Ionic liquid catalyst for producing renewable fuel from waste oil and fat, preparation method and application thereof

Abstract

This application discloses an ionic liquid catalyst for producing renewable fuel from waste oils and fats, as well as its preparation method and application, belonging to the field of waste oil and fat processing technology. Using a self-synthesized ionic liquid catalyst to catalyze the hydrogenation of waste oils and fats to produce renewable fuels, this catalyst can adsorb or convert impurities in the waste oils and fats into products, improving product yield and quality. This paves the way for the industrialized production of second-generation biodiesel from waste oils and fats.

Description

Technical Field

[0001] The present application relates to an ionic liquid catalyst for producing renewable fuel from waste oil and fat, a preparation method thereof, and an application thereof, and belongs to the technical field of waste oil and fat treatment. Background Art

[0002] With the implementation of environmental protection and carbon emission reduction initiatives, the use of green fuels such as biodiesel and biojet fuel, produced from bio-based oils and fats, has been increasing year by year, leading to an increasing shortage of raw material sources. Expanding the raw material sources for green fuels has become a pressing issue. Industries such as catering, food processing, oil production and processing, meat processing, and fur processing generate waste oils and fats annually, including acidified oils, waste cooking oils, sewage oils, rancid oils, and animal fats. These oils and fats have low usable value and a long degradation process, contributing to eutrophication of water bodies and foul air odors.

[0003] If it is used as a raw material for green fuel, it will produce good social benefits and considerable economic gains. Currently, researchers are committed to using the above-mentioned waste oil to prepare renewable fuels such as diesel.

[0004] However, waste bio-based oils and fats are highly impure and severely deteriorated. They contain not only natural components like phospholipids, proteins, glycosyl diglycerides, heavy metal ions, and unsaturated compounds, but also oxidative and deteriorative components like alcohols, ketones, aldehydes, and acids, as well as impurities like dust, salt, and moisture. These substances often exist in the oil in a colloidal form that is difficult to separate and remove, causing the waste oil to exhibit thermal aggregation. Consequently, during the initial heating process at the start of production, thermal aggregation occurs, causing it to adhere to or accumulate on heating equipment. This hinders heat conduction and causes overheating of heat transfer components, further exacerbating the occurrence of thermal aggregation and creating a vicious cycle. If thermal aggregation is not promptly removed, it can quickly lead to blockage of material passages in heat exchange components and coking of heat exchange surfaces, making it difficult to continue continuous production.

[0005] To address this issue, the industry's latest approach involves extracting a portion of the non-thermopolymerizable intermediate hot oil after reactor upgrading, further heating it to the desired temperature in a furnace, and then adding it to the feed port and mixing it with the cold initial feed in a proportional manner. This "heats" the cold feed oil and dilutes its impurities. Because the process involves circulating hot oil, this method achieves equipment-free heating of the feed oil. This not only fundamentally avoids the problem of coking and carbonization on heating equipment, but also improves the quality of the feed oil to a certain extent, helping to reduce pressure on subsequent processes.

[0006] For example, Patent 202211376662.X and Patent 202310606126.2 both use this method and cooperate with specific catalysts for hydrogenation pretreatment operations. However, the catalysts used are carbon-based catalysts, which are a type of solid catalyst. Solid catalysts are easily affected by impurities in the raw materials and become clogged, resulting in a short overall process operation cycle. Therefore, the use of carbon-based catalysts in the above two patents is mainly due to its impurity resistance. However, this type of catalyst has high requirements for equipment and is generally used in crude oil refining. If it is to be used for industrial applications to treat waste oil, the raw oil must be specially treated before mixing.

[0007] In response to the above shortcomings, researchers have begun to develop liquid catalysts and ionic liquid catalysts to replace traditional carbon-based catalysts. For example, patent HK1212547A discloses an ionic liquid catalyst for catalyzing the production of biodiesel from oils and fats. However, this ionic liquid catalyst catalyzes a transesterification reaction, and the resulting biodiesel belongs to the first-generation biodiesel, while the structure and performance of the second-generation biodiesel are closer to petrochemical diesel. To produce second-generation biodiesel, patent 202210251260.0 discloses an oil-soluble molybdenum-based ionic liquid catalyst, which can catalyze waste oils and fats to produce second-generation biodiesel, and can achieve a yield of more than 85% for the second-generation biodiesel in the liquid phase product. In order to improve the catalytic efficiency of the catalyst and reduce production costs, patent 202311642817.4 is committed to using bimetallic ionic liquid catalysis to achieve an alkane yield of more than 90%. However, the yields and other parameters obtained in the above literature are all based on laboratory research. Since waste oils contain many impurities and are severely deteriorated, they are still prone to coking and difficult to produce when used in industrial catalytic hydrogenation to produce diesel, alkanes and other products. When using such ionic liquid catalysts for industrial catalytic hydrogenation production, it is still necessary to pre-treat the waste oils with a treatment agent or filter to remove solid impurities. For example, in patent 202311773339.0, it is necessary to use a pre-treatment agent to perform an ester exchange reaction and an impurity removal reaction on the waste oils to reduce the acid value and impurities of the waste oils before they can be used to produce renewable fuels such as diesel. Summary of the Invention

[0008] To address the above-mentioned problems, an ionic liquid catalyst for producing renewable fuel from waste oil and fat is provided. The liquid catalyst introduces functional chain segments into the ionic liquid catalyst through self-prepared functional halogenated alkane monomers, thereby ensuring the lipophilicity of the ionic liquid catalyst while removing metal ions, impurities and phospholipids from the waste oil and fat. Therefore, the waste oil and fat can be used for industrial production of second-generation biodiesel, and the yield of second-generation biodiesel can be further improved.

[0009] The method for producing renewable fuel by treating waste oil with ionic liquid catalyst adopts circulating oil to heat the raw waste oil, while increasing the amount of circulating oil added. This can significantly reduce the impurity concentration in the raw oil, which is more conducive to the catalysis of the liquid catalyst. The step of reheating after mixing the liquid catalyst is omitted, the heat exchanger is omitted, and there is no need for repeated mixing of the raw materials. The operation process is simple, which is conducive to industrial promotion and use, and can also synergistically improve the yield and quality of the product.

[0010] According to one aspect of the present application, a method for preparing an ionic liquid catalyst for producing renewable fuel from waste oil and fat is provided, comprising the following steps:

[0011] (1) Preparation of functional halogenated alkane monomers: a halogenated alkane containing a carboxyl group and a functional monomer containing a hydroxyl group are reacted and treated to obtain a functional halogenated alkane monomer, wherein the functional monomer containing a hydroxyl group is selected from at least one of N-cyclohexylhydroxylamine, N-(benzylcarbonyloxy)hydroxylamine, N-hydroxymethylnicotinamide, 5-hydroxytryptamine, and N-benzylethanolamine;

[0012] (2) Preparation of intermediate B: reacting a monomer containing a tertiary amine with a functional halogenated alkane monomer, treating the monomer to obtain intermediate A, and treating intermediate A with a strong basic anion exchange resin to obtain intermediate B;

[0013] (3) Preparation of ionic liquid catalyst: Intermediate B and polymetallic acid salt are mixed and heated to react, and then dried to obtain an ionic liquid catalyst.

