Nim@zsm-5 / al2o3 catalyst, method for preparing the same, and use thereof

Abstract

The application provides a NiM@ZSM-5 / Al2O3 catalyst, a preparation method and use thereof, and the preparation method comprises the following steps: mixing a NiM@ZSM-5 precursor and an alumina source, and sequentially performing forming, drying, calcining and reduction to obtain the NiM@ZSM-5 / Al2O3 catalyst; wherein M is a metal other than nickel. The catalyst provided by the application has a high boiling cracking rate of more than 95% and a chlorosilane monomer selectivity of more than 95% when used in the directional catalytic preparation of chlorosilane monomers from organic silicon high boiling substances, and has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of organosilicon technology, and in particular to a NiM@ZSM-5 / Al2O3 catalyst, its preparation method, and its uses. Background Technology

[0002] With the rapid development of organosilicon monomers, the output of high-boiling-point substances, a byproduct of monomer production, has surged, leading to large-scale stockpiling and storage blockages. This causes environmental and safety issues, as well as significant resource waste. Currently, high-boiling-point substances in organosilicon have become a major obstacle to the sustainable development of the industry. There is an urgent need to develop efficient and green catalysts for the decomposition of high-boiling-point substances in organosilicon to support the industry's green development.

[0003] Currently, tri-n-butylamine is commonly used as a catalyst to crack high-boiling-point substances to prepare chlorosilane monomers. Although the operating temperature and pressure are low, there are still fundamental problems that are difficult to overcome, as analyzed below:

[0004] (1) The catalyst tri-n-butylamine is a highly toxic chemical and must be strictly controlled during its use period. It is used as a consumable.

[0005] (2) The target product M2 has low selectivity, and the main products are low-value monomethyltrichlorosilane and monomethyldichlorosilane;

[0006] (3) The cracking rate is low, and only chlorine-rich Si-Si cracking can be achieved; the uncracked high-boiling substances mix with it to form hazardous waste, which further causes secondary pollution to human health and the ecological environment, and wastes resources; subsequent treatment is more complicated and difficult, and the environmental protection cost is huge.

[0007] (4) In a homogeneous batch reaction system, it is difficult to separate the product from the catalyst and unreacted raw materials, resulting in poor product purity;

[0008] (5) Stir-fry reaction system: Due to the limited processing scale, and given the current rapid expansion of monomer production capacity, there is an urgent need to develop a continuous and stable catalytic reaction system.

[0009] Patent literature related to the pyrolysis of organosilicon high-boiling-point compounds to prepare dimethyldichlorosilane mainly falls into the following categories:

[0010] (1) Noble metal catalysts: CN1071927A, JP54-9228, and JP54-119417 reported the cracking of high-boiling substances using noble metals Pd and Pt as catalysts, with HCl as the cracking gas source, and requiring toluene or xylene as a solvent in the reactor. However, noble metal catalysts are expensive, difficult to recycle, and difficult to purify, making large-scale industrial application difficult.

[0011] (2) Aluminum-based catalysts: US5430168, US5321147, CN1169996A, CN1634937A, CN1634936A, CN1915999A, etc., disclose a catalyst using aluminum trichloride (AlCl3) as a catalyst and HCl as the cracking gas, in a slurry bed or fixed bed reaction. Typical process conditions: reaction temperature is 300-500℃, reaction pressure is 4-7MPa, but the M2 yield is low. During the reaction, the active component AlCl3 is easily sublimated and lost, making it difficult to regenerate and recycle the catalyst. High-pressure operation places stringent requirements on the equipment.

[0012] (3) Molecular sieve and activated carbon catalyst: Dow Corning uses LZ-Y-74 molecular sieve as catalyst to crack methylchlorosilane (Si-Si) and HCl as cracking gas. To reduce costs, the company chooses activated carbon to replace molecular sieve, but the reaction temperature is 500℃ higher and the energy consumption is higher (see "Resource Utilization of By-products in the Production of Methylchlorosilane Monomer", Li Bin, Master's Thesis of Beijing University of Chemical Technology).

[0013] CN115746042A discloses a method for catalytic cracking of high-boiling organosilicon compounds, wherein the catalyst is one or more of Fe, Zn, Ni, Ti, and Mo supported on a molecular sieve, but the cracking temperature is high, exceeding 550℃.

[0014] Given the problems of low catalyst cracking rate, low target product selectivity, difficulty in recycling, and limited processing scale in the reaction of organosilicon high-boiling-point cracking to prepare dimethyldichlorosilane, there is an urgent need to develop a new type of highly efficient and green catalyst and process for the preparation of dimethyldichlorosilane by cracking organosilicon high-boiling-point cracking. Summary of the Invention

[0015] To address the shortcomings of existing technologies, the present invention aims to provide a NiM@ZSM-5 / Al2O3 catalyst, its preparation method, and its applications. The NiM bimetallic nanoparticles encapsulated in this catalyst exhibit better stability. The catalyst obtained through molding, calcination, and reduction effectively protects the NiM bimetallic nanoparticles, thereby achieving superior cracking rate and chlorosilane monomer selectivity in the cracking and disproportionation reaction of organosilicon high-boiling compounds.

