A method for preparing liquid fuel by selective catalytic deoxygenation of oil and fat

Abstract

The present invention provides a method for preparing liquid fuel by selective catalytic deoxygenation of oils and fats, wherein the method comprises: S1: first converting oils and fats into fatty acid methyl esters by methyl esterification; S2: then converting fatty acid methyl esters into fatty alcohols by catalytic hydrogenation; S3: then converting fatty alcohols into long-chain hydrocarbons by intramolecular dehydration; S4: finally isomerizing long-chain hydrocarbons to prepare liquid fuels. The method for preparing liquid fuel by selective catalytic deoxygenation of oils and fats provided by the present invention has the advantages of strong raw material adaptability, simple process flow, cheap and easy-to-obtain catalysts, significantly reduced hydrogen consumption, good selectivity of the obtained fuel products, and increased production of glycerol.

Description

Technical Field

[0001] The invention relates to a method for preparing liquid fuel by selective catalytic deoxidation of oil and fat, belonging to the technical field of biomass energy. Background Art

[0002] Liquid fuels, such as gasoline, diesel, and aviation fuel, are very important power fuels and an important material basis for economic and social development. The long-term and large-scale use of fossil resources to prepare liquid fuels has had negative impacts on the environment, such as the greenhouse effect. Moreover, the reserves of these non-renewable resources will decrease year by year with continuous consumption. Deoxygenated liquid fuels prepared from renewable animal and plant oils and fats have high calorific value, good combustion performance, similar composition to fossil fuels, good compatibility and other excellent characteristics, and are widely valued. Therefore, countries around the world are increasingly paying attention to the research on the technology of preparing deoxygenated liquid fuels from oils and fats.

[0003] To prepare deoxygenated liquid fuel, the oil can be firstly treated with sulfurized NiMo / γ-Al 2 O 3 or CoMo / γ-Al 2 O 3 Under the action of catalyst, the long-chain alkanes are converted into long-chain alkanes by hydrodeoxygenation, and the long-chain alkanes are then catalytically isomerized to prepare liquid fuels by acidic molecular sieve catalysts (such as Pt / ZSM-22) loaded with precious metals such as Pt and Pd. By changing the catalyst and isomerization conditions, gasoline, diesel or aviation kerosene fuel can be selectively produced. For example, the technology of hydrogenating oils and fats to prepare high cetane diesel developed by the Canadian Canmet Energy Technology Center, the technology of preparing diesel by catalytic hydrodeoxygenation of oils and fats established in Porvoo by Finland's Neste Oil Company, and the technology of preparing aviation kerosene from biomass developed by UOP.

[0004] Sulfurized hydrogenation catalysts will reduce their catalytic activity due to sulfur loss, thus generating sulfur pollution. The use of hydrogenation metal catalysts such as nickel, palladium, platinum, and ruthenium can avoid sulfur-related problems. Recently, Chinese patent CN 102876350A disclosed a technology for preparing alkane fuels by catalyzing the hydrodeoxygenation of oils or fatty acids with Ru-based catalysts. Alternatively, a bifunctional catalyst can be directly used to couple hydrodeoxygenation and cracking / isomerization in a single stage. For example, Herskowitz et al. (Earth and Environmental Science 93 (2017) 012003) used Pt / SAPO-11 to catalyze oils at 300-450°C, 1-6MPa, and 0.5-5.0h -1 Under the conditions of the next step, the diesel component with lower pour point and cold filter point is obtained.

[0005] Direct hydrogenation and deoxygenation of oils and fats completely removes oxygen in the form of water, which not only consumes a large amount of hydrogen but also causes loss of glycerol (hydrogenation produces propane). For example, the theoretical hydrogen consumption for complete hydrogenation and deoxygenation of each mole of fatty acid glyceride is not less than 12 moles.

[0006] The oil is first hydrolyzed (or methylated) to release glycerol, and then the fatty acids (or fatty acid methyl esters) are selectively decarboxylated / carbonylated to allow oxygen to be converted to CO 2 / CO can significantly reduce hydrogen consumption. Murzin et al. (Top Catal (2011) 54:460–466) reported that Al loaded with Pt and Pd noble metals 2 O 3 or SiO 2 The catalyst can catalyze the decarboxylation of fatty acids with high selectivity. Under the conditions of 250-350°C and 0.1-2MPa, the conversion rate of stearic acid is greater than 80%, and the selectivity of n-heptadecane is about 93%. Compared with the hydrodeoxygenation reaction, the hydrogen consumption is reduced by 70%-90%. Catalysts for the selective decarboxylation / carbonylation of fatty acid esters have also been reported, for example, Pt / Al 2 O 3 Catalytic non-hydrogenation deoxygenation of methyl stearate (Catal Lett (2009) 130: 9-18). These non-hydrogenation deoxygenation reactions by decarboxylation / carbonylation usually have a pressure lower than 2 MPa and consume little or no hydrogen. These advantages have aroused great interest among researchers.

[0007] Hydrodeoxygenation of oils and fats to obtain alkanes, or selective decarboxylation / decarbonylation of fatty acids or their methyl esters to obtain alkanes, and subsequent hydrogenation / isomerization of alkanes all require the use of precious metals such as Pt and Pd, which significantly increases the cost of the catalyst.

