阅读说明：本技术 一种SiO2包覆分子筛负载双金属催化剂及其制备方法和应用 (SiO (silicon dioxide)2Coated molecular sieve supported bimetallic catalyst and preparation method and application thereof ) 是由 宋文静 宋梦雪 蔡文青 舒嘉壕 姜兴茂 于 2021-10-12 设计创作，主要内容包括：本发明公开了一种SiO-(2)包覆分子筛负载双金属催化剂及其制备方法和应用。该催化剂包括活性金属Pt、第二金属M、分子筛载体和包覆在分子筛载体表面的介孔SiO-(2)包覆层；其中介孔SiO-(2)和分子筛的质量比为0.9～3.0：1；第二金属M负载在分子筛载体中且限域于介孔SiO-(2)包覆层内部,活性金属Pt分布于介孔SiO-(2)包覆层和分子筛中。其制备为：首先制备负载金属M前驱盐的分子筛,然后进行介孔SiO-(2)包覆,最后加入到Pt前驱盐溶液中,搅拌、干燥、还原即可。该催化剂用于催化苯氧基乙苯的氢转移裂化反应时有利于生成高收率的苯、乙苯、苯酚等高附加值产物,显著降低异构产物收率,且过程简单,通用性强。(The invention discloses a SiO 2 Coated molecular sieve loaded bimetallic catalyst and preparation method thereofAnd applications. The catalyst comprises an active metal Pt, a second metal M, a molecular sieve carrier and mesoporous SiO coated on the surface of the molecular sieve carrier 2 A coating layer; wherein the mesoporous SiO 2 The mass ratio of the molecular sieve to the molecular sieve is 0.9-3.0: 1; the second metal M is loaded in the molecular sieve carrier and limited in the mesoporous SiO 2 Inside the coating layer, active metal Pt is distributed in the mesoporous SiO 2 Coating layer and molecular sieve. The preparation method comprises the following steps: firstly, preparing a molecular sieve loaded with metal M precursor salt, and then carrying out mesoporous SiO 2 And (4) coating, finally adding the coated particles into a Pt precursor salt solution, stirring, drying and reducing. The catalyst is used for catalyzing the hydrogen transfer cracking reaction of phenoxyl ethylbenzene, is beneficial to generating high-yield high-added-value products such as benzene, ethylbenzene, phenol and the like, obviously reduces the yield of isomeric products, and has simple process and strong universality.)

1. SiO (silicon dioxide)₂The coated molecular sieve supported bimetallic catalyst is characterized by comprising an active metal Pt, a second metal M, a molecular sieve carrier and mesoporous SiO coated on the surface of the molecular sieve carrier₂A coating layer; wherein the mesoporous SiO₂The mass ratio of the molecular sieve to the molecular sieve is 0.9-3.0: 1; the second metal M is loaded in the molecular sieve carrier and limited in the mesoporous SiO₂Inside the coating layer, active metal Pt is distributed in the mesoporous SiO₂Coating layer and molecular sieve.

2. The catalyst according to claim 1, wherein the second metal M is 0.3 to 10 wt% in the catalyst; the active metal Pt accounts for 0.2-2.0 wt%; the mesoporous SiO₂The thickness of the coating layer is 10-90 nm.

3. The catalyst of claim 1, wherein the molecular sieve is at least one of an HY, MCM, ZSM-5 type molecular sieve; the metal M is at least one of Ni, Sn, Co, Pd or Ru.

4. The catalyst of claim 1, wherein the catalyst is prepared by the steps of: firstly, loading a second metal M precursor salt on a molecular sieve carrier to obtain a molecular sieve loaded with the metal M precursor salt; secondly, in the presence of an organic template agent, the mesoporous SiO is wrapped on the surface of the metal M precursor salt-loaded molecular sieve by hydrolyzing an organic silicon source₂To obtain mesoporous SiO₂A coated metal M precursor salt loaded molecular sieve; finally dipping Pt precursor salt solution, drying, calcining and reducing to obtain SiO₂The coated molecular sieve supports the bimetallic catalyst.

