Preparation method for refining biodiesel from animal waste

Abstract

The invention relates to a preparation method for refining biodiesel from animal waste, and belongs to the technical field of biodiesel. The preparation method comprises the following steps: (1) carrying out anaerobic heating and drying on raw materials, crushing the dried raw materials into powder, mixing the powder with a fermentation product, spreading the mixture, and carrying out aerobic fermentation to obtain a pretreated raw material; (2) heating and sterilizing the pretreated raw materials, pressing the pretreated raw materials into square blocks, gasifying the square blocks in a gasification furnace, cooling mixed gas through a pipeline, and separating fatty acid and tar from condensed liquid by using a nanofiltration membrane; (3) introducing the uncondensed gas into a Fischer-Tropsch synthesis tower after passing through a purifying agent, and synthesizing biodiesel under the action of a catalyst; and (4) carrying out catalytic hydrogenation on fatty acid, adding into an esterification reaction kettle, adding methanol and amino acid ionic liquid, stirring, heating, cooling, separating condensate by using a separating funnel, taking supernatant liquid, washing by using hot water, heating to remove moisture to obtain biodiesel, and combining the biodiesel with the biodiesel in the step (3).

Description

Technical Field

[0001] The present invention belongs to the technical field of biodiesel, and relates to a preparation method for refining animal feces into biodiesel. Background Art

[0002] Animal feces mainly contain organic matter (15%-25%), cellulose, hemicellulose and lignin, as well as a small amount of undigested protein and fat, and the content of undigested cellulose in herbivore feces is relatively high; it also contains a large amount of elements such as nitrogen, phosphorus, potassium and trace elements such as calcium, magnesium, sulfur and zinc; in addition, there are a large number of bacteria and heavy metals in feces, which need to be scientifically treated to avoid soil and water pollution.

[0003] At present, the main treatment methods for feces are aerobic composting and vermicomposting, while the research on using feces to prepare biodiesel is very few.

[0004] The raw materials for biodiesel include animal and vegetable oils and fats, waste oils and fats, microbial oils and fats, as well as waste biomass such as straw. Due to different types of raw materials, the preparation processes of biodiesel are also different. The transesterification method uses animal and vegetable oils and fats as raw materials, and uses lower alcohols to react with triglycerides under the action of a catalyst to generate fatty acid methyl esters and glycerol; the gas synthesis method: the biodiesel production technology mainly gasifies biomass raw materials such as straw-like agricultural and forestry waste and then synthesizes biodiesel. Specifically, the biomass raw materials enter the gasifier after simple crushing and processing, and undergo high-temperature cracking and redox reactions in gasification media such as air, oxygen or water vapor to generate synthesis gas containing substances such as CO and H2. After the synthesis gas is purified, through processes such as catalysis, hydrogenation and Fischer-Tropsch synthesis technology, biodiesel is finally synthesized. During the gasification process, as the temperature rises to 400-600 °C, the chemical bonds in the lignin molecule, especially the ether bond and carbon-carbon bond, break at high temperature, generating non-condensable gases and small molecule tars, and these tars gradually convert to macromolecular polycyclic aromatic hydrocarbon tars after further cracking.

[0005] And in the Fischer-Tropsch synthesis reaction, the catalyst has a great influence on the synthesis gas through the Fischer-Tropsch synthesis reaction path, and there are side reactions such as methanation during the synthesis process. The main reactions involved in the Fischer-Tropsch synthesis reaction are: CO + 3H2 → CH4 + H2O (1); nCO + (2n + 1)H2 → CnH2n+2 + nH2O (2); nCO + 2nH2 → CnH2n + nH2O (3); CO + H2O → CO2 + H2. In addition, using a catalyst can directionally adjust the carbon atom number distribution in the product. Therefore, the catalyst has both metal active sites that promote the reaction of carbon monoxide hydrogenation to form carbon chains, and acidic sites that promote the isomerization reaction of carbon chain elongation.