[0016] To achieve this objective, the present invention adopts the following technical solution:

[0017] In a first aspect, the present invention provides a method for preparing a NiM@ZSM-5 / Al2O3 catalyst, the method comprising the following steps: mixing a NiM@ZSM-5 precursor and an alumina source, and sequentially subjecting the mixture to molding, drying, calcination and reduction to obtain a NiM@ZSM-5 / Al2O3 catalyst; wherein, M is a metal other than nickel.

[0018] Compared to industrially commonly used catalysts such as triethylamine, tri-n-butylamine, and aluminum powder, the catalyst provided by this invention achieves both Si-Si and Si-C... n (n>4) The Si-CH2-Si cleavage bond is broken, and the Si, CH3 and Cl functional groups in the chlorosilane monomer obtained by the cleavage are directionally disproportionated and rearranged to obtain higher dimethyldichlorosilane.

[0019] This invention encapsulates NiM bimetals, using the second metal to influence and suppress the migration and aggregation of Ni nanoparticles during the molding process, thereby ensuring efficient pyrolysis of organosilicon high-boiling compounds and selectivity of chlorosilane monomers, especially dimethyldichlorosilane.

[0020] Preferably, the amount of Ni encapsulated in the NiM@ZSM-5 precursor is 1.0 to 5.0 wt%, for example, it can be 1.0 wt%, 1.5 wt%, 1.9 wt%, 2.4 wt%, 2.8 wt%, 3.3 wt%, 3.7 wt%, 4.2 wt%, 4.6 wt%, or 5.0 wt%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0021] Preferably, the amount of M in the NiM@ZSM-5 precursor is 1.0 to 10.0 wt%, for example, it can be 1.0 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, or 10.0 wt%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0022] Preferably, M comprises a non-precious metal.

[0023] Preferably, M includes any one or at least two combinations of Co, Mo, Fe, Zn, Mg or Cu, wherein typical but non-limiting combinations are combinations of Co and Mo, Fe and Mo, Co and Fe, Zn and Mo, Co and Mg, and Cu and Mo.

[0024] Preferably, the molar ratio of SiO2 / Al2O3 in the NiM@ZSM-5 precursor is 50 to 500:1, for example, it can be 50:1, 100:1, 150:1, 200:1, 250:1, 300:1, 350:1, 400:1, 450:1 or 500:1, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0025] Preferably, the preparation of the NiM@ZSM-5 precursor includes: mixing a silicon source, an aluminum source, a structure directing agent, a Ni source, an M source and water, and then sequentially subjecting the mixture to hydrothermal crystallization, solid-liquid separation, drying and calcination to obtain the NiM@ZSM-5 precursor.

[0026] Preferably, the silicon source includes any one or a combination of at least two of silica, silica sol, solid silica gel, water glass, or tetraethyl orthosilicate, wherein typical but non-limiting combinations are a combination of silica and silica sol, a combination of solid silica gel and silica sol, a combination of silica and solid silica gel, a combination of water glass and silica sol, a combination of silica and tetraethyl orthosilicate, and a combination of tetraethyl orthosilicate and silica sol.

[0027] Preferably, the aluminum source includes any one or a combination of at least two of boehmite, SB powder, or aluminum sol, wherein typical but non-limiting combinations are a combination of boehmite and SB powder, a combination of aluminum sol and SB powder, or a combination of boehmite and aluminum sol.

[0028] Preferably, the structure-directing agent comprises any one or a combination of at least two of n-butylamine, triethylamine, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetramethylethyldiammonium, or dimethyldiethylammonium hydroxide, wherein typical but non-limiting combinations are the combination of tetraethylammonium hydroxide and tetrapropylammonium hydroxide, the combination of tetramethylethyldiammonium and tetrapropylammonium hydroxide, the combination of tetraethylammonium hydroxide and tetramethylethyldiammonium, or the combination of dimethyldiethylammonium hydroxide and tetrapropylammonium hydroxide.

[0029] Preferably, the Ni source comprises a complex solution formed by a nickel-containing compound and ethylenediamine; the nickel-containing compound comprises nickel nitrate, nickel chloride, and / or nickel sulfate.

[0030] Preferably, the M source comprises a salt of M.

[0031] Preferably, the M source includes any one or a combination of at least two of cobalt nitrate, ammonium molybdate, ferric nitrate, zinc nitrate, magnesium nitrate, or copper nitrate, wherein typical but non-limiting combinations are the combination of cobalt nitrate and ammonium molybdate, the combination of ferric nitrate and ammonium molybdate, the combination of cobalt nitrate and ferric nitrate, and the combination of magnesium nitrate and ammonium molybdate.

[0032] Preferably, the hydrothermal crystallization time is 24 to 96 hours, for example, it can be 24 hours, 32 hours, 40 hours, 48 ​​hours, 56 hours, 64 hours, 72 hours, 80 hours, 88 hours or 96 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0033] Preferably, the hydrothermal crystallization temperature is 100–170°C, for example, it can be 150°C, 153°C, 155°C, 157°C, 159°C, 162°C, 164°C, 166°C, 168°C or 170°C, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 150–170°C.

