A process for catalytic cracking of organosilicon high boilers

Abstract

The application provides a method for catalytically cracking organosilicon high-boiling substances. The method comprises the following steps: contacting an organosilicon high-boiling substance raw material with a cracking catalyst to generate a cracking reaction; the reaction temperature of the cracking reaction is not lower than 500 DEG C; the cracking catalyst comprises a carrier and a metal active component loaded on the carrier, the metal active component at least comprises one or more of Fe, Zn, Ni, Ti and Mo, the mass content of the metal active component in the cracking catalyst is not less than 1%, the carrier at least comprises a molecular sieve, and the mass content of the carrier in the cracking catalyst is not less than 10%. The catalyst used in the cracking reaction of the application does not contain heavy metals, and has high selectivity to methyl chlorosilane monomers such as monomethyltrichlorosilane, dimethyldichlorosilane and trimethylmonochlorosilane, especially can effectively improve the selectivity of dimethyldichlorosilane, and has mild and efficient reaction conditions, high catalytic efficiency.

Description

Technical Field

[0001] This invention belongs to the field of chemical engineering and relates to the treatment and utilization of organochlorosilane high-boiling-point byproducts (hereinafter referred to as organosilicon high-boiling-point byproducts) generated during the production of organosilicon materials, and particularly relates to a method for catalytic cracking of organosilicon high-boiling-point byproducts. Background Technology

[0002] Organosilicon high-boiling-point byproducts generated during the synthesis of methylchlorosilane monomers, with a boiling range of 80–215°C, are mixtures of high-boiling-point polysilanes mainly composed of silicon-silicon and silicon-carbon-silicon bonds. With the continuous expansion of demand and production scale for methylchlorosilane monomers, the recycling of organosilicon high-boiling-point byproducts, which account for approximately 5% of the monomer composition, is becoming increasingly prominent.

[0003] Converting high-boiling-point organosilicon compounds into high-value-added chlorosilane monomers is an ideal approach to achieve comprehensive utilization of these compounds. High-boiling-point organosilicon compounds can be converted into chlorosilane monomers through thermal and catalytic cracking. The main cracking products include methyldichlorosilane (MeHSiCl2), methyltrichlorosilane (MeSiCl3), and dimethyldichlorosilane (Me2SiCl2). Among these, dimethyldichlorosilane is the most abundant and important (accounting for approximately 80 wt% of the total chlorosilane monomer production, wt% being the mass fraction), and its price is relatively high. Its production technology and level are crucial to the success of the organosilicon industry.

[0004] From the 1950s to the 1970s, thermal cracking was the main method used to crack high-boiling-point organosilicon compounds. For example, patent US2681355A reported a method for thermal cracking high-boiling-point organosilicon compounds at 200–900 °C. However, due to the excessively high reaction temperature of thermal cracking, the material in the reactor was severely carbonized, and the yield of dimethyldichlorosilane did not exceed 12%, so the cracking effect was not ideal.

[0005] Since the 1970s, catalytic cracking has gradually replaced thermal cracking as the dominant catalyst, primarily using metal catalysts and organic amine catalysts. However, some existing catalysts have drawbacks: some require large quantities, leading to high catalytic costs; others are difficult to recycle and may even contaminate the product; still others contain environmentally harmful elements, increasing the technical difficulty and cost of the process. Furthermore, existing catalysts generally exhibit low selectivity for dimethyldichlorosilane in the cracking products of high-boiling-point substances. To improve the selectivity of dimethyldichlorosilane, the reaction needs to be carried out under high pressure, placing stringent requirements on the equipment. Summary of the Invention

[0006] To address the above problems, this invention provides a method for catalytic cracking of high-boiling organosilicon compounds. This method can achieve efficient cracking of high-boiling organosilicon compounds and can significantly improve the selectivity of monomethyltrichlorosilane, dimethyltrichlorosilane, and trimethylmonochlorosilane, especially significantly improving the selectivity of dimethyldichlorosilane.

[0007] This invention provides a method for catalytic cracking of high-boiling organosilicon compounds, comprising contacting the high-boiling organosilicon compound feedstock with a cracking catalyst to induce a cracking reaction;

[0008] The reaction temperature of the pyrolysis reaction is not lower than 500℃;

[0009] The cracking catalyst comprises a support and a metal active component supported on the support. The metal active component includes at least one or more of Fe, Zn, Ni, Ti, and Mo. The mass content of the metal active component in the cracking catalyst is not less than 1%. The support includes at least a molecular sieve, and the mass content of the support in the cracking catalyst is not less than 10%.

[0010] The catalytic cracking method of the present invention can achieve efficient cracking of organosilicon high-boiling-point raw materials without the use of cracking gas under the condition of not less than 500°C by selecting the above cracking catalyst. The cracking rate can reach more than 90%, and the mass content of the three chlorosilane monomers, namely monomethyltrichlorosilane, dimethyldichlorosilane, and trimethylmonochlorosilane, in the cracking products can reach 65%, and the mass content of dimethyldichlorosilane in the three chlorosilane monomers is basically not less than 45%.

[0011] Unless otherwise specified, the mass content of the metal active component in the cracking catalyst refers to the percentage of the mass of the metal oxide relative to the total mass of the cracking catalyst, calculated based on the metal oxide corresponding to that metal.

[0012] The mass content of the metal active component in the cracking catalyst is not less than 1%, preferably 1% to 25%, and more preferably 1% to 15%.