[0006] Microbial oil, also known as single-cell oil, refers to the large amount of oil produced in bacteria, yeast, molds, algae and other microorganisms under certain conditions by using hydrocarbons and ordinary oils as carbon sources. The fatty acid composition of most microbial oils is similar to that of general vegetable oils, mainly composed of C16-C18 fatty acids. However, in inferior substrates, the components are often complex and contain a large number of substances that inhibit the growth and metabolism of strains, making it difficult for the strains to effectively utilize the carbon and nitrogen sources in the substrate; the relatively thick yeast cell wall has a certain resistance to most solvents, and it is necessary to break the yeast cell wall and cell membrane before the extraction process. Currently, the extraction methods mainly include chemical methods (acid heat, alkali heat, surfactants and osmotic pressure methods, etc.), enzymatic methods and physical methods (ultrasonic, high-pressure homogenization, bead milling and microwave, etc.), but these extraction methods are not applicable to single-cell oils in feces. Therefore, based on the above technologies, the present invention is further optimized to provide a preparation method for refining animal feces into biodiesel. Summary of the Invention

[0007] The present invention relates to a preparation method for refining animal feces into biodiesel, belonging to the technical field of biodiesel. The present invention discloses that the preparation method of biodiesel includes the following steps: (1) The raw materials are dried by anaerobic heating and crushed into powders, mixed with the fermentation products, spread out and then subjected to aerobic fermentation to obtain the pretreated raw materials; (2) The pretreated raw materials are heated for sterilization, pressed into blocks and then put into a gasifier for gasification. The mixed gas is cooled through a pipeline, and the condensed liquid is separated into fatty acids and tar by a nanofiltration membrane; (3) The uncondensed gas is passed through a purifying agent and then introduced into a Fischer-Tropsch synthesis tower, and biodiesel is synthesized under the action of a catalyst; (4) The fatty acids are catalytically hydrogenated, then added to an esterification reaction kettle, methanol and amino acid ionic liquid are added and stirred and heated. After cooling, the condensed liquid is separated by a separating funnel, the upper layer liquid is taken and washed with hot water, and after heating to remove the water, it is biodiesel, which is combined with the biodiesel in step (3).

[0008] The object of the present invention can be achieved by the following technical solutions: A preparation method for refining animal feces into biodiesel, the preparation method for refining animal feces into biodiesel includes the following steps: (1) The raw materials are dried by anaerobic heating and crushed into powders, mixed with the fermentation products, spread out and then subjected to aerobic fermentation to obtain the pretreated raw materials; (2) The pretreated raw materials are heated for sterilization, pressed into blocks and then put into a gasifier for gasification. The generated mixed gas is cooled through a pipeline, and the condensed liquid is separated into fatty acids and tar by a nanofiltration membrane; (3) The uncondensed gas is passed through a purifying agent and then introduced into a Fischer-Tropsch synthesis tower, and biodiesel is synthesized under the action of a catalyst; (4) The fatty acids in step (2) are catalytically hydrogenated and then put into an esterification reactor. Methanol and amino acid ionic liquid are added, and the mixture is stirred and heated. After cooling, the condensate is separated using a separating funnel. The upper layer liquid is taken and washed with hot water. Then, the water is removed by heating to obtain biodiesel, which is combined with the biodiesel in step (3) to complete the whole process.

[0009] Further, in step (1), the raw materials are human feces, poultry feces, and livestock feces. The temperature of the anaerobic heating is 160 - 180 °C, the water content of the powder is 35 - 45%, the mass ratio of the powder to the fermented product is 100 - 120:1 - 3, the thickness of the paving is 0.5 - 0.7 m, and the temperature, relative air humidity, and time of the aerobic fermentation are 28 - 32 °C, 75 - 85%, and 24 - 36 h respectively.