[0014] The ionic liquid catalyst prepared in the present application uses a synthetic functional halogenated alkane monomer so that the catalyst contains a long-chain alkyl group with a functional group. The introduction of the long-chain alkyl group with a functional group can ensure the lipophilicity of the ionic liquid catalyst, promote the uniform dispersion of the ionic liquid catalyst in the raw material, and achieve adsorption of metal ions, impurities and phospholipids during the catalytic hydrogenation process of the ionic liquid catalyst, thereby reducing the content of harmful substances in the raw oil and reducing coking, thereby facilitating industrial continuous production.

[0015] Optionally, the carboxyl-containing halogenated alkane has 6 to 11 carbon atoms;

[0016] Preferably, the carboxyl-containing halogenated alkane is selected from at least one of 6-chlorohexanoic acid, 7-chloroheptanoic acid, 8-chlorooctanoic acid, 9-chlorononanoic acid, 10-chlorodecanoic acid, 11-chloro-undecanoic acid, 6-bromohexanoic acid, 7-bromoheptanoic acid, 8-bromooctanoic acid, 9-bromononanoic acid, 10-bromodecanoic acid, and 11-bromo-undecanoic acid.

[0017] The above-mentioned halogenated alkane containing a carboxyl group contains at least 6 carbon atoms, and reacts with a functional monomer containing a hydroxyl group to prepare a long-chain halogenated alkane monomer with a functional group, so that the functional halogenated alkane monomer retains the original long-chain alkane and can introduce functional groups such as amino, cycloalkyl, carbonyl, ester, and benzene ring, thereby achieving the removal of metal ions, impurities, and phospholipids.

[0018] In addition, the ionic liquid catalyst for the synthesis of functional halogenated alkanes prepared in this application can also hydrogenate alcohols, aldehydes, ketones, acids and other substances in waste oils and fats into alkanes, thereby reducing the impurity content of the product and improving the yield of second-generation biodiesel.

[0019] Optionally, in step (3), the molar ratio of intermediate B to polymetallic acid salt is (3-4):1, the reaction temperature is 60-70°C, the reaction time is 60-72h, nitrogen is continuously introduced during the reaction, the tail gas is introduced into dilute sulfuric acid, the molar ratio of dilute sulfuric acid to polymetallic acid salt is 1:0.06, the concentration of ammonium sulfate in dilute sulfuric acid is detected, and when the concentration is ≤1mmol / L, the reaction is terminated, followed by rotary evaporation drying at 80-90°C, and finally vacuum drying at 80°C for at least 72h.

[0020] Optionally, the functional monomer containing a hydroxyl group is selected from N-(benzylcarbonyloxy)hydroxylamine.

[0021] The N-cyclohexylhydroxylamine functional monomer contains amino groups and cycloalkyl groups, wherein the amino groups can improve the removal rate of ions, impurities and phospholipids, and the cycloalkyl groups can increase the lipophilicity of the ionic liquid catalyst, thereby achieving uniform dispersion of the ionic liquid catalyst.

[0022] N-(Benzylcarbonyloxy)hydroxylamine contains an amino group, an ester group, and a benzene ring. The amino group and the benzene ring can remove metal ions, impurities, and phospholipids. The ester group can increase compatibility with waste oils and fats, achieving uniform dispersion of the ionic liquid catalyst. In addition, the benzene ring structure can also improve the temperature resistance of the ionic liquid catalyst, allowing the ionic liquid catalyst to maintain a high catalytic effect even at high temperatures.

[0023] N-hydroxymethylnicotinamide contains an amino group, a carbonyl group, and a benzene ring. The carbonyl group is used to increase lipophilicity, but compared with the ester group, its compatibility with waste oils and fats is reduced. Therefore, the catalytic effect of N-hydroxymethylnicotinamide is lower than that of N-(benzylcarbonyloxy)hydroxylamine.

[0024] 5-Hydroxytryptamine contains two amino groups that can increase the adsorption of metal ions, impurities and phospholipids, but its lipophilicity is lower than that of N-(benzylcarbonyloxy)hydroxylamine. In addition, since the hydroxyl group is located on the benzene ring, the reaction yield with halogenated alkanes containing carboxyl groups is reduced, and the production cost increases.

[0025] The benzene ring contained in N-benzylethanolamine can improve the temperature resistance of ionic liquid catalysts. However, the tertiary amine group it contains has a lower adsorption effect on metal ions, impurities, and phospholipids than the amino group of N-(benzylcarbonyloxy)hydroxylamine, and long-term operation still poses a risk of coking in the system.

[0026] Optionally, the monomer containing a tertiary amine is selected from at least one of trihexylamine, triheptylamine, trioctylamine, pyridine, N-methylimidazole, N-methylpyrrole, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethyl-1,4-butanediamine, N,N,N',N'-tetramethylhexanediamine, and 4,4'-bipyridine.

[0027] Preferably, the monomer containing tertiary amine is selected from at least one of N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethyl-1,4-butanediamine, N,N,N',N'-tetramethylhexanediamine and 4,4'-bipyridine.

[0028] The above-mentioned tertiary amine monomer contains two tertiary amine groups. When it is combined with a functional halogenated alkane monomer to prepare intermediate A, intermediate A contains a diquaternary ammonium salt structure. Compared with ionic liquid catalysts prepared from other monomers, it has higher dispersibility and catalytic efficiency in waste oils and fats. In addition, it has a bisymmetrical structure, which can ensure the same catalytic efficiency of the catalytic active center after combining with the polymetallic acid salt, thereby improving the catalytic uniformity of the waste oils and fats, so as to obtain second-generation biodiesel with higher yield and more stable performance.

[0029] Optionally, the polymetallate is a trimetallate comprising at least molybdenum and nickel;

[0030] Preferably, the trimetallic acid salt is selected from at least one of molybdenum nickel cobaltate, molybdenum nickel manganate, and molybdenum nickel zincate;

[0031] More preferably, the preparation method of the trimetallic acid salt is:

[0032] Hydrogen peroxide, nickel sulfate and a third metal sulfate are added to deionized water, and then slowly added dropwise to a boiling ammonium molybdate solution. The ammonium molybdate solution is kept boiling during the addition. After the addition is completed, the solution is boiled for 1-2 hours to obtain a trimetallic acid salt, wherein the third metal sulfate is selected from one of cobalt sulfate, manganese sulfate or zinc sulfate.

[0033] Although the catalytic activity of molybdenum is lower than that of nickel, the content of molybdenum involved in the catalysis is high. The catalytic activity of nickel is high, but there will be more nickel that cannot effectively participate in the catalytic process. Therefore, the molybdenum and nickel in the above-mentioned trimetallic acid salt are used as basic catalytic metals, which can synergize the catalytic properties of the two metals, so that the catalytic efficiency can be further improved when combined with the third metal. At the same time, it is not easily affected by the metal elements, impurities and phospholipids in the waste oil, thereby improving the service life of the catalyst. In addition, the trimetallic acid salt has a good reaction combination effect with the intermediate B prepared above, and a better catalytic hydrogenation effect is obtained on the waste oil raw material.