[0013] Specifically, the elements Fe, Zn, Ni, Ti, and Mo in the active metal components can all originate from their corresponding metal salts, including but not limited to oxoacid salts, non-oxoacid salts, or metal oxides. For example, Fe can originate from one or more of ferric nitrate, ferric chloride, ferric sulfate, and ferric oxalate; Zn can originate from one or more of zinc nitrate, zinc chloride, zinc sulfate, zinc oxalate, and zinc acetate. It is understood that the corresponding metal salt contains only that one metal.

[0014] The support for the cracking catalyst of the present invention includes at least a molecular sieve, wherein the molecular sieve can provide acidic central active sites for metal active components such as Fe, Zn, Ni, Ti, and Mo. While improving the cracking rate, the confinement effect of the molecular sieve channels can also prevent the polymerization reaction of polymers, promote the generation of chlorosilane monomers, and further improve the selectivity of dimethyldichlorosilane.

[0015] The silica-to-alumina ratio (i.e., the molar ratio of silica to alumina in the molecular sieve) is a key factor affecting the density of acid centers on the support surface. Selecting a molecular sieve with a suitable silica-to-alumina ratio is beneficial for improving the catalytic performance of the cracking catalyst. Preferably, the silica-to-alumina ratio of the molecular sieve of the present invention is ≤100.

[0016] In addition to molecular sieves, the support in a cracking catalyst may also include components such as diluents or binders for the molecular sieves, specifically including but not limited to raw materials such as kaolin, montmorillonite, boehmite, alumina sol, and silica sol. Before use, the catalyst support needs to be tableted, extruded, or spray-molded to obtain the catalyst particle size required for the fluidized bed reactor.

[0017] The metal active component described in this invention can be loaded onto a molecular sieve or one or more supports including a molecular sieve, and then molded. Alternatively, the metal active component can be loaded after molding.

[0018] The present invention can use conventional loading methods in the art to load the metal active component on the carrier, including but not limited to one or more of the following: excess solution impregnation method, equal volume impregnation method, ion exchange method, high temperature and high pressure impregnation method and solid grinding method.

[0019] Taking the equal-volume impregnation method as an example, a catalyst support can be purchased commercially or prepared in-house. Then, the impregnation solution of the metal salt corresponding to the prepared metal active component is added dropwise to the catalyst support to obtain a catalyst semi-finished product. The catalyst semi-finished product is then left to stand in air for 2–24 hours, followed by drying in an oven at around 120°C, and finally calcined at 200–800°C for 2–8 hours to obtain the cracking catalyst.

[0020] In one specific embodiment, the metal active component in the cracking catalyst of the present invention is further selected from Fe, Zn, Ni or Fe-Zn composite components, or Fe, Zn or Fe-Zn further composited with at least one of Ni, Ti or Mo.

[0021] Among them, Fe, Zn, and Fe-Zn are further compounded with one of Ni, Ti, and Mo, including Fe-Ni bicomponent, Fe-Ti bicomponent, Fe-Mo bicomponent, Zn-Ni bicomponent, Zn-Ti bicomponent, Zn-Mo bicomponent, Fe-Zn-Ni tricomponent, Fe-Zn-Ti tricomponent, Fe-Zn-Mo tricomponent, etc.

[0022] More preferably, the metal active component in the cracking catalyst of the present invention includes a first metal active component and a second active metal component, wherein the first metal active component is selected from Fe and / or Zn, and the second active metal component is selected from at least one of Ni, Ti, and Mo.

[0023] The molecular sieve of the present invention is preferably a zeolite molecular sieve, wherein the mass content of the zeolite molecular sieve in the cracking catalyst support is not less than 10%, preferably not less than 30%.

[0024] Furthermore, the aforementioned zeolite molecular sieves include, but are not limited to, one or more of Y-type molecular sieves, HZSM-5 molecular sieves, Beta molecular sieves, or MOR molecular sieves.

[0025] It is worth mentioning that the pyrolysis reaction of the present invention is very efficient, and the efficient pyrolysis of organosilicon high-boiling-point compounds can be completed in a reaction time of ≤10 min.

[0026] Furthermore, the pyrolysis reaction is preferably carried out at a reaction time of ≤5 min and a reaction temperature of ≥550 °C.

[0027] The pyrolysis reaction of the present invention does not require a harsh high-pressure environment and can be achieved at a reaction pressure of 0 to 3 MPa, with low requirements for equipment and operation.

[0028] The pyrolysis reaction of this invention can control the weight hourly space velocity to be 0.3–96 h⁻¹. -1 Preferably 3.2–48h -1 Studies have shown that varying the weight hourly space velocity (WHSV) within the above range has little impact on the cracking rate and the selectivity of chlorosilane monomers. This means that a small amount of catalyst can be used to achieve efficient cracking of high-boiling-point organosilicon compounds, reducing the cost of the cracking reaction. At the same time, a higher WHSV can be used to improve the cracking efficiency per unit mass of catalyst.

[0029] Studies have shown that the pyrolysis reaction of this invention can be completed efficiently without or without pyrolysis gas. The pyrolysis gas can be selected from pyrolysis gases such as hydrogen chloride, hydrogen, methane, and ethane. Studies have also found that the pyrolysis effect using pyrolysis gases such as methane, ethane, and hydrogen is comparable to that without pyrolysis gas. While using hydrogen chloride as the pyrolysis gas achieves a higher pyrolysis rate and a higher total conversion rate of the three monomers (methyltrichlorosilane, dimethyldichlorosilane, and trimethylchlorosilane), the selectivity of the dimethyldichlorosilane monomer is significantly lower compared to when no pyrolysis gas is used. Preferably, the pyrolysis reaction of this invention is carried out without the use of pyrolysis gas or auxiliaries.