[0034] Preferably, the calcination temperature is 400-600℃, for example, it can be 400℃, 423℃, 445℃, 467℃, 489℃, 512℃, 534℃, 556℃, 578℃ or 600℃, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0035] Preferably, the calcination time is 4 to 12 hours, for example, 4 hours, 4.9 hours, 5.8 hours, 6.7 hours, 7.6 hours, 8.5 hours, 9.4 hours, 10.3 hours, 11.2 hours or 12 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0036] Preferably, the alumina source includes any one or a combination of at least two of boehmite, dry adhesive powder, SB powder, or alumina sol, wherein typical but non-limiting combinations are a combination of boehmite and dry adhesive powder, a combination of SB powder and dry adhesive powder, a combination of boehmite and SB powder, or a combination of alumina sol and dry adhesive powder.

[0037] Preferably, the roasting temperature is 400 to 700°C, for example, 400°C, 434°C, 467°C, 500°C, 534°C, 567°C, 600°C, 634°C, 667°C, or 700°C, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] The present invention preferably controls the calcination temperature within the above-mentioned range. When the calcination temperature is too high, there is a problem of damaging the basic structure of the material.

[0039] Preferably, the roasting time is 4 to 12 hours, for example, it can be 4 hours, 4.9 hours, 5.8 hours, 6.7 hours, 7.6 hours, 8.5 hours, 9.4 hours, 10.3 hours, 11.2 hours or 12 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0040] Preferably, the roasting atmosphere is any one or a combination of at least two of air, oxygen, nitrogen or argon, wherein typical but non-limiting combinations are combinations of air and oxygen, combinations of nitrogen and oxygen, combinations of air and nitrogen, combinations of argon and oxygen, and combinations of air and argon.

[0041] Preferably, the reduction temperature is 400 to 600°C, for example, 400°C, 423°C, 445°C, 467°C, 489°C, 512°C, 534°C, 556°C, 578°C or 600°C, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0042] Preferably, the reduction time is 10 to 20 hours, for example, it can be 10 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours or 20 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0043] Preferably, the reducing atmosphere is a hydrogen atmosphere.

[0044] In a second aspect, the present invention provides a NiM@ZSM-5 / Al2O3 catalyst, wherein the NiM@ZSM-5 / Al2O3 catalyst is prepared by the preparation method of the NiM@ZSM-5 / Al2O3 catalyst described in the first aspect.

[0045] Preferably, the NiM@ZSM-5 / Al2O3 catalyst comprises a NiM@ZSM-5 active component and an Al2O3 support, wherein M is a metal other than nickel.

[0046] Preferably, the Ni content in the NiM@ZSM-5 active component is 1.0 to 5.0 wt%, and the M content is 1.0 to 10.0 wt%, for example, it can be 1.0 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, or 10.0 wt%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0047] Preferably, M includes any one or at least two combinations of Co, Mo, Fe, Zn, Mg or Cu, wherein typical but non-limiting combinations are combinations of Co and Mo, combinations of Fe and Mo, combinations of Co and Fe, combinations of Zn and Mo, and combinations of Cu and Mo.

[0048] Preferably, the Ni and M form bimetallic nanoparticles.

[0049] Preferably, the particle size of the bimetallic particles is in the range of 1 to 10 nm, for example, it can be 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm or 10 nm, but is not limited to the listed values. Other unlisted values ​​in this range are also applicable.

[0050] The present invention preferably uses bialloy particles with a particle size within the above-mentioned range, which has a better catalytic effect.

[0051] Preferably, the content of NiM@ZSM-5 active component in the NiM@ZSM-5 / Al2O3 catalyst is 50-70 wt%, for example, it can be 50 wt%, 54 wt%, 57 wt%, 60 wt%, 64 wt%, 67 wt%, or 70 wt%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0052] Preferably, the content of Al2O3 in the NiM@ZSM-5 / Al2O3 catalyst is 30-50 wt%, for example, it can be 30 wt%, 34 wt%, 37 wt%, 40 wt%, 44 wt%, 47 wt%, or 50 wt%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0053] In this invention, the content of the NiM@ZSM-5 active component in the NiM@ZSM-5 / Al2O3 catalyst is controlled within the above-mentioned range. When the content is too high, there is a problem of incomplete encapsulation; when the content is too low, there is a problem of low catalytic activity.

[0054] Thirdly, the present invention provides the use of the NiM@ZSM-5 / Al2O3 catalyst described in the second aspect in the disproportionation reaction of organosilicon high-boiling-point compounds.

[0055] The NiM@ZSM-5 / Al2O3 catalyst provided by this invention is used in the cracking and disproportionation reaction of high-boiling-point organosilicon compounds. It employs a fixed-bed catalytic process with mild reaction conditions and a reaction pressure of 0.1–1.5 MPa, significantly lower than that of a batch reactor (3–7 MPa), thus greatly reducing equipment investment costs. The catalyst described in this invention is lossless and additive-free during use, environmentally friendly, highly efficient in cracking, and easily scalable.

[0056] Preferably, the application includes: the pyrolysis and disproportionation reaction of organosilicon high-boiling-point substances and pyrolysis gas under the action of NiM@ZSM-5 / Al2O3 catalyst.