[0034] Optionally, the molar ratio of the nickel sulfate to ammonium molybdate is (0.5-0.8):1, the molar ratio of the cobalt sulfate, manganese sulfate or zinc sulfate to ammonium molybdate is (0.3-0.4):1, the hydrogen peroxide accounts for 8-10wt% of the weight of the ammonium molybdate, and the concentration of hydrogen peroxide in the hydrogen peroxide is 30wt%.

[0035] Based on the catalytic properties of molybdenum and nickel described above, the molar ratio of the trimetallic salt nickel sulfate to ammonium molybdate, and the molar ratio of cobalt sulfate, manganese sulfate, or zinc sulfate to ammonium molybdate, that is, the ratio of nickel, molybdenum, and the third metal (cobalt, manganese, zinc) in the ionic liquid catalyst, can improve the catalytic activity of the ionic liquid catalyst at the above ratios, so that it can still maintain high activity at high temperatures of catalytic hydrogenation. If the proportion of ammonium molybdate decreases, the overall catalytic activity of the liquid catalyst decreases; if the molar ratio of nickel sulfate decreases, the service life of the ionic liquid catalyst decreases, resulting in a significant decrease in the catalytic efficiency in the later stages of catalytic hydrogenation, thereby reducing the product yield; if the proportion of the third metal decreases, the overall catalytic activity and service life of the catalyst will also be reduced, thereby reducing the product yield.

[0036] Optionally, in step (1), the specific method for reacting and treating the carboxyl-containing halogenated alkane and the hydroxyl-containing functional monomer to obtain the functional halogenated alkane monomer is:

[0037] A carboxyl-containing halogenated alkane and a hydroxyl-containing functional monomer in a molar ratio of 1:(1.1-1.2) are dissolved in a solvent, concentrated sulfuric acid is added as a catalyst, and then the reaction is carried out at 60-70°C for at least 5 hours to obtain a crude product. The solvent is removed by distillation under reduced pressure, and the product is extracted with ethyl acetate for 3-5 times and dried to obtain the product.

[0038] Optionally, in step (2), the specific method for reacting the monomer containing the tertiary amine with the functional halogenated alkane monomer and treating to obtain the intermediate A is:

[0039] The monomer containing the tertiary amine and the functional halogenated alkane monomer are dissolved in a solvent, heated under reflux for 22-24 hours, the solvent is removed by rotary evaporation, and the mixture is extracted with a mixed solvent of ether and acetonitrile for 3-5 times, and then dried to obtain intermediate A.

[0040] Optionally, in step (2), the specific method for treating intermediate A with a strong basic anion exchange resin to obtain intermediate B is:

[0041] Dissolve intermediate A in an organic solvent and then add it to a - The product was added to an ion exchange column of a strong basic anion exchange resin, eluted with ethanol, and the strong basic eluate with a pH>8 was collected and dried to obtain intermediate B.

[0042] According to another aspect of the present application, an ionic liquid catalyst prepared by any of the above-mentioned methods for preparing an ionic liquid catalyst for producing renewable fuel from waste oils and fats is provided.

[0043] According to another aspect of the present application, a method for producing renewable fuel by treating waste oil and fat with an ionic liquid catalyst is provided, comprising the following steps:

[0044] S1: Mix circulating oil, waste grease and ionic liquid catalyst in a weight ratio of (1-6):1:

[0045] (0.002-0.005) is mixed to form a premix, and then the temperature is raised to 280-380 ° C and then enters the first reactor for hydrogenation catalysis, wherein the ionic liquid catalyst is the ionic liquid catalyst prepared by the preparation method according to claim 1;

[0046] S2: The gaseous effluent from the first reactor enters the second reactor for further hydrogenation and catalysis to obtain reactants and circulating oil. The bottom effluent from the first reactor enters the ash discharge hot high-pressure separator to discharge waste containing high-ash oil and tailings;

[0047] S3: The reactants flow out to the hot high-pressure separator to separate into gas phase A and liquid phase A. The gas phase A enters the cold high-pressure separator to separate circulating hydrogen, combined distillate oil and residual oil. Part of the liquid phase A is used as circulating oil, and the other part enters the hot low-pressure separator to separate waste containing high-ash oil, tailings and liquid phase B;

[0048] S4: Liquid phase B enters a fractionation tower for fractionation to obtain renewable fuel.

[0049] Although some production processes also use recycled oil to be returned and mixed with raw oil for catalytic hydrogenation, the amount of recycled oil used is relatively small. When waste oil is produced industrially, coking problems still exist due to the excessive impurity content in the waste oil. After running for a certain period of time, the system often needs to be shut down for cleaning, which increases manpower and material resources and reduces production efficiency. The preparation method of the present application uses recycled oil with a high circulation ratio and waste oil for mixing and catalytic hydrogenation. On the basis of saving heat energy, it dilutes the colloid in the raw material, making the production system less likely to coke, ensuring production continuity, and in the long run, it will still increase industrial production capacity and have the best comprehensive benefits. It can also dilute or adsorb the sulfide and chloride in the raw material, thereby reducing the sulfur content and chlorine content in the product.

[0050] The first reactor used in the above method is a suspended bed reactor, which reduces the impurity content during the catalytic hydrogenation process of the ionic liquid catalyst, thereby ensuring the smooth reaction of the second reactor. In addition, the circulating oil used in this application is large in amount and has better affinity with the long-chain alkyl groups of the functional groups in the ionic liquid catalyst. Therefore, the circulating oil can promote the uniform dispersion of the above-mentioned ionic liquid catalyst in the waste oil feedstock, promote the ionic liquid catalyst to better play a catalytic role, improve the catalytic efficiency, and thus improve the product yield; and due to its ability to be evenly dispersed and its better affinity with the circulating oil and waste oil, the long-chain alkyl groups of the functional groups in the ionic liquid catalyst in the above process can play a better role in removing impurities, metal ions and phospholipids, thereby reducing the content of impurities in the product.

[0051] Optionally, the temperature of the premix after heating is 300-360°C.

[0052] Optionally, the circulating oil has a density of 0.76-0.82 g / ml, and is a biomass hydrocarbon compound with a cetane index of 80 or more.

[0053] Optionally, the renewable fuel includes biodiesel and / or biojet fuel;

[0054] Preferably, the renewable fuel includes hydrocarbon-based biodiesel, naphtha and kerosene.

[0055] Optionally, the waste grease includes at least one of acidified oil, waste kitchen grease, sewage oil, and animal fat, and the acid value of the waste grease is greater than 40 mgKOH / g.

[0056] According to another aspect of the present application, there is provided the use of any of the above-mentioned methods for treating waste oil and fat with an ionic liquid catalyst to produce renewable fuel in the preparation of bioenergy, biodiesel, and biojet fuel.