[0008] In order to reduce or even avoid the use of precious metal isomerization catalysts, reduce catalyst costs, and simplify the isomerization process, Chinese patent CN107987868A discloses a method for preparing liquid fuels by step-by-step deoxygenation of oils and fats, wherein the oils and fats are simultaneously catalytically deoxygenated / isomerized by fatty alcohols to prepare fuels. However, the water produced by the catalytic deoxygenation of fatty alcohols usually leads to an increase in the oxygen content of the isomerized product and shortens the catalyst life. In order to reduce the adverse effects of by-product water, Chinese patent CN110066679A discloses a method for preparing liquid fuels from fatty alcohols, wherein the water produced by the deoxygenation of fatty alcohols and the cracked gas are continuously separated together, and the reaction products are hydrogenated and refined to obtain fuels.

[0009] In order to further reduce the hydrogen consumption of oil deoxygenation, avoid the use of sulfide catalysts and precious metal catalysts, increase glycerol production, and achieve consumption reduction and efficiency improvement for the preparation of deoxygenated liquid fuel from oil, providing a new method for preparing liquid fuel by selective catalytic deoxygenation of oil has become a technical problem that needs to be solved urgently in this field. Summary of the invention

[0010] In order to solve the above-mentioned shortcomings and deficiencies, the object of the present invention is to provide a method for preparing liquid fuel by selective catalytic deoxygenation of oils and fats.

[0011] In order to achieve the above objectives, the present invention provides a method for preparing liquid fuel by selective catalytic deoxygenation of oils and fats, wherein the method comprises:

[0012] S1: First, convert the oil into fatty acid methyl ester by methyl esterification;

[0013] S2: then catalytically hydrogenating the fatty acid methyl ester into fatty alcohol;

[0014] S3: dehydrating the fatty alcohol molecules to convert them into long-chain hydrocarbons;

[0015] S4: Finally, the long-chain hydrocarbons are isomerized to prepare liquid fuels.

[0016] As a specific embodiment of the above method of the present invention, the oil is animal oil and / or vegetable oil, and the carbon chain length of the oil is C 12 -C 24 The fatty acid content is greater than 80wt%, and the total content of fatty acid glycerides and free fatty acids is greater than 90wt%.

[0017] As a specific embodiment of the above method of the present invention, the oil includes animal and plant oils such as butter, lard, chicken oil, rapeseed oil, soybean oil, cottonseed oil, palm oil, corn oil, rubber seed oil, waste oil from the catering industry, gutter oil, acidified oil, rancid oil, or inferior oils such as frying oil, grease and lubricating oil whose main fatty acid structure has not changed after other uses.

[0018] In order to improve the quality of liquid fuel, simplify the subsequent refining process, and extend the life of the catalyst, the content of impurities such as sulfur, phosphorus, nitrogen, chlorine and metals in the oil raw material should be appropriately reduced. In some embodiments of the present invention, the content of impurities such as sulfur, phosphorus, nitrogen, chlorine and metals in the oil raw material after refining should be less than 100ppm, 200ppm, 300ppm, 400ppm and 1000ppm respectively.

[0019] As a specific embodiment of the above method of the present invention, in S1, the oil methyl esterification is to convert the oil into fatty acid methyl ester by reacting the oil with methanol.

[0020] As a specific embodiment of the above method of the present invention, in S1, oil and methanol are reacted under critical methanol conditions, enzyme catalysis conditions, homogeneous or heterogeneous acid catalysis conditions, or homogeneous or heterogeneous base catalysis conditions to be converted into fatty acid methyl esters.

[0021] The present invention does not make any specific requirements on the reactor, process conditions and catalyst used for oil methyl esterification in S1. Those skilled in the art can make reasonable choices according to actual operation needs as long as the purpose of the present invention can be achieved.

[0022] In some embodiments of the present invention, different catalysts are required to catalyze the methyl esterification of oils and fats of different qualities. For oils and fats of different qualities and different catalysts, the process conditions for methyl esterification of oils and fats include: temperature 60-300°C, pressure 0.1-20MPa, mass space velocity 0.3-5h -1 , alcohol-oil molar ratio 3:1-16:1;

[0023] The reactor used can be a continuous reactor such as a tower reactor or a tubular reactor to improve the reaction efficiency.

[0024] In the above method, the mixture after methyl esterification of fats and oils can be further refined and separated or distilled under reduced pressure.

[0025] As a specific embodiment of the above method of the present invention, in S1, after the oil is methylated and refined, the content of fatty acid methyl ester in the obtained product is not less than 80wt%.

[0026] As a specific embodiment of the above method of the present invention, in S1, after the oil is methylated and refined, the content of fatty acid methyl ester in the obtained product is not less than 85wt%.

[0027] As a specific embodiment of the above method of the present invention, in S1, after the oil is methyl esterified and refined, the fatty acid methyl ester content in the obtained product is 95-100wt%.

[0028] As a specific embodiment of the above method of the present invention, in S2, the catalyst used for catalytic hydrogenation of fatty acid methyl ester into fatty alcohol is a supported catalyst, and the hydrogenation active metal used in the supported catalyst includes one or more of platinum, palladium, gold, silver, cobalt, molybdenum, copper, nickel, zinc, iron, chromium, barium and manganese, and the carrier is activated carbon, Al 2 O 3 Or SiO 2 Equal surface area carrier.

