Preparation method and application of catalyst

Abstract

The invention discloses a preparation method of a catalyst. The preparation method comprises the following steps: (1) preparing a guiding agent A; (2) preparing a mixture B; (3) carrying out hydrothermal crystallization on the mixture B; (4) preparing an HY molecular sieve; (5) loading active metal on the HY molecular sieve; and (6) activating with H2 to obtain the catalyst. The invention also discloses application of the catalyst in hydroisomerization conversion of polycyclic aromatic hydrocarbon into alkyl adamantane.

Description

Technical Field

[0001] The invention belongs to the field of organic catalysis, and specifically relates to a preparation method of a high-silicon micro-mesoporous Y catalyst and its use in catalyzing the hydrogenation isomerization of polycyclic aromatic hydrocarbons to prepare adamantane. Background Art

[0002] The rapid development of modern aviation technology has put forward higher requirements for the flight performance and propulsion capability of aircraft. Among them, improving the density and volume calorific value of aviation fuel is an important method to improve the propulsion performance of aircraft. Compared with traditional liquid fuels such as gasoline and diesel, high energy density fuel (HEDF) has higher density and larger volume calorific value. The application of HEDF is of great significance for compressing the size of aircraft fuel tanks, extending the range and increasing the speed. The number of carbon atoms of polycyclic aromatic hydrocarbons (PAHs) (such as phenanthrene, fluorene, acenaphthene, etc.) is similar to that of aviation fuel. Therefore, it is a common method to prepare HEDF by deep hydrogenation of PAHs. In addition, the fully hydrogenated products of PAHs can be converted into adamantane and alkyldecalin through further isomerization and selective ring-opening reactions, thereby further improving the low temperature performance and heat absorption capacity of the fuel; among them, alkyladamantane has better thermal stability, higher density and larger volume combustion calorific value, and is an ideal high energy density fuel. However, the high resonance energy and steric resistance of aromatics make the hydrogenation conversion of polycyclic aromatic hydrocarbons very difficult, and the structure of tricyclic compounds is more complex, so hydrogenation isomerization is more difficult.

[0003] At present, metal-zeolite bifunctional catalysts are used for the hydroisomerization reaction of polycyclic aromatic hydrocarbons (PAHs) such as phenanthrene. The literature ChemCatChem 12 (2020) 3477-3488. reported that Pt / silica-alumina (ASA), Pt / Beta and Pt / USY catalysts were used for the hydroisomerization of perhydrophenanthrene (PHP). It was found that ASA became the catalyst with the lowest activity due to its low acidity, while the reduced catalytic activity of Beta was due to the restriction of the process of reactants entering its micropores. It showed better isomerization performance in USY zeolite. Introducing mesopores into zeolite can effectively improve diffusion limitation and improve catalytic activity while maintaining high catalytic shape selectivity. Acid-base post-treatment methods are usually used to produce mesopores. Chemical Industry and Engineering Journal, 2021, 72 (10): 5196-5205. reported that Pt / USY catalyst was prepared using USY zeolite treated with different concentrations of aluminum oxalate as a carrier for the hydroisomerization reaction of phenanthrene. However, due to the acidic post-treatment, the acid content and acid strength of the carrier are reduced, and the final product is mainly a hydrogenation saturation reaction product, and the yield of alkyl adamantane is only 2.3%. Chemical Engineering Science, 2023, 279: 118957. reported that USY zeolite was treated with sodium hydroxide solution to expand the mesopores and adjust the acidity, inhibit the cracking reaction, and promote the isomerization of perhydrophenanthrene to alkyl adamantane, increasing its yield to 32%. However, acid-base post-treatment will cause serious damage to the zeolite framework, loss of activity of the acidic sites in the micropores, and the product yield needs to be improved.