[0057] Preferably, the high-boiling organosilicon compounds include Si-Si, Si-CH2-Si, and Si-C. n A mixture composed of bonds such as (n>4); wherein the proportion of silane containing Si-Si exceeds 70%, for example, it can be 71%, 72%, 75%, 78%, 79%, 80%, 81%, 82%, 83%, 84% or 85%, etc.

[0058] Preferably, the pyrolysis gas includes any one or a combination of at least two of hydrogen, hydrogen chloride, or chloromethane.

[0059] Preferably, the temperature of the pyrolysis disproportionation reaction is 250 to 450°C, for example, it can be 260°C, 280°C, 300°C, 320°C, 340°C, 360°C, 380°C, 400°C, 420°C, 440°C or 450°C, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0060] Preferably, the pressure of the pyrolysis disproportionation reaction is 0.1 to 1.5 MPa, for example, it can be 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa, 1.2 MPa or 1.5 MPa, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0061] Preferably, the mass hourly space velocity (MSV) of the high-boiling-point organosilicon compound in the pyrolysis disproportionation reaction is 0.05–1.0 h⁻¹. -1 For example, it could be 0.05h -1 0.16h -1 0.27h -1 0.37h -1 0.48h -1 0.58h -1 0.69h -1 0.79h -1 0.9h -1 or 1.0h -1 This includes, but is not limited to, the listed values; other unlisted values ​​within this range also apply.

[0062] Preferably, the reactor for the pyrolysis disproportionation reaction includes any one of a fixed bed, a moving bed, a fluidized bed, or a slurry bed.

[0063] The present invention does not impose any special restrictions on the solid-liquid separation in the above process. Any device and method known to those skilled in the art for solid-liquid separation can be used. It can also be adjusted according to the actual process. For example, it can be filtration, centrifugation or sedimentation separation, or a combination of different methods.

[0064] The present invention does not impose any special restrictions on the drying process described above. Any device and method known to those skilled in the art for drying can be used. Adjustments can also be made according to the actual process. For example, it can be air drying, vacuum drying, oven drying, or freeze drying, or a combination of different methods.

[0065] Compared with the prior art, the present invention has at least the following beneficial effects:

[0066] (1) The NiM@ZSM-5 / Al2O3 catalyst provided by the present invention encapsulates NiM bimetal, so that the second metal influences and inhibits the migration and aggregation of Ni nanoparticles during the forming process, thereby ensuring efficient cracking of organosilicon high-boiling substances and selectivity of chlorosilanes.

[0067] (2) The NiM@ZSM-5 / Al2O3 catalyst provided by this invention can be used in the cracking and disproportionation reaction of organosilicon high-boiling-point compounds to achieve not only the cracking of low-alkyl Si-Si bonds, but also the cracking of alkyl-rich Si-Si and Si-C bonds. n The catalyst involves the cleavage of (n>4) and Si-CH2-Si bonds, and employs a fixed-bed reactor. On this catalyst, high-boiling-point organosilicon compounds and the cleavage gas flow undergo a continuous gas-solid phase catalytic reaction. Under preferred conditions, this catalyst exhibits a high-boiling-point cleavage rate exceeding 95%, a chlorosilane monomer selectivity exceeding 95%, and superior catalytic stability. In lifetime testing, this catalyst operated stably for over 1000 hours in laboratory-scale trials, with no significant changes in cleavage rate or chlorosilane monomer selectivity throughout the process. Attached Figure Description

[0068] Figure 1 The image shows an HRTEM image of the NiMg@ZSM-5 / Al2O3 catalyst prepared in Example 2.

[0069] Figure 2 The image shows an HRTEM image of the NiZn@ZSM-5 / Al2O3 catalyst prepared in Example 3.

[0070] Figure 3 The image shows the HRTEM image of the Ni@ZSM-5 / Al2O3 catalyst prepared in Comparative Example 1. Detailed Implementation

[0071] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0072] Example 1

[0073] This embodiment provides a method for preparing a NiCo@ZSM-5 / Al2O3 catalyst, the preparation method comprising the following steps:

[0074] (1) Preparation of NiCo@ZSM-5 precursor: The method disclosed in ZL201910092388.5 was followed. A silicon source (silica sol), an aluminum source (SB powder), a structure directing agent (tetrapropylammonium hydroxide), a Ni source (a complex solution formed by nickel nitrate and ethylenediamine), an M source (cobalt nitrate) and water were mixed. The core molar ratio of the resulting mixture was: SiO2:Al2O3:TPAOH:H2O=1:0.003:0.5:30. The mixture was then subjected to hydrothermal crystallization at 120℃ for 96h, filtered, dried and calcined at 550℃ for 10h to obtain the NiCo@ZSM-5 precursor. The Ni content was 4.5wt% and the Co content was 5.2wt%.

[0075] (2) The NiCo@ZSM-5 precursor and alumina source (dry adhesive powder) were mixed according to the set mass ratio, and then successively extruded, dried, calcined at 550°C in air for 10 h, and reduced at 500°C in hydrogen for 12 h to obtain the NiCo@ZSM-5 / Al2O3 catalyst. The mass ratio of NiCo@ZSM-5 to Al2O3 was 60:40.