[0029] Taking into account the catalyst cost, activity and selectivity, a supported catalyst with one or more non-precious metals such as copper, cobalt, molybdenum, nickel, iron, zinc and manganese as the active center is preferred.

[0030] As a specific embodiment of the above method of the present invention, in S2, the process conditions for catalytic hydrogenation of fatty acid methyl esters into fatty alcohols include: temperature 160-300°C, pressure 2-20MPa, mass space velocity 0.3-3h -1 , hydrogen to oil volume ratio 500:1-15000:1. By-product methanol can be recycled.

[0031] As a specific embodiment of the above method of the present invention, in S2, the reactor used for catalytic hydrogenation of fatty acid methyl esters into fatty alcohols can be a reactor, a tower reactor, a fixed bed reactor, etc., preferably a tower reactor or a fixed bed tubular reactor.

[0032] As a specific embodiment of the above method of the present invention, in S2, after the fatty acid methyl ester is catalytically hydrogenated and refined, the fatty alcohol content in the obtained product is greater than 86 wt%.

[0033] As a specific embodiment of the above method of the present invention, in S2, after the fatty acid methyl ester is catalytically hydrogenated and refined, the fatty alcohol content in the obtained product is 92-100wt%. In order to improve the subsequent reaction effect, the high boiling point component can be separated by adsorption, distillation and the like.

[0034] As a specific embodiment of the above method of the present invention, in S3, the catalyst used for the intramolecular dehydration of fatty alcohols into long-chain hydrocarbons is NH 3 The acid catalyst has a desorption temperature of 150-600°C after adsorption. The acid catalyst can selectively catalyze the intramolecular dehydration of long-chain fatty alcohols into long-chain hydrocarbons under non-hydrogen atmosphere conditions. As a specific embodiment of the above method of the present invention, in S3, the acid catalyst includes γ-Al 2 O 3 、ZrO 2 , ZSM-22, ZSM-23, ZSM-48, ZSM-35, SAPO-31, SAPO-11, ZSM-5, Y molecular sieve and β molecular sieve, etc.

[0035] In some preferred embodiments of the present invention, in S3, the acid catalyst comprises γ-Al 2 O 3 and / or ZrO 2 , and γ-Al 2 O 3 and / or ZrO 2With one or more of ZSM-22, ZSM-23, ZSM-48, ZSM-35, SAPO-31, SAPO-11, ZSM-5, Y molecular sieve and β molecular sieve, etc.

[0036] As a specific embodiment of the method described above, in S3, when γ-Al 2 O 3 and / or ZrO 2 When used as an acid catalyst with one or more of ZSM-22, ZSM-23, ZSM-48, ZSM-35, SAPO-31, SAPO-11, ZSM-5, Y molecular sieve and β molecular sieve, the weakly acidic γ-Al 2 O 3 The content of ZrO is greater than 20wt%, and the weakly acidic ZrO 2 The content is greater than 20wt%.

[0037] As a specific embodiment of the method described above, in S3, the reaction involved in the dehydration conversion process within the fatty alcohol molecule includes one or more reactions such as dehydration, cleavage, isomerization, and cyclization.

[0038] As a specific embodiment of the above method of the present invention, in S3, the process conditions for converting fatty alcohol molecules into long-chain hydrocarbons by dehydration include: temperature 250-400°C, pressure -0.1MPa to 0.5MPa, mass space velocity 0.2-4h -1 .

[0039] As a specific embodiment of the above method of the present invention, in S3, after the fatty alcohol is dehydrated and refined within the molecule, the oxygen content in the obtained long-chain hydrocarbon is less than 0.1 wt%.

[0040] As a specific embodiment of the above method of the present invention, in S3, after the fatty alcohol is dehydrated and refined, the oxygen content in the obtained long-chain hydrocarbon is less than 0.05wt%. In order to improve the subsequent reaction effect, the high boiling point component can be separated by adsorption, distillation and the like.

[0041] As a specific embodiment of the above method of the present invention, in S3, the reactor used for the intramolecular dehydration conversion of fatty alcohols can be a reaction kettle, a tower reactor, a fixed bed reactor, etc., preferably a tower reactor or a fixed bed reactor.

[0042] As a specific embodiment of the method described above, in S4, the catalyst used for isomerization of long-chain hydrocarbons to prepare liquid fuel is NH 3The acid catalyst has a desorption temperature of 150-600° C. after adsorption. The acid catalyst can selectively catalyze the isomerization of long-chain hydrocarbons to obtain liquid fuel under non-hydrogen atmosphere conditions.

[0043] As a specific embodiment of the above method of the present invention, in S4, the acid catalyst includes one or more of ZSM-22, ZSM-23, ZSM-48, ZSM-35, SAPO-31, SAPO-11, ZSM-5, EU-1, Y molecular sieve and β molecular sieve.

[0044] As a specific embodiment of the method described above in the present invention, in S4, the reactions involved in the long-chain hydrocarbon isomerization process include one or more of cracking, isomerization, cyclization, and superposition.

[0045] As a specific embodiment of the method described above, in S4, the process conditions for isomerizing long-chain hydrocarbons to prepare liquid fuels include: temperature 200-420°C, pressure -0.1MPa to 4MPa, mass space velocity 0.2-3h -1 .

