A method for realizing the resource utilization of frying waste oil based on a starch-based Pickering emulsion system

Abstract

The present invention discloses a method for resourcefully utilizing fried waste oil to produce hydrocarbon fuels based on a starch-based Pickering emulsion system, belonging to the field of high-value utilization of food waste resources. By constructing a dual-enzyme cascade starch-based Pickering emulsion catalytic reaction system of lipase and decarboxylase, the lipase and photo decarboxylase are dispersed in the aqueous phase, and after being mixed with the reaction substrates, fried waste oil and interfacial active starch particles, they are mechanically emulsified to form a Pickering emulsion interfacial catalytic system. Under blue light irradiation, through the dual-enzyme cascade catalytic hydrolysis and deacidification reactions, the one-pot production of hydrocarbon fuels from fried waste oil is realized, and the reaction yield can reach more than 90%. The reaction conditions of the present invention are mild, the reaction yield is high, and the economy is good. The reuse of waste oil resources is completed, and the prepared products can be widely applied in fields such as the food industry and military.

Description

Technical Field

[0001] The present invention relates to a method for realizing the resource utilization of fried waste oil based on a starch-based Pickering emulsion system, belonging to the field of high-value utilization of food waste resources. Background Art

[0002] Oils and fats are a typical type of renewable biomass resources, with low prices and rich sources. With the improvement of industrialization and refinement levels, a lot of oil and fat resources worldwide have not been effectively developed due to their low value, and at the same time, a large amount of waste oil has been directly discarded due to the lack of reasonable recycling channels. In China, about 4 - 8 million tons of catering waste oil are generated annually, of which about 1.5 million tons are fried waste oil, resulting in resource waste, increased environmental burden, and indirectly increasing the costs of other industrial sectors. Therefore, recycling and reusing fried waste oil through effective means meets the requirements of modern society for environmental protection and sustainable development.

[0003] Catering fried waste oil contains a large amount of recyclable organic substances, which are cheap and easily available, and can be turned into valuable products after processing and refining, showing good application prospects in the fields of preparing daily chemical products, chemical raw materials, surfactants, biodiesel, etc. Hydrocarbon fuels (such as gasoline, etc.), as representative energy sources of petroleum energy, have characteristics such as low flash point, high anti-stability, small viscosity, and good ignition performance, and are widely used in fields such as aviation, military, and transportation machinery. However, the over-exploitation and use of fossil energy have caused the world energy crisis and also led to serious environmental problems. Therefore, how to convert fried waste oil into green hydrocarbon fuels while reducing the production cost of fuels and ensuring the recycling of resources has always been the focus of research.

[0004] Research on the resource utilization of fried waste oil at home and abroad often adopts the method of hydrogenation catalysis to prepare renewable alkanes. However, the production process usually has harsh conditions, many side reactions, and difficulties in separating subsequent products. In contrast, the enzymatic method to convert waste oil into hydrocarbon fuels through steps such as hydrolysis, oxidation, and decarboxylation is a more green and sustainable method. This method is simple to operate, has mild conditions, and the products are easy to separate. However, in the step-by-step catalysis production, the loss of intermediate products is large during the operation process, and the yield is low. The immiscibility between the enzyme and the reaction substrate leads to a limited reaction contact area in the biphasic system, and the damage of organic solvents to the enzyme activity will also cause a decrease in the catalytic reaction rate and poor enzyme activity stability, thus increasing the reaction cost. At present, many studies have used Pickering emulsions as microreaction systems for waste oil treatment. The common method is to convert fatty acids in oils and fats into corresponding fatty acid methyl esters or ethyl esters. However, for this form of biofuel, its true energy and usage efficiency cannot replace traditional petroleum fuels mainly composed of alkanes (alkenes). In addition, most of these reaction systems use inorganic particles such as silica as particle emulsifiers, which have defects such as complex processing, non-renewability, and poor biocompatibility. Summary of the Invention

[0005] Aiming at at least one of the above problems, the present invention provides a method for realizing the resource utilization of fried waste oil based on a starch-based Pickering emulsion system. By constructing a dual-enzyme cascade Pickering emulsion catalytic reaction system of lipase and decarboxylase, the reaction steps and the loss of intermediate products during the separation process can be effectively reduced, and the one-pot cascade production of hydrocarbon fuels can be realized. In addition, using the starch-based Pickering emulsion as a biocatalytic reaction system provides a large reaction interface area and effectively avoids enzyme denaturation and inactivation caused by organic solvents and polar substrates. At the same time, using interfacial active starch particles as particle emulsifiers to stabilize the emulsion system is more green and safe and convenient for recycling.