[0057] The beneficial effects of this application include but are not limited to:

[0058] 1. According to the method of the present application for treating waste oil and fat with an ionic liquid catalyst to produce renewable fuel, the waste oil and fat are treated by using circulating oil with a high circulation ratio and a liquid catalyst agent, and the ionic liquid catalyst is combined with the efficient catalysis and impurity removal. This fundamentally avoids the problems of coking and clogging of equipment (heating furnace tubes) caused by raw materials, improves the continuity of the production system operation, and reduces the system's heat energy consumption, reduces costs, saves investment, and facilitates industrial production and processing.

[0059] 2. According to the method of producing renewable fuel by treating waste oil with an ionic liquid catalyst in the present application, the content of metal ions and other impurities in the waste oil can be reduced through the improvement of the ionic liquid catalyst, and the oxidative deterioration components can be turned into treasure and directly converted into the final desired product. This solves the technical problem of low product yield and low quality caused by the large variety and high content of impurities in waste oil, and has great economic benefits.

[0060] 3. The method of producing renewable fuel by treating waste oil with an ionic liquid catalyst according to the present application does not add any additional processing steps to the original waste oil hydrogenation treatment. Therefore, the method has a simple operation process, increases the amount of renewable fuel generated, has high production efficiency, and is easy to promote industrial production.

[0061] 4. According to the ionic liquid catalyst for producing renewable fuel from waste oil and fat in the present application, by improving the long-chain alkyl groups carried by the existing ionic liquid catalyst, it is possible to remove metal ions, impurities and phospholipids in the waste oil and fat while ensuring the lipophilicity of the ionic liquid catalyst. The ionic liquid catalyst can directly catalyze the treatment of waste oil and fat to prepare second-generation biodiesel without pretreatment of the waste oil and fat, reduce coking, and can be used for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0063] Figure 1 This is a schematic diagram of a system for producing renewable fuel by treating waste oil through hot oil circulation according to Example 1 of the present application.

[0064] List of parts and reference numerals:

[0065] 1. Crude oil storage tank; 2. Booster pump; 3. Circulating oil heater; 4. First reactor; 5. Second reactor; 6. Circulating oil pump; 7. Hot high-pressure separator; 8. Hot low-pressure separator; 9. Fractionation oil heater; 10. Distillation tower; 11. One-side oil; 12. Two-side oil; 13. Three-side oil; 14. Ash discharge hot high-pressure separator; 15. Ash settling tank; 16. Cold high-pressure separator; 17. Circulating hydrogen compressor; 18. Fresh hydrogen compressor; 19. Catalyst tank. DETAILED DESCRIPTION

[0066] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0067] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0068] Unless otherwise specified, the methods used in the embodiments of the present application are conventional methods in the prior art.

[0069] Example 1

[0070] refer to Figure 1 This embodiment discloses a system for producing renewable fuel by treating waste oil through hot oil circulation, which includes a raw oil storage tank 1, a booster pump 2, a circulating oil heater 3, a first reactor 4, a second reactor 5, a circulating oil pump 6, a hot high-pressure separator 7, a hot low-pressure separator 8, a fractionation oil heater 9, a fractionation tower 10, a first side line oil 11, a second side line oil 12, a third side line oil 13, an ash discharge hot high-pressure separator 14, an ash settling tank 15, a cold high-pressure separator 16, a circulating hydrogen compressor 17, a fresh hydrogen compressor 18, and a catalyst tank 19.

[0071] The basic process for producing renewable fuel using this system is:

[0072] S1: The waste oil after mechanical impurities and clear water are removed is placed in the raw oil storage tank 1 for storage, and dimethyl sulfide accounting for 2wt% of the waste oil is added to the raw oil storage tank 1 to mix it evenly with the waste oil. The waste oil is then pressurized by the booster pump 2 and then mixed with hydrogen to form a hydrogen-mixed oil. The hydrogen-mixed oil is then mixed with the circulating oil from the circulating heating furnace 3 and the ionic liquid catalyst from the catalyst tank 19 and then heated and homogenized to form a feed oil with a temperature of 280-380°C. The feed oil enters the first reactor 4 for catalytic hydrogenation, during which degumming, demetallization and other reactions and the removal of ash impurities in the product are also completed;

[0073] S2: The bottom material of the first reactor 4 is discharged through the ash discharge hot high-pressure separator 14 to discharge waste containing high-ash oil and tailings. The gaseous effluent of the first reactor 4 enters the second reactor 5 for hydrofining treatment to obtain reactants and circulating oil. The circulating oil is returned to the circulating heating furnace 3 through the circulating oil pump 6 for further temperature increase and is used to homogenize the hydrogen mixed oil;

[0074] S3: The reactants flow out to the hot high-pressure separator 7 for separation to obtain gas phase A and liquid phase A. The gas phase A enters the cold high-pressure separator 16 for separation and removal of water and water-soluble salts to obtain circulating hydrogen, combined distillate oil and residual oil. The circulating hydrogen is combined with fresh hydrogen supplied by the fresh hydrogen compressor 18, and then the pressure is increased by the circulating hydrogen compressor 17. The combined distillate oil is introduced into the feed end and mixed with the raw oil for recycling. The combined distillate oil passes through the fractionation oil heating furnace 9 and enters the fractionation tower 10. The residual oil is discharged for treatment.

[0075] Part of the liquid phase A is used as circulating oil and enters the circulating oil heating furnace 3 through the circulating oil pump 6, and the other part enters the hot low-pressure separator 8 to separate the liquid phase B and waste containing high-ash oil and tailings;

[0076] S4: Liquid phase B enters the fractionation tower 10 for fractionation to obtain first-line oil 11 (naphtha), second-line oil 12 (kerosene), and third-line oil 13 (hydrocarbon-based biodiesel), which are various product oils that can be blended with green diesel and jet fuel. The residue at the bottom of the fractionation tower 10 is mainly unreacted heavy oil components, which are returned to the feed end and mixed with the raw oil for further processing;

[0077] The waste containing high-ash oil and tailings discharged from the bottom of the first reactor 4 and the hot low-pressure separator 8 enters the ash settling tank 15 for separation, and the residual oil is discharged for treatment. The rest is returned to the initial end of the process and mixed with the raw oil for further hydrogenation treatment.

[0078] Specifically, the temperature of the first reactor is 280-380°C, the pressure is 4-10 MPa, and the hydrogen-oil ratio is 600-1000; the temperature of the second reactor is 260-320°C, the pressure is 4-8 MPa, the volume space velocity is 0.5-3.0 h-1, and the hydrogen-oil ratio is 400-800.