[0030] The pyrolysis reaction of the present invention is carried out in conventional reactors in the art, including but not limited to fixed-bed reactors, batch reactors, fluidized-bed reactors, tubular reactors, etc., with a preferred fluidized-bed reactor. In a specific embodiment, the pyrolysis reaction of the present invention is preferably carried out in a fluidized bed, while controlling the weight hourly space velocity of the pyrolysis reaction to be 0.3 to 96 h⁻¹. -1 Preferably 3.2–48h -1 .

[0031] The implementation of this invention has at least the following advantages:

[0032] 1. The catalyst used in the catalytic cracking method of the present invention does not contain heavy metals, has low cost, and is environmentally friendly.

[0033] 2. The catalyst used in the catalytic cracking method of the present invention has high selectivity for methylchlorosilane monomers such as monomethyltrichlorosilane, dimethyldichlorosilane, and trimethylmonochlorosilane, and can especially effectively improve the selectivity of dimethyldichlorosilane.

[0034] 3. The catalytic cracking method of the present invention has high catalytic efficiency, achieving a cracking rate of over 90% within 10 minutes. Furthermore, the selectivity for the three methylchlorosilane monomers—monomethyltrichlorosilane, dimethyldichlorosilane, and trimethylmonochlorosilane—can reach over 65%, with the mass content of dimethyldichlorosilane being approximately no less than 45%. Under preferred conditions, the cracking rate of high-boiling organosilicon compounds can reach over 95%, and the selectivity for the three methylchlorosilane monomers can reach over 75%, with the mass content of dimethyldichlorosilane reaching over 55%.

[0035] 4. The catalytic cracking method of the present invention can achieve the cracking of high-boiling organosilicon compounds without the need for cracking gases (such as HCl, hydrogen, etc.), which simplifies the difficulty and risk of cracking operation.

[0036] 5. The catalytic cracking method of the present invention can achieve efficient cracking of organosilicon high-boiling substances with a small amount of catalyst, which can significantly improve the cracking efficiency and reduce the cracking cost. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0038] The following will provide a more detailed description of the hydrodesulfurization catalyst, its preparation method, and its application provided by the present invention through specific embodiments.

[0039] It should be noted that in the following examples and comparative examples, the high-boiling-point organosilicon compounds used were all provided by Jiangxi Lanxing Xinghuo Organosilicon Co., Ltd., and their main components were MeCl2Si-SiCl2Me, CH2=CHCH2SiMe2Cl, ClMe2Si-SiMe2Cl, etc.; the HZSM-5 molecular sieves used were all commercially available products with a silicon-to-aluminum ratio of 29; and the pseudoboehmite used were all commercially available products with a specific surface area of ​​300 m². 2 / g, pore volume is 0.6mL / g; all USY molecular sieves used are commercially available products with a silicon-to-aluminum ratio of 8.68; unless otherwise specified, all raw materials used can be prepared by commercial purchase or conventional methods, and experimental methods without specific conditions are conventional methods and conditions well known in the field.

[0040] Example 1

[0041] The method for catalytically cracking high-boiling-point organosilicon compounds in this embodiment includes the following steps:

[0042] 1. Using an equal-volume impregnation method, 40g of an aqueous solution of ferric nitrate nonahydrate was impregnated onto 100g of a 40-60 mesh HZSM-5 / Al2O3 composite support. The amount of water used to prepare the ferric nitrate nonahydrate impregnation solution was determined by the saturated water absorption capacity of the support. The HZSM-5 / Al2O3 composite support was obtained by extruding 35wt% HZSM-5 molecular sieve and 65wt% boehmite strips, and was pulverized to 40-60 mesh before use. The iron-impregnated composite support was then dried in an oven at approximately 120℃ for 6 hours, and finally calcined at 600℃ for 5 hours to obtain the iron-supported catalyst. The iron content in the catalyst was 5.6% by mass.

[0043] 2. 100g of catalyst is loaded into a fixed fluidized bed, and N2 is introduced at a rate of 1.0L / min to keep the catalyst in a fluidized state;

[0044] 3. Set the preheater temperature to 300℃, the reactor temperature to 600℃, and the pressure to atmospheric pressure; after the reactor temperature reaches 600℃ and stabilizes for 30 minutes, add the high-boiling-point organosilicon compound for 3.2 hours. -1 Under the heavy time space velocity conditions, the gas is introduced into the reactor using a metering pump;

[0045] 4. After the high-boiling-point organosilicon compound is introduced into the reactor for five minutes, the product components are detected by online gas chromatography to determine the pyrolysis rate; the reaction liquid is collected, and the composition and content of methylchlorosilane in the liquid product are detected by gas chromatography.

[0046] Example 2

[0047] The method for catalytically cracking high-boiling-point organosilicon compounds in this embodiment includes the following steps:

[0048] 1. Using an equal-volume impregnation method, 11g of an aqueous solution of zinc nitrate hexahydrate was impregnated onto 100g of a 40-60 mesh HZSM-5 / Al2O3 composite support. The amount of water used in the impregnation solution was determined by the saturated water absorption capacity of the support. The HZSM-5 / Al2O3 composite support was obtained by extruding 35wt% HZSM-5 molecular sieve and 65wt% boehmite, and was pulverized to 40-60 mesh before use. The zinc-impregnated composite support was then dried in an oven at approximately 120℃ for 6 hours, and finally calcined at 600℃ for 5 hours to obtain a zinc-supported catalyst. The zinc content in the catalyst was 2.7% by mass.

