Metal-encapsulated hydroisomerization catalyst, preparation method thereof and application of metal-encapsulated hydroisomerization catalyst in preparation of biological aviation kerosene from cyperus esculentus oil

Abstract

The invention relates to a metal-encapsulated hydroisomerization catalyst, a preparation method thereof and application of the metal-encapsulated hydroisomerization catalyst in preparation of biological aviation kerosene from cyperus esculentus oil, metal species are encapsulated into a framework of a molecular sieve SAPO-11 through an in-situ encapsulation method, and the hydroisomerization catalyst with proper isomerization performance and cracking performance is prepared; the catalyst has relatively high thermal stability, and can have relatively high yield and isomerization ratio when being applied to a reaction for preparing biological aviation kerosene by hydroisomerization and hydrocracking of a hydrodeoxygenation product of vegetable oil.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts, and in particular relates to a catalyst containing metal, specifically a metal-encapsulated hydroisomerization catalyst, a preparation method thereof, and an application thereof in preparing bio-jet fuel from cyperus oleifera oil. Background Art

[0002] In recent years, biomass energy research has become a cutting-edge research hotspot due to its good application prospects in alleviating the depletion of non-renewable energy and environmental pollution. As the power source of aircraft engines, aviation fuel plays an important role in air transportation. The growing demand for aviation fuel accounts for a large proportion of transportation energy consumption worldwide. There are many ways to produce renewable biojet fuel, and vegetable oil hydroisomerization has been proven to be the most feasible way.

[0003] At present, the preparation of bio-jet fuel from vegetable oil is mainly achieved through a two-step hydrogenation process. The two-step hydrogenation process is a common way to convert vegetable oil into high-energy-density, low-oxygen-content hydrocarbon compounds using a bifunctional catalyst. The hydrodeoxygenation (HDO) reaction is the first step, and the vegetable oil is converted into alkanes through hydrogenation, saturation, deoxygenation, decarbonization and decarboxylation reactions; the second step is through hydrocracking and hydroisomerization to obtain an alkane mixture containing bio-jet fuel components. Common raw materials are vegetable oils extracted from oil crops, such as soybeans, rapeseed, sunflower, castor, jatropha, camelina or algae and other plants with high oil content.

[0004] In order to meet the standards of bio-jet fuel, that is, the physical and chemical properties meet the standards, the second step of hydrocracking and isomerization plays a vital role. For example, to meet the freezing point standard, the isoparaffin components and short carbon chain components must reach a certain ratio. At the same time, to meet the flash point requirements, the carbon chain cannot be too short, which places extremely high demands on the catalyst carrier. Therefore, hydroisomerization and hydrocracking have been widely studied. Although researchers have studied various zeolites as catalysts or carriers, producing bio-jet fuel with high yields is still a major challenge at present.

[0005] The existing catalysts for preparing bio-jet fuel from vegetable oil are mainly zeolite molecular sieves loaded with active metals, and the carrier or active metal is modified to achieve the purpose of high activity and high conversion rate. In patent CN 114540077A, the molecular sieve is modified and phosphorus modified, and the noble metal is loaded for isomerization of animal and vegetable oils and catering waste oil HDO products to prepare aviation kerosene products with a freezing point below -40°C. In patent CN 105582991 A, the noble metal of group VIII is loaded on the molecular sieve, and the catalyst precursor is roasted in an atmosphere formed by a gas containing an oxidizing gas and a halogen-containing compound to synthesize the preparation of bio-jet fuel, but the catalyst acid carrier in the patent is strong, resulting in more cracked light alkane components in the product, and the jet fuel yield is low. It can be seen from this that the existing loaded catalysts for preparing bio-jet fuel from vegetable oil have a complicated preparation process, uncontrollable cracking products, and the active metals are easy to agglomerate at high temperatures, and the stability is poor. How to reduce cracking during the isomerization process and improve the isomerization ratio and catalyst stability in jet fuel products are still difficult problems that need to be solved. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a metal-encapsulated hydroisomerization catalyst and a preparation method thereof, and application thereof in the preparation of bio-jet fuel from cyperus oleifera oil.

[0007] The technical solution adopted by the present invention is: a method for preparing a metal-encapsulated hydroisomerization catalyst, comprising the following steps:

[0008] Step 1: Stirring a phosphorus source and an aluminum source in a water environment for reaction, adding a silicon source and stirring, and then adding di-n-propylamine and diisopropylamine and stirring for reaction to obtain sample A;

[0009] The noble metal compound and the organic ligand are mixed and stirred to obtain a solution B;

[0010] Add solution B and non-noble metal precursor to sample A, and stir to react to obtain sample C;

[0011] The molar ratio of aluminum source, phosphorus source, silicon source, water, di-n-propylamine, diisopropylamine, noble metal compound, organic ligand and non-noble metal precursor is: 1:0.5-1.5:0.2-0.8:50-100:0.6-1.2:0.2-1.2:0.0007-0.004:0.02-0.2:0.007-0.042;

[0012] Step 2: crystallize sample C at 60-200°C;

[0013] Step 3: Wash and dry the crystallized product and then calcine it at 400-700°C to obtain a metal encapsulated catalyst.

