A method for preparing high-quality fuel oil from bio-oil

Abstract

The present invention provides a method for preparing high-quality fuel oil from bio-oil, which belongs to the technical field of bio-oil, and comprises the following steps: S1: preparing bio-oil, by constructing an algae-bacteria system with an oil-containing industrial microalgae and a yeast mixture for mixed culture, and extracting to obtain bio-oil; S2: preparing Ba(OH)2 / Cu composite nanocatalyst, by mixing Ba(OH)2 solution and CuSO4 solution evenly, adding multi-walled carbon nanotubes for impregnation, filtering, washing with deionized water, vacuum drying, and calcining to obtain Ba(OH)2 / Cu composite nanocatalyst; S3: preparing high-quality fuel oil, mixing the bio-oil, Ba(OH)2 / Cu composite nanocatalyst, and methanol obtained in step S1 evenly, stirring the reaction, centrifuging, evaporating, washing, and drying to obtain high-quality fuel oil. The technical scheme of the present invention achieves the purpose of improving the quality of bio-oil while achieving high conversion rate and high yield.

Description

Technical Field

[0001] The present invention relates to the technical field of biofuel, and in particular to a method for preparing high-quality fuel from bio-grease. Background Art

[0002] With the continuous growth of global energy demand and the gradual depletion of fossil fuel resources, the development of sustainable and environmentally friendly alternative energy has become an urgent need. As a renewable resource, bio-oil has attracted much attention due to its low carbon emissions and wide range of raw material sources. At present, how to fully and effectively utilize biomass resources has become the focus of people's research and attention.

[0003] At present, the preparation of biofuels from microalgae has received great attention from governments and researchers around the world. Microalgae biofuel is considered to be the third generation of biofuel after food and cellulose biofuel. Algae will soon become one of the most important sources of biofuel. The extensive use of microalgae energy can significantly alleviate the negative impact of fossil energy on society and the environment, and will become a trend in the development of bioenergy in the future. Microalgae is a type of low-level plant with a simple structure and rapid growth. It is widely distributed around the world. Some microalgae are high-quality potential raw materials for the preparation of bioenergy because they are rich in oil.

[0004] Microalgae can be used for energy by extraction and esterification, which first extracts and separates lipids from microalgae cells and then converts them into biofuels through ester exchange reactions. However, microalgae are composed of biochemical components such as proteins, polysaccharides and lipids. The simple use of extraction and esterification can only utilize the lipid components, and it will also be accompanied by the production of a large amount of by-product crude glycerol. High content of crude glycerol will lead to an increase in engine deposits, so the treatment and reuse of crude glycerol is also a technical problem that needs to be solved in the industry.

[0005] On the other hand, the transesterification process for preparing biofuel is a reversible process, which results in a low yield of biofuel prepared by transesterification. The limitation of reaction equilibrium makes the overall reaction less efficient in the forward direction, so the selection and optimization of catalysts are crucial. At present, commonly used catalysts such as alkaline catalysts (NaOH, KOH) and acidic catalysts (H 2 SO 4 ) have problems such as poor stability and easy deactivation. Therefore, it is necessary to conduct in-depth research and develop an efficient, stable and low-cost catalyst to increase the yield of biofuel.

[0006] Therefore, it is necessary to provide a method for preparing high-quality fuel oil from bio-oil to solve the problems existing in the above-mentioned prior art. Summary of the invention

[0007] In view of this, the present invention provides a method for preparing high-quality fuel oil from bio-oil, which can improve the conversion rate of bio-oil by mixed cultivation of microalgae and yeast, and improve the yield of bio-oil while preparing high-quality fuel oil from bio-oil.

[0008] To achieve the above object, the present invention provides a method for preparing high-quality fuel oil from bio-oil, comprising the following steps:

[0009] Step S1: preparing bio-oil by constructing an algae-bacteria system with a mixture of oil-containing industrial microalgae and yeast for mixed culture, and then extracting the bio-oil;

[0010] Step S2: Preparation of Ba(OH) 2 / Cu composite nanocatalyst by Ba(OH) 2 Solution, CuSO 4 The solution was mixed evenly, multi-walled carbon nanotubes were added for impregnation, filtered, washed with deionized water, vacuum dried, and calcined to obtain Ba(OH) 2 / Cu composite nanocatalyst;

[0011] Step S3: Prepare high-quality fuel oil by mixing the bio-oil and Ba(OH) 2 The / Cu composite nano-catalyst and methanol are uniformly mixed, stirred for reaction, centrifuged, evaporated, washed and dried to obtain high-quality fuel oil.

[0012] The present invention prepares bio-oil by constructing an algae-bacteria system. In the algae-bacteria system, the organic matter produced by microalgae through photosynthesis can be used as a carbon source for yeast growth, and the carbon dioxide produced by yeast metabolism can be used by microalgae for photosynthesis, forming an efficient material circulation system. This symbiotic relationship can not only promote the growth of microalgae and yeast, but also increase the lipid content in the cells, that is, increase the accumulation of triglycerides in microalgae and fatty acids in yeast, and increase the output of bio-oil. Combined with the extraction and methanol in Ba(OH) 2 The reaction catalyzed by Cu / Cu composite nanocatalyst further improves the yield of biofuel.