[0079] Example 2

[0080] This embodiment relates to the preparation of an ionic liquid catalyst, and the specific steps are as follows:

[0081] (1) Preparation of functional halogenated alkane monomers: a halogenated alkane containing a carboxyl group and a functional monomer containing a hydroxyl group are reacted and treated to obtain a functional halogenated alkane monomer, wherein the functional monomer containing a hydroxyl group is selected from at least one of N-cyclohexylhydroxylamine, N-(benzylcarbonyloxy)hydroxylamine, N-hydroxymethylnicotinamide, 5-hydroxytryptamine, and N-benzylethanolamine;

[0082] (2) Preparation of intermediate B: reacting a monomer containing a tertiary amine with a functional halogenated alkane monomer, treating the monomer to obtain intermediate A, and treating intermediate A with a strong basic anion exchange resin to obtain intermediate B;

[0083] (3) Preparation of ionic liquid catalyst: Intermediate B and polymetallic acid salt are mixed and heated to obtain ionic liquid catalyst.

[0084] The carboxyl-containing halogenated alkane is selected from at least one of 6-chlorohexanoic acid, 7-chloroheptanoic acid, 8-chlorooctanoic acid, 9-chlorononanoic acid, 10-chlorodecanoic acid, 11-chloro-undecanoic acid, 6-bromohexanoic acid, 7-bromoheptanoic acid, 8-bromooctanoic acid, 9-bromononanoic acid, 10-bromodecanoic acid, and 11-bromo-undecanoic acid.

[0085] The monomer containing a tertiary amine is selected from at least one of trihexylamine, triheptylamine, trioctylamine, pyridine, N-methylimidazole, N-methylpyrrole, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethyl-1,4-butanediamine, N,N,N',N'-tetramethylhexanediamine, and 4,4'-bipyridine.

[0086] The polymetallate is a trimetallate comprising at least molybdenum and nickel;

[0087] Preferably, the trimetallate is selected from at least one of molybdenum nickel cobaltate, molybdenum nickel manganate, and molybdenum nickel zincate, and the preparation method of the trimetallate is:

[0088] Hydrogen peroxide, nickel sulfate and a third metal sulfate are added to deionized water, and then slowly added dropwise to a boiling ammonium molybdate solution. The ammonium molybdate solution is kept boiling during the addition process. After the addition is completed, the solution is continued to boil to obtain a trimetallic acid salt, wherein the third metal sulfate is selected from one of cobalt sulfate, manganese sulfate or zinc sulfate.

[0089] Ionic liquid catalysts 1#-13# and comparative ionic liquid catalysts D1#-D2# were prepared according to the above preparation method. The specific preparation methods are as follows:

[0090] Ionic liquid catalyst 1#

[0091] (1) Preparation of functional halogenated alkane monomer: 0.1 mol of 6-chlorohexanoic acid and 0.11 mol of N-cyclohexylhydroxylamine were dissolved in a mixed solvent of ethanol and N,N-dimethylformamide (the volume ratio of ethanol to N,N-dimethylformamide was 1:1), and concentrated sulfuric acid accounting for 2 wt% of 6-chlorohexanoic acid was added as a catalyst. The mixture was reacted at 60°C for 8 h to obtain a crude product, which was then distilled under reduced pressure to remove the solvent, extracted with ethyl acetate three times, and dried to obtain the product.

[0092] (2) Preparation of intermediate B: 0.08 mol of trihexylamine and 0.08 mol of functional halogenated alkane monomer were dissolved in a mixed solvent of ethanol and acetone (the volume ratio of ethanol and acetone was 1:1), heated under reflux for 24 h, and the solvent was removed by rotary evaporation. The intermediate A was extracted three times with a mixed solvent of ether and acetonitrile in a volume ratio of 1:1, and then dried to obtain the intermediate A. The intermediate A was dissolved in ethanol and added to a flask filled with OH - The mixture was added to an ion exchange column of a strong basic anion exchange resin, eluted with ethanol, and the strong basic eluate with a pH>8 was collected and dried at 80°C for 24 hours to obtain intermediate B;

[0093] (3) Preparation of ionic liquid catalyst: Hydrogen peroxide (hydrogen peroxide concentration is 30 wt %) accounting for 8 wt % of the weight of ammonium molybdate, 0.05 mol of nickel sulfate and 0.04 mol of zinc sulfate are added to deionized water, and then slowly added dropwise to a boiling 0.1 mol ammonium molybdate solution at a drop rate of 2 drops / second. The ammonium molybdate solution is kept boiling during the addition. After the addition is completed, the solution is boiled for 1 hour to obtain trimetallic acid salt. Intermediate B and trimetallic acid salt in a molar ratio of 3:1 are mixed and heated to 60°C for reaction for 72 hours. Nitrogen is continuously introduced during the reaction, and the tail gas is introduced into dilute sulfuric acid. The molar ratio of dilute sulfuric acid to trimetallic acid salt is 1:0.06. The concentration of ammonium sulfate in the dilute sulfuric acid is detected. When the concentration is ≤1 mmol / L, the reaction is terminated. The mixture is then rotary dried at 80°C for 6 hours and finally vacuum dried at 80°C for 72 hours to obtain ionic liquid catalyst 1#.

[0094] Ionic liquid catalyst 2#

[0095] (1) Preparation of functional halogenated alkane monomer: 0.1 mol of 11-chloro-undecanoic acid and 0.11 mol of N-hydroxymethylnicotinamide were dissolved in a mixed solvent of ethanol and N,N-dimethylformamide (the volume ratio of ethanol to N,N-dimethylformamide was 1:1), and concentrated sulfuric acid accounting for 2 wt% of 11-chloro-undecanoic acid was added as a catalyst. The mixture was reacted at 70°C for 5 h to obtain a crude product, which was then distilled under reduced pressure to remove the solvent, extracted with ethyl acetate five times, and dried to obtain the product.

[0096] (2) Preparation of intermediate B: 0.08 mol of pyridine and 0.08 mol of functional halogenated alkane monomer were dissolved in a mixed solvent of ethanol and acetone (the volume ratio of ethanol and acetone was 1:1), heated under reflux for 22 h, and the solvent was removed by rotary evaporation. The mixture was extracted with a mixed solvent of ether and acetonitrile in a volume ratio of 1:1 for 5 times, and then dried to obtain intermediate A. Intermediate A was dissolved in ethanol and added to a flask filled with OH - The mixture was added to an ion exchange column of a strong basic anion exchange resin, eluted with ethanol, and the strong basic eluate with a pH>8 was collected and dried at 80°C for 24 hours to obtain intermediate B;

[0097] (3) Preparation of ionic liquid catalyst: Hydrogen peroxide (hydrogen peroxide concentration is 30 wt%) accounting for 10 wt% of the weight of ammonium molybdate, 0.08 mol of nickel sulfate and 0.03 mol of manganese sulfate are added to deionized water, and then slowly added dropwise to a boiling 0.1 mol ammonium molybdate solution at a drop rate of 1 drop / second. The ammonium molybdate solution is kept boiling during the addition. After the addition is completed, the solution is boiled for 2 hours to obtain trimetallic acid salt. Intermediate B and trimetallic acid salt in a molar ratio of 4:1 are mixed and heated to 70°C for reaction for 60 hours. Nitrogen is continuously introduced during the reaction, and the tail gas is introduced into dilute sulfuric acid. The molar ratio of dilute sulfuric acid to trimetallic acid salt is 1:0.06. The concentration of ammonium sulfate in the dilute sulfuric acid is detected. When the concentration is ≤1 mmol / L, the reaction is terminated. The mixture is then rotary dried at 90°C for 4 hours and finally vacuum dried at 80°C for 72 hours to obtain ionic liquid catalyst 2#.