[0004] The present invention is proposed to solve the above-mentioned problems. Summary of the invention

[0005] In order to solve the shortcomings and deficiencies of the above-mentioned prior art, the present invention adopts different types of mesoporous templates when preparing multi-level porous high-silicon Y zeolite to obtain zeolite carriers with different pore sizes and acidities, and then adopts an electrostatic adsorption method to load active metals to prepare a metal-zeolite bifunctional catalyst. The excellent mesoporous structure and suitable acidity distribution have high catalytic performance, and the catalyst is successfully applied to the catalytic reaction of the high-energy fuel of preparing alkyl adamantane by the hydrogenation isomerization of polycyclic aromatic hydrocarbon phenanthrene, and the yield can reach more than 45%.

[0006] The technical solution of the present invention is as follows:

[0007] The first method for preparing the catalyst of the present invention comprises the following steps:

[0008] (1) mixing a first aluminum source, a first silicon source, a first alkali source, a first template and water to prepare a mixture A, aging the mixture A at a certain temperature for a period of time to obtain a directing agent A;

[0009] (2) mixing the directing agent A, the second aluminum source, the second silicon source, the second alkali source, the second template and water to prepare a mixture B;

[0010] (3) hydrothermally crystallizing the mixture B under certain conditions for a period of time;

[0011] (4) separating, washing, drying and calcining the product of step (3) to obtain a NaY molecular sieve; placing the obtained NaY molecular sieve in an ammonium chloride solution for ion exchange at least three times, and then separating, washing, drying and calcining to obtain a HY molecular sieve;

[0012] (5) The HY molecular sieve is loaded with active metals by electrostatic adsorption and then crushed into particles;

[0013] (6) Activating the particles obtained in step (5) using H2 under certain conditions to obtain the catalyst.

[0014] Preferably, the first aluminum source in step (1) is aluminum isopropoxide, the first silicon source is tetraethyl silicate (TEOS), the first alkali source is sodium hydroxide, and the first template is tetraethylammonium hydroxide, and the added molar ratio is SiO2:Al2O3:first template:first alkali source:H2O=1:(0.1-5):(0.01-1):(0.5-10):(10-50); the aging step is: aging at 50-100°C for 12-24h, and then aging at 100-150°C for 36-48h.

[0015] Preferably, a mesoporous template is added in step (2); wherein the second aluminum source is sodium aluminate, the second silicon source is silica gel, and the second alkali source is sodium hydroxide; the second template is tetrabutylammonium hydroxide; the mesoporous template is one of polyoxypropylene polyoxyethylene copolymer, amphiphilic organosilane or organosilane; the added molar ratio is SiO2:Al2O3:second template:second alkali source:mesoporous template:H2O=1:(0.1-5):(0.01-1):(0.1-1):(0.005-1):(10-50); the amount of directing agent A added is such that the content of SiO2 in directing agent A is 10wt% of the content of SiO2 in mixture B.

[0016] Preferably, the polyoxypropylene polyoxyethylene copolymer is one of polyether P123, polyether F127, polyether F108 or polyether L64; the amphiphilic organosilane is dimethyloctadecyl [3- (trimethoxysilyl) propyl] ammonium chloride (TPOAC); the organosilane is one or more of 3- (phenylamino) propyltrimethoxysilane (PHAPTMS), 3-aminopropyltrimethoxysilane (APTMS), 3-aminopropyltriethoxysilane (APTES), isobutyltriethoxysilane (IBTES), octadecyltrimethoxysilane (ODTMS), (N,N-diethyl-3-aminopropyl)trimethoxysilane (DATMS), 3-mercaptopropyltriethoxysilane (MPS), or allyltriethoxysilane (ATMS).

[0017] Preferably, the mesoporous template is a polyoxypropylene-polyoxyethylene copolymer.

[0018] Preferably, the hydrothermal crystallization temperature in step (3) is 100-150°C, and the time is 3-6 days; and the calcination temperature in step (4) is 500-600°C.