[0076] Example 2

[0077] This embodiment provides a method for preparing a NiMg@ZSM-5 / Al2O3 catalyst, the preparation method comprising the following steps:

[0078] (1) Preparation of NiMg@ZSM-5 precursor: The method disclosed in ZL201910092388.5 was followed. A mixture of silicon source (tetraethyl orthosilicate), aluminum source (boehmite), structure directing agent (tetrapropylammonium hydroxide), Ni source (a complex solution formed by nickel nitrate and ethylenediamine), Mg source (magnesium nitrate) and water was prepared. The core molar ratio of the resulting mixture was: SiO2:Al2O3:TPAOH:Ni:Mg:H2O=1:0.003:0.5:30. The mixture was then subjected to hydrothermal crystallization at 170℃ for 48h, filtered, dried and calcined at 400℃ for 12h to obtain the NiMg@ZSM-5 precursor. The Ni content was 4.5wt% and the Mg content was 4.5wt%.

[0079] (2) The NiMg@ZSM-5 precursor and alumina source (dry adhesive powder) were mixed according to the set mass ratio, and then successively extruded, dried, calcined at 700℃ for 4h in a nitrogen atmosphere, and reduced at 600℃ for 10h in a hydrogen atmosphere to obtain the NiMg@ZSM-5 / Al2O3 catalyst. The mass ratio of NiMg@ZSM-5 to Al2O3 was 70:30.

[0080] Example 3

[0081] This embodiment provides a method for preparing a NiZn@ZSM-5 / Al2O3 catalyst, the preparation method comprising the following steps:

[0082] (1) Preparation of NiZn@ZSM-5 precursor: The method disclosed in ZL201910092388.5 was followed. A mixture of silicon source (solid silica gel), aluminum source (aluminum sol), structure directing agent (tetrapropylammonium hydroxide), Ni source (a complex solution formed by nickel nitrate and ethylenediamine), Zn source (zinc nitrate) and water was prepared. The core molar ratio of the resulting mixture was: SiO2:Al2O3:TPAOH:Ni:Zn:H2O=1:0.003:0.5:30. The mixture was then subjected to hydrothermal crystallization at 150℃ for 96h, filtered, dried and calcined at 600℃ for 4h to obtain the NiZn@ZSM-5 precursor. The Ni content was 4.5wt% and the Zn content was 5.7wt%.

[0083] (2) The NiZn@ZSM-5 precursor and alumina source (aluminum sol) were mixed according to the set mass ratio, and then successively extruded, dried, calcined at 400°C for 12 h in an oxygen atmosphere, and reduced at 400°C for 20 h in a hydrogen atmosphere to obtain the NiZn@ZSM-5 / Al2O3 catalyst. The mass ratio of NiZn@ZSM-5 to Al2O3 was 70:30.

[0084] Example 4

[0085] This embodiment provides a method for preparing NiCu@ZSM-5 / Al2O3 catalyst, wherein cobalt nitrate is replaced with copper nitrate in the preparation method, and the core molar ratio in the resulting mixture is: SiO2:Al2O3:TPAOH:H2O=1:0.003:0.7:30; the rest are the same as in Example 1, and will not be repeated here.

[0086] Example 5

[0087] This embodiment provides a method for preparing NiMo@ZSM-5 / Al2O3 catalyst, wherein cobalt nitrate is replaced with ammonium molybdate in the preparation method, and the molar ratio of the resulting mixture is: SiO2:Al2O3:TPAOH:H2O=1:0.003:0.7:30; the rest is the same as in Example 1, and will not be repeated here.

[0088] Example 6

[0089] This embodiment provides a method for preparing NiFe@ZSM-5 / Al2O3 catalyst, wherein cobalt nitrate is replaced with iron nitrate in the preparation method, and the molar ratio of the resulting mixture is: SiO2:Al2O3:TPAOH:H2O=1:0.003:0.8:30; the rest are the same as in Example 1, and will not be repeated here.

[0090] Example 7

[0091] This embodiment provides a method for preparing a NiCo@ZSM-5 / Al2O3 catalyst. Except for the calcination temperature of 800℃, the preparation method is the same as that in Example 1, and will not be repeated here.

[0092] Example 8

[0093] This embodiment provides a method for preparing a NiCo@ZSM-5 / Al2O3 catalyst. Except for the mass ratio of NiCo@ZSM-5 active component to Al2O3 support being 90:10, the preparation method is the same as in Example 1, and will not be repeated here.

[0094] Example 9

[0095] This embodiment provides a method for preparing a NiCo@ZSM-5 / Al2O3 catalyst. Except for the mass ratio of NiCo@ZSM-5 active component to Al2O3 support being 40:60, the preparation method is the same as in Example 1, and will not be repeated here.

[0096] Example 10

[0097] This embodiment provides a method for preparing a NiCo@ZSM-5 / Al2O3 catalyst. The preparation method is the same as in Example 1, except that in the preparation of the NiCo@ZSM-5 precursor, Ni is first encapsulated in situ, then impregnated with cobalt nitrate by impregnation, and then filtered, dried and calcined at 550°C for 10 h. The rest of the preparation method is the same as in Example 1 and will not be described again here.