[0046] As a specific embodiment of the method described above, in S4, the reactor used for isomerizing long-chain hydrocarbons to prepare liquid fuels can be a reactor, a tower reactor, a fixed bed reactor, etc., preferably a tower reactor or a fixed bed reactor.

[0047] According to the differences in the composition of the oil raw material, the catalyst and the process conditions, the main components of the engine liquid fuel obtained by the method for preparing liquid fuel by selective catalytic deoxygenation of oil provided by the present invention are C 6 -C 20 The composition of liquid fuel can be adjusted by changing the fatty acid composition of the oil raw materials, catalysts and process conditions.

[0048] In order to obtain high-quality products suitable for gasoline, diesel or aviation kerosene, the liquid fuel can be further hydro-refined or distilled to obtain target products with appropriate fractions.

[0049] The method for preparing liquid fuel by selective catalytic deoxygenation of oil and fat provided by the present invention has significant beneficial effects, including:

[0050] 1. This method has strong adaptability to raw materials and can directly process inferior oil raw materials, which can significantly reduce the cost of raw materials;

[0051] 2. This method can also avoid the problems related to sulfidation catalysts and significantly simplify the process;

[0052] 3. This method can also avoid the use of precious metal catalysts. The catalysts used are cheap and readily available, thus reducing the catalyst cost;

[0053] 4. This method can also significantly reduce hydrogen consumption and material consumption;

[0054] 5. This method can also increase the production of glycerol with higher added value and improve the output value;

[0055] 6. The reaction process of this method is highly controllable and the target product has good selectivity;

[0056] 7. In addition, the product composition can be flexibly adjusted and market adaptability can be improved by changing the raw materials, catalysts and process conditions in the method. DETAILED DESCRIPTION

[0057] It should be noted that the term "comprises" and any variations thereof in the specification and claims of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or inherent to these processes, methods, products or devices.

[0058] "Scope" disclosed in the present invention is given in the form of lower limit and upper limit. It can be one or more lower limits, and one or more upper limits respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower limit and upper limit define the boundaries of a particular range. All ranges defined in this way are combinable, i.e. any lower limit can be combined with any upper limit to form a range. For example, for a specific parameter, a range of 60-120 and 80-110 is listed, and it is understood that a range of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​listed are 1 and 2, and the maximum range values ​​listed are 3, 4 and 5, then the following ranges can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5.

[0059] In the present invention, unless otherwise specified, the numerical range "ab" represents an abbreviation of any real number combination between a and b, where a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed in the present invention, and "0-5" is just an abbreviation of these numerical combinations.

[0060] In the present invention, unless otherwise specified, all embodiments and preferred embodiments mentioned in the present invention can be combined with each other to form a new technical solution.

[0061] In the present invention, unless otherwise specified, all technical features and preferred features mentioned in the present invention can be combined with each other to form a new technical solution.

[0062] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with examples. The following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention. If the specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially. The experimental methods used are all existing conventional methods unless otherwise specified.

[0063] Example 1

[0064] This embodiment provides a method for preparing liquid fuel by selective catalytic deoxygenation of oil and fat, wherein the method comprises the following specific steps:

[0065] Methylation of fats and oils into fatty acid methyl esters:

[0066] Sodium methoxide (0.5% of the mass of refined soybean oil) was used to catalyze the reaction of refined soybean oil and methanol at 80°C and normal pressure, and the alcohol-oil molar ratio was controlled to be 7:1, and the mass space velocity was 0.7h -1 , to methylate refined soybean oil. After separation of methanol and glycerol (yield of nearly 10wt%), the content of fatty acid methyl ester in the obtained product is 97wt%.

[0067] Catalytic hydrogenation of fatty acid methyl esters into fatty alcohols:

[0068] Fatty acid methyl ester was catalytically hydrogenated in a tubular reactor filled with a 10-mesh copper-zinc-aluminum catalyst (the molar ratio of Cu:Zn:Al was 1:0.8:4, prepared by coprecipitation method). The process conditions were: temperature 240 °C, pressure 20 MPa, volume ratio of hydrogen to fatty acid methyl ester 15000:1, mass space velocity 0.5 h -1 After the fatty acid methyl ester is catalytically hydrogenated, the fatty alcohol content obtained after flash distillation reaches 98wt%.

[0069] Fatty alcohols are dehydrated intramolecularly to convert into long-chain hydrocarbons:

[0070] After loading ZSM-22 and γ-Al 2 O 3 In a tubular reactor containing a catalyst (mass ratio of 1:1), fatty alcohol molecules are dehydrated to convert into long-chain hydrocarbons. The reaction process conditions are: temperature 380°C, pressure 0.1 MPa, and mass space velocity of fatty alcohol 3h -1The obtained reaction product is separated by distillation, and the long-chain hydrocarbon content is greater than 98wt%, and the oxygen content in the long-chain hydrocarbon is less than 0.04wt%.

[0071] Long-chain hydrocarbon isomerization to produce liquid fuels:

[0072] In a tubular reactor loaded with ZSM-48 and ZSM-22 (mass ratio of 1:1) catalysts, long-chain hydrocarbons are isomerized to prepare isomerized liquid fuels, wherein the reaction process conditions are: temperature 300 ° C, pressure 0.1 MPa, mass space velocity of long-chain hydrocarbons 1 h -1 .