[0010] Further, the preparation method of the fermented product is as follows: The strain is first inoculated into a solid medium and cultured at 30 - 35 °C for 72 - 84 h, then the colonies are scraped and inoculated into a liquid medium and cultured at 30 °C for 40 - 50 h. Subsequently, the solid and liquid are separated to obtain its bacterial liquid, which is mixed with starch and fermented at room temperature for 3 - 5 h to form the fermented product.

[0011] Further, the mass ratio of the strain to the solid medium is 1:20. The solid medium consists of glucose, yeast powder, peptone, and agar powder with a mass ratio of 2:1:1:1.8 - 2. The mass ratio of the colonies to the liquid medium is 1:100. The liquid medium consists of glucose, yeast powder, peptone, and deionized water with a mass ratio of 2:1:1:3 - 5. The solid - liquid ratio of the starch to the bacterial liquid is 1:2 - 3 kg / mL, where the concentration of the bacterial liquid is 1.5 - 1.8×10 8 CFU / mL, and the strain is Lipomyces starkeyi.

[0012] Further, in step (2), the temperature and time of the heating and sterilization are 70 - 80 °C and 30 - 50 min respectively. The temperature of the gasification is 400 - 600 °C. The mixed gas includes CO, H2, CH4, fatty acids, and tar. The temperature of the cooling is 120 - 150 °C, and the pressure of the nanofiltration membrane is 2 - 3 Mpa.

[0013] Further, in step (3), the purifying agent is a methane adsorbent. The temperature and pressure of the Fischer - Tropsch synthesis tower are 180 - 220 °C and 1 - 3 Mpa respectively. The preparation method of the catalyst is as follows: Cobalt nitrate solution, manganese dioxide, and porous silica are mixed and dried after standing to obtain the catalyst.

[0014] Further, the concentration of the cobalt nitrate solution is 50 - 100 g / L, the mass ratio of the cobalt nitrate solution, manganese dioxide, and porous silica is 3 - 5:0.2:10 - 14, the standing time is 12 - 20 h, and the drying temperature is 120 - 130 °C.

[0015] Further, in the step (4), the catalyst for catalytic hydrogenation is metallic platinum, the mass ratio of the fatty acid, methanol, and amino acid ionic liquid is 1:1 - 4:0.05, where the amino acid ionic liquid is glutamic acid ionic liquid, and the mass fraction of the glutamic acid ionic liquid is 10 - 12%.

[0016] Further, in the step (4), the heating temperature and time are 100 - 110 °C and 2 - 3 h respectively, the temperature of the hot water is 70 - 80 °C, and the temperature for heating to remove moisture is 110 - 120 °C.

[0017] Advantages of the present invention: 1. In the present invention, first, through fecal fermentation, substances such as oils and fats and proteins in feces that are difficult to gasify into syngas are converted into fatty acids with C16 - C18, and then biodiesel is generated with methanol. Through the treatment of the above steps, not only can bacteria be killed, but heavy metals in the ash can be simply separated and recovered, solving the environmental pollution problem. At the same time, syngas passes through a Fischer - Tropsch synthesis tower to obtain biodiesel. The present invention synthesizes biodiesel through a dual process, improving the conversion rate of biodiesel. 2. In the fecal fermentation process, Lipomyces starkeyi is used and fermented under specific conditions, effectively overcoming the inhibition of the growth of the strain. By directly destroying the cell structure of Lipomyces starkeyi through high - temperature gasification, fatty acids are fully released, while other components of the cells are gasified into syngas, greatly improving the extraction rate of fatty acids. 3. The nanofiltration membrane of the present invention effectively separates tar and fatty acids, with a simple method and improved purity of fatty acids. In addition, the condensate gas before entering the Fischer - Tropsch synthesis tower is purified by a methane adsorbent, purifying the syngas, preventing catalyst poisoning during the Fischer - Tropsch synthesis process, and reducing by - products. 4. During the preparation of the catalyst, manganese dioxide is added, improving the selectivity for biodiesel. At the same time, it can interact with the O atoms adsorbing CO, thereby promoting the adsorption and dissociation of CO, and further improving the conversion rate of biodiesel. Specific embodiments

[0018] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following combines examples to detail the specific embodiments, structures, features, and their effects of the present invention as follows.