5. An SiO as claimed in any of claims 1 to 4₂The preparation method of the coated molecular sieve supported bimetallic catalyst is characterized by comprising the following steps:

1) adding a molecular sieve carrier into a metal M precursor salt solution, stirring and drying to prepare the molecular sieve loaded with the metal M precursor salt;

2) dispersing the molecular sieve loaded with the metal M obtained in the step 1) in an aqueous solution of an organic template, and adding ammonia water under stirring at room temperature; adding ethanol and an organic silicon source in sequence, stirring and reacting at a certain temperature, washing, drying and calcining after the reaction is finished to obtain mesoporous SiO₂A coated metal M precursor salt loaded molecular sieve;

3) subjecting the mesoporous SiO obtained in the step 2) to₂Adding the coated molecular sieve loaded with metal M precursor salt into the Pt precursor salt solution, stirring at room temperature, drying and reducing to obtain SiO₂The coated molecular sieve supports the bimetallic catalyst.

6. The production method according to claim 5,

in the step 1), the molecular sieve carrier is selected from at least one of HY, MCM and ZSM-5, and the metal M precursor salt is selected from at least one of nitrate, halide, chlorate and acetylacetone salt of Ni, Sn, Co, Pd and Ru;

in the step 2), the organic silicon source is selected from at least one of ethyl orthosilicate, methyl orthosilicate, tributylsilane and ethyltriethoxysilane, and the organic template is selected from at least one of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride and polyvinylpyrrolidone;

in the step (3), the Pt metal precursor salt is selected from H₂PtCl₆、Na₂PtCl₄、Pt(NO₂)₂(NH₃)₂、Pt(NH₃)₄(NO₃)₂、Pt(NH₃)₄Cl₂At least one of (1).

7. The production method according to claim 5,

in the step 2), the mass ratio of the organic template to the molecular sieve loaded with the metal M is 1-2.5: 0.1-0.5; the organic silicon source in the step 2) is mesoporous SiO₂The mass ratio of the molecular sieve to the molecular sieve in the step 1) is 0.9-3.0: 1;

SiO obtained by using metal M in metal M precursor salt, molecular sieve and organic silicon source₂And the sum of the mass of the metal Pt in the Pt precursor salt is the total mass, wherein the mass percentage of the metal M in the metal M precursor salt accounts for 0.3-10 wt% of the total mass; the metal Pt in the Pt precursor salt accounts for 0.2-2.0 wt% of the total mass.

8. The production method according to claim 5,

in the step 2), the stirring reaction conditions at a certain temperature are as follows: the reaction temperature is 20-80 ℃, and the reaction time is 6-24 h; calcining for 2-8 h at the temperature of 450-650 ℃;

in the step (3), the reduction process comprises the following steps: reducing for 2-4h at the temperature of 400-600 ℃ in a reducing atmosphere.

9. An SiO as claimed in any of claims 1 to 4₂The coated molecular sieve supported bimetallic catalyst is applied to the phenoxy ethylbenzene hydrogen transfer cracking reaction.

10. The application according to claim 9, wherein the application is: taking phenoxyl ethylbenzene as a reactant, and adding SiO₂Coating a molecular sieve loaded bimetallic catalyst to perform hydrogen transfer cracking reaction, wherein the mass ratio of reactants to the catalyst is (0.5-5): 1, the reaction temperature is 180-300 ℃, and the reaction time is 1-5 h.

Technical Field

The invention belongs to the field of catalytic material synthesis, and particularly relates to SiO₂A coated molecular sieve loaded bimetallic catalyst and a preparation method thereof, and also relates to the application of the catalyst in the hydrogen transfer cracking reaction of phenoxyl ethylbenzene.

Background

The bimetallic catalyst can be widely applied to heterogeneous catalytic processes such as selective hydrogenation, hydrogenolysis, isomerization, cracking and the like due to adjustable composition and structure and synergistic effect. The alloy structure, the heterostructure and the core-shell structure can be divided according to the distribution condition of two metals. Mixing metal nano catalyst with mesoporous SiO₂The core-shell structure is formed by compounding, so that the problem of agglomeration of metal nano particles can be effectively solved, and compared with a naked metal nano catalyst, the shell layer is introduced to screen and delay the contact of reactants and metal active sites through a pore effect, so that the catalytic reaction path is changed, and the product distribution is changed. Therefore, designing and synthesizing the core-shell structure catalyst has important significance for improving the selectivity of catalytic reaction, but the controllable preparation of the material is still more challenging.