[0019] Preferably, the specific steps of step (5) are: using an ammonia solution to adjust the pH value of the active metal precursor solution to 10-12, then placing the HY molecular sieve in the active metal precursor solution for electrostatic adsorption for 2-4 hours, then separating, drying, calcining, and finally crushing and sieving to 20-40 mesh; the active metal is one or more of platinum, palladium or nickel; the amount of the active metal precursor is such that the metal loading in the obtained catalyst is 1-5wt% of the metal in the molecular sieve.

[0020] Preferably, the conditions for H2 activation in step (6) are: temperature of 400-500° C. and time of 3-5 h.

[0021] The second aspect of the present invention discloses the use of the catalyst prepared by the preparation method for hydroisomerization of polycyclic aromatic hydrocarbons into alkyl adamantane.

[0022] Preferably, the polycyclic aromatic hydrocarbon is phenanthrene, and the reaction conditions are a temperature of 160-280°C, a hydrogen partial pressure of 3-5 MPa, and a space velocity of 2-30 h -1 .

[0023] Beneficial effects of the present invention:

[0024] The multi-level pore (microporous or micro-mesoporous) high-silicon Y catalyst prepared by the preparation method of the present invention can efficiently hydroisomerize polycyclic aromatic hydrocarbon phenanthrene into alkyl adamantane high-energy fuel. The method of the present invention uses different types of mesoporous templates to hydrothermally synthesize multi-level pore high-silicon Y zeolite in situ, and uses electrostatic adsorption to load metal Pt to prepare a hydrogenation isomerization bifunctional catalyst. The obtained mesoporous structure can improve the mass transfer performance and change the distribution of B acid and L acid in the catalyst, so that it has a relatively excellent catalytic effect. The preparation method of the multi-level pore high-silicon Y molecular sieve of the present invention draws on the preparation method of patent CN2021115229672, but the present invention finds that the effect is better when the mesoporous template is a polyoxypropylene polyoxyethylene copolymer, and has the most suitable B acid distribution and a larger mesoporous structure. The yield of alkyl adamantane is the highest, reaching 45.89%, and the polycyclic aromatic hydrocarbon phenanthrene is completely converted. In addition, the pure microporous high-silicon Y catalyst of the present invention is used for phenanthrene hydroisomerization, and the yield of alkyl adamantane can also reach 40.33%. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a scanning electron microscope (SEM) photograph of the catalyst prepared in Example 1.

[0026] Figure 2 This is a transmission electron microscope (TEM) photograph of the catalyst prepared in Example 1.

[0027] Figure 3 It is a photograph of the isothermal adsorption diagram of the catalyst prepared in Example 1-5.

[0028] Figure 4 It is the pyridine infrared spectrum photograph of B acid and L acid of the catalyst obtained in Example 1. DETAILED DESCRIPTION

[0029] The present invention is described in detail below in conjunction with some specific embodiments. These embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The embodiments in the examples are only preferred embodiments, but the present invention is not limited to the preferred embodiments.

[0030] Example 1: Preparation of catalyst Pt / MSY-P1, comprising the following steps:

[0031] (1) Preparation of directing agent A: 6.80 g of aluminum isopropoxide was added to 84.51 g of tetraethylammonium hydroxide solution, stirred until transparent, then 0.13 g of sodium hydroxide was added, stirred for 30 minutes, and finally 34.72 g of TEOS was added, stirred for 4 hours, and then the solution was transferred to a sealed stainless steel reactor, statically aged at 50° C. for 0.5 day and statically aged at 100° C. for 2 days to obtain the desired directing agent A;

[0032] (2) 0.42 g of sodium hydroxide was dissolved in 23.07 g of deionized water, and then 0.87 g of sodium aluminate was added, and the mixture was stirred until transparent; then 11.61 g of tetrabutylammonium hydroxide was added, and the mixture was stirred until clear; then 0.45 g of a mesoporous template polyoxypropylene polyoxyethylene copolymer solution (polyether P123, ≥99 wt%, Tianjin Xiens Biochemical Technology Co., Ltd.) was added, and the mixture was stirred for a certain period of time, and then 5.4 g of silica gel was added, and finally 6.60 g of the directing agent A in step (1) was added, and the mixture was stirred until uniform to obtain a mixture B;

