A method for cracking methyl organosilicon high boiling points using a catalytic cracking catalyst

Abstract

The present invention provides a method for cracking high-boiling methyl organosilicon products. The method uses a molecular sieve or activated carbon loaded with a Lewis acidic active center element and having disproportionation properties as a cracking catalyst. The method can catalytically crack the high-boiling methyl organosilicon products into methyl organosilicon monomers at a reaction temperature of 300-700°C and a reaction pressure of 0-0.5 MPa (the pressure is gauge pressure) with or without the introduction of cracking gas.

Description

Technical Field

[0001] The invention belongs to the field of comprehensive utilization of organosilicon by-products, and particularly relates to a method for catalytic cracking of methyl organosilicon high-boiling products using a catalyst with disproportionation cracking function. Background Art

[0002] High-boiling methyl silicone products (hereinafter referred to as "high-boiling products") refer to byproducts with a boiling point range of 80-215°C produced during the direct production of methylchlorosilane. These products are primarily composed of disilazane hydrocarbon components such as Si-Si, Si-C-Si, and Si-O-Si, as well as a small amount of chlorosilane monomers, and some chlorinated hydrocarbons and alkane organic compounds. Due to their complex composition and the presence of a large number of highly active Si-Cl bond compounds, they are difficult to store. Most domestic companies use them to prepare high-boiling silicone oils, silicone waterproofing agents, silicone resins, and secondary silicone oil products such as defoamers. However, the production of these low-end products also produces a large number of byproducts, posing significant HSE risks to the companies involved.

[0003] By cracking high-boiling methyl organosilicon products to prepare methylchlorosilane monomers, high-boiling methyl organosilicon products can be converted into main silicone products such as methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, etc., which is an ideal way to solve the comprehensive utilization of high-boiling methyl organosilicon products.

[0004] Patent application CN1560056A discloses a method for preparing methylchlorosilane by catalytically cracking high-boiling organosilicon products using N,N-dimethylaniline. By controlling the reaction temperature at 90-110°C, the selectivity for dimethyldichlorosilane reaches 29-37%, while the selectivity for trimethylmonochlorosilane is very low, less than 2%. This technical solution only cracks methylchlorodisilazane containing Si-Si bonds in the high-boiling products, and cannot crack other components containing Si-O-Si or Si-C-Si, resulting in a low conversion rate for the high-boiling products.

[0005] Patent application CN102558215A relates to a process for cracking high-boiling organic silicon. Using high-boiling organic silicon as raw material, after impurities are removed, the process is catalytically cracked using N,N-dimethylaniline, N,N-diethylformamide, and tri-n-butylamine as catalysts in a reactor flowing with hydrogen chloride gas.

[0006] US5292912A uses LZY-74 molecular sieve as a catalyst and hydrogen chloride as a cracking aid, and the mass fraction of chlorosilane monomer in the product is about 81%. Summary of the Invention

[0007] The present invention provides a method for cracking high-boiling methyl organosilicon products, which catalytically cracks the high-boiling methyl organosilicon products into methyl organosilicon monomers at a reaction temperature of 300-700°C and a reaction pressure of 0-0.5 MPa (the pressure is gauge pressure) with or without the introduction of cracking gas. The method is characterized in that a molecular sieve or activated carbon with disproportionation performance and loaded with a Lewis acidic active center element is used as a cracking catalyst.

[0008] The molecular sieve with disproportionation performance is selected from USY molecular sieve, HZSM-5 molecular sieve, Y molecular sieve, LZY molecular sieve, etc., preferably USY molecular sieve or HZSM-5 molecular sieve. The Lewis acidic active center element is selected from nickel, iron, cobalt, zinc, molybdenum, manganese, aluminum, etc., preferably iron, zinc, and molybdenum.

[0009] The cracking gas is hydrogen chloride, hydrogen, C 1-6 Alkanes such as methane and ethane.

[0010] The reaction temperature is preferably 500-650° C., and the reaction pressure is 0-0.3 MPa, which is gauge pressure.

[0011] The method involves reacting in a fixed-bed or fluidized-bed reactor. A dust filtration device is connected after the reactor to separate solid particles, such as catalyst, from the reaction gases. The dust filtration device can be a known cyclone separator, bag filter, basket filter, or ceramic membrane filter, with cyclone separators and ceramic membrane filters being preferred.

[0012] The fluidized bed is a fluidized bed, an MTO fluidized bed, a DMTO fluidized bed, etc., preferably an MTO fluidized bed or a DMTO fluidized bed.

[0013] In the method, the cracking product is separated by a separation device to obtain a methyl organosilicon component. The separation device is a distillation device. The distillation device is an independent distillation device or a distillation system synthesized using the original methyl organosilicon monomer.

[0014] In one embodiment of the present invention, high boiling materials are preheated and vaporized before entering the cracking catalytic reaction.

[0015] The present invention also provides a method for preparing the above-mentioned cracking catalyst, comprising loading a Lewis acidic active center element on the surface or in the pores of a molecular sieve or activated carbon by methods known in the art, such as impregnation, atom transfer, and ion exchange.

[0016] In some embodiments of the present invention, the preparation method of the cracking catalyst is: preparing a water-soluble salt of a Lewis acidic active center element into an aqueous solution of appropriate concentration, impregnating a molecular sieve or activated carbon therein, removing it, drying it, and then calcining it to obtain a molecular sieve or activated carbon loaded with the corresponding Lewis acidic active center element.

[0017] Glossary:

[0018] The methyl silicone monomer refers to methylchlorosilanes such as methyltrichlorosilane, dimethyldichlorosilane, and trimethylchlorosilane obtained by the Rochow reaction, and is also referred to as a methyl silicone monomer.