[0006] The first object of the present invention is to provide a method for realizing the resource utilization of fried waste oil based on a starch-based Pickering emulsion system. The method is to construct a dual-enzyme cascade starch-based Pickering emulsion catalytic reaction system of lipase and decarboxylase and use it in the catalytic reaction with fried waste oil as the raw material. Among them, lipase and photodecarboxylase are dispersed in Tris-HCl buffer as the aqueous phase system, and the reaction substrate fried waste oil is used as the oil phase system. After adding interfacial active starch particles, a Pickering emulsion reaction system is prepared by mechanical emulsification. Through the dual-enzyme cascade catalytic hydrolysis and decarboxylation reactions, the one-pot production of hydrocarbon biofuels is realized.

[0007] In one embodiment of the present invention, the method includes:

[0008] (1) Preparation of surfactant starch particles: 1% - 5% (w / v, accounting for the total volume of the ethanol solution) of nano-starch was added to anhydrous ethanol containing 0.5% - 1% (w / v, accounting for the total volume of the ethanol solution) of methoxysilane, and its pH was adjusted to 4 with acetic acid. After stirring and centrifuging to obtain the lower-layer precipitate, it was dried by hot air and then dried under a nitrogen atmosphere to obtain surfactant starch particles;

[0009] (2) Preparation of the aqueous phase system: Lipase, photodecarboxylase were mixed evenly with Tris-HCl buffer solution with pH = 7 - 9 as the aqueous phase system, where the addition amount of lipase was 10 - 30 U / g of fried waste oil, and the addition amount of photodecarboxylase was 30 - 50 U / g of fried waste oil;

[0010] (3) Construction of the starch-based Pickering emulsion catalytic system: Using the reaction substrate, fried waste oil, as the oil phase system, under the conditions that the volume ratio of the oil-water two-phase is 1:1 - 1:5 and the addition amount of surfactant starch particles is 0.5% - 4% (w / v, accounting for the total volume ratio of the oil-water two-phase), after mixing, it was sheared by a high-speed shearer at 8000 - 12000 r / min for 2 - 4 min to obtain the starch-based Pickering emulsion catalytic system;

[0011] (4) Preparation of hydrocarbon fuel: The starch-based Pickering emulsion catalytic reaction system prepared in step (3) was placed in a rotary incubator or shaker at 30 - 37 °C, the rotation speed was set at 100 - 200 r / min, and irradiated with blue light for reaction for 15 - 18 h;

[0012] (5) Separation and purification: After the reaction, the upper organic phase was separated by shaking and standing, and separated by multiple extractions and silica gel column chromatography, and the solvent was removed by a vacuum rotary evaporator to obtain the prepared hydrocarbon fuel.

[0013] In an embodiment of the present invention, in (1), it was stirred at room temperature for 2 h and then centrifuged to obtain the lower-layer precipitate, dried by hot air at 45 °C and then dried at 120 °C for 2 h under a nitrogen atmosphere.

[0014] In an embodiment of the present invention, the methoxysilane in step (1) may include at least one of dodecyltrimethoxysilane, hexadecyltrimethoxysilane, and octadecyltrimethoxysilane.

[0015] In an embodiment of the present invention, the nano-starch in step (1) refers to an organic material with a particle size less than 300 nm using natural starch as the raw material.

[0016] In one embodiment of the present invention, the preparation method of the nano starch in step (1) includes the following steps: The starch raw material is made into a starch milk with a concentration of 10% (w / w, the dry starch basis accounts for the total mass of the aqueous phase) using a disodium hydrogen phosphate-citric acid buffer solution (pH = 4.8 - 5.2). It is heated and gelatinized in a boiling water bath, cooled, and then pullulanase is added and enzymolyzed at 58°C for 8 h. After the enzymolysis is completed, heating is carried out to inactivate the enzyme, and centrifugation is performed. The supernatant is taken for recrystallization, and after washing and drying, nano starch is obtained.

[0017] In one embodiment of the present invention, the starch type in the preparation method of the nano starch in step (1) may include any one of corn starch, rice starch, cassava starch, potato starch, quinoa starch, and wheat starch; pullulanase is added with an enzyme activity of 10 - 20 U / g of dry starch; the recrystallization temperature and time are 4°C and 6 - 10 h respectively.