[0014] Preferably, the phosphorus source is phosphoric acid, the aluminum source is pseudo-boehmite, and the silicon source is a combination of one or more of alkaline silica sol, acidic silica sol, fumed silica and tetraethyl silicate.

[0015] Preferably, the organic ligand is a combination of one or more of cetyltrimethylammonium bromide, polyvinylpyrrolidone, ethylenediamine, sodium citrate and triethylamine.

[0016] Preferably, the noble metal compound is a combination of one or more of palladium chloride, palladium nitrate, chloropalladic acid, platinum chloride, platinum nitrate, chloroplatinic acid, ruthenium trichloride, potassium chlororuthenate and sodium chlororuthenate;

[0017] The non-precious metal precursor is a combination of one or more of nickel acetylacetonate, cobalt acetylacetonate, iron acetylacetonate, triethylenediamine nickel trichloride, diethylenediamine cobalt trichloride, triethylenediamine iron trichloride, disodium nickel ethylenediaminetetraacetate, disodium iron ethylenediaminetetraacetate, dicobalt ethylenediaminetetraacetate, nickel tartrate, cobalt tartrate and iron tartrate.

[0018] Preferably, the crystallization conditions in step 2 are 60-200° C. and crystallization for 24-72 hours;

[0019] In step 3, the crystallized product is calcined in an air atmosphere with a volume space velocity of 40–80 h –1 , heating rate is 2-10℃·min -1 The calcination temperature is 400-700℃ and the calcination time is 4-10h.

[0020] Preferably, before calcination, the crystallized product is washed by multiple centrifugations until the supernatant is neutral.

[0021] The catalyst is prepared by the method for preparing a metal-encapsulated hydroisomerization catalyst.

[0022] Application of catalysts in the hydrogenation of vegetable oils to produce bio-jet fuel.

[0023] Preferably, the hydrodeoxygenation product of jatropha oil is used to prepare bio-jet fuel.

[0024] Preferably, the specific steps are as follows:

[0025] Step 1: Load the catalyst into the constant temperature range of the continuous flow high pressure fixed bed reactor, and load at least 20 cm of ceramic rings on the catalyst as a preheating layer, and heat to 300-350°C in a flowing hydrogen atmosphere for pretreatment for at least 1 hour;

[0026] Step 2: 40-100 wt% of cyperus oleifera oil HDO product-cyclohexane solution is pumped into the reactor by a pressure pump, wherein the liquid hourly space velocity of the mixed solution is 0.5-1.5 h –1, reaction temperature is 280-400℃, hydrogen pressure is 2-4.0MPa, hydrogen-oil ratio is 400-1400;

[0027] Step 3: After collecting the product by condensation, the product after the reaction is qualitatively and quantitatively analyzed by gas chromatography;

[0028] Step 4: After the reaction is completed, stop feeding first, then continue to purge with hydrogen for at least 1 hour and then cool down. Turn off the hydrogen after the temperature drops below 100°C.

[0029] The advantages and positive effects of the present invention are as follows: the metal species are encapsulated into the framework of the molecular sieve SAPO-11 by an in-situ encapsulation method to obtain the M@SAPO-11 catalyst; the metal ions are encapsulated in the framework of the molecular sieve, which will not reduce the mass transfer rate of alkanes in the SAPO-11 pores, so that when the catalyst is used at a subsequent high temperature, the migration and agglomeration of the active metal in the carrier are avoided, thereby improving the thermal stability of the catalyst and facilitating the maintenance of the catalytic activity; the added organic ligand forms a complex with the noble metal compound, and the non-noble metal precursor is also a complex of the metal ion and the organic ligand, which further reduces the influence of the added metal ions on the formation of the molecular sieve framework;

[0030] Based on the characteristics of the hydroisomerization catalyst, it is applied to the hydroisomerization of the hydrodeoxygenation product of jatropha oil and the hydrocracking reaction to prepare bio-jet fuel, which can achieve a higher jet fuel yield and isomerization ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 XRD spectra of the catalysts prepared in Example 1 and Comparative Examples 2-4;

[0032] Figure 2 TG-DTA curves of Example 1, Comparative Example 3, Comparative Example 4 and SAPO-11 without metal loading in Comparative Example 1. DETAILED DESCRIPTION

[0033] The embodiments of the present invention are described below with reference to the accompanying drawings.