[0049] 2. 100g of catalyst is loaded into a fixed fluidized bed, and N2 is introduced at a rate of 1.0L / min to keep the catalyst in a fluidized state;

[0050] 3. Set the preheater temperature to 300℃, the reactor temperature to 600℃, and the pressure to atmospheric pressure; after the reactor temperature reaches 600℃ and stabilizes for 30 minutes, add the high-boiling-point organosilicon compound for 3.2 hours. -1 Under the heavy time space velocity conditions, the gas is introduced into the reactor using a metering pump;

[0051] 4. After the high-boiling-point organosilicon compound is introduced into the reactor for five minutes, the product components are detected by online gas chromatography to determine the pyrolysis rate; the reaction liquid is collected and the composition and content of methylchlorosilane are detected by gas chromatography.

[0052] Example 3

[0053] The method for catalytically cracking high-boiling-point organosilicon compounds in this embodiment includes the following steps:

[0054] 1. Using an equal-volume impregnation method, 13g of an aqueous solution of nickel nitrate hexahydrate was impregnated onto 100g of a 40-60 mesh HZSM-5 / Al2O3 composite support. The amount of water used in the impregnation solution was determined by the saturated water absorption capacity of the support. The HZSM-5 / Al2O3 composite support was obtained by extruding 35wt% HZSM-5 molecular sieve and 65wt% boehmite, and was pulverized to 40-60 mesh before use. The nickel-impregnated composite support was then dried in an oven at approximately 120℃ for 6 hours, and finally calcined at 600℃ for 5 hours to obtain a nickel-supported catalyst. The nickel content in the catalyst was 3% by mass.

[0055] 2. 100g of catalyst is loaded into a fixed fluidized bed, and N2 is introduced at a rate of 1.0L / min to keep the catalyst in a fluidized state;

[0056] 3. Set the preheater temperature to 300℃, the reactor temperature to 600℃, and the pressure to atmospheric pressure; after the reactor temperature reaches 600℃ and stabilizes for 30 minutes, add the high-boiling-point organosilicon compound for 3.2 hours. -1 Under the heavy time space velocity conditions, the gas is introduced into the reactor using a metering pump;

[0057] 4. After the high-boiling-point organosilicon compound is introduced into the reactor for five minutes, the product components are detected by online gas chromatography to determine the pyrolysis rate; the reaction liquid is collected and the composition and content of methylchlorosilane are detected by gas chromatography.

[0058] Example 4

[0059] The method for catalytically cracking high-boiling-point organosilicon compounds in this embodiment includes the following steps:

[0060] 1. Using an equal-volume impregnation method, an aqueous solution of 28.34 g of ferric nitrate nonahydrate and 11.68 g of nickel nitrate hexahydrate was impregnated onto 91.4 g of a 40-60 mesh HZSM-5 / Al2O3 composite support. The amount of water used in the impregnation solution was determined by the saturated water absorption capacity of the support. The HZSM-5 / Al2O3 composite support was obtained by extruding 35 wt% HZSM-5 molecular sieve and 65 wt% boehmite, and was pulverized to 40-60 mesh before use. The iron- and nickel-impregnated composite support was then dried in an oven at approximately 120°C for 6 hours, and finally calcined at 600°C for 5 hours to obtain a catalyst supported on iron and nickel. The mass content of iron in the catalyst was 5.6%, and the mass content of nickel was 3%.

[0061] 2. 100g of catalyst is loaded into a fixed fluidized bed, and N2 is introduced at a rate of 1.0L / min to keep the catalyst in a fluidized state;

[0062] 3. Set the preheater temperature to 300℃, the reactor temperature to 600℃, and the pressure to atmospheric pressure; after the reactor temperature reaches 600℃ and stabilizes for 30 minutes, add the high-boiling-point organosilicon compound for 3.2 hours.-1 Under the heavy time space velocity conditions, the gas is introduced into the reactor using a metering pump;

[0063] 4. After the high-boiling-point organosilicon compound is introduced into the reactor for five minutes, the product components are detected by online gas chromatography to determine the pyrolysis rate; the reaction liquid is collected and the composition and content of methylchlorosilane are detected by gas chromatography.

[0064] Example 5

[0065] The method for catalytically cracking high-boiling-point organosilicon compounds in this embodiment includes the following steps:

[0066] 1. Using an equal-volume impregnation method, an aqueous solution of 28.34 g of ferric nitrate nonahydrate and 9.87 g of zinc nitrate hexahydrate was impregnated onto 91.7 g of a 40-60 mesh HZSM-5 / Al2O3 composite support. The amount of water used in the impregnation solution was determined by the saturated water absorption capacity of the support. The HZSM-5 / Al2O3 composite support was obtained by extruding 35 wt% HZSM-5 molecular sieve and 65 wt% boehmite, and pulverized to 40-60 mesh before use. The iron- and zinc-impregnated composite support was then dried in an oven at approximately 120°C for 6 hours, and finally calcined at 600°C for 5 hours to obtain an iron- and zinc-supported catalyst. The mass content of iron in the catalyst was 5.6%, and the mass content of zinc was 2.7%.

[0067] 2. 100g of catalyst is loaded into a fixed fluidized bed, and N2 is introduced at a rate of 1.0L / min to keep the catalyst in a fluidized state;

[0068] 3. Set the preheater temperature to 300℃, the reactor temperature to 500℃, and the pressure to atmospheric pressure; after the reactor temperature reaches 500℃ and stabilizes for 30 minutes, add the high-boiling-point organosilicon compound for 3.2 hours. -1 Under the heavy time space velocity conditions, the gas is introduced into the reactor using a metering pump;

[0069] 4. After the high-boiling-point organosilicon compound is introduced into the reactor for five minutes, the product components are detected by online gas chromatography to determine the pyrolysis rate; the reaction liquid is collected and the composition and content of methylchlorosilane are detected by gas chromatography.