In recent years, a method for preparing a supported core-shell structure catalyst by using a wrapped carbon layer, a wrapped silicon layer and an wrapped oxide layer to improve the reactivity has been reported. Literature [ Science 371(2021)1257]By adding Pt/Al₂O₃Upper atomic layer deposition growthIn₂O₃Preparation of (Pt/Al)₂O₃)@xcIn₂O₃Catalyst for promoting Pt to catalyze Propane Dehydrogenation (PDH) to prepare propylene by surface hydrogen atom transfer, wherein hydrogen is further In₂O₃The upper selective combustion does not excessively combust hydrocarbons. The idea of using the core-shell structure catalyst for serial catalysis provides greater opportunity for efficient selective catalysis. Chinese patent CN 111450843A utilizes SiO₂The RuCo nano particles are confined in the carbon spheres by the template, and the catalyst has higher ammonia synthesis performance and thermal stability. Document [ ACS Catal.9(2019)1993]Using SiO₂The Pd is wrapped, the activity of selectively synthesizing the cis-stilbene is obviously improved, and the yield reaches 95 percent. Similarly, Chinese patent CN 107096545B successfully prepares Au @ Fe₃O₄@m-SiO₂The catalyst can obtain higher performance of catalyzing and reducing 4-nitrophenol. In summary, the supported core-shell structure catalytic material shows higher research value in the heterogeneous catalysis field, especially in the selective reaction process due to the unique structural characteristics. The method has the advantages of complex reaction process for catalyzing hydrogen transfer cracking reaction, synchronous operation of a plurality of reaction processes such as isomerization-hydrogen transfer-cracking and the like, poor selectivity, development of a core-shell structure catalyst with high catalytic activity, stability and selectivity, and great significance for efficiently converting ether reactants into high value-added chemicals.

Disclosure of Invention

The invention aims to provide SiO₂A coated molecular sieve loaded bimetallic catalyst, a preparation method and application thereof. The catalyst can control the diffusion and distribution of reactants on the catalyst and limit the reactants to SiO₂In the shell layer, the concentration of reactants on the surface of the molecular sieve and in the pore channel is further improved, and when the catalyst is used for catalyzing the hydrogen transfer cracking reaction of phenoxyl ethylbenzene, the catalyst is favorable for generating high-yield high-added-value products such as benzene, ethylbenzene, phenol and the like, and the yield of isomeric products is obviously reduced.

In order to solve the technical problems, the invention adopts the following technical scheme:

providing a SiO₂Coated molecular sieve loaded bimetallicThe catalyst comprises an active metal Pt, a second metal M, a molecular sieve carrier and mesoporous SiO coated on the surface of the molecular sieve carrier₂A coating layer; wherein the mesoporous SiO₂The mass ratio of the molecular sieve to the molecular sieve is 0.9-3.0: 1; the second metal M is loaded in the molecular sieve carrier and limited in the mesoporous SiO₂Inside the coating layer, active metal Pt is distributed in the mesoporous SiO₂Coating layer and molecular sieve.

According to the scheme, the mesoporous SiO₂The thickness of the coating layer is 10-90 nm.

According to the scheme, in the catalyst, the second metal M is 0.3-10 wt% in percentage by mass; the active metal Pt accounts for 0.2-2.0 wt%.

According to the scheme, the molecular sieve is at least one of HY, MCM and ZSM-5 type molecular sieves.

According to the scheme, the metal M is at least one of Ni, Sn, Co, Pd or Ru.

According to the scheme, the catalyst is prepared by the following steps: firstly, loading a second metal M precursor salt on a molecular sieve carrier to obtain a molecular sieve loaded with the metal M precursor salt; secondly, in the presence of an organic template agent, the mesoporous SiO is wrapped on the surface of the metal M precursor salt-loaded molecular sieve by hydrolyzing an organic silicon source₂To obtain mesoporous SiO₂A coated metal M precursor salt loaded molecular sieve; finally dipping Pt precursor salt solution, drying, calcining and reducing to obtain SiO₂The coated molecular sieve supports the bimetallic catalyst.