[0018] In one embodiment of the present invention, the oil component of the frying waste oil in step (2) is mainly free fatty acids and glycerides, and the content of free fatty acids accounts for about 40% of the total mass.

[0019] In one embodiment of the present invention, the separation and purification in (5) is specifically: after the reaction is completed, the upper organic phase is separated by vortex oscillation and standing for 30 min, and after multiple extractions and silica gel column chromatography separation, the solvent is removed by a rotary evaporator under vacuum to obtain the prepared hydrocarbon fuel.

[0020] In one embodiment of the present invention, the extraction in step (5) is to extract the reaction mixture with 2 times the volume of ethyl acetate; the silica gel column chromatography is eluted with a gradient of a n-heptane solution containing 10% - 50% ethyl acetate; the vacuum degree of the rotary evaporation is set to 0.2 MPa and the temperature is 40°C.

[0021] In one embodiment of the present invention, the method further includes step (6): recycling and reuse; specifically, recycling the Pickering emulsifier and / or the catalyst, and continuing to be used in steps (3) - (5).

[0022] In one embodiment of the present invention, step (6) is specifically: after one reaction is completed, the lower phase of the previous batch of reactions is oscillated at 50°C in a thermostatic oscillator for 1 h to evaporate the trace organic solvents remaining in the lower phase, and then the reaction substrate frying waste oil is added to re-emulsify. After high-speed shearing, the next cycle starts.

[0023] In one embodiment of the present invention, step (6) can also be: after separating the upper oil phase, the remaining material is heated with water to be fully dissolved, filtered to obtain a filter cake, washed 3 - 5 times with water and then dried, which can be reused as a Pickering emulsifier; the catalyst is recovered by evaporation and crystallization of the aqueous solution and can be reused.

[0024] The second object of the present invention is to provide a method for the high-value utilization of food waste oil, expand the application fields of oil, and achieve the effective recycling of resources.

[0025] The third object of the present invention is to provide the hydrocarbon biofuel prepared by the above method and its applications in the fields of food industry, military, etc.

[0026] Advantages of the present invention:

[0027] (1) In the present invention, nano-starch is used as the substrate for preparing Pickering emulsion stabilizer, and the raw materials are environmentally friendly and easily available; the surface chemical modification of starch is carried out by silane coupling, and the conditions are mild and the operation is simple.

[0028] (2) By constructing a double-enzyme cascade Pickering emulsion catalytic reaction system of lipase and decarboxylase, through hydrolysis and decarboxylation reactions, the one-pot production of hydrocarbon fuel from frying waste oil is realized, which has the advantages of fewer operation steps, fewer by-products, and less loss of intermediate products.

[0029] (3) Using Pickering emulsion as the synthesis system of hydrocarbon fuel in the present invention provides a large catalytic reaction interface. Compared with the traditional two-phase reaction system, the production efficiency is increased from 54.3% to 98.5%, realizing the efficient synthesis of hydrocarbon fuel.

[0030] (4) The Pickering emulsion encapsulating lipase and photo-decarboxylase prepared in the present invention, the aqueous medium in the emulsion can provide a natural environment for enzyme molecules, effectively solve the problem of incompatibility between water-soluble enzyme preparations and organic reaction substrates, and at the same time, the catalyst and Pickering emulsifier can be recycled, with good economy.

[0031] (5) The present invention recycles frying waste oil to produce hydrocarbon fuel, completes the reuse of waste oil, realizes the effective recycling of resources, provides a basis for developing safe, efficient, low-carbon and environmentally friendly high-value utilization technologies of agricultural waste resources; the prepared hydrocarbon fuel can be widely applied in the fields of aerospace, military, food industry, etc. Specific embodiments

[0032] The following are the preferred embodiments of the present invention. It should be understood that the embodiments are for better explaining the present invention and are not intended to limit the present invention.