[0070] Example 6

[0071] The method for catalytic cracking of high-boiling-point organosilicon compounds in this embodiment is basically the same as that in Example 5, except that in step 3, the preheater temperature is set to 300°C, the reactor temperature to 550°C, and the pressure to atmospheric pressure; after the reactor temperature reaches 550°C and stabilizes for 30 minutes, the high-boiling-point organosilicon compounds are subjected to 3.2 hours of [further processing]. -1 The material is introduced into the reactor using a metering pump under the heavy time space velocity conditions.

[0072] Example 7

[0073] The method for catalytic cracking of high-boiling-point organosilicon compounds in this embodiment is basically the same as that in Example 5, except that in step 3, the preheater temperature is set to 300°C, the reactor temperature to 580°C, and the pressure to atmospheric pressure; after the reactor temperature reaches 580°C and stabilizes for 30 minutes, the high-boiling-point organosilicon compounds are subjected to 3.2 hours of [further processing]. -1 The material is introduced into the reactor using a metering pump under the heavy time space velocity conditions.

[0074] Example 8

[0075] The method for catalytic cracking of high-boiling-point organosilicon compounds in this embodiment is basically the same as that in Example 5, except that in step 3, the preheater temperature is set to 300°C, the reactor temperature to 600°C, and the pressure to atmospheric pressure; after the reactor temperature reaches 600°C and stabilizes for 30 minutes, the high-boiling-point organosilicon compounds are subjected to 3.2 hours of [further processing]. -1 The material is introduced into the reactor using a metering pump under the heavy time space velocity conditions.

[0076] Example 9

[0077] The method for catalytic cracking of high-boiling-point organosilicon compounds in this embodiment is basically the same as that in Example 5, except that in step 3, the preheater temperature is set to 300°C, the reactor temperature to 620°C, and the pressure to atmospheric pressure; after the reactor temperature reaches 620°C and stabilizes for 30 minutes, the high-boiling-point organosilicon compounds are subjected to 3.2 hours... -1 The material is introduced into the reactor using a metering pump under the heavy time space velocity conditions.

[0078] Example 10

[0079] The method for catalytic cracking of high-boiling-point organosilicon compounds in this embodiment is basically the same as that in Example 5, except that in step 3, the preheater temperature is set to 300°C, the reactor temperature to 650°C, and the pressure to atmospheric pressure; after the reactor temperature reaches 650°C and stabilizes for 30 minutes, the high-boiling-point organosilicon compounds are subjected to 3.2 hours of [further processing]. -1 The material is introduced into the reactor using a metering pump under the heavy time space velocity conditions.

[0080] Example 11

[0081] The method for catalytic cracking of high-boiling-point organosilicon compounds in this embodiment is basically the same as that in Example 8, except that in step 3, the high-boiling-point organosilicon compounds are subjected to 1.6 hours of [further processing]. -1 The material is introduced into the reactor using a metering pump under the heavy time space velocity conditions.

[0082] Example 12

[0083] The method for catalytic cracking of high-boiling-point organosilicon compounds in this embodiment is basically the same as that in Example 8, except that in step 3, the high-boiling-point organosilicon compounds are subjected to 14.4 hours of [further processing]. -1 The material is introduced into the reactor using a metering pump under the heavy time space velocity conditions.

[0084] Example 13

[0085] The method for catalytic cracking of high-boiling-point organosilicon compounds in this embodiment is basically the same as that in Example 8, except that in step 3, the high-boiling-point organosilicon compounds are subjected to 48 hours of [further processing / processing]. -1 The material is introduced into the reactor using a metering pump under the heavy time space velocity conditions.

[0086] Example 14

[0087] The method for catalytic cracking of high-boiling organosilicon compounds in this embodiment is basically the same as that in Example 8. The difference is that in step 3, HCl is fed along with the high-boiling organosilicon compounds, and the feed flow rate of HCl is 0.2 L / min.

[0088] Example 15

[0089] The method for catalytic cracking of organosilicon high-boiling-point compounds in this embodiment is basically the same as that in Example 8. The difference is that in step 3, CH4 is fed along with the organosilicon high-boiling-point compounds, and the feed flow rate of CH4 is 0.2 L / min.

[0090] Example 16

[0091] The method for catalytic cracking of high-boiling organosilicon compounds in this embodiment is basically the same as that in Example 8. The difference is that in step 3, C2H6 is fed along with the high-boiling organosilicon compounds, and the feed flow rate of C2H6 is 0.2 L / min.

[0092] Example 17

[0093] The method for catalytic cracking of high-boiling organosilicon compounds in this embodiment is basically the same as that in Example 8. The difference is that in step 4, after the high-boiling organosilicon compounds are introduced into the reactor for ten minutes, the product components are detected by online gas chromatography to determine the cracking rate; the reaction liquid is collected, and the composition and content of methylchlorosilane are detected by gas chromatography.

[0094] Example 18

[0095] The method for catalytic cracking of high-boiling organosilicon compounds in this embodiment is basically the same as that in Example 8. The difference is that in step 4, after the high-boiling organosilicon compounds are introduced into the reactor for 30 minutes, the product components are detected by online gas chromatography to determine the cracking rate; the reaction liquid is collected, and the composition and content of methylchlorosilane are detected by gas chromatography.