Providing the above SiO₂The preparation method of the coated molecular sieve supported bimetallic catalyst specifically comprises the following steps:

1) adding a molecular sieve carrier into a metal M precursor salt solution, stirring and drying to prepare the molecular sieve loaded with the metal M precursor salt;

2) dispersing the molecular sieve loaded with the metal M obtained in the step 1) in an aqueous solution of an organic template, and adding ammonia water under stirring at room temperature; adding ethanol and an organic silicon source in sequence, stirring and reacting at a certain temperature, washing, drying and calcining after the reaction is finished to obtain mesoporous SiO₂A coated metal M precursor salt loaded molecular sieve;

3) subjecting the mesoporous SiO obtained in the step 2) to₂Adding the coated molecular sieve loaded with metal M precursor salt into the Pt precursor salt solution, stirring at room temperature, drying and reducing to obtain SiO₂The coated molecular sieve supports the bimetallic catalyst.

According to the scheme, in the step 1), the molecular sieve carrier is selected from at least one of HY, MCM and ZSM-5; the metal M precursor salt is at least one selected from nitrate, halide, chlorate and acetylacetone salt of Ni, Sn, Co, Pd and Ru.

According to the scheme, in the step 2), the organic silicon source is selected from at least one of tetraethoxysilane, methyl orthosilicate, tributylsilane and ethyltriethoxysilane, and preferably tetraethoxysilane; the organic template is selected from at least one of Cetyl Trimethyl Ammonium Bromide (CTAB), Cetyl Trimethyl Ammonium Chloride (CTAC) and polyvinylpyrrolidone (PVP), and CTAB is preferable.

According to the scheme, in the step 2), the mass ratio of the organic template to the molecular sieve loaded with the metal M is 1-2.5: 0.1-0.5; the organic silicon source in the step 2) is mesoporous SiO₂The mass ratio of the molecular sieve to the molecular sieve in the step 1) is 0.9-3.0: 1.

according to the scheme, SiO is obtained by using metal M, a molecular sieve and an organic silicon source in metal M precursor salt₂And the sum of the mass of the metal Pt in the Pt precursor salt is the total mass, wherein the mass percentage of the metal M in the metal M precursor salt accounts for 0.3-10 wt% of the total mass; the metal Pt in the Pt precursor salt accounts for 0.2-2.0 wt% of the total mass.

According to the scheme, the mass ratio of the organic template agent, the ammonia water and the ethanol in the step 2) is 1-2.5:1-4: 80-120.

According to the scheme, in the step 2), the stirring reaction conditions at a certain temperature are as follows: the reaction temperature is 20-80 ℃, preferably 30-50 ℃; the reaction time is 6-24h, preferably 10-18 h; the calcination condition is calcination at 450-650 ℃ for 2-8 h.

According to the scheme, in the step (3), the Pt metal precursor salt is selected from H₂PtCl₆、Na₂PtCl₄、Pt(NO₂)₂(NH₃)₂、Pt(NH₃)₄(NO₃)₂、Pt(NH₃)₄Cl₂At least one of (1).

According to the scheme, in the step (3), the reduction process comprises the following steps: reducing for 2-4h at the temperature of 400-600 ℃ in a reducing atmosphere. Preferably, the reducing atmosphere is 5% H₂and/Ar mixed gas.

Providing the above SiO₂The coated molecular sieve supported bimetallic catalyst is applied to the phenoxy ethylbenzene hydrogen transfer cracking reaction.

According to the scheme, the application is as follows: taking phenoxyl ethylbenzene as a reactant, and adding SiO₂Coating a molecular sieve loaded bimetallic catalyst to perform hydrogen transfer cracking reaction, wherein the mass ratio of reactants to the catalyst is (0.5-5): 1, the reaction temperature is 180-300 ℃, and the reaction time is 1-5 h.

Compared with the prior art, the invention has the following advantages:

1. the invention provides SiO₂The coated molecular sieve supported bimetallic catalyst is of a core-shell structure, takes a molecular sieve as a core and adopts SiO₂The coating layer is a shell layer and is formed by regulating SiO₂The thickness of the shell layer can control the diffusion and distribution of reactants on the catalyst, and the concentration of the reactants on the surface of the molecular sieve and in the pore channel is effectively improved; simultaneously matched with a molecular sieve carrier and limited in the mesoporous SiO₂Metal M nano-particles in the coating layer and SiO distributed in the mesopores₂Metal Pt nano-particles on coating layer and molecular sieve, reactant in SiO₂The Pt of the shell layer is diffused to SiO after isomerization, hydrogen transfer and other processes₂Cracking on a molecular sieve in a shell; when the catalyst is used for catalyzing phenoxyl ethylbenzene to perform hydrogen transfer cracking reaction, the conversion rate can reach 100%, high-yield high-value-added products such as benzene, ethylbenzene, phenol and the like are generated, the yield of isomeric products is obviously reduced, the catalytic performance is excellent, and the catalyst has important industrial application value.