[0019] The Yarrowia lipolytica involved in the present invention was purchased from the China General Microbiological Culture Collection Center, with the preservation number CGMCC 2.229; the yeast powder was purchased from Shandong Kunteng Chemical Co., Ltd.; the peptone was purchased from Shandong Qiyuan Chemical Co., Ltd.; the agar powder was purchased from Langfang Qianyao Technology Co., Ltd.; the nanofiltration membrane was purchased from Xiamen Jiarong Technology Co., Ltd., and the model and maximum passing molecular weight were S-3014 and 400 respectively; the methane adsorbent was purchased from Shandong Zhongmei Intelligent Equipment Co., Ltd.; the porous silica was purchased from Qinghe County Chaotai Metal Materials Co., Ltd., and the CAS number was 1889-4-2;.

[0020] Example 1

[0021] A preparation method of biodiesel refined from animal feces, the preparation method of biodiesel refined from animal feces includes the following steps: (1) The raw materials are dried by anaerobic heating, crushed into powder, mixed with the fermented product, spread out and then subjected to aerobic fermentation to obtain the pretreated raw materials; (2) The pretreated raw materials are heated and sterilized, pressed into blocks and then put into a gasifier for gasification. The generated mixed gas is cooled through a pipeline, and the condensed liquid is separated by a nanofiltration membrane to obtain fatty acids and tar; (3) The uncondensed gas is passed through a purifying agent and then introduced into a Fischer-Tropsch synthesis tower, and biodiesel is synthesized under the action of a catalyst; (4) The fatty acids in step (2) are catalytically hydrogenated, then put into an esterification reaction kettle, methanol and amino acid ionic liquid are added, stirred and heated, and after cooling, the condensed liquid is separated by a separating funnel. The upper layer liquid is taken and washed with hot water, and then the water is removed by heating to obtain biodiesel, which is combined with the biodiesel in step (3) to complete the whole process.

[0022] In the step (1), the raw materials are human feces, poultry feces and livestock feces. The temperature of the anaerobic heating is 160 °C, the water content of the powder is 35%, the mass ratio of the powder to the fermented product is 100:1, the thickness of the spread is 0.7 m, and the temperature, air relative humidity and time of the aerobic fermentation are 32 °C, 85% and 36 h respectively.

[0023] The preparation method of the fermented product is as follows: The strain is first inoculated into a solid medium and cultured at 35 °C for 84 h, then the colonies are scraped and inoculated into a liquid medium and cultured at 30 °C for 50 h. Subsequently, the solid-liquid separation is carried out to obtain the bacterial liquid, which is mixed with starch and fermented at room temperature for 5 h to form the fermented product.

[0024] The mass ratio of the strain to the solid medium is 1:20. The solid medium is composed of glucose, yeast powder, peptone, and agar powder with a mass ratio of 2:1:1:1.2. The mass ratio of the colony to the liquid medium is 1:100. The liquid medium is composed of glucose, yeast powder, peptone, and deionized water with a mass ratio of 2:1:1:5. The solid-liquid ratio of starch to the bacterial liquid is 1:3 kg / mL, where the concentration of the bacterial liquid is 1.8×10 8 CFU / mL. The strain is Lipomyces starkeyi.

[0025] In step (2), the temperature and time for heating and sterilization are 80°C and 50 min respectively. The temperature for gasification is 600°C. The mixed gas includes CO, H2, CH4, fatty acids, and tar. The temperature for cooling is 150°C. The pressure of the nanofiltration membrane is 3 Mpa.

[0026] In step (3), the purifying agent is a methane adsorbent. The temperature and pressure of the Fischer-Tropsch synthesis tower are 220°C and 3 Mpa respectively. The preparation method of the catalyst is as follows: A cobalt nitrate solution, manganese dioxide, and porous silica are mixed, and after standing, it is dried to obtain the catalyst.