[0013] The present invention produces biofuel through the ester exchange of triglycerides in industrial microalgae with methanol, and also produces crude glycerol as a by-product. In order to effectively utilize the crude glycerol, another purpose of cooperating with yeast is to convert the crude glycerol and the fatty acids produced by the yeast into glycerol fatty acid esters, which can be used as biofuel later, thereby reducing by-products and improving the bio-oil conversion rate.

[0014] The present invention prepares a Ba(OH) 2 / Cu composite nanocatalyst, using the advantage of multi-walled carbon nanotubes with large specific surface area, avoids the problem of low catalytic activity and small specific surface area of ​​traditional oxides when used as carriers to load metals. 2 The high catalytic activity of the catalyst combined with the Cu element promotes the polarization of the chemical bond OH in the alcohol, reduces the energy required for its breakage, thereby activating the substrate and reducing trans-esterification. In addition, multi-walled carbon nanotubes are used as carriers to increase the contact area between the reactants and the catalyst to accelerate the reaction rate, thereby better realizing the conversion of bio-oil into bio-fuel during the esterification process. The loaded catalyst can also be removed by filtration for repeated recycling.

[0015] Optionally, in step S1, the oil-containing industrial microalgae, yeast mixture, and 1.5% NaCl solution are placed in a closed photobioreactor, stirred evenly, mixed and cultured, centrifuged, the supernatant is discarded, the solid phase is washed with distilled water for 5 to 10 times, and then dried at 60°C for 12 to 18 hours. After adding a mixed solution of chloroform and methanol for extraction, the mixture is washed with 0.9% NaCl solution, centrifuged, the supernatant is discarded, and the solid phase is dried at 80°C under argon flow for 30 to 60 minutes to obtain bio-oil.

[0016] The present invention is carried out in a closed environment, and yeast consumes a certain nitrogen source to construct a nitrogen-restricted environment for microalgae combined with a salt stress effect. Since the ion balance and osmotic pressure regulation mechanism under a low salinity level can effectively maintain the normal physiological function of the cell, and the shared nitrogen source also limits the nitrogen source in the yeast growth environment, thereby realizing the synthesis of lipids in the microalgae and promoting the generation of a large amount of triglycerides, and also better realizing the accumulation of its fatty acids. The high yield of triglycerides and fatty acids further improves the yield of subsequent production of biofuels; in addition, after the mixed culture is centrifuged, distilled water is used to wash the microbial cells mainly to remove impurities on the cell surface, such as residual salts and metabolic wastes, so as to improve the purity of subsequent lipid extraction.

[0017] In the present invention, argon is introduced to provide an inert gas environment to prevent the biological oil from coming into contact with oxygen in the air and undergoing an oxidation reaction. The oxidation reaction may cause the oil to deteriorate, produce an unpleasant odor and taste, and even form harmful substances. Therefore, the use of argon can effectively protect the oil and maintain its stable quality, and also help to improve the purity and stability of the final product.

[0018] Optionally, the volume ratio of chloroform to methanol in the mixed solution of chloroform and methanol is 2:1; the mixed culture is carried out at 180-300 r / min, the mixed culture time is 7-10 days, and the mixed culture temperature is 30°C; in the step S1, the centrifugation rate is 3000-4000 r / min, and the centrifugation time is 15-30 min.

[0019] The present invention is more conducive to the growth of yeast and microalgae under the condition of 30°C, so as to better realize the production of lipids and to the accumulation of lipids. In addition, within the optimal growth temperature range, it is conducive to the rapid reproduction of yeast and microalgae and the production of metabolically active substances, and further improves the conversion rate of biological oils.

[0020] Optionally, in step S1, the yeast mixture includes fission yeast, Hansenula, Saccharomyces cerevisiae, Trichosporon, Pichia pastoris, and Kluyveromyces.

[0021] Optionally, in step S2, Ba(OH) 2 The solution is composed of Ba(OH) 2 The powder was mixed in deionized water, stirred magnetically, and filtered to obtain the product; wherein Ba(OH) 2 The mass ratio of powder to deionized water is 1:(25~30).

[0022] Optionally, the CuSO in step S2 4 The concentration of the solution is 0.2%~0.3%.

[0023] Optionally, in step S2, the immersion time is 18-24 hours, the number of washings with deionized water is 3-5 times, the vacuum drying temperature is 50-60°C and the time is 8-10 hours, and the calcination temperature is 500-600°C and the time is 20-30 minutes.

[0024] Optionally, in step S3, the bio-oil, methanol, Ba(OH) 2 The / Cu composite nanocatalyst was stirred at 70-80°C for 4-6 hours. After the reaction was completed, it was centrifuged at 3000-4000 r / min for 10-20 minutes, the upper liquid was collected, evaporated at 50-60°C for 1-2 hours, and finally rinsed with deionized water at 80-90°C and dried at 130°C for 12-18 hours to obtain high-quality fuel oil.