[0098] Ionic liquid catalyst 3#

[0099] (1) Preparation of functional halogenated alkane monomer: 0.1 mol of 9-bromononanoic acid and 0.11 mol of N-(benzylcarbonyloxy)hydroxylamine were dissolved in a mixed solvent of methanol and dimethyl sulfoxide (the volume ratio of methanol to dimethyl sulfoxide was 1:1), and concentrated sulfuric acid accounting for 2 wt% of 9-bromononanoic acid was added as a catalyst. The mixture was reacted at 65°C for 6 h to obtain a crude product, which was then distilled under reduced pressure to remove the solvent, extracted with ethyl acetate five times, and dried to obtain the product.

[0100] (2) Preparation of intermediate B: 0.08 mol N-methylimidazole and 0.08 mol functional halogenated alkane monomer were dissolved in a mixed solvent of methanol and chloroform (methanol and chloroform volume ratio was 1:1) and heated under reflux for 22 h. The solvent was removed by rotary evaporation. The mixture was extracted with a mixed solvent of ether and acetonitrile (volume ratio was 1:1) for 5 times. After drying, intermediate A was obtained. Intermediate A was dissolved in methanol and added to a flask filled with OH - The mixture was added to an ion exchange column of a strong basic anion exchange resin, eluted with methanol, and the strong basic eluate with a pH value greater than 8 was collected and dried at 80°C for 24 hours to obtain intermediate B.

[0101] (3) Preparation of ionic liquid catalyst: Hydrogen peroxide (hydrogen peroxide concentration is 30 wt %) accounting for 10% of the weight of ammonium molybdate, 0.06 mol of nickel sulfate and 0.04 mol of cobalt sulfate are added to deionized water, and then slowly added dropwise to a boiling 0.1 mol ammonium molybdate solution at a drop rate of 2 drops / second. The ammonium molybdate solution is kept boiling during the addition. After the addition is completed, it is boiled for 1.5 hours to obtain trimetallic acid salt. Intermediate B and trimetallic acid salt in a molar ratio of 4:1 are mixed and heated to 65°C for reaction for 70 hours. Nitrogen is continuously introduced during the reaction, and the tail gas is introduced into dilute sulfuric acid. The molar ratio of dilute sulfuric acid to trimetallic acid salt is 1:0.06. The concentration of ammonium sulfate in the dilute sulfuric acid is detected. When the concentration is ≤1 mmol / L, the reaction is terminated. The mixture is then rotary dried at 80°C for 6 hours and finally vacuum dried at 80°C for 72 hours to obtain ionic liquid catalyst 3#.

[0102] Ionic liquid catalyst 4#

[0103] The difference between this ionic liquid catalyst and ionic liquid catalyst 3# is that 5-hydroxytryptamine is used to replace N-(benzylcarbonyloxy)hydroxylamine, and the rest is the same as ionic liquid catalyst 3#.

[0104] Ionic liquid catalyst 5#

[0105] The difference between this ionic liquid catalyst and ionic liquid catalyst 3# is that N-benzylethanolamine is used to replace N-(benzylcarbonyloxy)hydroxylamine, and the rest is the same as ionic liquid catalyst 3#.

[0106] Ionic liquid catalyst 6#

[0107] The difference between this ionic liquid catalyst and ionic liquid catalyst 3# is that N-methylpyrrole is used to replace N-methylimidazole, and the rest is the same as ionic liquid catalyst 3#.

[0108] Ionic liquid catalyst 7#

[0109] The difference between this ionic liquid catalyst and ionic liquid catalyst 3# is that 0.04 mol of N,N,N',N'-tetramethylethylenediamine is used to replace 0.08 mol of N-methylimidazole, and the rest is the same as ionic liquid catalyst 3#.

[0110] Ionic liquid catalyst 8#

[0111] The difference between this ionic liquid catalyst and ionic liquid catalyst 3# is that 0.04 mol of N,N,N',N'-tetramethyl-1,4-butanediamine is used to replace 0.08 mol of N-methylimidazole, and ethanol is used as the solvent instead of methanol. The rest is the same as ionic liquid catalyst 3#.

[0112] Ionic liquid catalyst 9#

[0113] The difference between this ionic liquid catalyst and ionic liquid catalyst 3# is that 0.04 mol of N,N,N',N'-tetramethylhexanediamine is used to replace 0.08 mol of N-methylimidazole, and acetone is used as the solvent instead of chloroform. The rest is the same as ionic liquid catalyst 3#.

[0114] Ionic liquid catalyst 10#

[0115] The difference between this ionic liquid catalyst and ionic liquid catalyst 3# is that 0.04 mol of 4,4'-bipyridine is used to replace 0.08 mol of N-methylimidazole, and the rest is the same as ionic liquid catalyst 3#.

[0116] Ionic liquid catalyst 11#

[0117] The difference between this ionic liquid catalyst and ionic liquid catalyst 3# is that in step (3), cobalt sulfate is replaced by nickel sulfate (nickel sulfate is 0.1 mol), and the rest is the same as ionic liquid catalyst 3#.

[0118] Ionic liquid catalyst 12#

[0119] The difference between this ionic liquid catalyst and ionic liquid catalyst 3# is that nickel sulfate is replaced by cobalt sulfate (0.1 mol of cobalt sulfate) in step (3), and the rest is the same as ionic liquid catalyst 3#.

[0120] Ionic liquid catalyst 13#

[0121] The difference between this ionic liquid catalyst and ionic liquid catalyst 3# is that nickel sulfate is replaced by manganese sulfate in step (3), and the rest is the same as ionic liquid catalyst 3#.

[0122] Comparison of ionic liquid catalyst D1#

[0123] The difference between this comparative ionic liquid catalyst and ionic liquid catalyst 3# is that dodecane bromide is used to replace the functional halogenated alkane monomer synthesized in step (1), and the rest is the same as ionic liquid catalyst 3#.

[0124] Comparison of ionic liquid catalyst D2#

[0125] The difference between the comparative ionic liquid catalyst and the ionic liquid catalyst 3# is that a monometallic salt is used instead of a trimetallic salt in step (3) to synthesize a monometallic ionic liquid catalyst. The specific steps of step (3) are as follows: an amount of hydrogen peroxide equal to that of the ionic liquid catalyst 3# is added to deionized water, and then slowly added dropwise to a boiling 0.1 mol ammonium molybdate solution at a dropping rate of 2 drops / second. During the dropping process, the ammonium molybdate solution is kept boiling. After the dropping is completed, the solution is continued to boil for 1.5 hours. To obtain molybdenum metal salt, the intermediate B and the molybdenum metal salt in a molar ratio of 4:1 were mixed, heated to 65°C and reacted for 70 hours. Nitrogen was continuously introduced during the reaction, and the tail gas was introduced into dilute sulfuric acid. The molar ratio of dilute sulfuric acid to molybdic acid was 1:0.06. The concentration of ammonium sulfate in the dilute sulfuric acid was detected. When the concentration was ≤1 mmol / L, the reaction was terminated. The catalyst was then rotary dried at 80°C for 6 hours and finally vacuum dried at 80°C for 72 hours to obtain comparative ionic liquid catalyst D2#. The rest was the same as ionic liquid catalyst 3#.