[0034] The present invention relates to metal encapsulation, and metal species are encapsulated into the framework of molecular sieve SAPO-11 by an in-situ encapsulation method, thereby obtaining M@SAPO-11 catalyst, and the stability of the catalyst is further improved under the premise of ensuring a low cracking ratio of the raw material and a high isoparaffin ratio of the aviation kerosene product. The catalyst is used in the reaction of hydroisomerization and hydrocracking of the hydrodeoxygenation product of vegetable oil to prepare bio-aviation kerosene, and has a high yield and isomerization ratio.

[0035] The catalyst preparation method is as follows:

[0036] Step 1: Phosphoric acid (85 wt%) and water are mixed and stirred evenly, pseudo-boehmite is added and stirred for 1-3 hours, and then a silicon source is added. After stirring for at least 10 minutes, templates di-n-propylamine and diisopropylamine are added respectively, and stirring is continued for 1-4 hours; sample A is obtained;

[0037] The noble metal compound and the organic ligand are mixed, and water is added and stirred for at least 30 minutes to completely dissolve the noble metal compound to obtain solution B;

[0038] Add the prepared solution B and the non-noble metal precursor to sample A, and continue stirring for 1-3 hours to obtain sample C;

[0039] The molar ratio of pseudo-boehmite (calculated as Al2O3), phosphoric acid (calculated as P2O5), silicon source, water (combined water I and water II), di-n-propylamine, diisopropylamine, noble metal compound, organic ligand and non-noble metal precursor is: 1: 0.5-1.5: 0.2-0.8: 50-100: 0.6-1.2: 0.2-1.2: 0.0007-0.004: 0.02-0.2: 0.007-0.042;

[0040] The silicon source is any one of alkaline silica sol, acidic silica sol, fumed silica, and tetraethyl silicate; the precious metal compound is any one of palladium chloride, palladium nitrate, chloropalladic acid, platinum chloride, platinum nitrate, chloroplatinic acid, ruthenium trichloride, potassium chlororuthenate, or sodium chlororuthenate; the organic ligand is any one of hexadecyltrimethylammonium bromide, polyvinylpyrrolidone, ethylenediamine, sodium citrate, and triethylamine; the non-precious metal precursor is any one of nickel acetylacetonate, cobalt acetylacetonate, iron acetylacetonate, nickel trichloride, diethylenediamine cobalt trichloride, triethylenediamine iron trichloride, disodium nickel ethylenediaminetetraacetate, disodium iron ethylenediaminetetraacetate, dicobalt ethylenediaminetetraacetate, nickel tartrate, cobalt tartrate, and iron tartrate;

[0041] Step 2: Place sample C in a high-pressure reactor lined with polytetrafluoroethylene for crystallization; the crystallization conditions are 60-200° C. and stand for crystallization for 24-72 hours;

[0042] Step 3: The obtained product is centrifuged and rinsed until the supernatant is neutral. The solid matter obtained by centrifugation is dried and placed in a muffle furnace for calcination in an air atmosphere. The conditions for calcination in the muffle furnace are that the air volume space velocity is 40-80h –1 , heating rate is 2-10℃·min -1 The calcination temperature is 400-700° C. and the calcination time is 4-10 h to obtain the catalyst.

[0043] The above method can be used to prepare a bimetallic catalyst, wherein the metal is encapsulated in the framework of the molecular sieve, rather than in the pores, and the mass transfer rate of alkanes in the SAPO-11 pores will not be reduced, which makes the catalyst avoid the migration and agglomeration of active metals in the carrier when used at a subsequent high temperature, thereby improving the thermal stability of the catalyst. Since the metal is encapsulated in the framework of the molecular sieve, the active center and the acid center of the catalyst are closer, and after the alkane is dehydrogenated to olefins at the active center, it will be adsorbed by the weak B acid in the molecular sieve in time, completing the subsequent carbon cation intermediate rearrangement process, reducing the probability of olefins escaping from the catalyst, and increasing the proportion of isomeric alkanes of the catalyst in the product. The introduction of bimetallic active centers can avoid the failure and deactivation of single metal catalysts under high temperature and pressure, thereby improving the catalytic efficiency.

[0044] During the preparation process, the amount of metal ions added is controlled to reduce the effect of metal ions on the crystallization of the molecular sieve, and the added organic ligands form complexes with the precious metal compounds; in addition, the non-precious metal precursor is also a complex of metal ions and organic ligands, which further reduces the effect of the added metal ions on the formation of the molecular sieve framework. Among them, the metal ions and organic ligands are added to the reaction system in a suitable proportion, which is more conducive to the formation of the metal-encapsulated molecular sieve framework. The added silicon source will generate amorphous silica in the gel, preferentially encapsulate the metal complex, and finally generate the metal-encapsulated SAPO-11 molecular sieve with the help of an organic template.