[0025] The evaporation in the present invention is to remove excess methanol in the biofuel and improve the quality of the prepared biofuel.

[0026] Optionally, the high-quality fuel oil comprises the following raw materials in parts by weight: 70-100 parts of bio-oil, 100-150 parts of methanol, Ba(OH) 2 / Cu composite nanocatalyst 0.5~1.7 parts.

[0027] Optionally, the bio-oil comprises the following raw materials in parts by volume: 75-100 parts of oil-containing industrial microalgae, 1 part of fission yeast, 1 part of Hansenula, 1 part of brewer's yeast, 1 part of Trichosporon, 1 part of Pichia pastoris, 1 part of Kluyveromyces, 200-300 parts of 1.5% NaCl solution, and 200 parts of a mixed solution of chloroform and methanol; the Ba(OH) 2 The / Cu composite nanocatalyst includes the following raw materials in parts by weight: Ba(OH) 2 Powder 15 parts, CuSO 4 400 parts of solution, 200-300 parts of multi-walled carbon nanotubes.

[0028] When the proportion of the multi-walled carbon nanotubes used in the present invention is too high, the copper and barium ions loaded on the multi-walled carbon nanotube carrier are low, and when the proportion is too low, the copper and barium ions are excessively left, increasing the cost.

[0029] The technical solution of the present invention achieves high yield and high conversion rate while improving the quality of biofuel.

[0030] The above technical solution of the present invention includes at least the following beneficial effects:

[0031] The present invention constructs algae-bacteria synergistic symbiosis by mixing oil-containing industrial microalgae and yeast to optimize the accumulation of biological oils, thereby greatly improving the output of biofuel raw materials, and using Ba(OH) 2 The Cu / Cu composite nanocatalyst accelerates the forward reaction efficiency of transesterification, which not only improves the production rate of biofuels, but also facilitates the recovery and recycling of the catalyst, enhancing the sustainability and economy of the process.

[0032] At the same time, when biofuel is produced by the ester exchange of triglycerides in industrial microalgae with methanol, crude glycerol will also be produced as a by-product. The by-product crude glycerol and the fatty acids produced by themselves are converted into glycerol fatty acid esters by yeast such as fission yeast. This not only reduces the waste of by-products and improves the conversion rate of bio-oils, but also increases the total output of biofuels, reflecting the recycling of resources and the integrated optimization of biorefining.

[0033] The present invention utilizes Ba(OH) 2 The high catalytic activity of the catalyst combined with the Cu element promotes the polarization of the chemical bond OH in the alcohol, reduces the energy required for its breakage, thereby activating the substrate and reducing trans-esterification. Multi-walled carbon nanotubes are used as carriers to increase the contact area between the reactants and the catalyst to accelerate the reaction rate, thereby better realizing the conversion of bio-oil into biofuel during the ester exchange process. The catalyst can be filtered out and recycled repeatedly. DETAILED DESCRIPTION

[0034] 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.

[0035] Example 1

[0036] Calculated by volume, 75 parts of oil-containing industrial microalgae, 1 part of fission yeast, 1 part of Hansenula, 1 part of brewer's yeast, 1 part of Trichosporon, 1 part of Pichia pastoris, 1 part of Kluyveromyces and 200 parts of 1.5% NaCl solution were placed in a closed photobioreactor to construct an algae-bacteria system, stirred and mixed evenly, cultured at 30°C and 180 r / min for 7 days, centrifuged at 3000 rpm for 15 min, discarded the supernatant and took the solid phase, washed with distilled water 5 times, dried at 60°C for 12 h, added 200 parts of a mixed solution of chloroform and methanol in a volume ratio of 2:1 for extraction, washed with 0.9% sodium chloride solution, centrifuged at 3000 rpm for 15 min, discarded the supernatant and took the solid phase, and dried at 80°C under argon flow for 30 min to obtain bio-oil.

[0037] Calculated by weight, 15 parts of Ba(OH) 2 The powder was mixed with 375 parts of deionized water, stirred magnetically for 30 min, and then filtered to obtain clear Ba(OH) 2 Solution: 400 parts of 0.2% CuSO 4 solution and 200 parts of multi-walled carbon nanotubes (CAS No.: 308068-56-6) were added to Ba(OH) 2 The solution was immersed at room temperature for 18 h, filtered and collected, washed with deionized water three times, dried under vacuum at 50 °C for 8 h, and calcined at 500 °C for 20 min to generate Ba(OH) 2 / Cu composite nanocatalyst.

[0038] Calculated by weight, 70 parts of bio-oil, 100 parts of methanol, and 0.5 parts of Ba(OH) 2 / Cu composite nanocatalyst was reacted by stirring at 70°C for 4 hours. After the reaction was completed, it was centrifuged at 3000rpm for 10 minutes and the upper liquid was collected. After evaporation at 50°C for 1 hour, it was rinsed with deionized water at 80°C until the washing liquid was clean, and dried at 130°C for 12 hours to obtain high-quality fuel oil.