[0073] In this embodiment, the liquid fuel prepared by a series of selective deoxygenation reactions of refined soybean oil is mainly composed of C 6 -C 20 The hydrocarbon fuel has a yield of 83.4 wt %. In addition, the liquid fuel obtained in this embodiment can be divided into gasoline, diesel and aviation kerosene components according to the boiling range, and can also be further hydro-refined to improve the quality of the product.

[0074] Example 2

[0075] This embodiment provides a method for preparing liquid fuel by selective catalytic deoxygenation of oil and fat, wherein the method comprises the following specific steps:

[0076] Methylation of fats and oils into fatty acid methyl esters:

[0077] The rubber seed oil with an acid value of 30 mgKOH / g was reacted with methanol at 300°C and 20 MPa, with an alcohol-to-oil molar ratio of 16:1 and a mass space velocity of 5 h -1 , in order to methylate the rubber seed oil. After the reaction mixture is separated and methanol and glycerol are recovered (yield is nearly 8wt%), the content of fatty acid methyl ester is 95wt%.

[0078] Catalytic hydrogenation of fatty acid methyl esters into fatty alcohols:

[0079] Fatty acid methyl ester was catalytically hydrogenated in a tubular reactor filled with a 20-mesh copper-nickel-aluminum catalyst (Cu:Ni:Al molar ratio of 1:0.3:4, prepared by coprecipitation method). The process conditions were: temperature 200°C, pressure 6 MPa, volume ratio of hydrogen to fatty acid methyl ester 8000:1, mass space velocity 2 h -1 After the selective catalytic hydrogenation reaction of fatty acid methyl ester is completed, the obtained product is flashed to obtain a fatty alcohol content of 94 wt%.

[0080] Fatty alcohols are dehydrated intramolecularly to convert into long-chain hydrocarbons:

[0081] In the case of γ-Al 2 O3 In the tower reactor with catalyst, fatty alcohol molecules are dehydrated to convert into long-chain hydrocarbons. The reaction process conditions are: temperature 380℃, pressure -0.08MPa, mass space velocity of fatty alcohol 1h -1 After the reaction is completed, the reaction product is separated to obtain a long-chain hydrocarbon content greater than 97wt%, and an oxygen content in the long-chain hydrocarbon is less than 0.03wt%.

[0082] Long-chain hydrocarbon isomerization to produce liquid fuels:

[0083] In a tubular reactor loaded with SAPO-31 and SAPO-11 (mass ratio of 1:1) catalysts, long-chain hydrocarbons were isomerized under nitrogen atmosphere to prepare isomerized liquid fuel. The reaction process conditions were: temperature 320°C, pressure 2MPa, mass space velocity of long-chain hydrocarbons 3h -1 .

[0084] In this embodiment, the liquid fuel prepared by a series of selective deoxygenation reactions of rubber seed oil is mainly composed of C 6 -C 20 The hydrocarbon fuel has a yield of 81.3 wt %. In addition, the liquid fuel obtained in this embodiment can be divided into gasoline, diesel and aviation kerosene components according to the boiling range, or further hydro-refined to improve the fuel quality.

[0085] Example 3

[0086] This embodiment provides a method for preparing liquid fuel by selective catalytic deoxygenation of oil and fat, wherein the method comprises the following specific steps:

[0087] Methylation of fats and oils into fatty acid methyl esters:

[0088] The rancid waste oil from the catering industry was catalyzed by ZSM-5 acidic molecular sieve and reacted with methanol at 160°C and 1 MPa, and the molar ratio of alcohol to oil was controlled to be 7:1 and the mass space velocity was 0.5 h -1 After the reaction, methanol and glycerol were separated (yield was about 5 wt%), and then the refined fatty acid methyl ester was obtained by vacuum distillation, with a content of 99 wt%.

[0089] Catalytic hydrogenation of fatty acid methyl esters into fatty alcohols:

[0090] Fatty acid methyl ester was catalytically hydrogenated in a tubular reactor filled with a 20-mesh copper-nickel-iron-aluminum catalyst (Cu:Ni:Fe:Al molar ratio of 1:0.3:0.3:4, prepared by coprecipitation method). The process conditions were: temperature 180 °C, pressure 10 MPa, volume ratio of hydrogen to fatty acid methyl ester 600:1, mass space velocity 0.3 h -1After the catalytic hydrogenation reaction of fatty acid methyl ester is completed, the content of fatty alcohol obtained by flash evaporation of the reaction product reaches 97wt%.

[0091] Fatty alcohols are dehydrated intramolecularly to convert into long-chain hydrocarbons:

[0092] After loading ZSM-35 and γ-Al 2 O 3 In a tubular reactor with a molecular sieve catalyst (mass ratio of 1:1), fatty alcohol molecules are dehydrated to convert into long-chain hydrocarbons. The reaction process conditions are: temperature 300°C, pressure 0.2MPa, mass space velocity of fatty alcohol 1h -1 The reaction product is separated by distillation to obtain a long-chain hydrocarbon content greater than 98 wt %, and an oxygen content in the long-chain hydrocarbon is less than 0.035 wt %.