[0045] The metal-encapsulated bimetallic catalyst prepared by the above method has better cracking performance and isomerization performance. Any type of hydrodeoxygenation catalyst disclosed in the prior art can be used in the first step reaction of preparing bio-jet fuel by the two-step method of vegetable oil, with the obtained hydrodeoxygenation product as the raw material. The vegetable oil hydrodeoxygenation catalyst can generally be a bifunctional catalyst with a metal-supported carrier, the metal is mainly one or more of the precious metals Pt, Pd, Ru, Rh, etc., the non-precious metal is mainly one or more of the transition metals such as Ni, Co, Mo, W, Fe, etc., and the supported carrier is mainly a metal oxide such as aluminum oxide, titanium oxide, zirconium oxide, or a composite carrier in which two of them are combined together. The hydrogen isomerization catalyst prepared by the above method is used in the second step reaction of preparing bio-jet fuel by the two-step method of vegetable oil. The specific method is as follows:

[0046] Step 0: Preparation of feedstock for metal-encapsulated bimetallic hydroisomerization: Place the hydrodeoxygenation catalyst in a fixed bed reactor and heat to 350°C under flowing hydrogen, where the volume space velocity of hydrogen is 200 h –1 , the hydrogen pressure was 3MPa; the reaction raw material was 60wt.% cyperus oleifera oil-cyclohexane solution, and the volume space velocity was 0.8h -1The upper organic phase of the product is used as the raw material for the hydrogenation isomerization of the metal-encapsulated bimetallic catalyst.

[0047] Step 1: Load the catalyst into the constant temperature range of the continuous flow high pressure fixed bed reactor, and load at least 20 cm of ceramic rings on the catalyst as a preheating layer, and heat to 300-350°C in a flowing hydrogen atmosphere for pretreatment for at least 1 hour;

[0048] Step 2: 40-100 wt% of cyperus oleifera oil HDO product-cyclohexane solution is pumped into the reactor by a pressure pump, wherein the liquid hourly space velocity of the mixed solution is 0.5-1.5 h –1 , reaction temperature is 280-400℃, hydrogen pressure is 2-4.0MPa, hydrogen-oil ratio is 400-1400;

[0049] Step 3: After collecting the product by condensation, the product after the reaction is qualitatively and quantitatively analyzed by gas chromatography;

[0050] Step 4: After the reaction is completed, stop feeding first, then continue purging with hydrogen for at least 1 hour, then cool down, and turn off the hydrogen after the temperature drops below 100°C.

[0051] The aviation kerosene that meets the standards requires a certain ratio of isoparaffin components and short carbon chain components. The higher the isomerization or cracking performance, the better. The isomerization ratio and cracking ratio need to be controlled by the catalyst. The catalyst prepared by the present invention can provide moderate cracking performance and isomerization performance. The prepared M@SAPO-11 catalyst can be used for further catalysis of various vegetable oil hydrodeoxygenation products, and can be used to prepare bio-aviation kerosene through further hydroisomerization and hydrocracking, and has a higher aviation kerosene yield and isomerization ratio.

[0052] The scheme of the present invention is described below in conjunction with the accompanying drawings, wherein the experimental methods without specific operating steps are all carried out in accordance with the corresponding product instructions, and the instruments, reagents, and consumables used in the examples can all be purchased from commercial companies unless otherwise specified.

[0053] Example 1

[0054] (1) After 24.93g phosphoric acid (85wt%) and 97.299g water were mixed and stirred for 30min at room temperature, pseudo-boehmite was added and stirred for 2h, followed by 8.664g 30% acidic silica sol, stirring for 30min, and then 6.564g di-n-propylamine and 4.374g diisopropylamine were added and stirred for 2h. Sample A was obtained. The ratio of each component in the gel was Al2O3: P2O5: SiO2: H2O: di-n-propylamine: diisopropylamine = 1:1:0.4:50:0.6:0.4.

[0055] (2) 3.8682 g of chloroplatinic acid solution and 0.6 g of ethylenediamine were mixed and stirred for 1 h to obtain solution B, wherein the molar ratio of ethylenediamine to Pt species was 35:1, and the mass content of the chloroplatinic acid solution was 0.011633 g / g.

[0056] (3) Solution B and 1.9702 g of nickel acetylacetonate were added to sample A and stirred for 1 h. After stirring, the gel was transferred to a polytetrafluoroethylene-lined autoclave, placed in an oven, and allowed to stand for crystallization at 200 °C for 24 h. The obtained product was washed with water by centrifugation until the supernatant was neutral, and then dried thoroughly at 120 °C to obtain sample C, in which the molar ratio of platinum to nickel was 1:10.

[0057] (4) Place sample C in a quartz reaction tube and introduce flowing air at 200 mL min -1 At a speed of 5℃·min -1 The temperature was raised to 600°C at a heating rate and calcined at this temperature for 5 hours to obtain the desired catalyst. The obtained catalyst is numbered Cat-1 and its composition is listed in Table 1.