[0039] Example 2

[0040] The algae-bacteria system was constructed by volume fraction calculation: 100 parts of oil-containing industrial microalgae, 1 part of fission yeast, 1 part of Hansenula, 1 part of brewer's yeast, 1 part of Trichosporon, 1 part of Pichia pastoris, 1 part of Kluyveromyces and 300 parts of 1.5% NaCl solution were placed in a closed photobioreactor, stirred and mixed evenly, cultured at 30°C and 300 r / min for 10 days, centrifuged at 4000 rpm for 30 min, discarded the supernatant and took the solid phase, washed with distilled water 10 times, dried at 60°C for 18 h, added 200 parts of a mixed solution of chloroform and methanol with a volume ratio of 2:1 for extraction, washed with 0.9% sodium chloride solution, centrifuged at 4000 rpm for 15 min, discarded the supernatant and took the solid phase, and dried at 80°C under argon flow for 60 min to obtain bio-oil.

[0041] Calculated by weight, 15 parts of Ba(OH) 2 The powder was mixed with 450 parts of deionized water, stirred magnetically for 30 min, and then filtered to obtain clear Ba(OH) 2 Solution: 400 parts of 0.3% CuSO 4 solution and 300 parts of multi-walled carbon nanotubes (CAS No.: 308068-56-6) were added to Ba(OH) 2 The solution was immersed at room temperature for 24 hours, filtered and collected, washed with deionized water 5 times, dried in vacuum at 60°C for 10 hours, and calcined at 600°C for 30 minutes to generate Ba(OH) 2 / Cu composite nanocatalyst.

[0042] Calculated by weight, 100 parts of bio-oil, 150 parts of methanol, and 1.7 parts of Ba(OH) 2 / Cu composite nanocatalyst was reacted by stirring at 80°C for 6 hours. After the reaction was completed, it was centrifuged at 4000rpm for 20 minutes to collect the upper liquid. After evaporation at 60°C for 2 hours, it was rinsed with deionized water at 90°C until the washing liquid was clean, and dried at 130°C for 18 hours to obtain high-quality fuel oil.

[0043] Example 3

[0044] The algae-bacteria system was constructed by volume fraction calculation: 80 parts of oil-containing industrial microalgae, 1 part of fission yeast, 1 part of Hansenula, 1 part of brewer's yeast, 1 part of Trichosporon, 1 part of Pichia pastoris, 1 part of Kluyveromyces and 220 parts of 1.5% NaCl solution were placed in a closed photobioreactor, stirred and mixed evenly, cultured at 30°C and 200 r / min for 8 days, centrifuged at 4000 rpm for 20 min, discarded the supernatant and took the solid phase, washed with distilled water 8 times, dried at 60°C for 16 h, added 200 parts of a mixed solution of chloroform and methanol with a volume ratio of 2:1 for extraction, washed with 0.9% sodium chloride solution, centrifuged at 3000 rpm for 15 min, discarded the supernatant and took the solid phase, and dried at 80°C under argon flow for 50 min to obtain bio-oil.

[0045] Calculated by weight, 15 parts of Ba(OH) 2 The powder was mixed with 400 parts of deionized water, stirred magnetically for 30 min, and then filtered to obtain clear Ba(OH) 2 Solution: 400 parts of 0.25% CuSO 4 solution and 230 parts of multi-walled carbon nanotubes (CAS No.: 308068-56-6) were added to Ba(OH) 2 The solution was immersed at room temperature for 20 h, filtered and collected, washed with deionized water 4 times, dried under vacuum at 55 °C for 9 h, and calcined at 550 °C for 25 min to generate Ba(OH) 2 / Cu composite nanocatalyst.

[0046] Calculated by weight, 90 parts of bio-oil, 100 parts of methanol, and 0.5 parts of Ba(OH) 2 / Cu composite nanocatalyst was reacted by stirring at 75°C for 5 hours. After the reaction was completed, it was centrifuged at 4000rpm for 10 minutes to collect the upper liquid; after evaporation at 55°C for 2 hours, it was rinsed with deionized water at 85°C until the washing liquid was clean, and dried at 130°C for 16 hours to obtain high-quality fuel oil.

[0047] Example 4

[0048] The algae-bacteria system was constructed by volume fraction calculation: 90 parts of oil-containing industrial microalgae, 1 part of fission yeast, 1 part of Hansenula, 1 part of brewer's yeast, 1 part of Trichosporon, 1 part of Pichia pastoris, 1 part of Kluyveromyces and 260 parts of 1.5% NaCl solution were placed in a closed photobioreactor to construct an algae-bacteria system, stirred and mixed evenly, cultured at 30°C and 200 r / min for 9 days, centrifuged at 4000 rpm for 20 min, discarded the supernatant and took the solid phase, washed with distilled water 9 times, dried at 60°C for 15, added 200 parts of a mixed solution of chloroform and methanol in a volume ratio of 2:1 for extraction, washed with 0.9% sodium chloride solution, centrifuged at 3000 rpm for 15 min, discarded the supernatant and took the solid phase, and dried at 80°C under argon flow for 50 min to obtain bio-oil.

