrogen and methanol at high temperature and high pressure to supply hydrogen, respectively, which have a certain impact on the flash point of the bio-jet fuel. Taking all factors into consideration, the performance of the bio-jet fuel prepared in Examples 1 to 6 is significantly higher than that prepared in Comparative Examples 1 to 4, and the density, freezing point, flash point, kinematic viscosity and net calorific value of Examples 1 to 6 meet the requirements of the national standard GB / 6537-2018, and can also meet the HEFA-SPK product index requirements in the international standard ASTM7566-2022.

[0086] Combined with the data in Table 1, the freezing point of the bio-jet fuel obtained in Comparative Examples 1 and 2 is higher than that in Examples 1 to 6, because the catalysts used in Comparative Examples 1 and 2 are different from those in Examples 1 to 6, and the Cu-Rh-phosphotungstic acid supported catalyst has a certain effect on the freezing point; the difference between Comparative Examples 3 and 4 and Examples 1 to 6 is that in Comparative Example 3, liquid hydrogen is used for hydrogen supply, and in Comparative Example 4, methanol is used for high temperature and high pressure hydrogen production, and the mixed bacteria containing Clostridium are no longer used to produce microbial oils, which also has a certain effect on the flash point of the product. In comparison, the bio-jet fuel produced in Examples 1 to 6 has a higher density, flash point, and net calorific value, and thus better combustion performance.

[0087] The components of the bio-jet fuels of Examples 1 to 6 and Comparative Examples 1 to 4 were determined. According to the requirements of the national standard GB / T6537-2018, the total acid value is ≤0.015 mg / g, the volume fraction of aromatics is ≤20.0%, and the volume fraction of olefins is ≤5.0%. The relevant component tests were performed, and the test results are shown in Table 2.

[0088] Table 2: Test results of relevant components of bio-jet fuel prepared in Examples 1 to 6 and Comparative Examples 1 to 4

[0089]

[0090] It can be seen from Table 2 that the components of the bio-jet fuel prepared in Examples 1 to 6 meet the HEFA-SPK product index requirements in the national standards GB / 6537-2018 and ASTM / 7566-2022.

[0091] Combined with the data in Table 1, the volume fractions of aromatics and olefins in Comparative Examples 1 to 4 are significantly higher than those in Examples 1 to 6, indicating that the Cu-Rh-phosphotungstic acid supported catalyst can more effectively reduce the content of olefins and aromatics and make the volume fractions of carbon and hydrogen higher, thereby making the bio-jet fuels in Examples 1 to 6 have higher purity and higher yield.

[0092] The above are preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for producing bio-jet fuel, characterized in that: The following steps are involved: Step S1: generating hydrogen and fermentation liquid by fermentation of mixed bacteria containing Clostridium, and collecting hydrogen for later use; centrifuging the fermentation liquid, discarding the supernatant, washing with deionized water, drying at 105° C. to constant weight, extracting with a mixed solution of chloroform and methanol, adding 3% sulfuric acid solution, and heating at 105° C. to extract to obtain microbial oil; the mixed bacteria containing Clostridium include Clostridium pasteurianum, Clostridium beijerinckii, Clostridium butyricum, anaerobic methanophilic bacteria and Propionibacterium; Step S2: immersing the porous ZnO support in a copper nitrate solution and mixing, immersing the support in a 60°C oven for 5 hours, drying the support in a 60°C oven, immersing the support in a rhodium chloride solution and mixing, immersing the support in a 60°C oven for 5 hours, drying the support in a 60°C oven, immersing the support in a phosphotungstic acid solution and mixing, immersing the support in a 5 hour oven, calcining the solution at 400°C for 2 hours, and obtaining a Cu-Rh-phosphotungstic acid supported catalyst; Step S3: putting microbial oil, restaurant waste oil, acidified oil, vegetable oil, Cu-Rh-phosphotungstic acid supported catalyst and methanol into a high-temperature and high-pressure reactor, ventilating, introducing the hydrogen collected in step S1, reacting to obtain bio-jet fuel; the bio-jet fuel comprises the following raw materials in parts by weight: 1-4 parts of methanol, 1-4 parts of hydrogen collected in step S1, 10-40 parts of restaurant waste oil, 1-20 parts of acidified oil, 4-15 parts of vegetable oil, 0.7-1.6 parts of Cu-Rh-phosphotungstic acid supported catalyst, and 15-65 parts of microbial oil.

2. The method for producing bio-jet fuel according to claim 1, characterized in that: In the step S1, the mixed bacteria containing Clostridium species are expanded and cultured, and then mixed with the bio-jet fuel by-product in a closed fermenter to obtain a fermentation liquid, and the hydrogen produced in the fermenter is collected.

3. The method for producing bio-jet fuel according to claim 2, characterized in that: The expansion culture time is 3 days, the expansion culture temperature is 35° C., and the expansion culture process is carried out at a rotation speed of 180 r / min; the fermentation time is 2 days, the fermentation temperature is 35° C., and the fermentation process is carried out at a rotation speed of 180 r / min.

4. The method for producing bio-jet fuel according to claim 1, characterized in that: In step S2, the porous ZnO carrier is prepared by uniformly mixing zinc nitrate solution and hexadecyltrimethylammonium bromide solution, adding 25% NH3·H2O to form a gel, standing for 24 hours, heat-treating at 80°C, and calcining at 400°C.

5. The method for producing bio-jet fuel according to claim 1, characterized in that: In the step S3, after adding the Cu-Rh-phosphotungstic acid supported catalyst, the air in the high-temperature and high-pressure reactor and the pipeline is purged with nitrogen, methanol is added and the hydrogen collected in the closed fermentation tank is introduced to carry out a one-step hydrogenation reaction under stirring to obtain bio-jet fuel; wherein the high-temperature and high-pressure reaction conditions are a temperature of 250-400°C, a pressure of 2-5MPa, a stirring rate of 550rpm, and a stirring time of 3.5-7h.

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