[0058] Example 2

[0059] The preparation steps of Example 2 are the same as those of Example 1, except that 8.664 g of 30% acidic silica sol in step (1) is replaced by 8.664 g of 30% alkaline silica sol. The resulting catalyst is numbered Cat-2, and its composition is listed in Table 1.

[0060] Example 3

[0061] The preparation steps of Example 3 are the same as those of Example 1, except that 8.664 g of 30% acidic silica sol in step (1) is replaced by 2.5992 g of fumed silica. The resulting catalyst is numbered Cat-3, and its composition is listed in Table 1.

[0062] Example 4

[0063] The preparation steps of Example 4 are the same as those of Example 1, except that the acidic silica sol in step (1) is replaced with 9.0121 g of tetraethyl silicate. The resulting catalyst is numbered Cat-4, and its composition is listed in Table 1.

[0064] Example 5

[0065] The preparation steps of Example 5 are the same as those of Example 1, except that 3.8682 g of chloroplatinic acid solution in step (2) is replaced with 0.0736 g of platinum nitrate. The resulting catalyst is numbered Cat-5, and its composition is listed in Table 1.

[0066] Example 6

[0067] The preparation steps of Example 6 are the same as those of Example 1, except that 0.0777 g of platinum chloride is used to replace 3.8682 g of chloroplatinic acid solution in step (2). The resulting catalyst is numbered Cat-6, and its composition is listed in Table 1.

[0068] Example 7

[0069] The preparation steps of Example 7 are the same as those of Example 1, except that 1.9702 g of nickel acetylacetonate in step (3) is replaced with 1.5856 g of nickel tartrate. The resulting catalyst is numbered Cat-7, and its composition is listed in Table 1.

[0070] Example 8

[0071] The preparation steps of Example 8 are the same as those of Example 1, except that the amount of chloroplatinic acid solution added in step (2) is replaced with 1.2894 g. The resulting catalyst is numbered Cat-8, and its composition is listed in Table 1.

[0072] Example 9

[0073] The preparation steps of Example 9 are the same as those of Example 1, except that 3.8682 g of chloroplatinic acid solution in step (2) is replaced with 0.075 g of palladium chloride. The resulting catalyst is numbered Cat-9, and its composition is listed in Table 1.

[0074] Example 10

[0075] The preparation steps of Example 10 are the same as those of Example 1, except that 3.8682 g of chloroplatinic acid solution in step (2) is replaced with 0.0924 g of ruthenium trichloride. The resulting catalyst is numbered Cat-10, and its composition is listed in Table 1.

[0076] Embodiment 11

[0077] The preparation steps of Example 11 are the same as those of Example 1, except that 1.9702 g of nickel acetylacetonate in step (3) is replaced with 1.9875 g of cobalt acetylacetonate. The resulting catalyst is numbered Cat-11, and its composition is listed in Table 1.

[0078] Example 12

[0079] The preparation steps of Example 12 are the same as those of Example 1, except that 1.9702 g of nickel acetylacetonate in step (3) is replaced with 2.7084 g of iron acetylacetonate. The resulting catalyst is numbered Cat-12, and its composition is listed in Table 1.

[0080] Embodiment 13

[0081] The preparation steps of Example 13 are the same as those of Example 1, except that 3.8682 g of chloroplatinic acid solution in step (2) is replaced by 0.075 g of palladium chloride, and 0.6 g of ethylenediamine is replaced by 1.2 g of hexadecyltrimethylammonium bromide. The resulting catalyst is numbered Cat-13, and its composition is listed in Table 1.

[0082] Embodiment 14

[0083] The preparation steps of Example 14 are the same as those of Example 1, except that 3.8682 g of chloroplatinic acid solution in step (2) is replaced by 0.0924 g of ruthenium trichloride, and 0.6 g of ethylenediamine is replaced by 1.01 g of triethylamine. The resulting catalyst is numbered Cat-14, and its composition is listed in Table 1.

[0084] Embodiment 15

[0085] The preparation steps of Example 15 are the same as those of Example 1, except that 0.6 g of ethylenediamine in step (2) is replaced by 1.2 g of polyvinylpyrrolidone, and 1.9702 g of nickel acetylacetonate is replaced by 1.5571 g of dicobalt ethylenediaminetetraacetate. The resulting catalyst is numbered Cat-15, and its composition is listed in Table 1.

[0086] Example 16

[0087] The preparation steps of Example 16 are the same as those of Example 1, except that the amount of nickel acetylacetonate in step (2) is replaced with 9.851 g, wherein the molar ratio of platinum to nickel is 1:50. The resulting catalyst is numbered Cat-16, and its composition is listed in Table 1.