[0049] Calculated by weight, 15 parts of Ba(OH) 2 The powder was mixed in 420 mL of deionized water, stirred magnetically for 30 min, and then filtered to obtain clear Ba(OH) 2 Solution: 400 parts of 0.3% CuSO 4 solution and 250 parts of multi-walled carbon nanotubes (CAS No.: 308068-56-6) were added to Ba(OH) 2 The solution was immersed at room temperature for 20 h, filtered and collected, washed with deionized water 4 times, dried under vacuum at 60 ° C for 10 h, and calcined at 600 ° C for 25 min to generate Ba(OH) 2 / Cu composite nanocatalyst.

[0050] Calculated by weight, 100 parts of bio-oil, 140 parts of methanol, and 1.6 parts of Ba(OH) 2 / Cu composite nanocatalyst was reacted by stirring at 80°C for 5 hours. After the reaction was completed, it was centrifuged at 3000rpm for 18 minutes and the upper liquid was collected. After evaporation at 60°C for 1.5 hours, it was rinsed with deionized water at 90°C until the washing liquid was clean, and dried at 130°C for 17 hours to obtain high-quality fuel oil.

[0051] Example 5

[0052] The algae-bacteria system was constructed by volume fraction calculation: 85 parts of oil-containing industrial microalgae, 1 part of fission yeast, 1 part of Hansenula, 1 part of brewer's yeast, 1 part of Trichosporon, 1 part of Pichia pastoris, 1 part of Kluyveromyces and 240 parts of 1.5% NaCl solution were placed in a closed photobioreactor to construct an algae-bacteria system, stirred and mixed evenly, cultured at 30°C and 300 r / min for 10 days, centrifuged at 4000 rpm for 20 min, discarded the supernatant and took the solid phase, washed with distilled water 6 times, dried at 60°C for 18 h, added 200 parts of a mixed solution of chloroform and methanol in a volume ratio of 2:1 for extraction, washed with 0.9% sodium chloride solution, centrifuged at 3000 rpm for 15 min, discarded the supernatant and took the solid phase, and dried at 80°C under argon flow for 40 min to obtain bio-oil.

[0053] Calculated by weight, 15 parts of Ba(OH) 2 The powder was mixed with 440 parts of deionized water, stirred magnetically for 30 min, and then filtered to obtain clear Ba(OH) 2 Solution: 400 parts of 0.2% CuSO 4 solution and 220 parts of multi-walled carbon nanotubes (CAS No.: 308068-56-6) were added to Ba(OH) 2 The solution was immersed at room temperature for 24 hours, filtered and collected, washed with deionized water three times, dried in vacuum at 55°C for 8 hours, and calcined at 500°C for 25 minutes to generate Ba(OH) 2 / Cu composite nanocatalyst.

[0054] Calculated by weight, 80 parts of bio-oil, 130 parts of methanol, and 0.7 parts of Ba(OH) 2 / Cu composite nanocatalyst was reacted by stirring at 85°C for 6 hours. After the reaction was completed, it was centrifuged at 3000rpm for 20 minutes to collect the upper liquid; after evaporation at 55°C for 1 hour, it was rinsed with deionized water at 85°C until the washing liquid was clean, and dried at 130°C for 18 hours to obtain high-quality fuel oil.

[0055] Example 6

[0056] The algae-bacteria system was constructed by volume fraction calculation: 95 parts of oil-containing industrial microalgae, 1 part of fission yeast, 1 part of Hansenula, 1 part of brewer's yeast, 1 part of Trichosporon, 1 part of Pichia pastoris, 1 part of Kluyveromyces and 280 parts of 1.5% NaCl solution were placed in a closed photobioreactor, stirred and mixed evenly, cultured at 30°C and 300 r / min for 7 days, centrifuged at 3000 rpm for 20 min, discarded the supernatant and took the solid phase, washed with distilled water 8 times, dried at 60°C for 15 h, added 200 parts of a mixed solution of chloroform and methanol in a volume ratio of 2:1 for extraction, washed with 0.9% sodium chloride solution, centrifuged at 3000 rpm for 15 min, discarded the supernatant and took the solid phase, and dried at 80°C under argon flow for 50 min to obtain bio-oil.

[0057] Calculated by weight, 15 parts of Ba(OH) 2 The powder was mixed with 420 parts of deionized water, stirred magnetically for 30 min, and then filtered to obtain clear Ba(OH) 2 Solution: 400 parts of 0.2% CuSO 4 The solution and 280 parts of multi-walled carbon nanotubes were added to the prepared Ba(OH) 2 The solution was immersed at room temperature for 22 hours, filtered and collected, washed with deionized water for 4 times, dried in vacuum at 60°C for 10 hours, and calcined at 500°C for 25 minutes to generate Ba(OH) 2 / Cu composite nanocatalyst.