2. The invention provides SiO₂Coated molecular sieve supported bimetallic catalysisThe preparation method of the catalyst has simple process and strong universality, and can provide reference and reference for the supported bimetallic core-shell structure catalyst and the preparation method thereof.

Drawings

FIG. 1 shows SiO prepared in example 1₂Schematic diagram of the coated molecular sieve supported bimetallic catalyst and the PtNi/HY catalyst prepared in comparative example 1.

FIG. 2 is an XRD spectrum of the catalyst and HY molecular sieve prepared in examples 2-4 and comparative examples 1-3.

FIG. 3 shows the results of nitrogen physical adsorption of the catalysts prepared in examples 2 to 4 and comparative examples 1 to 3 and an HY molecular sieve.

Detailed Description

The following examples are for a SiO used in hydrogen transfer cracking reactions in accordance with the present invention₂The coated molecular sieve supported bimetallic catalyst and the preparation method thereof are further described in detail in order to help the reader to better understand the invention with reference to the attached drawings, but do not constitute any limitation to the operable scope of the invention.

Example 1

Providing a SiO₂The preparation method of the coated molecular sieve supported bimetallic catalyst specifically comprises the following steps:

1) mixing 0.50g HY molecular Sieve (SiO)₂/Al₂O₃And 5) adding the mixture into an aqueous solution in which 0.13g of nickel nitrate hexahydrate is dissolved, stirring at room temperature, and drying to prepare the nickel nitrate-loaded HY molecular sieve (Ni/HY).

2) Dispersing the Ni/HY sample in an aqueous solution dissolved with 2.5g CTAB, and dropwise adding 5.0mL of 28% ammonia water at room temperature under stirring; then adding 120mL of ethanol and 1.557g of tetraethoxysilane in sequence, stirring and reacting for 12 hours at the temperature of 30 ℃, washing and drying after the reaction is finished, and calcining for 4 hours at the temperature of 550 ℃ to obtain the mesoporous SiO₂Coated nickel nitrate-loaded molecular sieve (Ni/HY @ SiO)₂)。

3) 0.177mL of a 0.1mol/L solution of chloroplatinic acid was added to water, the above sample was added and stirred at room temperature, dried and 5% H₂Reducing for 4 hours at 450 ℃ under the atmosphere of/Ar mixed gas to prepare SiO₂Molecular sieve coated supported bimetallic catalyst PtNi/HY @ SiO₂-0.9，SiO₂the/HY mass ratio is 0.9; wherein the mass percent of the metal Pt is 0.6 percent, the mass percent of the metal Ni is 5 percent, and the mesoporous SiO is₂The cladding layer is approximately 32nm thick.

And (3) phenoxy ethylbenzene hydrogen transfer cracking reaction: the catalyst activity evaluation was carried out in a reaction vessel. 0.198g of phenoxyethylbenzene was dissolved in 10mL of cyclohexane before evaluation, and 0.15g of PtNi/HY @ SiO₂-0.9 catalyst, flushed several times with nitrogen, and then purged with nitrogen at atmospheric pressure. Subsequently, the reaction kettle was heated to 250 ℃ with a stirring rate of 1200rpm, and after 4 hours of reaction, the product was detected and analyzed by GC-MS. The specific analysis results are shown in Table 1, and it can be seen from Table 1 that PtNi/HY @ SiO₂The PEB conversion of the-0.9 catalyst was 99.5%, the aromatics yield was 68.5%, the phenol yield was 79.2%, and the isomerate yield was 20.3%.

Example 2

Example 2 the catalyst was prepared as in example 1, except that: the mass of the added tetraethoxysilane is 2.076g, thus obtaining PtNi/HY @ SiO₂Catalyst-1.2, SiO₂HY mass ratio of 1.2, mesoporous SiO₂The thickness of the cladding layer is about 40 nm.