[0126] Example 3

[0127] A method for producing renewable fuel by hydrotreating waste oil and fat using the system for producing renewable fuel from waste oil and fat using hot oil circulation in Example 1 is described. The ionic liquid catalyst used in this example is the ionic liquid catalyst prepared in Example 2. Specific differences in the treatment methods are shown in Table 1 below. In Table 1, "-" indicates the same as in Method 4. The density of the circulating oil used is 0.76-0.82 g / ml, and it is a biomass hydrocarbon compound with a cetane index of 80 or above.

[0128] Table 1

[0129]

[0130] Test Case

[0131] The hydrocarbon-based biodiesel, naphtha, and kerosene prepared by the methods of Example 3 were calculated, and each oil product was tested. The test results are shown in Tables 2-4 below.

[0132] Table 2 Hydrocarbon-based biodiesel

[0133]

[0134] The C15-C18 alkane content in Table 2 is tested and calculated in accordance with SH / T 0410, and the index is ≥70% for passing. The sulfur content is tested and calculated in accordance with GB / T 34100, and the index is ≤10 mg / kg for passing. The total pollutant content refers to the content of all pollutants including metal ions, impurities and phospholipids, and is tested and calculated in accordance with GB / T33400, and the index is ≤24 mg / kg for passing. The acidity is measured in KOH, and is tested and calculated in accordance with GB / T7304, and the index is ≤5 mg / 100 ml for passing. The oxidation stability is measured in total insoluble matter, and is tested and calculated in accordance with SH / T 0175, and the index is ≤2.5 mg / 100 ml for passing.

[0135] Table 3 Naphtha

[0136]

[0137] The sulfur content in Table 3 is tested and calculated in accordance with SH / T 0689, and the index is qualified if it is ≤10mg / kg; the iron content is tested and calculated in accordance with SH / T 0712, and the index is qualified if it is ≤0.01g / L; the colloid content is tested and calculated in accordance with GB / T8019, and the unwashed solvent colloid content is qualified if it is ≤30mg / 100ml; the phosphorus content is tested and calculated in accordance with SH / T0020, and the index is qualified if it is ≤0.0002. The “-” in Table 3 represents that the content was not measured.

[0138] Table 4 Kerosene

[0139]

[0140]

[0141] The halogen content in Table 4 is tested and calculated according to ASTM D7359, and the index is ≤1 mg / kg for passing. The metal content refers to the total content of aluminum, calcium, cobalt, chromium, copper, iron, potassium, lithium, magnesium, manganese, molybdenum, sodium, nickel, phosphorus, lead, palladium, platinum, tin, strontium, titanium, vanadium, and zinc. It is tested and calculated according to NB / SH / T 0892, and the content of each metal is ≤0.1 mg / kg for passing. There are a total of 22 metal elements mentioned above. Therefore, the metal content in Table 4 is ≤2.2 mg / kg, which is considered to be qualified. The sulfur content is tested and calculated according to SH / T 2689, and the index is ≤15 mg / kg for passing. The acid value is tested and calculated according to GB / T 12574, and the index is ≤0.015 mgKOH / g for passing.

[0142] According to the above data, the ionic liquid catalyst prepared in the present application can catalyze the catalytic hydrogenation of waste oils and fats to obtain naphtha, kerosene and hydrocarbon-based biodiesel, wherein the total yields of the three products are: method 1 is 87.1%, method 2 is 86.2%, method 3 is 86.3%, method 4 is 86.9%, method 5 is 83.9%, method 6 is 84.2%, method 7 is 86.3%, method 8 is 87.3%, method 9 is 87.7%, method 10 is 87.8%, method 11 is 87.4%, method 12 is 84.4%, method 13 is 84.3%, method 14 is 84.2%, method 15 is 83.0%, method 16 is 83.2%, and method 17 is 83.6%. It is proved that the use of ionic liquid catalysts in the present application to catalyze waste grease can generate great economic benefits. At the same time, the above methods can be carried out in batch production in the system of Example 1 without causing coking of the equipment and without the need to add pretreatment agents to the waste grease for additional pretreatment, thereby reducing the cost of waste grease recycling and improving the operational convenience and controllability of the process.

[0143] According to the comparison between method 4 and methods 5 and 6, the type of functional monomer containing hydroxyl groups can change the type of functional groups in the long chain carried by the ionic liquid catalyst, thereby affecting the catalytic efficiency of the ionic liquid catalyst and the removal effect of metal ions, impurities and phospholipids.

[0144] According to the comparison between Method 7-Method 11 and Method 4, the type of tertiary amine monomer in the ionic liquid catalyst will also affect the catalytic efficiency and the removal effect of metal ions, impurities and phospholipids. Among them, the tertiary amine monomers used in Method 8-Method 11 all contain two tertiary amines, thereby forming two quaternary ammonium salt groups. Compared with the tertiary amine monomer with only one tertiary amine, its catalytic activity is higher and the removal effect of metal ions, impurities and phospholipids is better.

[0145] According to the comparison of method 12, method 13 and method 4, when intermediate B remains unchanged, the simple molybdenum-cobalt catalyst and molybdenum-nickel catalyst bimetallic acid salt will reduce the catalytic efficiency of the ionic liquid catalyst under the same catalytic conditions compared with the molybdenum-nickel-cobalt trimetallic acid salt, and the removal effect of metal ions, impurities and phospholipids will also decrease. Therefore, the trimetallic acid salt with a third metal added based on molybdenum-nickel in this application has a better coordination effect with intermediate B; according to the comparison of method 14 and method 4, when the molybdenum-nickel base metal replaces the molybdenum-manganese base metal, even at the same content and with the cooperation of the third catalytic metal, its catalytic activity and the removal effect of metal ions, impurities and phospholipids are reduced, thereby proving that the trimetallic salt of this application makes full use of the catalytic properties of molybdenum-nickel to obtain the best catalytic effect; according to the comparison of method 16 and method 4, the catalytic efficiency of the ionic liquid catalyst D2# formed by the single metal and the intermediate B decreases more, and the removal effect of metal ions, impurities and phospholipids decreases more than the dimetallic acid salt of method 12.