[0027] The concentration of the cobalt nitrate solution is 100 g / L. The mass ratio among the cobalt nitrate solution, manganese dioxide, and porous silica is 5:0.2:14. The standing time is 20 h. The drying temperature is 130°C.

[0028] In step (4), the catalyst for catalytic hydrogenation is platinum metal. The mass ratio of fatty acids, methanol, and amino acid ionic liquid is 1:4:0.05, where the amino acid ionic liquid is glutamic acid ionic liquid, and the mass fraction of the glutamic acid ionic liquid is 12%.

[0029] In step (4), the heating temperature and time are 110°C and 3 h respectively. The temperature of the hot water is 80°C. The temperature for heating to remove moisture is 120°C.

[0030] The preparation method of the glutamic acid ionic liquid is as follows: Glutamic acid and triethylamine are mixed according to a mass ratio of 1:1, and then dehydrated to obtain the glutamic acid ionic liquid.

[0031] Example 2

[0032] A preparation method for refining animal feces into biodiesel. The preparation method for refining animal feces into biodiesel includes the following steps: (1) The raw materials are subjected to anaerobic heating and drying, crushed into powder, mixed with the fermented product, spread out, and then subjected to aerobic fermentation to obtain the pretreated raw materials; (2) Pre-treat the raw materials by heating them up for sterilization, press them into blocks and then put them into the gasifier for gasification. The generated mixed gas is cooled through a pipeline, and the condensed liquid is separated into fatty acids and tar through a nanofiltration membrane; (3) The uncondensed gas passes through a purifying agent and then is introduced into the Fischer-Tropsch synthesis tower to synthesize biodiesel under the action of a catalyst; (4) The fatty acids in step (2) are subjected to catalytic hydrogenation, then put into an esterification reaction kettle, methanol and amino acid ionic liquid are added, stirred and heated. After cooling, the condensate is separated using a separating funnel. The upper layer liquid is taken and washed with hot water, and then the water is removed by heating to obtain biodiesel, which is combined with the biodiesel in step (3) to complete the whole process.

[0033] In the above step (1), the raw materials are human feces, poultry feces and livestock feces. The temperature of the anaerobic heating is 170 °C, the water content of the powder is 40%, the mass ratio of the powder to the ferment is 110:2, the thickness of the paving is 0.6 m, and the temperature, relative air humidity and time of the aerobic fermentation are 30 °C, 80% and 28 h respectively.

[0034] The preparation method of the ferment is as follows: The strain is first inoculated into a solid medium and cultured at 32 °C for 76 h, then the colony is scraped and inoculated into a liquid medium and cultured at 30 °C for 45 h. Subsequently, solid-liquid separation is carried out to take the bacterial liquid, which is mixed with starch and fermented at room temperature for 4 h to form the ferment.

[0035] The mass ratio of the strain to the solid medium is 1:20. The solid medium is composed of glucose, yeast powder, peptone and agar powder with a mass ratio of 2:1:1:1.9. The mass ratio of the colony to the liquid medium is 1:100. The liquid medium is composed of glucose, yeast powder, peptone and deionized water with a mass ratio of 2:1:1:4. The solid-liquid ratio of the starch to the bacterial liquid is 1:2.5 kg / mL, and the concentration of the bacterial liquid is 1.6×10 8 CFU / mL. The strain is Lipomyces starkeyi.

[0036] In step (2), the temperature and time of the heating and sterilization are 76 °C and 40 min respectively, the temperature of the gasification is 500 °C, the mixed gas includes CO, H2, CH4, fatty acids and tar, the temperature of the cooling is 135 °C, and the pressure of the nanofiltration membrane is 2.5 Mpa.

[0037] In step (3), the purifying agent is a methane adsorbent. The temperature and pressure of the Fischer-Tropsch synthesis tower are 200 °C and 2 Mpa respectively. The preparation method of the catalyst is as follows: Cobalt nitrate solution, manganese dioxide and porous silica are mixed and dried after standing to obtain the catalyst.