[0096] Example 19

[0097] The method for catalytic cracking of high-boiling organosilicon compounds in this embodiment is basically the same as that in Example 8. The difference is that in step 4, after the high-boiling organosilicon compounds are introduced into the reactor for 120 minutes, the product components are detected by online gas chromatography to determine the cracking rate; the reaction liquid is collected, and the composition and content of methylchlorosilane are detected by gas chromatography.

[0098] Example 20

[0099] The method for catalytically cracking high-boiling-point organosilicon compounds in this embodiment includes the following steps:

[0100] 1. Using an equal-volume impregnation method, an aqueous solution of 28.34 g of ferric nitrate nonahydrate, 9.87 g of zinc nitrate hexahydrate, and 8.95 g of nickel nitrate hexahydrate was impregnated onto 89.4 g of a 40-60 mesh HZSM-5 / Al2O3 composite support. The amount of water used in the impregnation solution was determined by the saturated water absorption capacity of the support. The HZSM-5 / Al2O3 composite support was obtained by extruding 35 wt% HZSM-5 molecular sieve and 65 wt% boehmite, and pulverized to 40-60 mesh before use. The iron, zinc, and nickel-impregnated composite support was then dried in an oven at approximately 120°C for 6 hours, and finally calcined at 600°C for 5 hours to obtain a catalyst supported on iron, zinc, and nickel. The mass content of iron in the catalyst was 5.6%, zinc was 2.7%, and nickel was 2.3%.

[0101] 2. 100g of catalyst is loaded into a fixed fluidized bed, and N2 is introduced at a rate of 1.0L / min to keep the catalyst in a fluidized state;

[0102] 3. Set the preheater temperature to 300℃, the reactor temperature to 600℃, and the pressure to atmospheric pressure; after the reactor temperature reaches 600℃ and stabilizes for 30 minutes, add the high-boiling-point organosilicon compound for 3.2 hours. -1 Under the heavy time space velocity conditions, the gas is introduced into the reactor using a metering pump;

[0103] 4. After the high-boiling-point organosilicon compound is introduced into the reactor for five minutes, the product components are detected by online gas chromatography to determine the pyrolysis rate; the reaction liquid is collected and the composition and content of methylchlorosilane are detected by gas chromatography.

[0104] Example 21

[0105] The method for catalytically cracking high-boiling-point organosilicon compounds in this embodiment includes the following steps:

[0106] 1. Using an equal-volume impregnation method, an aqueous solution of 28.34 g of ferric nitrate nonahydrate, 9.87 g of zinc nitrate hexahydrate, and 2.3 g of molybdenum trioxide was impregnated onto 89.4 g of a 40-60 mesh HZSM-5 / Al2O3 composite support. The amount of water used in the impregnation solution was determined by the saturated water absorption capacity of the support. The HZSM-5 / Al2O3 composite support was obtained by extruding 35 wt% HZSM-5 molecular sieve and 65 wt% boehmite, and pulverized to 40-60 mesh before use. The composite support impregnated with iron, zinc, and molybdenum was then dried in an oven at approximately 120°C for 6 hours, and finally calcined at 600°C for 5 hours to obtain a catalyst supported on iron, zinc, and molybdenum. The mass content of iron in the catalyst was 5.6%, zinc was 2.7%, and molybdenum was 2.3%.

[0107] 2. 100g of catalyst is loaded into a fixed fluidized bed, and N2 is introduced at a rate of 1.0L / min to keep the catalyst in a fluidized state;

[0108] 3. Set the preheater temperature to 300℃, the reactor temperature to 600℃, and the pressure to atmospheric pressure; after the reactor temperature reaches 600℃ and stabilizes for 30 minutes, add the high-boiling-point organosilicon compound for 3.2 hours. -1 Under the heavy time space velocity conditions, the gas is introduced into the reactor using a metering pump;

[0109] 4. After the high-boiling-point organosilicon compound is introduced into the reactor for five minutes, the product components are detected by online gas chromatography to determine the pyrolysis rate; the reaction liquid is collected and the composition and content of methylchlorosilane are detected by gas chromatography.

[0110] Example 22

[0111] The method for catalytically cracking high-boiling-point organosilicon compounds in this embodiment includes the following steps:

[0112] 1. Using an equal-volume impregnation method, an aqueous solution of 28.34 g of ferric nitrate nonahydrate, 9.87 g of zinc nitrate hexahydrate, and 6.07 g of titanium tetrachloride was impregnated onto 89.4 g of a 40-60 mesh HZSM-5 / Al2O3 composite support. The amount of water used in the impregnation solution was determined by the saturated water absorption capacity of the support. The HZSM-5 / Al2O3 composite support was obtained by extruding 35 wt% HZSM-5 molecular sieve and 65 wt% boehmite, and pulverized to 40-60 mesh before use. The composite support impregnated with iron, zinc, and titanium was then dried in an oven at approximately 120°C for 6 hours, and finally calcined at 600°C for 5 hours to obtain a catalyst supported on iron, zinc, and titanium. The mass content of iron in the catalyst was 5.6%, zinc was 2.7%, and titanium was 2.3%.

[0113] 2. 100g of catalyst is loaded into a fixed fluidized bed, and N2 is introduced at a rate of 1.0L / min to keep the catalyst in a fluidized state;

[0114] 3. Set the preheater temperature to 300℃, the reactor temperature to 600℃, and the pressure to atmospheric pressure; after the reactor temperature reaches 600℃ and stabilizes for 30 minutes, add the high-boiling-point organosilicon compound for 3.2 hours. -1 Under the heavy time space velocity conditions, the gas is introduced into the reactor using a metering pump;

[0115] 4. After the high-boiling-point organosilicon compound is introduced into the reactor for five minutes, the product components are detected by online gas chromatography to determine the pyrolysis rate; the reaction liquid is collected and the composition and content of methylchlorosilane are detected by gas chromatography.