[0058] Calculated by weight, 80 parts of bio-oil, 120 parts of methanol, and 1.5 parts of Ba(OH) 2 / Cu composite nanocatalyst was reacted by stirring at 75°C for 5 hours. After the reaction was completed, it was centrifuged at 3000rpm for 15 minutes and the upper liquid was collected. After evaporation at 50°C for 1.5 hours, it was rinsed with deionized water at 90°C until the washing liquid was clean, and dried at 130°C for 12 hours to obtain high-quality fuel oil.

[0059] The present invention also carries out comparative examples and related tests.

[0060] Comparative Example 1

[0061] The steps are basically the same as those in Example 1, except that 0.5 parts of Ba(OH) 2 / Cu composite nanocatalyst was replaced by 0.5 parts of Cu and Ba(OH) 2 A mixture of Cu, Ba(OH) 2 The mass ratio is 1:1, and the remaining raw materials and steps are consistent with Example 1, and finally high-quality fuel oil is prepared.

[0062] Comparative Example 2

[0063] The steps are basically the same as those in Example 1, except that 0.5 parts of Ba(OH) 2 The / Cu composite nanocatalyst was replaced by 0.5 parts of 3% sulfuric acid solution, and the remaining raw materials and steps were consistent with those in Example 1, and finally high-quality fuel was prepared.

[0064] Comparative Example 3

[0065] Calculated by volume, 75 parts of oil-containing industrial microalgae and 200 parts of 1.5% NaCl were placed in a closed photobioreactor, stirred and mixed evenly, cultured at 30°C and 180 r / min for 7 days, centrifuged at 3000 rpm for 15 min, discarded the supernatant and took the solid phase, washed with distilled water 5 times, dried at 60°C for 12 h, added 200 parts of a mixed solution of chloroform and methanol in a volume ratio of 2:1 for extraction, washed with 0.9% sodium chloride solution, centrifuged at 3000 rpm for 15 min, discarded the supernatant and took the solid phase, and dried at 80°C under argon flow for 30 min to obtain bio-oil.

[0066] Calculated by weight, 15 parts of Ba(OH) 2 The powder was mixed with 375 parts of deionized water, stirred magnetically for 30 min, and then filtered to obtain clear Ba(OH) 2 Solution: 400 parts of 0.2% CuSO 4 solution and 200 parts of multi-walled carbon nanotubes (CAS No.: 308068-56-6) were added to Ba(OH) 2 The solution was immersed at room temperature for 18 h, filtered and collected, washed with deionized water three times, dried under vacuum at 50 °C for 8 h, and calcined at 500 °C for 20 min to generate Ba(OH) 2 / Cu composite nanocatalyst.

[0067] Calculated by weight, 70 parts of bio-oil, 100 parts of methanol, and 0.5 parts of Ba(OH) 2 / Cu composite nanocatalyst was reacted by stirring at 70°C for 4 hours. After the reaction was completed, it was centrifuged at 3000rpm for 10 minutes and the upper liquid was collected. After evaporation at 50°C for 1 hour, it was rinsed with deionized water at 80°C until the washing liquid was clean, and dried at 130°C for 12 hours to obtain high-quality fuel oil.

[0068] Comparative Example 4

[0069] Calculated by weight, 15 parts of Ba(OH) 2The powder was mixed with 375 parts of deionized water, stirred magnetically for 30 min, and then filtered to obtain clear Ba(OH) 2 Solution: 400 parts of 0.2% CuSO 4 solution and 200 parts of multi-walled carbon nanotubes (CAS No.: 308068-56-6) were added to Ba(OH) 2 The solution was immersed at room temperature for 18 h, filtered and collected, washed with deionized water three times, dried under vacuum at 50 °C for 8 h, and calcined at 500 °C for 20 min to generate Ba(OH) 2 / Cu composite nanocatalyst.

[0070] Calculated by volume, 200 parts of a mixed solution of chloroform and methanol in a volume ratio of 2:1 were added to 75 parts of waste cooking oil for extraction, then washed with a 0.9% sodium chloride solution, centrifuged at 3000 rpm for 15 minutes, the supernatant was discarded, and the solid phase was dried at 80°C under argon flow for 30 minutes to obtain bio-oil.

[0071] Calculated by weight, 70 parts of bio-oil, 100 parts of methanol, and 0.5 parts of Ba(OH) 2 / Cu composite nanocatalyst was reacted by stirring at 70°C for 4 hours. After the reaction was completed, it was centrifuged at 3000rpm for 10 minutes and the upper liquid was collected. After evaporation at 50°C for 1 hour, it was rinsed with deionized water at 80°C until the washing liquid was clean, and dried at 130°C for 12 hours to obtain high-quality fuel oil.