[0038] The concentration of the cobalt nitrate solution is 75 g / L, and the mass ratio among the cobalt nitrate solution, manganese dioxide and porous silica is 4:0.2:12. The standing time is 16 h, and the drying temperature is 125 °C.

[0039] In the step (4), the catalyst for catalytic hydrogenation is metallic platinum. The mass ratio of the fatty acid, methanol and amino acid ionic liquid is 1:3:0.05, where the amino acid ionic liquid is glutamic acid ionic liquid, and the mass fraction of the glutamic acid ionic liquid is 11%.

[0040] In the step (4), the heating temperature and time are 105 °C and 2.5 h respectively. The temperature of the hot water is 75 °C, and the temperature for heating to remove moisture is 115 °C.

[0041] The preparation method of the glutamic acid ionic liquid is as follows: glutamic acid and triethylamine are mixed according to a mass ratio of 1:1, and then dehydrated to obtain the glutamic acid ionic liquid.

[0042] Example 3

[0043] A preparation method for refining animal feces into biodiesel, the preparation method for refining animal feces into biodiesel comprises the following steps: (1) The raw materials are subjected to anaerobic heating and drying, crushed into powder, mixed with the fermented product, spread out and then subjected to aerobic fermentation to obtain the pretreated raw materials; (2) The pretreated raw materials are heated for sterilization, pressed into blocks and then put into a gasifier for gasification. The generated mixed gas is cooled through a pipeline, and the condensed liquid is separated by a nanofiltration membrane to obtain fatty acid and tar; (3) The uncondensed gas passes through a purifying agent and then is introduced into a Fischer-Tropsch synthesis tower to synthesize biodiesel under the action of a catalyst; (4) The fatty acid in the step (2) is subjected to catalytic hydrogenation, then put into an esterification reaction kettle, methanol and amino acid ionic liquid are added, stirred and heated. After cooling, the condensed liquid is separated by a separating funnel, the upper layer liquid is taken and washed with hot water, and then the water is removed by heating to obtain biodiesel, which is combined with the biodiesel in the step (3) to complete the whole process.

[0044] In the step (1), the raw materials are human feces, poultry feces and livestock feces. The anaerobic heating temperature is 180 °C, the water content of the powder is 45%, the mass ratio of the powder to the fermented product is 120:3, the spreading thickness is 0.7 m, and the temperature, air relative humidity and time of the aerobic fermentation are 32 °C, 85% and 36 h respectively.

[0045] The preparation method of the fermented product is as follows: The strain is first inoculated into a solid medium and cultured at 35°C for 84 h, then the colonies are scraped and inoculated into a liquid medium and cultured at 30°C for 50 h. Subsequently, solid-liquid separation is carried out to obtain the bacterial liquid, which is mixed with starch and fermented at room temperature for 5 h to form the fermented product.

[0046] The mass ratio of the strain to the solid medium is 1:20. The solid medium is composed of glucose, yeast powder, peptone, and agar powder with a mass ratio of 2:1:1:2. The mass ratio of the colonies to the liquid medium is 1:100. The liquid medium is composed of glucose, yeast powder, peptone, and deionized water with a mass ratio of 2:1:1:5. The solid-liquid ratio of the starch to the bacterial liquid is 1:3 kg / mL, where the concentration of the bacterial liquid is 1.8×10 8 CFU / mL, and the strain is Lipomyces starkeyi.

[0047] In step (2), the temperature and time for heating and sterilization are 80°C and 50 min respectively. The gasification temperature is 600°C. The mixed gas includes CO, H2, CH4, fatty acids, and tar. The cooling temperature is 150°C. The pressure of the nanofiltration membrane is 3 Mpa.

[0048] In step (3), the purifying agent is a methane adsorbent. The temperature and pressure of the Fischer-Tropsch synthesis tower are 220°C and 3 Mpa respectively. The preparation method of the catalyst is as follows: A cobalt nitrate solution, manganese dioxide, and porous silica are mixed, and after standing, it is dried to obtain the catalyst.