[0033] 1. Reaction yield

[0034] The content of hydrocarbons was determined by gas chromatography. After the reaction ended, it was vortexed and then allowed to stand for 30 min. 1 mL of the upper organic phase was taken, filtered through an organic microporous membrane, and placed in a 2 mL chromatographic injection vial for detection using a gas chromatograph. The gas chromatography conditions were as follows: Agilent KB-FFAP (0.25 mm × 0.25 μm × 30 m); injection port temperature: 250 °C; FID detector temperature: 280 °C; carrier gas was high-purity nitrogen; constant pressure mode, pressure 20 psi; injection volume 1 μL; split ratio 10:1; temperature programming: initial temperature 110 °C, held for 3 min, heated at a rate of 25 °C / min to 190 °C, held for 2 min; then heated at a rate of 25 °C / min to 230 °C, held for 2 min; finally heated at a rate of 30 °C / min to 250 °C, held for 12 min. n-Octanol was used as an internal standard for quantitative analysis. The reaction yield was calculated according to the following formula:

[0035] Reaction yield (%) = (W2 / W1) × 100

[0036] Where: W2 - the mass of hydrocarbons in the system after the reaction; W1 - the mass of the main oil components (free fatty acids and glycerides) in the system before the reaction.

[0037] 2. Cycling stability test

[0038] After one reaction ended, the lower phase of the previous batch of reactions was oscillated at 50 °C for 1 h in a thermostatic shaker to evaporate the trace organic solvents remaining in the lower phase, and then the reaction substrate frying waste oil was added again for re-emulsification. After high-speed shearing, the next cycle began. The reaction yield in each cycle was measured to characterize the cycling stability of the system.

[0039] 3. Reagents

[0040] The pullulanase used in the following experiments was purchased from Novozymes (China) Biotechnology Co., Ltd., with an enzyme activity of 3000 U / mL; lipase (derived from Candida rugosa) was purchased from Sigma Co., Ltd. in the United States, with an enzyme activity of 10000 U / g; the photo-decarboxylase was obtained by fermenting the Chlorella variabilis NC64A strain according to the literature (SOROGUE D., HADJIDEMETRIOU K., BLANGY S., et al. Mechanism and dynamics of fatty acid photodecarboxylase[J]. Science, 2017, 372(6538): 5687.), with an enzyme activity of 3000 U / g.

[0041] Example 1:

[0042] (1) Preparation of surfactant starch particles: Corn starch was dispersed in a disodium hydrogen phosphate-citrate buffer solution with a pH of 5.0 and heated and gelatinized in a boiling water bath. The concentration of corn starch in the buffer solution was 10.0% (w / w, dry starch basis accounting for the total mass of the aqueous phase); then it was cooled to 58 °C, pullulanase at 30 U / g dry starch was added, and enzymolysis was carried out at 58 °C for 8 h. Then it was heated in a boiling water bath to inactivate the enzyme, and the supernatant was obtained by centrifugation; then the supernatant was recrystallized at 4 °C for 8 h, and the obtained precipitate was washed to neutrality and dried to obtain nano-starch; 5% (w / w, accounting for the total mass of the ethanol solution) nano-starch was dispersed in absolute ethanol, 1% (w / w, accounting for the total mass of the ethanol solution) of cetyltrimethoxysilane was added, and its pH was adjusted to 4 with acetic acid. After stirring at room temperature for 2 h, it was centrifuged at 5000 r / min for 15 min to take the lower-layer precipitate, and the ethanol was removed by hot air drying at 45 °C, and then dried at 120 °C for 2 h in a nitrogen atmosphere to obtain surfactant-containing starch particles;

[0043] (2) Preparation of the aqueous phase system: 30 U / g of frying waste oil lipase and 50 U / g of frying waste oil photo-decarboxylase were added and mixed evenly with a Tris-HCl buffer solution with a pH = 8 as the aqueous phase system;

[0044] (3) Construction of the starch-based Pickering emulsion catalytic system: Using the reaction substrate frying waste oil as the oil phase system, when the volume ratio of the oil-water two phases was 1:5, the mass of the added surfactant starch particles was 1% (w / v, accounting for the total volume ratio of the oil-water two phases). After mixing, it was subjected to high-speed shearing at 12000 r / min for 2 min to obtain the starch-based Pickering emulsion catalytic system;

[0045] (4) Preparation of hydrocarbon fuel: The Pickering emulsion reaction system prepared in step (3) was placed on a constant-temperature shaker, maintaining the temperature at 30 °C, the rotation speed at 200 r / min, and irradiated with blue light for 18 h;

[0046] (5) Separation and purification: After the reaction was completed, the upper organic phase was separated by high-speed centrifugation and standing for 30 min. The reaction mixture was extracted with ethyl acetate, and the upper-layer product was collected and further separated and purified by silica gel column chromatography, using a n-heptane solution containing 10% - 50% ethyl acetate for gradient elution; finally, the solvent was removed by rotary evaporation at a vacuum degree of 0.2 MPa and 40 °C to obtain the prepared hydrocarbon fuel.