[0093] Long-chain hydrocarbon isomerization to produce liquid fuels:

[0094] In a tubular reactor loaded with ZSM-5 and Y molecular sieve (mass ratio of 1:1) catalyst, long-chain hydrocarbons are isomerized to prepare isomerized liquid fuel. The reaction process conditions are: temperature 240°C, pressure -0.05MPa, mass space velocity of long-chain hydrocarbons 0.3h -1 .

[0095] In this embodiment, the liquid fuel prepared by a series of selective deoxygenation reactions of waste oil from the catering industry is mainly composed of C 6 -C 20 The hydrocarbon fuel has a yield of 81.3 wt %. In addition, the liquid fuel prepared in this embodiment can be divided into gasoline, diesel and aviation kerosene components according to the boiling range, or further hydro-refined to improve the fuel quality.

[0096] Example 4

[0097] This embodiment provides a method for preparing liquid fuel by selective catalytic deoxygenation of oil and fat, wherein the method comprises the following specific steps:

[0098] Methylation of fats and oils into fatty acid methyl esters:

[0099] The beef tallow and methanol were reacted at 260℃ and 6MPa, and the molar ratio of alcohol to oil was controlled to be 10:1 and the mass space velocity was 0.5h -1 After the reaction, the content of fatty acid methyl ester was 97 wt % after separation and recovery of methanol and glycerol (glycerol yield was about 8 wt %).

[0100] Catalytic hydrogenation of fatty acid methyl esters into fatty alcohols:

[0101] Fatty acid methyl ester was catalytically hydrogenated in a tubular reactor filled with a commercial copper-zinc-aluminum catalyst. The process conditions were: temperature 230°C, pressure 16 MPa, volume ratio of hydrogen to fatty acid methyl ester 6000:1, mass space velocity 1.2 h -1 The fatty alcohol content of the product obtained by the catalytic hydrogenation reaction of fatty acid methyl ester reaches 96wt%.

[0102] Fatty alcohols are dehydrated intramolecularly to convert into long-chain hydrocarbons:

[0103] After loading ZSM-23 and γ-Al 2 O 3 In a tower reactor containing a catalyst (mass ratio of 1:1), fatty alcohol molecules are dehydrated to convert into long-chain hydrocarbons. The reaction process conditions are: temperature 280°C, pressure -0.09MPa, and mass space velocity of fatty alcohol 0.5h -1 The reaction product is separated to obtain a long-chain hydrocarbon content greater than 97 wt %, and an oxygen content in the long-chain hydrocarbon less than 0.04 wt %.

[0104] Long-chain hydrocarbon isomerization to produce liquid fuels:

[0105] In a tubular reactor loaded with ZSM-48 and SAPO-11 (mass ratio of 1:1) catalysts, long-chain hydrocarbons are isomerized to prepare isomerized liquid fuels. The reaction process conditions are: temperature 300°C, pressure 0.1 MPa, mass space velocity of long-chain hydrocarbons 1 h -1 .

[0106] In the embodiment of the present invention, the liquid fuel prepared by deoxygenating butter through a series of selective reactions is mainly composed of C 6 -C 20 The hydrocarbon fuel has a yield of 82.5 wt %. In addition, the liquid fuel prepared in this embodiment can be divided into gasoline, diesel and aviation kerosene components according to the boiling range, or further hydro-refined to improve the fuel quality.

[0107] Example 5

[0108] This embodiment provides a method for preparing liquid fuel by selective catalytic deoxygenation of oil and fat, wherein the method comprises the following specific steps:

[0109] Methylation of fats and oils into fatty acid methyl esters:

[0110] Cottonseed oil and methanol were reacted at 210°C and 6 MPa, and the alcohol-oil molar ratio was controlled to be 9:1 and the mass space velocity was 0.5 h -1 After the reaction, the content of fatty acid methyl ester was 96 wt % after separation and recovery of methanol and glycerol (yield was about 9 wt %).

[0111] Catalytic hydrogenation of fatty acid methyl esters into fatty alcohols:

[0112] Fatty acid methyl ester was catalytically hydrogenated in a tubular reactor filled with a commercial copper-zinc-aluminum catalyst. The process conditions were: temperature 250°C, pressure 10 MPa, volume ratio of hydrogen to fatty acid methyl ester 2000:1, mass space velocity 0.5 h -1 The fatty alcohol content of the product obtained by the catalytic hydrogenation reaction of fatty acid methyl ester reaches 97wt%.

[0113] Fatty alcohols are dehydrated intramolecularly to convert into long-chain hydrocarbons:

[0114] After filling with ZrO 2 In a tubular reactor containing a molecular sieve catalyst of 1:1 and ZSM-22 (the two are mixed in a mass ratio of 1:1), fatty alcohol molecules are dehydrated to convert into long-chain hydrocarbons. The reaction process conditions are: temperature 250°C, pressure 0.1 MPa, and mass space velocity of fatty alcohol 0.2 h -1 The reaction product is separated, and the content of long-chain hydrocarbons obtained is greater than 96wt%, and the oxygen content in the long-chain hydrocarbons is less than 0.04wt%.

[0115] Long-chain hydrocarbon isomerization to produce liquid fuels:

[0116] In a tubular reactor loaded with ZSM-48 and ZSM-23 (mass ratio of 1:1) catalysts, long-chain hydrocarbons are isomerized to prepare isomerized liquid fuels. The reaction process conditions are: temperature 280°C, pressure -0.06MPa, mass space velocity of long-chain hydrocarbons 0.5h -1 .