[0049] The concentration of the cobalt nitrate solution is 100 g / L. The mass ratio among the cobalt nitrate solution, manganese dioxide, and porous silica is 5:0.2:14. The standing time is 20 h, and the drying temperature is 130°C.

[0050] In step (4), the catalyst for catalytic hydrogenation is platinum metal. The mass ratio of the fatty acid, methanol, and amino acid ionic liquid is 1:4:0.05, where the amino acid ionic liquid is glutamic acid ionic liquid, and the mass fraction of the glutamic acid ionic liquid is 12%.

[0051] In step (4), the heating temperature and time are 110°C and 3 h respectively. The temperature of the hot water is 80°C, and the temperature for heating to remove moisture is 120°C.

[0052] The preparation method of the glutamic acid ionic liquid is as follows: Glutamic acid and triethylamine are mixed in a mass ratio of 1:1, and then dehydrated to obtain the glutamic acid ionic liquid.

[0053] Comparative Example 1 Based on Example 2, the fermentation step is only removed from the raw materials, and other conditions are the same as those in Example 2.

[0054] Comparative Example 2 On the basis of Example 2, the fermentation temperature and relative air humidity were adjusted to 35°C and 95% respectively, and other conditions were the same as those in Example 2.

[0055] Comparative Example 3 On the basis of Example 2, the fermentation temperature and relative air humidity were adjusted to 25°C and 70% respectively, and other conditions were the same as those in Example 2.

[0056] Comparative Example 4 On the basis of Example 2, the step of passing through the purifying agent in step (3) was removed, and other conditions were the same as those in Example 2.

[0057] Comparative Example 5 On the basis of Example 2, manganese dioxide in the preparation of the catalyst was removed, and other conditions were the same as those in Example 2.

[0058] Performance Test The biodiesel prepared in Examples 1-3 and Comparative Examples 1-5 was used as a sample, and the cetane number of the sample was tested according to the requirements of the national standard CB / T19147-2003. In addition, the yield of the biodiesel prepared from the sample was calculated respectively. Specifically: Biodiesel yield = total mass of biofuel / mass of raw material × 100%. The evaluation results of the samples are shown in Table 1.

[0059] Table 1

[0060] Note: The standard cetane number of the national standard CB / T19147-2003 is not less than 49 It can be analyzed from the results in Table 1 that the cetane numbers of Examples 1-3 and Comparative Examples 1-4 all meet the standards, only the cetane number of Comparative Example 5 is less than 49, and the yields of Examples 1-3 are much higher than those of Comparative Examples 1-5, among which the yield of Comparative Example 1 is the lowest. In Comparative Example 1, without the fermentation step, the direct gasification of the difficult-to-decompose organic matter in the feces not only reduces the yield of biodiesel but also affects the purity; in Comparative Examples 2-3, changing the fermentation conditions is not conducive to the growth of Lipomyces starkeyi, thereby reducing the conversion of biodiesel; in Comparative Example 4, removing the purifying agent step, the presence of methane not only affects the purity of the product but also inhibits the synthesis of biodiesel, thus reducing its yield; in Comparative Example 5, due to the absence of manganese dioxide, the selectivity of the catalyst for the synthesis direction of biodiesel decreases, thus directly affecting the yield and purity of biodiesel.

[0061] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments with equivalent changes within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A preparation method for refining animal feces into biodiesel, characterized in that, The preparation method of extracting biodiesel from animal feces includes the following steps: (1) The raw materials are subjected to anaerobic heating and drying, crushed into powders, mixed with the fermented product, spread out flat, and then subjected to aerobic fermentation to obtain pretreated raw materials; (2) The pretreated raw materials are heated to sterilize, pressed into blocks, and then put into a gasifier for gasification. The generated mixed gas is cooled through a pipeline, and the condensed liquid is separated by a nanofiltration membrane to obtain fatty acids and tar; (3) The uncondensed gas passes through a purifying agent and then is introduced into a Fischer-Tropsch synthesis tower, and biodiesel is synthesized under the action of a catalyst; (4) The fatty acids in step (2) are subjected to catalytic hydrogenation, then put into an esterification reaction kettle, methanol and amino acid ionic liquid are added, stirred and heated, and after cooling, the condensate is separated by a separating funnel. The upper layer liquid is taken and washed with hot water, and then the water is removed by heating to obtain biodiesel, which is combined with the biodiesel in step (3) to complete the whole process.