[0098] Compared with the catalyst prepared in Example 1, the NiCo bimetallic nanoparticles in the catalyst prepared in this example are unevenly distributed and have non-uniform particle size, resulting in low catalytic activity in the high-boiling-point cracking reaction.

[0099] Comparative Example 1

[0100] This comparative example provides a method for preparing a Ni@ZSM-5 / Al2O3 catalyst. The preparation method is the same as that in Example 1 except that cobalt nitrate is not added in step (1), and will not be repeated here.

[0101] Comparative Example 2

[0102] This comparative example provides a method for preparing a NiCo@ZSM-5 / SiO2 catalyst. The preparation method is the same as in Example 1 except that the dry adhesive powder is replaced with silica sol in step (2), and will not be repeated here.

[0103] Taking Examples 2-3 and Comparative Example 1 as examples, HRTEM was used to detect the catalysts and the resulting images are shown below. Figures 1-3 As shown, from Figures 1-3 It can be seen that, Figures 1-2 No obvious metal nanoparticles were present, while Figure 3 There is obvious removal or aggregation of metallic nickel nanoparticles.

[0104] The size of bimetallic particles in the catalyst was determined by HRTEM analysis, the composition of the catalyst was determined by XRF analysis, and the strength of the catalyst was tested by a strength tester.

[0105] The main components and contents of the catalysts in the above embodiments and comparative examples are shown in Table 1.

[0106] Table 1

[0107]

[0108] The composition of the high-boiling-point organosilicon compounds in the application examples is shown in Table 2.

[0109] Table 2

[0110]

[0111]

[0112] Application Example 1-1

[0113] This application example provides a method for the pyrolysis and disproportionation reaction of organosilicon high-boiling-point compounds, the method comprising:

[0114] A fixed-bed reactor was used to pass high-boiling-point organosilicon compounds (composition shown in Table 2) and hydrogen / hydrogen chloride into a catalyst packed with the catalyst prepared in Example 1. The reactor was operated at a temperature of 320°C, a pressure of 0.3 MPa, and a feed mass hourly space velocity (WHSV) of 0.5 h⁻¹ for the high-boiling-point organosilicon compounds. -1 Under certain conditions, a pyrolysis reaction is carried out to obtain reactants containing chlorosilane monomers.

[0115] Application Example 1-2

[0116] This application example provides a method for the pyrolysis and disproportionation reaction of organosilicon high-boiling-point compounds. The only difference between this method and Application Example 1-1 is that the pyrolysis reaction temperature is 450°C, the pressure is 0.5 MPa, and the feed mass hourly space velocity (WHSV) of the organosilicon high-boiling-point compounds is 1.0 h⁻¹. -1 .

[0117] Application Example 2-1

[0118] This application example provides a method for the pyrolysis and disproportionation reaction of organosilicon high-boiling-point compounds, the method comprising:

[0119] A fixed-bed reactor was used to pass high-boiling-point organosilicon compounds (composition shown in Table 2) and hydrogen / hydrogen chloride into a catalyst packed with the catalyst prepared in Example 2. The reactor was operated at a temperature of 380°C, a pressure of 0.3 MPa, and a feed mass hourly space velocity (WHSV) of 0.06 h⁻¹ for the high-boiling-point organosilicon compounds. -1 Under certain conditions, a pyrolysis reaction is carried out to obtain reactants containing chlorosilane monomers.

[0120] Application Example 2-2

[0121] This application example provides a method for the pyrolysis and disproportionation reaction of organosilicon high-boiling-point compounds. The only difference between this method and Application Example 2-1 is that the pyrolysis reaction temperature is 450°C, the pressure is 1.0 MPa, and the feed mass hourly space velocity (WHSV) of the organosilicon high-boiling-point compounds is 0.1 h⁻¹. -1 .

[0122] Application Example 3-1

[0123] This application example provides a method for the pyrolysis and disproportionation reaction of organosilicon high-boiling-point compounds, the method comprising:

[0124] A fixed-bed reactor was used to pass high-boiling-point organosilicon compounds (composition shown in Table 2) and hydrogen / hydrogen chloride into a catalyst packed with the catalyst prepared in Example 3, at a temperature of 350°C, a pressure of 0.3 MPa, and a feed mass hourly space velocity (WHSV) of 0.1 h⁻¹ for the high-boiling-point organosilicon compounds. -1 Under certain conditions, a pyrolysis reaction is carried out to obtain reactants containing chlorosilane monomers.

[0125] Application Example 3-2

[0126] This application example provides a method for the pyrolysis and disproportionation reaction of organosilicon high-boiling-point compounds. The only difference between this method and Application Example 3-1 is that the pyrolysis reaction temperature is 450°C, the pressure is 1.0 MPa, and the feed mass hourly space velocity (WHSV) of the organosilicon high-boiling-point compounds is 0.3 h⁻¹. -1 .