[0072] Performance testing

[0073] The physical and chemical properties of the biofuels of Examples 1 to 6 and Comparative Examples 1 to 4 were measured, and relevant performance tests were performed in accordance with the national standard GB / T25199-2017 B5 diesel standard requirements, requiring oxidation stability ≤ 2.5 mg / 100 mL, flash point ≥ 60 ° C, and kinematic viscosity (20 ° C) of 3.0~8.0 mm 2 / s, copper sheet corrosion (50℃, 3h) ≤ level 1, and the density test was carried out using the GB / T1884-2000 crude oil and liquid petroleum product density laboratory determination method (densitometer method). The final test results are shown in Table 1.

[0074] Table 1: Test results of basic properties of biofuels prepared in Examples 1 to 6 and Comparative Examples 1 to 4

[0075]

[0076] From the results in Table 1, it can be seen that the biofuels prepared by Examples 1 to 6 of the method of the present invention all meet the standard of GB / 25199-2017 B5 diesel, wherein the oxidation stability is ≤2.5 mg / 100 mL, and the kinematic viscosity (20°C) is 3.0 to 8.0 mm 2 / s, flash point ≥60℃, copper sheet corrosion (50℃, 3h) ≤1 level, excellent performance.

[0077] Combined with the data in Table 1, Comparative Example 1 does not use Ba(OH) 2 / Cu composite nanocatalyst causes more impurities in the product, which in turn has a significant impact on the oxidation stability and kinematic viscosity; in Comparative Example 2, sulfuric acid solution is used as a catalyst, which significantly increases the corrosion of the copper sheet; in Comparative Examples 3 and 4, only microalgae or catering waste oil are used as raw materials, respectively, and the consumption of residual methanol is not achieved, resulting in a lower flash point of the biofuel; and the biofuel prepared in Examples 1 to 6 has significantly better basic performance than that in Comparative Examples 1 to 4, and is of excellent quality.

[0078] The relevant components in the biofuels of Examples 1 to 6 and Comparative Examples 1 to 4 were determined, wherein the sulfur content, water content, sulfur content, ash content, cetane number, and 10% distillation residue carbon content were tested according to the national standard GB / T25199-2017 B5 diesel standard requirements, the methanol content was tested according to the methanol content detection method in GB / T31776-2015 automotive methanol gasoline, and the total glycerol content was tested according to the standard test method for determining total monoglyceride, total diglyceride, total triglyceride, free glycerol and total glycerol in B-100 biodiesel methyl ester by gas chromatography according to ASTM / D6584. The final test results are shown in Table 2.

[0079] Table 2: Test results of biofuel components prepared in Examples 1 to 6 and Comparative Examples 1 to 4

[0080]

[0081] From the results in Table 2, it can be seen that the biofuels prepared by Examples 1 to 6 of the method of the present invention all meet the standards for the content of components in GB / 25199-2017 B5 diesel and ASTM / D6751-2003 biofuel, wherein the sulfur content is ≤10 mg / kg, the water content is ≤0.03%, the ash content is ≤0.01%, the cetane number is ≥45%, the 10% distillation residue carbon is ≤0.3%, and the total glycerol is ≤0.24%, and the quality is good.

[0082] Combined with the data in Table 2, the sulfur content and ash content of Comparative Example 2 did not meet the standards due to the use of sulfuric acid solution as a catalyst, and Comparative Example 1 did not use Ba(OH) 2 / Cu composite nanocatalyst as a catalyst and comparative example 4 using restaurant waste oil as a raw material to prepare biofuel resulted in excessive impurities such as residual carbon and total glycerol in the product. The biofuel prepared in Examples 1 to 6 was of higher quality than that in Comparative Examples 1 to 4.

[0083] The bio-oil conversion rate and bio-oil conversion rate of the bio-oil prepared in Examples 1 to 6 and Comparative Examples 1 to 4 were calculated, and the yield of bio-oil was further calculated. The results are shown in Table 3 below.

[0084] Table 3: Biofuel yield and conversion rate

[0085]

[0086] According to the data in Table 3, in Comparative Examples 1 and 2, Ba(OH) 2 / Cu composite nanocatalyst biofuel conversion rate significantly decreased, compared with the yield and conversion rate of Examples 1 to 6 are significantly higher than those of Comparative Examples 1 to 4, wherein the biofuel yield of Examples 1 to 6 is 91.4% to 94.9%, the bio-oil conversion rate is 92.9% to 96.1%, and the bio-oil conversion rate is 98.4% to 99.7%; while in Comparative Examples 1 and 2, due to the different catalysts used, the bio-fuel yield is only 70.0% and 59.7%, and the bio-fuel conversion rate is only 76.3% and 65.1%. In Comparative Examples 3 and 4, the conversion rate of bio-oil using microalgae or restaurant waste oil directly as raw material is significantly reduced, thereby affecting the yield of bio-oil, wherein in Comparative Example 3, the bio-fuel yield of only 59.2% and the bio-oil conversion rate of only 63.8% in the raw material for preparing bio-oil using only microalgae as raw material, and the bio-oil yield of only 72.1% and the bio-oil conversion rate of only 75.4% in the raw material for preparing bio-oil using restaurant waste oil directly in Comparative Example 4.