[0117] In this embodiment, the liquid fuel prepared by deoxygenating cottonseed oil through a series of selective reactions is mainly composed of C 6 -C 20 The hydrocarbon fuel has a yield of 82.3 wt %. In addition, the liquid fuel prepared in this embodiment can be divided into gasoline, diesel and aviation kerosene components according to the boiling range, or further hydro-refined to improve the fuel quality.

[0118] Comparative Example 1

[0119] This comparative example provides a method for preparing liquid fuel by selective catalytic deoxygenation of oil and fat, wherein the method comprises the following specific steps:

[0120] Methylation of fats and oils into fatty acid methyl esters:

[0121] The rubber seed oil with an acid value of 30 mgKOH / g was reacted with methanol at 300°C and 20 MPa, and the alcohol-to-oil molar ratio was controlled to be 16:1 and the mass space velocity was 5 h -1, in order to methylate the rubber seed oil. After the reaction mixture is separated and methanol and glycerol are recovered (yield is nearly 8wt%), the content of fatty acid methyl ester is 95wt%.

[0122] Catalytic hydrogenation of fatty acid methyl esters into fatty alcohols:

[0123] Fatty acid methyl ester was catalytically hydrogenated in a tubular reactor filled with a 20-mesh copper-nickel-aluminum catalyst (Cu:Ni:Al molar ratio of 1:0.3:4, prepared by coprecipitation method). The process conditions were: temperature 200°C, pressure 6 MPa, volume ratio of hydrogen to fatty acid methyl ester 8000:1, mass space velocity 2 h -1 After the selective catalytic hydrogenation reaction of fatty acid methyl ester is completed, the obtained product is flashed to obtain a fatty alcohol content of 94 wt%.

[0124] Liquid fuel preparation:

[0125] The fatty alcohol is directly passed through a tubular reactor loaded with SAPO-31 and SAPO-11 (mass ratio is 1:1) catalysts, and the fatty alcohol is dehydrated and isomerized under the action of the catalyst under a nitrogen atmosphere to obtain an isomerized liquid fuel. The process conditions for dehydration and isomerization are: temperature 320°C, pressure 2MPa, and mass space velocity of fatty alcohol 3h -1 .

[0126] Comparison of Example 2 and Comparative Example 1 shows that in Example 2, the fatty alcohol molecules are dehydrated to convert into long-chain hydrocarbons, specifically: 2 O 3 In the tower reactor with catalyst, fatty alcohol molecules are dehydrated to convert into long-chain hydrocarbons. The reaction process conditions are: temperature 380℃, pressure -0.08MPa, mass space velocity of fatty alcohol 1h -1 . After the reaction is completed, the reaction product is separated to obtain a long-chain hydrocarbon content greater than 97wt%, and the oxygen content in the long-chain hydrocarbon is less than 0.03wt%. The long-chain hydrocarbons obtained are mainly terminal olefins, and their content is greater than 95wt%. Subsequently, this type of high-purity long-chain terminal olefins are subjected to long-chain terminal olefin isomerization reaction in a tubular reactor loaded with SAPO-31 and SAPO-11 (mass ratio of 1:1) catalysts under nitrogen atmosphere to obtain isomerized liquid fuel. The specific reaction process conditions are: temperature 320°C, pressure 2MPa, mass space velocity of long-chain terminal olefins 3h -1 In Example 2, the method of first dehydrating the fatty alcohol molecules into long-chain hydrocarbons and then isomerizing the long-chain hydrocarbons to prepare liquid fuel can inhibit the generation of cracking reaction products, wherein C 12 -C 18The selectivity of the components is greater than 80%, and the oxygen content in the liquid fuel is almost zero; in comparison, in Comparative Example 1, the fatty alcohol obtained by catalytic hydrogenation of fatty acid methyl ester is directly dehydrated and isomerized to prepare the isomerized liquid fuel. This method of preparing the liquid fuel cannot inhibit the generation of the cracking reaction product. Accordingly, in Comparative Example 1, C 12 -C 18 The selectivity of the components dropped to 62%, and the oxygen content in the liquid fuel was about 2.8 wt%.

[0127] In summary, the method for preparing liquid fuel by selective catalytic deoxygenation of oils and fats provided in the embodiments of the present invention first dehydrates fatty alcohol molecules into long-chain hydrocarbons, and then isomerizes the long-chain hydrocarbons to prepare liquid fuel, which can avoid the increase in oxygen content of isomerized products caused by water produced by catalytic deoxygenation of fatty alcohols, thereby reducing the adverse effects of by-product water and extending the service life of the catalyst; at the same time, the method can significantly reduce hydrogen consumption by dehydrating fatty alcohol molecules into long-chain hydrocarbons and then isomerizing the long-chain hydrocarbons to prepare liquid fuel.

[0128] The above is only a specific embodiment of the present invention, and cannot be used to limit the scope of the invention. Therefore, the replacement of equivalent components, or equivalent changes and modifications made according to the protection scope of the patent of the present invention, should still fall within the scope of this patent. In addition, the technical features of the present invention can be freely combined with each other, with each other and with each other, and with each other.