[0033] (3) placing the mixture B obtained in step (2) in a high-temperature and high-pressure stainless steel reactor, and hydrothermally crystallizing it at 120° C. for 3.5 days under dynamic conditions;

[0034] (4) After the hydrothermal crystallization is completed, the solid product is filtered, washed with distilled water, and dried at 120° C. for 12 hours to remove moisture. The dried particles are then calcined at 550° C. in an air atmosphere and heated at a rate of 5° C. / min to remove the organic solvent, thereby obtaining a Na-MSY-P1 molecular sieve. The particles are then ion exchanged three times in an ammonium chloride solution, and after separation, washing, drying, and calcination, the H-MSY-P1 molecular sieve is obtained.

[0035] (5) The H-MSY-P1 molecular sieve obtained in step (2) is loaded with metal Pt by electrostatic adsorption to obtain a bifunctional Pt / MSY-P1 catalyst, which is then crushed and sieved to 20-40 mesh, wherein the Pt loading is 2 wt%.

[0036] Example 2: Preparation of catalyst Pt / MSY-TP.

[0037] The conditions and steps were the same as those in Example 1, except that the mesoporous template was 1.59 g of TPOAC solution (42 wt %, Sigma-Aldrich Company), to obtain a Pt / MSY-TP catalyst.

[0038] Example 3: Preparation of catalyst Pt / MSY-PH.

[0039] The conditions and steps were the same as those in Example 1, except that the mesoporous template was 0.35 g of PHAPTMS solution (96 wt %, Tianjin Xiensi Biochemical Technology Co., Ltd.) to obtain a Pt / MSY-PH catalyst.

[0040] Example 4: Preparation of catalyst Pt / MSY-AP.

[0041] The conditions and steps were the same as those in Example 1, except that the mesoporous template was 0.25 g of APTMS solution (97 wt %, Tianjin Xiensi Biochemical Technology Co., Ltd.) to obtain a Pt / MSY-AP catalyst.

[0042] Example 5: Preparation of catalyst Pt / SY.

[0043] The conditions and steps were the same as those in Example 1, but no mesoporous template was added to obtain a Pt / SY catalyst.

[0044] Figure 1 is a scanning electron microscope (SEM) photograph of Pt / MSY-P1 prepared in Example 1, Figure 2 This is a transmission electron microscope (TEM) photograph of Pt / MSY-P1 prepared in Example 1. Figure 3 It is a picture of the isothermal adsorption line diagram of different hydroisomerization catalysts prepared in Examples 1-5. Figure 4 Pyridine infrared spectra of B acid and L acid of the catalyst Pt / MSY-P1 prepared in Example 1. Figure 1 SEM and Figure 2 It can be seen from the TEM that the obtained catalyst has a typical faujasite morphology and has a large number of obvious mesoporous structures, which can greatly reduce the diffusion resistance of macromolecular reactants such as polycyclic aromatic hydrocarbons. Figure 3 It can be seen from the isothermal adsorption line diagram that the molecular sieves with different types of mesoporous template agents all have H4 type hysteresis loops, indicating the existence of mesoporous structures; it can reduce the diffusion resistance of the reactant molecules. The SY molecular sieve without the addition of mesoporous template agents has a pure microporous structure. Figure 4 It can be seen that the Pt / MSY-P1 catalyst prepared in Example 1 has abundant Acid sites, with high The higher the ratio of B acid, the more favorable the isomerization of PAHs will be.

[0045] Example 6-10: Hydroisomerization reaction of polycyclic aromatic hydrocarbons catalyzed by Pt / MSY-P1.