[0116] Example 23

[0117] The method for catalytically cracking high-boiling-point organosilicon compounds in this embodiment includes the following steps:

[0118] 1. Using an equal-volume impregnation method, 40g of an aqueous solution of ferric nitrate nonahydrate was impregnated onto 100g of a 40-60 mesh USY / Al2O3 composite support. The amount of water used in the impregnation solution was determined by the saturated water absorption capacity of the support. The USY / Al2O3 composite support was obtained by extruding 35wt% USY molecular sieve and 65wt% boehmite, and was pulverized to 40-60 mesh before use. The iron-impregnated composite support was then dried in an oven at approximately 120℃ for 6 hours, and finally calcined at 600℃ for 5 hours to obtain an iron-supported catalyst. The iron content in the catalyst was 5.6% by mass.

[0119] 2. 100g of catalyst is loaded into a fixed fluidized bed, and N2 is introduced at a rate of 1.0L / min to keep the catalyst in a fluidized state;

[0120] 3. Set the preheater temperature to 300℃, the reactor temperature to 600℃, and the pressure to atmospheric pressure; after the reactor temperature reaches 600℃ and stabilizes for 30 minutes, add the high-boiling-point organosilicon compound for 3.2 hours. -1 Under the heavy time space velocity conditions, the gas is introduced into the reactor using a metering pump;

[0121] 4. After the high-boiling-point organosilicon compound is introduced into the reactor for five minutes, the product components are detected by online gas chromatography to determine the pyrolysis rate; the reaction liquid is collected and the composition and content of methylchlorosilane are detected by gas chromatography.

[0122] Example 24

[0123] The method for catalytic cracking of high-boiling organosilicon compounds in this embodiment is basically the same as that in Example 8. The difference is that in step 3, H2 is fed along with the high-boiling organosilicon compounds, and the feed flow rate of H2 is 0.2 L / min.

[0124] Comparative Example 1

[0125] This comparative method for catalytic cracking of high-boiling-point organosilicon compounds includes the following steps:

[0126] 1. Purge the fixed fluidized bed device with nitrogen gas at a rate of 1.0 L / min for 30 min without adding a catalyst;

[0127] 2. Set the preheater temperature to 300℃, the reactor temperature to 600℃, and the pressure to atmospheric pressure; after the reactor temperature reaches 600℃ and stabilizes for 30 minutes, add the high-boiling-point organosilicon compound for 3.2 hours. -1 Under the heavy time space velocity conditions, the gas is introduced into the reactor using a metering pump;

[0128] 3. After the high-boiling-point organosilicon compound is introduced into the reactor for five minutes, the product components are detected by online gas chromatography to determine the pyrolysis rate; the reaction liquid is collected and the composition and content of methylchlorosilane are detected by gas chromatography.

[0129] Comparative Example 2

[0130] This comparative method for catalytic cracking of high-boiling-point organosilicon compounds includes the following steps:

[0131] 1. 100g of 40-60 mesh HZSM-5 / Al2O3 composite support (obtained by extruding, drying, and calcining 35wt% HZSM-5 molecular sieve and 65wt% boehmite, and pulverizing to 40-60 mesh before use) is loaded into a fixed fluidized bed as a catalyst, and 1.0L / min of N2 is introduced to keep the catalyst in a fluidized state.

[0132] 2. Set the preheater temperature to 300℃, the reactor temperature to 600℃, and the pressure to atmospheric pressure; after the reactor temperature reaches 600℃ and stabilizes for 30 minutes, add the high-boiling-point organosilicon compound for 3.2 hours. -1 Under the heavy time space velocity conditions, the gas is introduced into the reactor using a metering pump;

[0133] 3. After the high-boiling-point organosilicon compound is introduced into the reactor for five minutes, the product components are detected by online gas chromatography to determine the pyrolysis rate; the reaction liquid is collected and the composition and content of methylchlorosilane are detected by gas chromatography.

[0134] Comparative Example 3

[0135] This comparative method for catalytic cracking of high-boiling-point organosilicon compounds includes the following steps:

[0136] 1. 100g of 40-60 mesh USY / Al2O3 composite support (obtained by extrusion, drying and calcination of 35wt% USY molecular sieve and 65wt% pseudoboehmite, and pulverized to 40-60 mesh before use) is loaded into a fixed fluidized bed as a catalyst, and 1.0L / min of N2 is introduced to keep the catalyst in a fluidized state.

[0137] 2. Set the preheater temperature to 300℃, the reactor temperature to 600℃, and the pressure to atmospheric pressure; after the reactor temperature reaches 600℃ and stabilizes for 30 minutes, add the high-boiling-point organosilicon compound for 3.2 hours. -1 Under the heavy time space velocity conditions, the gas is introduced into the reactor using a metering pump;

[0138] 3. After the high-boiling-point organosilicon compound is introduced into the reactor for five minutes, the product components are detected by online gas chromatography to determine the pyrolysis rate; the reaction liquid is collected and the composition and content of methylchlorosilane are detected by gas chromatography.