And (3) phenoxy ethylbenzene hydrogen transfer cracking reaction: the reaction conditions were the same as in example 1, except that: using PtNi/HY @ SiO₂-1.2 catalyst. As shown in Table 1, PtNi/HY @ SiO₂The PEB conversion of the-1.2 catalyst was 100%, the aromatics yield was 85.0%, the phenol yield was 90.0%, and the isomerate yield was 10.0%.

Example 3

Example 3 the catalyst was prepared as in example 1, except that: the mass of the added tetraethoxysilane is 3.460g, thus obtaining PtNi/HY @ SiO₂Catalyst-2.0, SiO₂HY mass ratio of 2.0, mesoporous SiO₂The cladding layer was approximately 78nm thick.

And (3) phenoxy ethylbenzene hydrogen transfer cracking reaction: the reaction conditions were the same as in example 1, except that: using PtNi/HY @ SiO₂-2.0 catalyst. As shown in Table 1, PtNi/HY @ SiO₂The PEB conversion of the-2.0 catalyst was 99.4%, the aromatics yield was 87.0%, the phenol yield was 90.2%, and the isomerate yield was9.6％。

Example 4

Example 4 the catalyst was prepared as in example 1, except that: the added tetraethoxysilane accounts for 5.190g in mass and PtNi/HY @ SiO is obtained₂Catalyst-3.0, SiO₂HY mass ratio of 3.0, mesoporous SiO₂The thickness of the cladding layer is about 82 nm.

And (3) phenoxy ethylbenzene hydrogen transfer cracking reaction: the reaction conditions were the same as in example 1, except that: using PtNi/HY @ SiO₂-3.0 catalyst. As shown in Table 1, PtNi/HY @ SiO₂The PEB conversion of the-3.0 catalyst was 99.2%, the aromatics yield was 70.0%, the phenol yield was 72.5%, and the isomerate yield was 27.5%.

Example 5

Example 5 the catalyst was prepared as in example 2, except that: adopting ZSM-5 molecular sieve to replace HY molecular sieve, wherein the mass of the added tetraethoxysilane is 2.076g, and obtaining PtNi/[email protected] SiO₂Catalyst-1.2, SiO₂ZSM-5 with the mass ratio of 1.2 and mesoporous SiO₂The thickness of the cladding layer is about 40 nm.

And (3) phenoxy ethylbenzene hydrogen transfer cracking reaction: the reaction conditions were the same as in example 1, except that: using PtNi/[email protected] SiO₂-1.2 catalyst. As can be seen from Table 1, PtNi/[email protected] SiO₂The PEB conversion of the-1.2 catalyst was 96.0%, the aromatics yield was 53.2%, the phenol yield was 56.2%, and the isomerate yield was 39.7%.

Example 6

Example 6 the catalyst was prepared as in example 2, except that: stannous chloride is used to replace nickel nitrate, and SnCl is added₂·2H₂The mass of O is 0.0066g, the mass of tetraethoxysilane is 2.076g, and PtSn/HY @ SiO is obtained₂Catalyst-1.2, SiO₂HY mass ratio of 1.2, mesoporous SiO₂The thickness of the cladding layer is about 40 nm.

And (3) phenoxy ethylbenzene hydrogen transfer cracking reaction: the reaction conditions were the same as in example 1, except that: using PtSn/HY @ SiO₂-1.2 catalyst. As can be seen from Table 1, PtSn/HY @ SiO₂-1.2 PEB conversion of catalyst 99.0% and aromatics yield of58.5%, phenol yield 62.0%, and isomerate yield 37.0%.

Example 7

Example 7 the catalyst was prepared as in example 2, except that: CTAC is adopted to replace CTAB, the mass of the added tetraethoxysilane is 2.076g, and PtNi/HY @ SiO is obtained₂1.2(CTAC) catalyst, SiO₂HY mass ratio of 1.2, mesoporous SiO₂The thickness of the cladding layer is about 40 nm.

And (3) phenoxy ethylbenzene hydrogen transfer cracking reaction: the reaction conditions were the same as in example 1, except that: using PtNi/HY @ SiO₂1.2(CTAC) catalyst. As shown in Table 1, PtNi/HY @ SiO₂The PEB conversion of the-1.2 (CTAC) catalyst was 92.3%, the aromatics yield was 51.4%, the phenol yield was 57.8%, and the isomerate yield was 34.5%.