2. The preparation method of converting animal feces into biodiesel according to claim 1, characterized in that, In the step (1), the raw materials are human feces, poultry feces and livestock feces. The temperature of the anaerobic heating is 160-180°C, the water content of the powder is 35-45%, the mass ratio of the powder to the fermented product is 100-120:1-3, the thickness of the spread is 0.5-0.7m, and the temperature, relative air humidity and time of the aerobic fermentation are 28-32°C, 75-85% and 24-36h respectively.

3. The preparation method of biodiesel refined from animal feces according to claim 1, characterized in that, The preparation method of the fermented product is as follows: The strain is first inoculated into a solid medium and cultured at 30-35°C for 72-84 h, then the colonies are scraped and inoculated into a liquid medium and cultured at 30°C for 40-50h. Subsequently, the solid-liquid separation is carried out to obtain its bacterial liquid, which is mixed with starch and fermented at room temperature for 3-5h to form a fermented product.

4. A preparation method for refining animal feces into biodiesel according to claim 3, characterized in that, The mass ratio of the strain to the solid medium is 1:

20. The solid medium consists of glucose, yeast powder, peptone, and agar powder with a mass ratio of 2:1:1:1.8 - 2. The mass ratio of the colony to the liquid medium is 1:

100. The liquid medium consists of glucose, yeast powder, peptone, and deionized water with a mass ratio of 2:1:1:3 - 5. The solid-liquid ratio of the starch to the bacterial liquid is 1:2 - 3 kg / mL, where the concentration of the bacterial liquid is 1.5 - 1.8×10 8 CFU / mL, and the strain is Lipomyces starkeyi.

5. A preparation method for refining animal feces into biodiesel according to claim 1, characterized in that, In the step (2), the temperature and time of heating to sterilize are 70-80°C and 30-50min respectively, the temperature of the gasification is 400-600°C, the mixed gas includes CO, H2, CH4, fatty acids and tar, the temperature of the cooling is 120-150°C, and the pressure of the nanofiltration membrane is 2-3Mpa.

6. The preparation method of converting animal feces into biodiesel according to claim 1, characterized in that, In the step (3), the purifying agent is a methane adsorbent. The temperature and pressure of the Fischer-Tropsch synthesis tower are 180-220°C and 1-3Mpa respectively. The preparation method of the catalyst is as follows: Cobalt nitrate solution, manganese dioxide and porous silica are mixed, and after standing, it is dried to obtain a catalyst.

7. A preparation method for refining animal feces into biodiesel according to claim 6, characterized in that, The concentration of the cobalt nitrate solution is 50-100g / L, the mass ratio among the cobalt nitrate solution, manganese dioxide and porous silica is 3-5:0.2:10-14, the standing time is 12-20h, and the drying temperature is 120-130°C.

8. A preparation method for refining animal feces into biodiesel according to claim 1, characterized in that, In the step (4), the catalyst for catalytic hydrogenation is platinum metal. The mass ratio of the fatty acid, methanol and amino acid ionic liquid is 1:1-4: 0.05, where the amino acid ionic liquid is glutamic acid ionic liquid, and the mass fraction of the glutamic acid ionic liquid is 10-12%.

9. The preparation method of converting animal feces into biodiesel according to claim 1, characterized in that, In the step (4), the heating temperature and time are 100-110°C and 2-3h respectively, the temperature of the hot water is 70-80°C, and the temperature for heating to remove water is 110-120°C.

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