[0088] Embodiment 17

[0089] The preparation steps of Example 17 are the same as those of Example 1, except that the crystallization temperature in step (3) is changed to 160°C. The resulting catalyst is numbered Cat-17, and its composition is listed in Table 1.

[0090] Embodiment 18

[0091] The preparation steps of Example 18 are the same as those of Example 1, except that the crystallization temperature in step (3) is changed to 180°C. The resulting catalyst is numbered Cat-18 and its composition is listed in Table 1.

[0092] Comparative Example 1

[0093] The purpose is to compare with Example 1 to illustrate the effect of encapsulating the metal into the SAPO-11 carrier on the catalyst in steps (2) and (3). This comparative example changes the loading method of the metal on SAPO-11 and loads the metal on the SAPO-11 carrier by an equal volume impregnation method. The specific operation is as follows:

[0094] (1) After 24.93g phosphoric acid (85wt%) and 97.299g water were mixed and stirred at room temperature for 30min, pseudo-boehmite was added and stirred for 2h, followed by 8.664g 30% acidic silica sol, stirred for 30min, and then 6.564g di-n-propylamine and 4.374g diisopropylamine were added and stirred for 2h. Sample A was obtained. The ratio of each component in the gel was Al2O3: P2O5: SiO2: H2O: di-n-propylamine: diisopropylamine = 1:1:0.4:50:0.6:0.4;

[0095] (2) Sample A was transferred to a polytetrafluoroethylene-lined autoclave, placed in an oven, and allowed to stand for crystallization at 200° C. for 24 h. The obtained product was centrifuged and washed with water, and then dried thoroughly at 120° C. to obtain sample B;

[0096] (4) Place sample B in a quartz reaction tube and introduce flowing air at 200 mL min -1 At a speed of 5℃·min -1 The temperature was raised to 600 °C at a rate of , and calcined at this temperature for 5 h to obtain sample C.

[0097] (5) Take 15 g of sample C, mix 3.8682 g of chloroplatinic acid solution and 1.9702 g of nickel acetylacetonate with a certain amount of water, and evenly drip the bimetallic solution onto sample C by equal volume impregnation method. After standing for 1 h, place it in a 120 °C oven to dry for 3 h. Then place the sample in a quartz reaction tube and let it flow with air at 200 mL min -1 At a speed of 5℃·min -1 The temperature was raised to 500°C at a heating rate of , and calcined at this temperature for 5h to obtain sample D, that is, the desired catalyst. The obtained catalyst is numbered Cat-19, and its composition is listed in Table 1. The mass fraction of chloroplatinic acid solution is 0.011633.

[0098] Comparative Example 2

[0099] The purpose is to compare with Example 1 to illustrate the effect of the metal-ligand complexation on the catalyst in steps (2) and (3). This comparative example eliminates the complexation of the noble metal compound with the organic ligand in step (2), and replaces the non-noble metal precursor in step (3) with the corresponding non-noble metal nitrate. The specific operation is as follows:

[0100] (1) After 24.93g phosphoric acid (85wt%) and 97.299g water were mixed and stirred at room temperature for 30min, pseudo-boehmite was added and stirred for 2h, followed by 8.664g 30% acidic silica sol, stirred for 30min, and then 6.564g di-n-propylamine and 4.374g diisopropylamine were added and stirred for 2h. Sample A was obtained. The ratio of each component in the gel was Al2O3: P2O5: SiO2: H2O: di-n-propylamine: diisopropylamine = 1:1:0.4:50:0.6:0.4;

[0101] (2) 3.8682 g of chloroplatinic acid solution and 2.2291 g of Ni(NO3)2·6H2O were added to sample A and stirred for 1 h to obtain sample B, wherein the molar ratio of platinum to nickel was 1:10.

[0102] (3) Gel B was transferred to a polytetrafluoroethylene-lined autoclave, placed in an oven, and allowed to crystallize at 200°C for 24 hours. The obtained product was centrifuged and washed with water, and then dried thoroughly at 120°C to obtain sample C;

[0103] (4) Place sample C in a quartz reaction tube and introduce flowing air at 200 mL min -1 At a speed of 5℃·min -1 The temperature was raised to 600°C at a heating rate and calcined at this temperature for 5 hours to obtain the desired catalyst. The obtained catalyst was numbered Cat-20 and its composition is listed in Table 1.

[0104] Comparative Example 3

[0105] The purpose is to compare with Example 1 to illustrate the effect of adding a non-precious metal precursor to form a bimetallic catalyst in step (3).

[0106] The preparation steps of Comparative Example 3 are the same as those of Example 1, except that the addition of nickel acetylacetonate is omitted in step (2). The resulting catalyst is numbered Cat-21, and its composition is listed in Table 1.

[0107] Comparative Example 4

[0108] The purpose is to make a comparison with Example 1 to illustrate the effect of adding a noble metal compound to form a bimetallic catalyst in step (3).