[0139] Comparative Example 4

[0140] This comparative method for catalytic cracking of high-boiling-point organosilicon compounds includes the following steps:

[0141] 1. 100g of 40-60 mesh HZSM-5 / Al2O3 composite support (obtained by extrusion, drying, and calcination of 35wt% HZSM-5 molecular sieve and 65wt% boehmite, and pulverized to 40-60 mesh before use) is loaded into a fixed fluidized bed as a catalyst; 1.0L / min of N2 is introduced to keep the catalyst in a fluidized state;

[0142] 2. Set the preheater temperature to 300℃, the reactor temperature to 600℃, and the pressure to atmospheric pressure; after the reactor temperature reaches 600℃ and stabilizes for 30 minutes, add the high-boiling-point organosilicon compound for 3.2 hours. -1 Under the condition of heavy hourly space velocity, the feed is introduced into the reactor using a metering pump, along with 0.2 L / min of H2.

[0143] 3. After the high-boiling-point organosilicon compound is introduced into the reactor for five minutes, the product components are detected by online gas chromatography to determine the pyrolysis rate; the reaction liquid is collected and the composition and content of methylchlorosilane are detected by gas chromatography.

[0144] The pyrolysis rate determined by chromatographic detection in the above examples and comparative examples, the individual mass content of the three methylchlorosilane components (M1), dimethyldichlorosilane (M2), and trimethylchlorosilane (M3), the total mass content of the three methylchlorosilane components, and the mass percentage of dimethyldichlorosilane in the three methylchlorosilanes are recorded in Table 1.

[0145] Table 1

[0146]

[0147]

[0148] Note: Cracking rate = 100% - High-boiling-point content in liquid product / High-boiling-point content in feedstock × 100%.

[0149] The following conclusions can be drawn from Table 1:

[0150] 1) Through the comparison of Examples 1, 2, 4, 8, 20-22, it can be seen that when iron-nickel bicomponent, iron-zinc bicomponent, iron-zinc-molybdenum tricomponent, iron-zinc-titanium tricomponent, and iron-zinc-nickel tricomponent are used as metal active centers, their pyrolysis effect is better than that of single-component iron and zinc as metal active components.

[0151] 2) The comparison of Examples 5-10 shows that the pyrolysis reaction is not effective at 500℃, but excellent pyrolysis effect can be obtained at temperatures above 550℃.

[0152] 3) A comparison of Examples 8 and 11-13 shows that changes in weight space velocity have little effect on the catalytic cracking effect;

[0153] 4) The comparison of Examples 8, 14-16, and 24 shows that the addition of hydrochloric acid cracking gas leads to a significant decrease in the selectivity of M2. The cracking effect is comparable to that without cracking gas when methane cracking gas, ethane cracking gas, and hydrogen cracking gas are added.

[0154] 5) The comparison of Examples 8 and 17-19 shows that the reaction of organosilicon high-boiling substances with the catalyst for 5 minutes is sufficient to complete the maximum degree of cracking. Increasing the reaction time will not increase the cracking rate, nor will it significantly change the selectivity of methylchlorosilane monomers.

[0155] 6) As can be seen from the comparison between Comparative Example 1 and the other examples and comparative examples, the pyrolysis effect of organosilicon high-boiling substances is the worst, the pyrolysis rate is the lowest, and the selectivity of methylchlorosilane monomers is also the worst when no catalyst is added.

[0156] The comparison between Comparative Example 2 and Examples 1-4, 8, 20-22, and the comparison between Comparative Example 3 and Example 23, shows that compared with the present invention, which uses a catalyst supported with a specific metal active component, the present invention only uses a support including zeolite molecular sieve as a catalyst to catalytically crack organosilicon high-boiling-point substances, and its cracking rate and selectivity for methylchlorosilane monomers are significantly worse.

[0157] The comparison between Comparative Example 2 and Comparative Example 4 shows that when HZSM-5 / Al2O3 composite support is used as catalyst for catalytic cracking of high-boiling organosilicon compounds, even if H2 is introduced as cracking gas to assist cracking, the cracking effect is not improved, and the cracking rate and the selectivity of methylchlorosilane monomers do not change significantly.

[0158] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for catalytically cracking high-boiling organosilicon compounds, characterized in that, This includes bringing high-boiling-point organosilicon feedstocks into contact with a cracking catalyst to induce a cracking reaction; The pyrolysis reaction has a reaction time of ≤5 min and a reaction temperature of ≥550℃. No pyrolysis gas or additives are used in the pyrolysis reaction. The cracking catalyst includes a support and a metal active component supported on the support. The metal active component includes a first metal active component and a second active metal component. The first metal active component is selected from Fe and / or Zn, and the second active metal component is selected from at least one of Ni, Ti, and Mo. The mass content of the metal active component in the cracking catalyst is not less than 1%. The support includes at least a molecular sieve, and the mass content of the support in the cracking catalyst is not less than 10%. The mass content of the molecular sieve in the support is not less than 10%, and the silica-alumina ratio of the molecular sieve is ≤100. The elements Fe, Zn, Ni, Ti, and Mo all come from the corresponding metal salts, which include oxyacid salts, non-oxyacid salts, or metal oxides of metals. The molecular sieve is selected from zeolite molecular sieves, and the zeolite molecular sieve is selected from Y-type molecular sieves, HZSM-5 molecular sieves, Beta molecular sieves or MOR molecular sieves.

2. The method according to claim 1, characterized in that, The reaction pressure of the pyrolysis reaction is 0~3MPa.

3. The method according to claim 1, characterized in that, The weight hourly space velocity (WHSV) of the pyrolysis reaction is 0.3–96 h⁻¹. -1 .

4. The method according to claim 1, characterized in that, The pyrolysis reaction is carried out in a fluidized bed.

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