[0047] As determined by gas chromatography, the product was mainly alkanes with C 11 ~C 17 The yield of this reaction system could reach 98.5%. The cyclic stability of this system was tested. After repeating the use for 10 cycles, the yield of this reaction system could still reach 81.2%. The results of the cyclic stability test are shown in Table 1.

[0048] Example 2:

[0049] (1) Preparation of surfactant starch granules: Adjust the addition amount of cetyltrimethoxysilane from 1% to 0.8% (w / w, accounting for the total mass of the ethanol solution), and other operating conditions are the same as in Example 1;

[0050] (2) - (5) are the same as in Example 1.

[0051] Determined by gas chromatography, the yield of this reaction system can reach 98.6%.

[0052] Example 3:

[0053] (1) Preparation of surfactant starch granules: The same as in Example 1;

[0054] (2) Preparation of the aqueous phase system: Add 10 U / g of frying waste oil lipase, 30 U / g of frying waste oil photodecarboxylase and mix evenly with Tris-HCl buffer solution with pH = 8 as the aqueous phase system;

[0055] (3) - (5) are the same as in Example 1.

[0056] Determined by gas chromatography, the yield of this reaction system can reach 95.6%.

[0057] Example 4:

[0058] (1) - (2): The same as in Example 1;

[0059] (3) Construction of the starch-based Pickering emulsion catalytic system: Use the reaction substrate frying waste oil as the oil phase system. When the volume ratio of the oil-water two-phase is 1:1, add 1% (w / v, accounting for the total volume ratio of the oil-water two-phase) of the mass of surfactant starch granules, and after mixing, prepare the starch-based Pickering emulsion catalytic system by high-speed shearing at 12000 r / min for 2 min;

[0060] (4) - (5) are the same as in Example 1.

[0061] Determined by gas chromatography, the yield of this reaction system can reach 92.9%.

[0062] Example 5:

[0063] (1) - (3): The same as in Example 1;

[0064] (4) Preparation of hydrocarbon fuel: Place the starch-based Pickering emulsion reaction system prepared in step (3) on a constant temperature shaker, keep the temperature at 35 °C, the rotation speed at 100 r / min, and irradiate with blue light for 18 h;

[0065] (5) Separation and recovery: The same as in Example 1.

[0066] Determined by gas chromatography, the yield of this reaction system can reach 94.1%.

[0067] Comparative Example 1:

[0068] Omit the cetyltrimethoxysilane in step (1) of Example 1, and keep other conditions or parameters the same as in Example 1. Compared with Example 1, the yield of this reaction system drops to 55.0%. During this process, without the modification of the methoxysilane that reduces the surface energy, the nano starch particles show strong hydrophilicity, and a stable oil-water interface cannot be formed. As a result, the diffusion distance of the substrate molecules and enzyme molecules increases, and it is difficult for the catalyst to contact the reaction substrate.

[0069] Comparative Example 2:

[0070] Omit the preparation of nano starch in step (1) of Example 1, and choose to react natural corn starch with cetyltrimethoxysilane, and keep other conditions or parameters the same as in Example 1. Compared with Example 1, the yield of this reaction system drops to 59.8%. During this process, it is difficult for the complete starch particles to react efficiently with the silane coupling agent. Therefore, the Pickering emulsion droplets formed by these particles for stabilizing the oil-water interface are larger, and the mass transfer distance between the enzyme molecules and the substrate molecules increases, resulting in a decrease in the reaction efficiency.

[0071] Comparative Example 3:

[0072] Omit the mixing evenly with Tirs-HCl buffer solution in step (2) of Example 1, add lipase and decarboxylase to the reaction substrate frying waste oil, and keep other conditions or parameters the same as in Example 1. Compared with Example 1, this system is a single-phase (oil phase) system, and the yield of this reaction system drops to 37.9%.

[0073] Comparative Example 4:

[0074] Adjust the addition amounts of lipase and decarboxylase in step (2) of Example 1 to 5 U / g frying waste oil and 20 U / g frying waste oil respectively, which are not in the optimal parameter range, and keep other conditions or parameters the same as in Example 1. Compared with Example 1, the yield of this reaction system drops to 61.5%.