[0109] The preparation steps of Comparative Example 4 are the same as those of Example 1, except that the addition of chloroplatinic acid solution and organic ligand in step (2) is omitted. The resulting catalyst is numbered Cat-22, and its composition is listed in Table 1.

[0110] The metals in the catalysts prepared in Examples 1-18 and Comparative Examples 1-4 were detected, and the results are shown in Table 1. It can be seen that the metals loaded on the catalysts did not disappear during the preparation process, but were stably loaded on the catalyst skeleton, and the actual metal content was very close to the theoretical metal content value, proving that the preparation method can effectively achieve bimetallic encapsulation.

[0111] Table 1

[0112]

[0113]

[0114] Example 19: Analysis of the effect of catalyst on the preparation of bio-jet fuel from vegetable oil hydrodeoxygenation products

[0115] Taking jatropha oil as an example, the process of preparing bio-jet fuel from vegetable oil is compared. The evaluation process and conditions of the catalyst are as follows:

[0116] (1) Using 15% Ni-loaded Al2O3 as a hydrodeoxygenation catalyst, 15% Ni / Al2O3 was placed in a fixed bed reactor and heated to 350°C under flowing hydrogen, with a volume space velocity of hydrogen of 200 h / min. –1 , the hydrogen pressure was 3MPa; the reaction raw material was 60wt.% cyperus oleifera oil-cyclohexane solution, and the volume space velocity was 0.8h -1 The upper organic phase of the product was taken as the raw material for catalyst hydroisomerization. The composition and proportion of the HDO product of jatropha oil are listed in Table 2;

[0117] (2) The catalyst prepared in the example or comparative example is loaded into the constant temperature range of a continuous flow high pressure fixed bed reactor, and a ceramic ring of at least 20 cm is loaded on the upper layer of the catalyst as a preheating layer, and the temperature is raised to 350° C. for pretreatment for 2 h under a flowing hydrogen atmosphere;

[0118] (3) A 60 wt% cyperus oil HDO product-cyclohexane solution was pumped into the reactor by a pressure pump, wherein the liquid hourly space velocity of the mixed solution was 1 h –1 , reaction temperature is 330℃, hydrogen pressure is 3MPa, hydrogen-to-oil ratio is 1000;

[0119] (4) collecting the product by condensation;

[0120] (5) After the reaction is completed, stop feeding first, then continue to purge with hydrogen for at least 1 hour, then cool down, and turn off the hydrogen after the temperature drops below 100°C.

[0121] The gas after the reaction was qualitatively and quantitatively analyzed by gas chromatography, and samples were taken every 1 hour. The product composition was analyzed by gas chromatography, and the sample was taken at the reaction point of 2 hours. The product composition and isomer ratio comparison data of different precious metal catalysts at different reaction temperatures are shown in Table 3. In the above embodiments and comparative examples, the product obtained by the reaction was distilled by the method specified in GB / T9168, and the fraction of 150-280°C was collected. The freezing point of the fraction of 150-280°C was determined by the method specified in GB / T2430-2018. Taking the catalyst Cat-1 as an example, the product prepared was distilled, and the bio-jet fuel component of 150-280°C was taken for detection. The physical and chemical parameters are shown in Table 3, which meets the domestic and international standards for bio-jet fuel.

[0122] Table 2 Components of cyperus oleifera oil hydrodeoxygenation (HDO) products

[0123] composition Cyclohexane C15 C16 nC17 nC18 nC18+ content(%) 40 2-5 1-4 25-35 15-20 0-3

[0124] Table 3

[0125] <![CDATA[Density / (kg / m 3 )]]> 790.6 Acid value / (mgKOH / g) 0.011 Flash point / (℃) 68 Freezing point / (℃) -45 S content (μg / g) 2.4 N content (μg / g) <1

[0126] Table 4

[0127]

[0128]

[0129] Figure 1 The XRD spectra of the catalysts prepared in Example 1 and Comparative Examples 2-4 show that the encapsulated metal molecular sieve catalyst was successfully synthesized. In addition, due to the low loading of platinum and nickel, there is no obvious metal diffraction peak. From the data in Table 1, it can be seen that by comparing Examples 1-18 with Comparative Example 2, it is proved that the in-situ encapsulated metal catalyst prepared by the present invention has no obvious loss of metal during the molecular sieve crystallization process, and the method of the present invention can achieve effective metal loading. Figure 2 The TG and DTA curves also indirectly indicate that the synthesized molecular sieve catalyst contains an organic ligand that protects metal ions, that is, during the molecular sieve synthesis process, the organic ligand forms a complex with the metal ion, which minimizes the influence of the metal ion on the molecular sieve framework and fixes the metal ion in the molecular sieve framework. In Table 4, by comparing Examples 1-18 with Comparative Example 1, the encapsulated catalyst has obvious advantages in improving the catalyst hydrogenation isomerization activity and reducing the decomposition of light components. By comparing Examples 1-18 with Comparative Examples 3 and Comparative Example 4, the catalytic activity of the bimetallic catalyst is significantly improved compared with the platinum-based catalyst and the nickel-based catalyst.