[0087] 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 preparing high-quality fuel oil from bio-oil, characterized in that: The following steps are involved: Step S1: preparing bio-grease, placing an oil-containing industrial microalgae, a yeast mixture, and a NaCl solution in a closed photobioreactor, stirring evenly, mixing and culturing, centrifuging, discarding the supernatant to obtain a solid phase, washing with distilled water, drying, adding a mixed solution of chloroform and methanol to extract, washing with a NaCl solution, centrifuging, discarding the supernatant to obtain a solid phase, and drying under an argon flow to obtain bio-grease; Step S2: preparing a Ba(OH)2 / Cu composite nanocatalyst by uniformly mixing a Ba(OH)2 solution and a CuSO4 solution, adding multi-walled carbon nanotubes for impregnation, filtering, washing with deionized water, vacuum drying, and calcining to obtain a Ba(OH)2 / Cu composite nanocatalyst; Step S3: prepare high-quality fuel oil, mix the bio-oil, Ba(OH)2 / Cu composite nano-catalyst and methanol prepared in step S1 evenly, stir to react, centrifuge, evaporate, wash and dry to obtain high-quality fuel oil.

2. The method for preparing high-quality fuel oil from bio-oil according to claim 1, characterized in that: In the step S1, the oil-containing industrial microalgae, yeast mixture, and 1.5% NaCl solution are placed in a closed photobioreactor, stirred evenly, mixed and cultured, centrifuged, the supernatant is discarded, the solid phase is washed with distilled water for 5 to 10 times, and then dried at 60° C. for 12 to 18 hours. A mixed solution of chloroform and methanol is added for extraction, and then washed with 0.9% NaCl solution, centrifuged, the supernatant is discarded, and the solid phase is dried at 80° C. under argon flow for 30 to 60 minutes to obtain bio-oil.

3. The method for preparing high-quality fuel oil from bio-oil according to claim 2, characterized in that: The volume ratio of chloroform to methanol in the mixed solution of chloroform and methanol is 2:1; the mixed culture is carried out at 180-300 r / min, the mixed culture time is 7-10 days, and the mixed culture temperature is 30°C; in the step S1, the centrifugal speed is 3000-4000 r / min, and the centrifugal time is 15-30 min.

4. The method for preparing high-quality fuel oil from bio-oil according to claim 1, characterized in that: In the step S1, the yeast mixture includes Schizosaccharomyces pombe, Hansenula, Saccharomyces cerevisiae, Trichosporon, Pichia pastoris, and Kluyveromyces.

5. The method for preparing high-quality fuel oil from bio-oil according to claim 1, characterized in that: In step S2, the Ba(OH)2 solution is prepared by mixing Ba(OH)2 powder in deionized water, stirring the mixture magnetically, and filtering the mixture; wherein the mass ratio of the Ba(OH)2 powder to the deionized water is 1:(25-30).

6. The method for preparing high-quality fuel oil from bio-oil according to claim 1, characterized in that: The concentration of the CuSO4 solution in step S2 is 0.2% to 0.3%.

7. The method for preparing high-quality fuel oil from bio-oil according to claim 5, characterized in that: In the step S2, the immersion time is 18-24 hours, the number of washings with deionized water is 3-5 times, the vacuum drying temperature is 50-60° C., the time is 8-10 hours, and the calcination temperature is 500-600° C., and the time is 20-30 minutes.

8. The method for preparing high-quality fuel oil from bio-oil according to claim 1, characterized in that: In the step S3, the bio-oil, methanol and Ba(OH)2 / Cu composite nano-catalyst prepared in the step S1 are stirred at 70-80°C for 4-6 hours. After the reaction is completed, they are centrifuged at 3000-4000 r / min for 10-20 minutes, the upper liquid is collected, evaporated at 50-60°C for 1-2 hours, and finally rinsed with deionized water at 80-90°C and dried at 130°C for 12-18 hours to obtain high-quality fuel oil.

9. The method for preparing high-quality fuel oil from bio-oil according to any one of claims 1 to 8, characterized in that: The high-quality fuel oil comprises the following raw materials in parts by weight: 70-100 parts of bio-oil, 100-150 parts of methanol, and 0.5-1.7 parts of Ba(OH)2 / Cu composite nano-catalyst.

10. The method for preparing high-quality fuel oil from bio-oil according to claim 9, characterized in that: The preparation of biological oil comprises the following raw materials in parts by volume: 75-100 parts of oil-containing industrial microalgae, 1 part of fission yeast, 1 part of Hansenula, 1 part of brewer's yeast, 1 part of Trichosporon, 1 part of Pichia pastoris, 1 part of Kluyveromyces, 200-300 parts of 1.5% NaCl solution, and 200 parts of a mixed solution of chloroform and methanol; the preparation of Ba(OH)2 / Cu composite nanocatalyst comprises the following raw materials in parts by weight: 15 parts of Ba(OH)2 powder, 400 parts of CuSO4 solution, and 200-300 parts of multi-walled carbon nanotubes.

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