[0075] Comparative Example 5:

[0076] Omit the addition of interfacial active starch particles in step (3) of Example 1, and keep other conditions or parameters the same as in Example 1. Compared with Example 1, the yield of this reaction system drops to 50.3%.

[0077] Comparative Example 6:

[0078] In Example 1, the oil-water ratio in step (3) was adjusted to 3:1, which is outside the optimal parameter range, and other conditions or parameters were the same as in Example 1. Compared with Example 1, the yield of this reaction system decreased to 50.1%.

[0079] Comparative Example 7:

[0080] In Example 1, the reaction temperature in step (4) was adjusted to 45°C, which is outside the optimal parameter range, and other conditions or parameters were the same as in Example 1. Compared with Example 1, the yield of this reaction system decreased to 81.1%.

[0081] Comparative Example 8:

[0082] The preparation of interfacial active starch particles in step (1) of Example 1 was omitted, and the interfacial active starch particles in step (3) of Example 1 were replaced with phospholipid molecules. Other conditions or parameters were the same as in Example 1. Compared with Example 1, this system was a traditional emulsion system. After the first reaction, the yield of this reaction system decreased to 93.7%; for the cyclic stability test of this system, after 6 cycles of reuse, the yield of this reaction system decreased to 65.8%.

[0083] Comparative Example 9:

[0084] The preparation method of hydrocarbon fuel in Example 1 was changed, and the hydrocarbon fuel was prepared by a stepwise catalysis method:

[0085] (1) Preparation of interfacial active starch particles: The same as in Example 1;

[0086] (2) Preparation of the aqueous phase system: 30 U / g of frying waste oil lipase, 50 U / g of frying waste oil photo-decarboxylase were added and mixed evenly with Tris-HCl buffer solution with a pH of 8 to form aqueous phase system 1 and aqueous phase system 2;

[0087] (3) Construction of the lipase-loaded Pickering emulsion catalytic system: Using the reaction substrate frying waste oil as the oil phase system, when the volume ratio of the oil-water phase system 1 was 1:5, and the mass of the added interfacial active starch particles was 1% (w / v, accounting for the total volume ratio of the oil and water phases), after mixing, it was sheared at a high speed of 12000 r / min for 2 min to obtain the Pickering emulsion catalytic system;

[0088] (4) Hydrolysis of frying waste oil by lipase: The above reaction system was placed on a constant temperature shaker, maintaining the temperature at 30°C and the rotation speed at 200 r / min for 18 h; after the reaction, it was vortexed and left to stand for 30 min to separate the upper organic phase for the next reaction;

[0089] (5) Construction of the decarboxylase Pickering emulsion catalytic system: Using the upper organic phase collected in step (4) as the oil phase, in an oil-water phase system with a two-phase volume ratio of 1:5, adding interfacial active starch particles with a mass of 1% (w / v, accounting for the total volume ratio of the oil and water phases), and after mixing, preparing the Pickering emulsion catalytic system by high-speed shearing at 12,000 r / min for 2 min;

[0090] (6) Preparation of hydrocarbon fuel: Placing the reaction system obtained in step (5) on a constant temperature shaker, maintaining the temperature at 30 °C, the rotation speed at 200 r / min, and irradiating with blue light for 18 h;

[0091] (7) Separation and purification: After the reaction is completed, separating the upper organic phase by vortex oscillation and standing for 30 min, extracting the reaction mixture with ethyl acetate, collecting the upper liquid layer product, and further separating and purifying it by silica gel chromatography, using a n-heptane solution containing 10% - 50% ethyl acetate for gradient elution; finally, removing the solvent by rotary evaporation at a vacuum degree of 0.2 MPa and a temperature of 40 °C to obtain the prepared hydrocarbon fuel.

[0092] As determined by gas chromatography, the product is mainly alkanes with C 11 ~C 17 , and the yield of this reaction system is reduced to 75.1%.

[0093] Table 1 Results of cyclic stability determination

[0094]

[0095] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various modifications and decorations without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be defined by the claims.