[0127] Application Examples 4-10 and Comparative Example 2

[0128] Application Examples 4-10 and Comparative Example 2 provide a method for the pyrolysis and disproportionation reaction of organosilicon high-boiling-point compounds. Except for the use of the catalysts in Examples 4-10 and Comparative Example 2, the method for the pyrolysis and disproportionation reaction of organosilicon high-boiling-point compounds is the same as that in Application Examples 1-1, and will not be described again here.

[0129] Application Comparative Example 1-1

[0130] This application provides a method for the pyrolysis and disproportionation reaction of organosilicon high-boiling-point substances. Except for the use of the catalyst in Comparative Example 1, the method for the pyrolysis and disproportionation reaction of organosilicon high-boiling-point substances is the same as that in Application Example 1-1, and will not be described again here.

[0131] Application Comparative Example 1-2

[0132] This application provides a method for the pyrolysis and disproportionation reaction of high-boiling-point organosilicon compounds. The only difference between this method and Application Comparative Example 1-1 is that the pyrolysis reaction temperature is 450℃, the pressure is 1.0 MPa, and the feed mass hourly space velocity (WHSV) of the high-boiling-point organosilicon compounds is 0.15 h⁻¹. -1 .

[0133] Application Comparative Examples 1-3

[0134] This application comparative example provides a method for the pyrolysis and disproportionation reaction of organosilicon high-boiling-point substances. The only difference between this method and application comparative example 1-1 is that the pyrolysis reaction temperature is 480℃.

[0135] Gas chromatography analysis was performed on the reactants in the above application examples and comparative examples. The test results of the above application examples and comparative examples are shown in Table 3.

[0136] Table 3

[0137]

[0138] In Tables 1-3, " / " indicates that there is no relevant data.

[0139] The following points can be observed from Tables 1 and 2:

[0140] (1) As can be seen from the comprehensive application examples 1 to 6, the NiM@ZSM-5 / Al2O3 catalyst provided by the present invention can form NiM bimetallic particles, and the particle size can be controlled within the range of 1 to 10 nm, and the strength is above 84 N. When this catalyst is applied to the cracking and disproportionation reaction of organosilicon high boiling point substances, the cracking rate of high boiling point substances is above 95%, preferably above 98%, the selectivity of chlorosilane monomers is above 95%, and the selectivity of dimethyldichlorosilane is above 60%.

[0141] (2) Combining Application Examples 1-1 and Application Example 7, it can be seen that the calcination temperature in Application Example 7 is 800℃. The basic structure of the catalyst is destroyed after calcination at 800℃, resulting in low catalytic activity and selectivity in the high-boiling-point cracking reaction. This indicates that the present invention preferably controls the calcination temperature within a reasonable range, which can further improve the catalytic activity of the catalyst and the selectivity of dimethyldichlorosilane.

[0142] (3) As can be seen from the combined application examples 1-1 and 8-9, the content of the NiM@ZSM-5 active component is significantly related to the strength and catalytic activity of the catalyst. When the content of the NiM@ZSM-5 active component is low, the catalyst has low catalytic activity in the high-boiling-point cracking reaction; while when the content of the NiM@ZSM-5 active component is high, the catalyst strength is poor, which leads to easy pulverization and blockage of the bed during the catalytic process, making it difficult to operate continuously. This shows that the present invention preferably controls the content of the NiM@ZSM-5 active component within a reasonable range, which can better improve the overall performance of the catalyst.

[0143] (4) Combining Application Examples 1-1 and 10, it can be seen that in the preparation process of NiCo@ZSM-5 precursor in Application Example 10, Ni is first encapsulated in situ, and then mixed with cobalt nitrate by impregnation method and impregnated. The resulting NiCo bimetallic particles have uneven particle size distribution and non-uniform particle size, resulting in low catalytic activity in high-boiling-point cracking reaction. This shows that the present invention preferably adopts the method of simultaneous in-situ encapsulation of two metals, which can better improve catalytic activity.

[0144] (5) It can be seen from the combined application examples 1-1 and application comparison examples 1-2 that application comparison example 1 uses only single metal Ni, resulting in low conversion rate of high boiling point substances and low selectivity of chlorosilanes. Application comparison example 2 uses silicon oxide as a support, resulting in extremely low catalyst strength, making it difficult to apply in a fixed bed and unable to operate continuously. This shows that the present invention uses bimetallic particles and alumina as a support, which has excellent catalytic activity for high boiling point substances and high selectivity of chlorosilane monomers.

[0145] The present invention has been illustrated with the above embodiments to illustrate its detailed features, but the present invention is not limited to the above detailed features, that is, it does not mean that the present invention must rely on the above detailed features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the selected technical features, additions of auxiliary technical features, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a NiM@ZSM-5 / Al2O3 catalyst, characterized in that, The preparation method includes the following steps: The NiM@ZSM-5 precursor and alumina source were mixed and then subjected to molding, drying, calcination and reduction in sequence to obtain the NiM@ZSM-5 / Al2O3 catalyst. Wherein, M is a metal other than nickel; M includes any one or a combination of at least two of Co, Mo, Fe, Zn, Mg or Cu; The preparation of the NiM@ZSM-5 precursor includes: The NiM@ZSM-5 precursor is obtained by mixing a silicon source, an aluminum source, a structure directing agent, a Ni source, an M source, and water, followed by hydrothermal crystallization, solid-liquid separation, drying, and calcination.