[0146] According to the comparison between Method 15 and Method 4, the ionic liquid catalyst prepared by the present application using the synthetic functional halogenated alkane monomer can significantly improve the catalytic efficiency of waste oil and improve the removal effect of metal ions, impurities and phospholipids compared to the ionic liquid catalyst prepared by ordinary long-chain halogenated alkanes, and is more suitable for industrial catalysis of waste oil to produce renewable fuels such as second-generation biodiesel. In addition, as the process proceeds, the coking rate of Method 15 is significantly higher than that of Method 4. When the comparative ionic liquid catalyst D1# is used to hydrogenate waste oil to produce second-generation biodiesel, it is necessary to shut down the system after a certain period of operation and clean the coking area before it can be used normally. The production efficiency is significantly reduced compared to Method 4.

[0147] A comparison of Method 17 and Method 4 shows that a decrease in the proportion of recycled oil leads to a decrease in the dilution effect of the raw waste oil, which in turn leads to a decrease in the dispersion of the ionic liquid catalyst in the waste oil, and thus a decrease in the catalytic efficiency and the removal of metal ions, impurities, and phospholipids. In addition, Method 17, like Method 15, has a significantly higher coking rate as the process progresses compared to Method 4. The system needs to be shut down after a certain period of operation to clean the coking area. This is intermittent production, and production efficiency is significantly lower than that of Method 4.

[0148] The foregoing is merely an embodiment of the present application. The scope of protection of the present application is not limited by these specific embodiments but is determined by the claims of the present application. Those skilled in the art will appreciate that various modifications and variations are possible in this application. Any modifications, equivalent substitutions, or improvements made within the technical concepts and principles of this application shall be included within the scope of protection of this application.

Claims

1. A method for preparing an ionic liquid catalyst for producing renewable fuel from waste oils and fats, characterized in that: The steps include: (1) Preparation of functional halogenated alkane monomers: a halogenated alkane containing a carboxyl group and a functional monomer containing a hydroxyl group are reacted and treated to obtain a functional halogenated alkane monomer, wherein the functional monomer containing a hydroxyl group is selected from at least one of N-cyclohexylhydroxylamine, N-(benzylcarbonyloxy)hydroxylamine, N-hydroxymethylnicotinamide, 5-hydroxytryptamine, and N-benzylethanolamine; (2) Preparation of intermediate B: reacting a monomer containing a tertiary amine with a functional halogenated alkane monomer, treating the monomer to obtain intermediate A, and treating intermediate A with a strong basic anion exchange resin to obtain intermediate B; (3) Preparation of ionic liquid catalyst: The intermediate B and the polymetallic acid salt are mixed and heated to react, and then dried to obtain the ionic liquid catalyst, wherein the polymetallic acid salt is a trimetallic acid salt containing at least molybdenum and nickel metals.

2. The method for preparing an ionic liquid catalyst for producing renewable fuel from waste oils and fats according to claim 1, wherein the number of carbon atoms in the halogenated alkane containing a carboxyl group is 6-11.

3. The method for preparing an ionic liquid catalyst for producing renewable fuel from waste oil and fat according to claim 2, wherein the carboxyl-containing halogenated alkane is selected from at least one of 6-chlorohexanoic acid, 7-chloroheptanoic acid, 8-chlorooctanoic acid, 9-chlorononanoic acid, 10-chlorodecanoic acid, 11-chloro-undecanoic acid, 6-bromohexanoic acid, 7-bromoheptanoic acid, 8-bromooctanoic acid, 9-bromononanoic acid, 10-bromodecanoic acid, and 11-bromo-undecanoic acid.

4. The method for preparing an ionic liquid catalyst for producing renewable fuel from waste oils and fats according to claim 1, wherein the functional monomer containing a hydroxyl group is selected from N-(benzylcarbonyloxy)hydroxylamine.

5. The method for preparing an ionic liquid catalyst for producing renewable fuel from waste oils and fats according to claim 1, wherein the monomer containing a tertiary amine is selected from at least one of trihexylamine, triheptylamine, trioctylamine, pyridine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethyl-1,4-butanediamine, and N,N,N',N'-tetramethylhexanediamine.

6. The method for preparing an ionic liquid catalyst for producing renewable fuel from waste oil and fat according to claim 1, wherein the trimetallic acid salt is selected from at least one of molybdenum nickel cobaltate, molybdenum nickel manganate, and molybdenum nickel zincate.

7. The method for preparing an ionic liquid catalyst for producing renewable fuel from waste oils and fats according to claim 1, wherein the preparation method of the trimetallic acid salt is: Hydrogen peroxide, nickel sulfate and a third metal sulfate are added to deionized water, and then slowly added dropwise to a boiling ammonium molybdate solution. The ammonium molybdate solution is kept boiling during the addition. After the addition is completed, the solution is boiled for 1-2 hours to obtain a trimetallic acid salt, wherein the third metal sulfate is selected from one of cobalt sulfate, manganese sulfate or zinc sulfate.

8. The ionic liquid catalyst prepared by the method for preparing an ionic liquid catalyst for producing renewable fuel from waste oils and fats according to any one of claims 1 to 7.

9. A method for producing renewable fuel by treating waste oil with an ionic liquid catalyst, characterized in that: The steps include: S1: Mix circulating oil, waste grease and ionic liquid catalyst in a weight ratio of (1-6):1: (0.002-0.005) are mixed to form a premix, and then the temperature is raised to 280-380°C before entering the first reactor (4) for hydrogenation catalysis, wherein the ionic liquid catalyst is the ionic liquid catalyst prepared by the preparation method according to claim 1; S2: The gaseous effluent from the first reactor (4) enters the second reactor (5) for further hydrogenation and catalysis to obtain reactants and circulating oil. The bottom effluent from the first reactor (4) enters the ash discharge hot high-pressure separator (14) to discharge waste containing high-ash oil and tailings; S3: The reactants flow out to the hot high-pressure separator (7) to separate into gas phase A and liquid phase A. The gas phase A enters the cold high-pressure separator (16) to separate circulating hydrogen, combined distillate oil and residual oil. A portion of the liquid phase A is used as circulating oil, and the other portion enters the hot low-pressure separator (8) to separate waste containing high-ash oil and tailings and liquid phase B. S4: Liquid phase B enters the fractionation tower (10) for fractionation to obtain renewable fuel.

10. The method for producing renewable fuel by treating waste oil and fat with an ionic liquid catalyst according to claim 9, characterized in that: The temperature of the premix after heating is 300-360°C; The waste oil and fat includes at least one of acidified oil, hogwash oil, and animal fat; The acid value of the waste oil is greater than 40 mgKOH / g; The renewable fuel includes biodiesel and / or biojet fuel.

11. The method for producing renewable fuel by treating waste oil and fat with an ionic liquid catalyst according to claim 10, characterized in that: The renewable fuels include hydrocarbon-based biodiesel, naphtha and kerosene.

12. The method for producing renewable fuel by treating waste oil and fat with an ionic liquid catalyst according to claim 9, characterized in that: The cycle oil has a density of 0.76-0.82 g / ml and is a biomass hydrocarbon compound with a cetane index of more than 80.

13. Use of the method for producing renewable fuel by treating waste oil and fat with an ionic liquid catalyst according to any one of claims 9 to 12 in the preparation of bioenergy.

14. The use according to claim 13, characterized in that The bioenergy is biodiesel and biojet fuel.

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