Claims

1. A method for realizing the resource utilization of fried waste oil based on a starch-based Pickering emulsion system, characterized in that, The method is to construct a dual-enzyme cascade starch-based Pickering emulsion catalytic reaction system with lipase and decarboxylase and apply it to the catalytic reaction using frying waste oil as the raw material. Among them, lipase and photo-decarboxylase are dispersed in Tris-HCl buffer as the aqueous phase system, and the reaction substrate frying waste oil is used as the oil phase system. After adding interfacial active starch particles, a Pickering emulsion reaction system is prepared by mechanical emulsification. Through dual-enzyme cascade catalyzed hydrolysis and decarboxylation reactions, one-pot production of hydrocarbon biofuels is achieved. Preparation of the interfacial active starch particles: Add nano-starch accounting for 1% - 5% w / v of the total volume of the ethanol solution to anhydrous ethanol containing methoxysilane accounting for 0.5% - 1% w / v of the total volume of the ethanol solution. Adjust its pH with acetic acid, stir, centrifuge, and take the lower layer precipitate. After hot air drying, dry it under a nitrogen atmosphere to obtain starch particles with interfacial activity.

2. The method according to claim 1, wherein The method includes: (1) Preparation of the interfacial active starch particles: Add nano-starch accounting for 1% - 5% w / v of the total volume of the ethanol solution to anhydrous ethanol containing methoxysilane accounting for 0.5% - 1% w / v of the total volume of the ethanol solution. Adjust its pH with acetic acid, stir, centrifuge, and take the lower layer precipitate. After hot air drying, dry it under a nitrogen atmosphere to obtain starch particles with interfacial activity; (2) Preparation of the aqueous phase system: Mix lipase and photo-decarboxylase with Tris-HCl buffer solution with pH = 7 - 9 evenly as the aqueous phase system, where the addition amount of lipase is 10 - 30 U / g of frying waste oil, and the addition amount of photo-decarboxylase is 30 - 50 U / g of frying waste oil; (3) Construction of the starch-based Pickering emulsion catalytic system: Using the reaction substrate frying waste oil as the oil phase system, under the conditions that the volume ratio of oil to water is 1:1 - 1:5 and the addition amount of interfacial active starch particles is 0.5% - 4% w / v of the total volume of the oil-water two phases, mix and shear with a high-speed shearing machine at 8000 - 12000 r / min for 2 - 4 min to obtain the starch-based Pickering emulsion catalytic system; (4) Preparation of hydrocarbon fuels: Place the starch-based Pickering emulsion catalytic reaction system prepared in step (3) in a rotary incubator or shaker at 30 - 37 °C, set the rotation speed to 100 - 200 r / min, and irradiate with blue light for 15 - 18 h; (5) Separation and purification: After the reaction is completed, shake and let it stand to separate the upper organic phase. After multiple extractions and silica gel column chromatography separation, remove the solvent with a vacuum rotary evaporator to obtain the prepared hydrocarbon fuels.

3. The method according to claim 1, wherein The methoxysilane includes at least one of dodecyltrimethoxysilane, cetyltrimethoxysilane, and octadecyltrimethoxysilane.

4. The method according to claim 1, characterized in that, The nano-starch refers to an organic material with a particle size less than 300 nm using natural starch as the raw material.

5. The method according to claim 1, wherein The preparation method of the nano starch comprises the following steps: preparing a starch milk with a starch raw material and a disodium hydrogen phosphate-citric acid buffer solution with a pH of 4.8-5.2 into a concentration of 10% w / w of the starch dry basis in the total mass of the aqueous phase, heating and gelatinizing it in a boiling water bath, adding pullulanase after cooling and enzymolyzing it at 58°C for 8 h, heating to inactivate the enzyme and centrifuging after the enzymolysis is completed, taking the supernatant for recrystallization, and obtaining nano starch after washing and drying.

6. The method according to claim 2, wherein In step (2), the oil component of the fried waste oil is mainly free fatty acid and glyceride, and the content of the free fatty acid accounts for 40% of the total mass.

7. The method according to claim 2, characterized in that, The method further comprises step (6): recycling and reusing; specifically, recycling the Pickering emulsifier and / or the catalyst and continuing to use them in steps (3)-(5).

8. The method according to claim 7, wherein Step (6) is specifically: after the end of the first reaction, oscillating the lower phase of the previous batch of reactions in a constant temperature oscillator at 50°C for 1 h to evaporate the trace organic solvent remaining in the lower phase, then adding the reaction substrate fried waste oil to re-emulsify, and starting the next cycle after high-speed shearing.

9. A hydrocarbon biofuel prepared by the method according to any one of claims 1-8.

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