[0130] The aviation kerosene components in the prepared product were tested as shown in Table 3, which met the parameter requirements in GB6537-2018.

[0131] The embodiments of the present invention are described in detail above, but the contents described are only preferred embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for preparing a metal-encapsulated hydroisomerization catalyst, characterized in that: The steps include: Step 1: Stirring a phosphorus source and an aluminum source in a water environment for reaction, adding a silicon source and stirring, and then adding di-n-propylamine and diisopropylamine and stirring for reaction to obtain sample A; The noble metal compound and the organic ligand are mixed and stirred to obtain a solution B; Add solution B and non-noble metal precursor to sample A, and stir to react to obtain sample C; The molar ratio of aluminum source, phosphorus source, silicon source, water, di-n-propylamine, diisopropylamine, noble metal compound, organic ligand and non-noble metal precursor is: 1:0.5-1.5:0.2-0.8:50-100:0.6-1.2:0.2-1.2:0.0007-0.004:0.02-0.2:0.007-0.042; Step 2: crystallize sample C at 60-200°C; Step 3: Wash and dry the crystallized product and then calcine it at 400-700°C to obtain a metal encapsulated catalyst.

2. The method for preparing a metal-encapsulated hydroisomerization catalyst according to claim 1, characterized in that: The phosphorus source is phosphoric acid, the aluminum source is pseudo-boehmite, and the silicon source is a combination of one or more of alkaline silica sol, acidic silica sol, fumed silica and tetraethyl silicate.

3. The method for preparing the metal-encapsulated hydroisomerization catalyst according to claim 1, characterized in that: The organic ligand is a combination of one or more of hexadecyltrimethylammonium bromide, polyvinylpyrrolidone, ethylenediamine, sodium citrate and triethylamine.

4. The method for preparing a metal-encapsulated hydroisomerization catalyst according to claim 1, characterized in that: The noble metal compound is a combination of one or more of palladium chloride, palladium nitrate, chloropalladic acid, platinum chloride, platinum nitrate, chloroplatinic acid, ruthenium trichloride, potassium chlororuthenate and sodium chlororuthenate; The non-precious metal precursor is a combination of one or more of nickel acetylacetonate, cobalt acetylacetonate, iron acetylacetonate, triethylenediamine nickel trichloride, diethylenediamine cobalt trichloride, triethylenediamine iron trichloride, disodium nickel ethylenediaminetetraacetate, disodium iron ethylenediaminetetraacetate, dicobalt ethylenediaminetetraacetate, nickel tartrate, cobalt tartrate and iron tartrate.

5. The method for preparing a metal-encapsulated hydroisomerization catalyst according to any one of claims 1 to 4, characterized in that: In step 2, the crystallization conditions are 60-200° C. and 24-72 hours of standing crystallization; In step 3, the crystallized product is calcined in an air atmosphere with a volume space velocity of 40–80 h –1 , heating rate is 2-10℃·min -1 The calcination temperature is 400-700℃ and the calcination time is 4-10h.

6. The method for preparing a metal-encapsulated hydroisomerization catalyst according to claim 5, characterized in that: Before calcination, the crystallized product is washed by multiple centrifugation until the supernatant is neutral.

7. The catalyst prepared by the method for preparing the metal-encapsulated hydroisomerization catalyst according to any one of claims 1 to 6.

8. Use of the catalyst according to claim 7 in the preparation of bio-jet fuel by hydrogenation of vegetable oil.

9. The use according to claim 8, characterized in that: Used to prepare bio-jet fuel from the hydrodeoxygenation product of jatropha oil.

10. The use according to claim 9, characterized in that: The specific steps are as follows: Step 1: Load the catalyst into the constant temperature range of the continuous flow high pressure fixed bed reactor, and load at least 20 cm of ceramic rings on the catalyst as a preheating layer, and heat to 300-350°C in a flowing hydrogen atmosphere for pretreatment for at least 1 hour; Step 2: 40-100 wt% of cyperus oleifera oil HDO product-cyclohexane solution is pumped into the reactor by a pressure pump, wherein the liquid hourly space velocity of the mixed solution is 0.5-1.5 h –1 , reaction temperature is 280-400℃, hydrogen pressure is 2-4.0MPa, hydrogen-oil ratio is 400-1400; Step 3: After collecting the product by condensation, the product after the reaction is qualitatively and quantitatively analyzed by gas chromatography; Step 4: After the reaction is completed, stop feeding first, then continue to purge with hydrogen for at least 1 hour and then cool down. Turn off the hydrogen after the temperature drops below 100°C.

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