Claims

1. A method for preparing liquid fuel by selective catalytic deoxygenation of oils and fats, wherein: The method comprises: S1: First, convert the oil into fatty acid methyl ester by methyl esterification; S2: then catalytically hydrogenating the fatty acid methyl ester into fatty alcohol; S3: Dehydrating the fatty alcohol molecules into long-chain hydrocarbons; in S3, the process conditions for dehydrating the fatty alcohol molecules into long-chain hydrocarbons include: temperature 250-400°C, pressure -0.1MPa to 0.5MPa, mass space velocity 0.2-4h -1 ; S4: Finally, the long-chain hydrocarbons are isomerized to prepare liquid fuels; in S4, the process conditions for isomerizing the long-chain hydrocarbons to prepare liquid fuels include: temperature 200-420°C, pressure -0.1MPa to 4MPa, mass space velocity 0.2-3h -1 .

2. The method according to claim 1, wherein: The oil is animal oil and / or vegetable oil, and the carbon chain length of the oil is C 12 -C 24 The fatty acid content is greater than 80wt%, and the total content of fatty acid glycerides and free fatty acids is greater than 90wt%.

3. The method according to claim 1 or 2, wherein: In S1, the oil methyl esterification is to convert the oil into fatty acid methyl ester by reacting the oil with methanol.

4. The method according to claim 3, wherein: In S1, the oil and fat are reacted with methanol under critical methanol conditions, enzyme catalysis conditions, homogeneous or heterogeneous acid catalysis conditions, or homogeneous or heterogeneous base catalysis conditions to be converted into fatty acid methyl esters.

5. The method according to claim 1 or 4, wherein: In S1, after the oil is methylated and refined, the fatty acid methyl ester content in the obtained product is not less than 80wt%.

6. The method according to claim 5, wherein: In S1, after the oil is methylated and refined, the fatty acid methyl ester content of the obtained product is 95-100wt%.

7. The method according to claim 1, wherein: In S2, the catalyst used for catalytic hydrogenation of fatty acid methyl esters into fatty alcohols is a supported catalyst, and the hydrogenation active metal used in the supported catalyst includes one or more of platinum, palladium, gold, silver, cobalt, molybdenum, copper, nickel, zinc, iron, chromium, barium and manganese, and the carrier is activated carbon, Al2O3 or SiO2.

8. The method according to claim 7, wherein: The hydrogenation active metal includes one or more of copper, cobalt, molybdenum, nickel, iron, zinc and manganese.

9. The method according to any one of claims 1, 7-8, wherein: In S2, the process conditions for catalytic hydrogenation of fatty acid methyl esters into fatty alcohols include: temperature 160-300°C, pressure 2-20MPa, mass space velocity 0.3-3h -1 , hydrogen-oil volume ratio 500:1-15000:

1.

10. The method according to any one of claims 1, 7-8, wherein: In S2, after the fatty acid methyl ester is catalytically hydrogenated and refined, the fatty alcohol content in the obtained product is greater than 86 wt%.

11. The method according to claim 10, wherein: In S2, after the fatty acid methyl ester is catalytically hydrogenated and refined, the fatty alcohol content in the obtained product is 92-100 wt%.

12. The method according to claim 1, wherein: In S3, the catalyst used for the intramolecular dehydration of fatty alcohols into long-chain hydrocarbons is an acid catalyst having a desorption temperature of 150-600°C after NH3 adsorption.

13. The method according to claim 12, wherein: In S3, the acid catalyst includes one or more of γ-Al2O3, ZrO2, ZSM-22, ZSM-23, ZSM-48, ZSM-35, SAPO-31, SAPO-11, ZSM-5, Y molecular sieve and β molecular sieve.

14. The method according to claim 13, wherein: In S3, when γ-Al2O3 and / or ZrO2 are used as an acid catalyst in combination with one or more of ZSM-22, ZSM-23, ZSM-48, ZSM-35, SAPO-31, SAPO-11, ZSM-5, Y molecular sieve and β molecular sieve, the content of γ-Al2O3 is greater than 20wt%, and the content of ZrO2 is greater than 20wt%.

15. The method according to claim 1, wherein: In S3, the reactions involved in the dehydration conversion process within the fatty alcohol molecule include one or more of dehydration, cleavage, isomerization, and cyclization reactions.

16. The method according to any one of claims 1, 12-15, wherein: In S3, after the fatty alcohol is dehydrated and refined within the molecule, the oxygen content in the obtained long-chain hydrocarbon is less than 0.1 wt%.

17. The method according to claim 16, wherein: In S3, after the fatty alcohol is dehydrated and refined within the molecule, the oxygen content in the obtained long-chain hydrocarbon is less than 0.05 wt%.

18. The method according to claim 1, wherein: In S4, the catalyst used for isomerization of long-chain hydrocarbons to prepare liquid fuel is an acid catalyst having a desorption temperature of 150-600°C after NH3 adsorption.

19. The method according to claim 18, wherein: In S4, the acid catalyst includes one or more of ZSM-22, ZSM-23, ZSM-48, ZSM-35, SAPO-31, SAPO-11, ZSM-5, EU-1, Y molecular sieve and β molecular sieve.

20. The method according to claim 1, wherein: In S4, the reactions involved in the long-chain hydrocarbon isomerization process include one or more of cracking, isomerization, cyclization, and superposition.