Example 8

Example 8 the catalyst was prepared as in example 2, except that: adopting methyl orthosilicate to replace ethyl orthosilicate, wherein the mass of the added methyl orthosilicate is 1.520g, and obtaining PtNi/HY @ SiO₂1.2(TMOS) catalyst, SiO₂HY mass ratio of 1.2, mesoporous SiO₂The thickness of the cladding layer is about 40 nm.

And (3) phenoxy ethylbenzene hydrogen transfer cracking reaction: the reaction conditions were the same as in example 1, except that: using PtNi/HY @ SiO₂1.2(TMOS) catalysts. As shown in Table 1, PtNi/HY @ SiO₂The PEB conversion of the-1.2 (TMOS) catalyst was 98.0%, the aromatics yield was 56.5%, the phenol yield was 65.2%, and the isomerate yield was 32.8%.

Comparative example 1

Comparative example 1 the catalyst was prepared as in example 1, except that: SiO elimination₂And (3) the packaging process is step 2, and the PtNi/HY catalyst is obtained.

And (3) phenoxy ethylbenzene hydrogen transfer cracking reaction: the reaction conditions were the same as in example 1, except that: PtNi/HY catalyst was used. From table 1, it is found that the PtNi/HY catalyst has a PEB conversion of 59.1%, an aromatics yield of 28.4%, a phenol yield of 33.2%, and an isomerate yield of 25.9%.

Comparative example 2

Comparative example 2 the catalyst was prepared as in example 1, except that: the added tetraethoxysilane has the mass of 0.519g to obtain PtNi/HY @ SiO₂-0.3 catalyst, SiO₂HY mass ratio of 0.3, mesoporous SiO₂The thickness of the cladding layer was about 13 nm.

And (3) phenoxy ethylbenzene hydrogen transfer cracking reaction: the reaction conditions were the same as in example 1, except that: using PtNi/HY @ SiO₂-0.3 catalyst. As shown in Table 1, PtNi/HY @ SiO₂The PEB conversion of the-0.3 catalyst was 100.0%, the aromatics yield was 34.0%, the phenol yield was 36.2%, and the isomerate yield was 63.8%.

Comparative example 3

Comparative example 3 the catalyst was prepared as in example 1, except that: the mass of the added tetraethoxysilane is 1.038g to obtain PtNi/HY @ SiO₂-0.6 catalyst, SiO₂HY mass ratio of 0.6, mesoporous SiO₂The thickness of the cladding layer is about 24 nm.

And (3) phenoxy ethylbenzene hydrogen transfer cracking reaction: the reaction conditions were the same as in example 1, except that: using PtNi/HY @ SiO₂-0.6 catalyst. As shown in Table 1, PtNi/HY @ SiO₂The PEB conversion of the-0.6 catalyst was 99.3%, the aromatics yield was 47.0%, the phenol yield was 50.5%, and the isomerate yield was 48.8%.

Comparative example 4

Comparative example 4 the catalyst was prepared as in example 2, except that: the catalyst of example 2 was subjected to secondary SiO coating₂I.e. PtNi/HY @ SiO₂1.2 sample dispersed again in 2.5g CTAB solution, at room temperature stirring dropwise 5mL 28% ammonia; adding appropriate amount of ethanol and 2.076g of tetraethoxysilane in sequence, stirring and reacting at the temperature of 30 ℃, washing, drying, calcining and reducing at the temperature of 450 ℃ after the reaction is finished to obtain (PtNi/HY @ SiO)₂)@SiO₂-1.2, secondary coating of SiO₂the/HY mass ratio was 1.2.

And (3) phenoxy ethylbenzene hydrogen transfer cracking reaction: the reaction conditions were the same as in example 1, except that: using (PtNi/HY @ SiO)₂)@SiO₂-1.2 catalyst. As shown in Table 1, (PtNi/HY @ SiO)₂)@SiO₂The PEB conversion of the-1.2 catalyst was 8.5%, the aromatics yield was 3.8%, the phenol yield was 4.2%, and the isomerate yield was 4.3%.

TABLE 1 hydrogen transfer cracking performance of phenoxyethylbenzene for catalysts prepared in examples and comparative examples.