[0046] The catalyst with a mesh size of 20 to 40 is loaded into a fixed bed device. The catalyst needs to be activated with H2 before the reaction. The activation temperature of the catalyst in a hydrogen atmosphere is 450°C and the activation time is 3.5h. After the activation is completed, the temperature is lowered to the required reaction temperature. The reaction temperature is 160-280°C, the hydrogen pressure is 3-5MPa, the hydrogen-to-oil ratio is 100-1500, and the mass space velocity is 2-30h. -1 .

[0047] Table 1 shows the isomerization results of the Pt / MSY-P1 catalyst of Example 1 under different conditions. It can be seen that when the mass space velocity is 8.4h -1 When the reaction temperature is 220℃ and the reaction pressure is 4MPa, phenanthrene (C8H 18) The highest yield of alkyladamantanes by hydrogenation is 45.89%, and the conversion rate of phenanthrene is 100%. The reaction temperature is relatively moderate.

[0048] Table 1

[0049]

[0050] Examples 11-15: Hydroisomerization of polycyclic aromatic hydrocarbons catalyzed by Pt / MSY-TP.

[0051] Table 2 shows the isomerization results of the catalyst in Example 2 under different conditions. It can be seen that when the mass space velocity is 8.4h -1 When the reaction temperature is 220℃ and the reaction pressure is 4MPa, phenanthrene (C8H 18 ) The highest yield of alkyladamantanes by hydrogenation is 42.41%, and the conversion rate of phenanthrene is 100%. The reaction temperature is relatively moderate.

[0052] Table 2

[0053]

[0054] Examples 16-20: Catalyst Pt / MSY-PH catalyzes the hydroisomerization reaction of polycyclic aromatic hydrocarbons.

[0055] Table 3 shows the isomerization results of the catalyst in Example 3 under different conditions. It can be seen that when the mass space velocity is 8.4h -1 When the reaction temperature is 230℃ and the reaction pressure is 4MPa, phenanthrene (C8H 18 ) The highest yield of alkyladamantanes by hydrogenation is 41.56%, and the conversion rate of phenanthrene is 100%. The reaction temperature is relatively moderate.

[0056] Table 3

[0057]

[0058] Examples 21-25: Catalyst Pt / MSY-AP catalyzes the hydroisomerization reaction of polycyclic aromatic hydrocarbons.

[0059] Table 4 shows the isomerization results of the catalyst of Example 4 under different conditions. It can be seen that when the mass space velocity is 8.4h -1 When the reaction temperature is 230℃ and the reaction pressure is 4MPa, phenanthrene (C8H 18 ) The highest yield of alkyladamantanes by hydrogenation is 43.28%, and the conversion rate of phenanthrene is 100%. The reaction temperature is relatively moderate.

[0060] Table 4

[0061]

[0062] Examples 26-30: Catalyst Pt / SY catalyzes the hydroisomerization reaction of polycyclic aromatic hydrocarbons.

[0063] Table 5 shows the isomerization results of the catalyst of Example 5 under different conditions. It can be seen that at a space velocity of 8.4 h -1 When the reaction temperature is 230℃ and the reaction pressure is 4MPa, phenanthrene (C8H 18 ) The highest yield of hydrogenation isomerization to alkyl adamantane is 40.33%, the conversion rate of phenanthrene is 100%, and the required reaction temperature is relatively moderate.

[0064] Table 5

[0065]

[0066] It can be seen from the results in Tables 1-5 that the yield of phenanthrene converted to alkyl adamantane using pure microporous molecular sieve catalyst can reach 40.33%; however, the yield of phenanthrene converted to alkyl adamantane using micro-mesoporous molecular sieve catalyst is higher. Among them, the yield of phenanthrene converted to alkyl adamantane using micro-mesoporous molecular sieve catalyst obtained when the mesoporous template agent is polyoxypropylene polyoxyethylene copolymer is the highest, which can reach 45.89%.