2. The preparation method according to claim 1, characterized in that, The amount of Ni encapsulated in the NiM@ZSM-5 precursor is 1.0~5.0wt%.

3. The preparation method according to claim 1, characterized in that, The amount of M encapsulated in the NiM@ZSM-5 precursor is 1.0~10.0 wt%.

4. The preparation method according to claim 1, characterized in that, The molar ratio of SiO2 / Al2O3 in the NiM@ZSM-5 precursor is 50~500:

1.

5. The preparation method according to claim 1, characterized in that, The silicon source includes any one or a combination of at least two of the following: silica, silica sol, solid silica gel, water glass, or tetraethyl orthosilicate.

6. The preparation method according to claim 1, characterized in that, The aluminum source includes any one or a combination of at least two of boehmite, SB powder, or aluminosilicate.

7. The preparation method according to claim 1, characterized in that, The structure-directing agent includes any one or a combination of at least two of the following: n-butylamine, triethylamine, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetramethylethyldiammonium, or dimethyldiethylammonium hydroxide.

8. The preparation method according to claim 1, characterized in that, The Ni source comprises a complex solution formed by a nickel-containing compound and ethylenediamine; the nickel-containing compound comprises nickel salts and / or nickel hydroxide.

9. The preparation method according to claim 1, characterized in that, The M source includes a salt of M.

10. The preparation method according to claim 1, characterized in that, The hydrothermal crystallization time is 24~96h.

11. The preparation method according to claim 1, characterized in that, The temperature for hydrothermal crystallization is 100~170℃.

12. The preparation method according to any one of claims 1 to 4, characterized in that, The alumina source includes any one or a combination of at least two of the following: boehmite, dry glue powder, SB powder, or alumina sol.

13. The preparation method according to claim 1, characterized in that, The roasting temperature is 400~700℃.

14. The preparation method according to claim 1, characterized in that, The roasting time is 4 to 12 hours.

15. The preparation method according to claim 1, characterized in that, The roasting atmosphere is any one or a combination of at least two of air, oxygen, nitrogen, or argon.

16. The preparation method according to any one of claims 1 to 5, characterized in that, The reduction temperature is 400~600°C.

17. The preparation method according to claim 1, characterized in that, The restoration time is 10-20 hours.

18. The preparation method according to claim 1, characterized in that, The reducing atmosphere is a hydrogen atmosphere.

19. A NiM@ZSM-5 / Al2O3 catalyst, characterized in that, The NiM@ZSM-5 / Al2O3 catalyst is prepared by the method described in any one of claims 1 to 18. The M includes any one or a combination of at least two of Co, Mo, Fe, Zn, Mg or Cu; The NiM@ZSM-5 / Al2O3 catalyst comprises a NiM@ZSM-5 active component and an Al2O3 support, wherein M is a metal other than nickel.

20. The NiM@ZSM-5 / Al2O3 catalyst according to claim 19, characterized in that, The NiM@ZSM-5 active component contains 1.0~5.0 wt% Ni and 1.0~10.0 wt% M.

21. The NiM@ZSM-5 / Al2O3 catalyst according to claim 20, characterized in that, The Ni and M form bimetallic particles.

22. The NiM@ZSM-5 / Al2O3 catalyst according to claim 21, characterized in that, The bimetallic particles have a particle size range of 1~10 nm.

23. The NiM@ZSM-5 / Al2O3 catalyst according to claim 19, characterized in that, The content of NiM@ZSM-5 active component in the NiM@ZSM-5 / Al2O3 catalyst is 50~70wt%.

24. The NiM@ZSM-5 / Al2O3 catalyst according to claim 19, characterized in that, The content of Al2O3 in the NiM@ZSM-5 / Al2O3 catalyst is 30~50wt%.

25. Use of the NiM@ZSM-5 / Al2O3 catalyst according to any one of claims 19 to 24 in the cracking and disproportionation reaction of organosilicon high-boiling compounds.

26. The use according to claim 25, characterized in that, The applications include the pyrolysis and disproportionation reaction of organosilicon high-boiling-point substances and pyrolysis gases in the presence of NiM@ZSM-5 / Al2O3 catalyst.

27. The use according to claim 26, characterized in that, The cracked gas includes any one or a combination of at least two of hydrogen, hydrogen chloride, or chloromethane.

28. The use according to claim 26, characterized in that, The temperature of the pyrolysis disproportionation reaction is 250~450℃.

29. The use according to claim 26, characterized in that, The pressure of the pyrolysis disproportionation reaction is 0.1~1.5 MPa.

30. The use according to claim 26, characterized in that, The mass hourly space velocity (MSV) of the high-boiling-point organosilicon compounds in the pyrolysis disproportionation reaction is 0.05–1.0 h⁻¹. -1 .

31. The use according to claim 26, characterized in that, The reactor for the pyrolysis disproportionation reaction includes any one of a fixed bed, a moving bed, a fluidized bed, or a slurry bed.

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