[0067] The above description is only used to introduce the specific implementation methods of the present invention in detail, but the technical solution proposed by the present invention is not limited to the above method. Without departing from the basic principles of the present technology, equivalent modifications and changes made by those skilled in the art to the technology proposed by the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a catalyst, characterized in that: The steps include: (1) mixing a first aluminum source, a first silicon source, a first alkali source, a first template and water to prepare a mixture A, aging the mixture A at a certain temperature for a period of time to obtain a directing agent A; (2) mixing the directing agent A, the second aluminum source, the second silicon source, the second alkali source, the second template and water to prepare a mixture B; (3) hydrothermally crystallizing the mixture B under certain conditions for a period of time; (4) separating, washing, drying and calcining the product of step (3) to obtain a NaY molecular sieve; placing the obtained NaY molecular sieve in an ammonium chloride solution for ion exchange at least three times, and then separating, washing, drying and calcining to obtain a HY molecular sieve; (5) The HY molecular sieve is loaded with active metals by electrostatic adsorption and then crushed into particles; (6) Activating the particles obtained in step (5) using H2 under certain conditions to obtain the catalyst.

2. The preparation method according to claim 1, characterized in that: The first aluminum source of step (1) is aluminum isopropoxide, the first silicon source is tetraethyl silicate, the first alkali source is sodium hydroxide, and the first template is tetraethylammonium hydroxide, and the added molar ratio is SiO2:Al2O3:first template:first alkali source:H2O=1:(0.1-5):(0.01-1):(0.5-10):(10-50); the aging step is: aging at 50-100°C for 12-24h, and then aging at 100-150°C for 36-48h.

3. The preparation method according to claim 1, characterized in that: Step (2) adding a mesoporous template; wherein the second aluminum source is sodium aluminate, the second silicon source is silica gel, and the second alkali source is sodium hydroxide; the second template is tetrabutylammonium hydroxide; the mesoporous template is one of polyoxypropylene polyoxyethylene copolymer, amphiphilic organosilane or organosilane; the added molar ratio is SiO2:Al2O3:second template:second alkali source:mesoporous template:H2O=1:(0.1-5):(0.01-1):(0.1-1):(0.005-1):(10-50); the amount of directing agent A added is such that the content of SiO2 in directing agent A is 10wt% of the content of SiO2 in mixture B.

4. The preparation method according to claim 3, characterized in that: The polyoxypropylene polyoxyethylene copolymer is one of polyether P123, polyether F127, polyether F108 or polyether L64; the amphiphilic organosilane is dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride; the organosilane is one or more of 3-(phenylamino)propyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, isobutyltriethoxysilane, octadecyltrimethoxysilane, (N,N-diethyl-3-aminopropyl)trimethoxysilane, 3-mercaptopropyltriethoxysilane, or allyltriethoxysilane.

5. The preparation method according to claim 3, characterized in that: The mesoporous template agent is a polyoxypropylene-polyoxyethylene copolymer.

6. The preparation method according to claim 1, characterized in that: The hydrothermal crystallization temperature of step (3) is 100-150°C and the time is 3-6 days; the calcination temperature of step (4) is 500-600°C.

7. The preparation method according to claim 1, characterized in that: The specific steps of step (5) are: using an ammonia solution to adjust the pH value of the active metal precursor solution to 10-12, then placing the HY molecular sieve in the active metal precursor solution for electrostatic adsorption for 2-4 hours, then separating, drying, calcining, and finally crushing and sieving to 20-40 mesh; the active metal is one or more of platinum, palladium or nickel; the amount of the active metal precursor is such that the metal loading in the obtained catalyst is 1-5wt% of the metal in the molecular sieve.

8. The preparation method according to claim 1, characterized in that: The conditions for H2 activation in step (6) are: temperature of 400-500°C and time of 3-5h.

9. Use of the catalyst prepared by the preparation method according to any one of claims 1 to 8 for the hydroisomerization conversion of polycyclic aromatic hydrocarbons into alkyladamantanes.

10. The method according to claim 9, characterized in that The PAH is phenanthrene, and the reaction conditions are temperature 160-280°C, hydrogen partial pressure 3-5MPa, and space velocity 2-30h -1 .

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