[0019] Methyl organosilicon high-boiling products refer to by-products with a boiling point range of 80-215°C produced during the direct production of methylchlorosilane, mainly consisting of disilane components such as Si-Si, Si-C-Si, Si-O-Si, as well as a small amount of chlorosilane monomers, some chlorinated hydrocarbons and alkane organic compounds.

[0020] Unless otherwise specified in the present invention, all pressures are gauge pressures.

[0021] Beneficial effects of the present invention:

[0022] 1. The present invention is the first to use molecular sieves or activated carbon loaded with Lewis acid active centers as cracking catalysts to catalyze the cracking of high-boiling organic silicon products;

[0023] 2. The method of the present invention uses Lewis acid elements with strong acid function and high temperature dehydrogenation function to enhance the cracking and disproportionation ability of high-boiling products of methyl silicone monomer, improve the cracking rate and selectivity of dimethyldichlorosilane, and improve the economic value.

[0024] 3. The method of the present invention improves the cracking rate and selectivity of high-boiling organosilicon products to methyl organosilicon monomers, raising the cracking rate to over 93% and the selectivity of methylchlorosilane to 75%. It realizes the comprehensive utilization of high-boiling organosilicon products, improves the production capacity of methyl organosilicon monomers of methyl organosilicon enterprises, reduces and avoids HSE risks, and is more environmentally friendly. DETAILED DESCRIPTION

[0025] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0026] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0027] The present invention will be described in detail below through examples.

[0028] Example 1

[0029] The catalyst preparation and cracking experiment of this embodiment include the following steps:

[0030] 8 g of ferric nitrate nonahydrate was dissolved in 100 g of deionized water, 50 g of USY molecular sieve with a diameter of 100 μm on a silicon-aluminum carrier was added, and the mixture was placed in an ultrasonic shaker for 8 hours, taken out and dried for 24 hours, and placed in a tube furnace, dried under nitrogen, and calcined at 700°C for 6 hours to obtain a USY molecular sieve with acid-active iron centers.

[0031] (1) 50 g of USY molecular sieve with acid active center iron was loaded into a fixed fluidized bed;

[0032] (2) Purge the device at 0.5 L / min for 30 min;

[0033] (3) Set the preheater temperature to 300°C, the reactor temperature to 600°C, and the pressure to atmospheric pressure;

[0034] (4) After the temperature stabilized, high-boiling methyl silicone compounds were introduced into the reactor at a rate of 0.86 ml / min;

[0035] (5) detecting product components by online gas chromatography to determine the cracking rate;

[0036] (6) Collect the reaction liquid and detect the methylchlorosilane component by gas chromatography.

[0037] Example 2

[0038] The catalyst preparation and cracking experiment of this embodiment include the following steps:

[0039] 6 g of zinc nitrate hexahydrate was dissolved in 100 g of deionized water, 50 g of USY molecular sieve with a diameter of 100 μm on a silicon-aluminum carrier was added, and the mixture was placed in an ultrasonic shaker for 8 hours, taken out and dried for 24 hours, and placed in a tube furnace, dried under nitrogen, and calcined at 700°C for 6 hours to obtain a USY molecular sieve with an acid active center zinc.

[0040] (1) 50 g of USY molecular sieve with acid active zinc center was loaded into a fixed fluidized bed;

[0041] (2) Purge the device at 0.5 L / min for 30 min;

[0042] (3) Set the preheater temperature to 300°C, the reactor temperature to 600°C, and the pressure to atmospheric pressure;

[0043] (4) After the temperature stabilized, high-boiling methyl silicone compounds were introduced into the reactor at a rate of 0.86 ml / min;

[0044] (5) detecting product components by online gas chromatography to determine the cracking rate;

[0045] (6) Collect the reaction liquid and detect the methylchlorosilane component by gas chromatography.

[0046] Example 3

[0047] The catalyst preparation and cracking experiment of this embodiment include the following steps:

[0048] 4 g of ammonium molybdate was dissolved in 100 g of deionized water, 50 g of USY molecular sieve with a diameter of 100 μm on a silicon-aluminum carrier was added, and the mixture was placed in an ultrasonic shaker for 8 hours, taken out and dried for 24 hours, and placed in a tube furnace, dried under nitrogen, and calcined at 700 ° C for 6 hours to obtain a USY molecular sieve with acid active molybdenum centers.

[0049] (1) 50 g of USY molecular sieve with acid active center molybdenum was loaded into a fixed fluidized bed;

[0050] (2) Purge the device at 0.5 L / min for 30 min;

[0051] (3) Set the preheater temperature to 300°C, the reactor temperature to 600°C, and the pressure to atmospheric pressure;

[0052] (4) After the temperature stabilized, high-boiling methyl silicone compounds were introduced into the reactor at a rate of 0.86 ml / min;

[0053] (5) detecting product components by online gas chromatography to determine the cracking rate;

[0054] (6) Collect the reaction liquid and detect the methylchlorosilane component by gas chromatography.

[0055] Example 4

[0056] The catalyst preparation and cracking experiment of this embodiment include the following steps:

[0057] 8 g of ferric nitrate nonahydrate was dissolved in 100 g of deionized water, 50 g of HZSM-5 silica-alumina molecular sieve with a diameter of 100 μm was added, and the mixture was placed in an ultrasonic shaker for 8 hours, taken out and dried for 24 hours, and placed in a tube furnace, dried under nitrogen, and calcined at 700°C for 6 hours to obtain an HZSM-5 molecular sieve with acid-active iron centers.

[0058] (1) 50 g of HZSM-5 molecular sieve with acid active iron centers was loaded into a fixed fluidized bed;

[0059] (2) Purge the device at 0.5 L / min for 30 min;

[0060] (3) Set the preheater temperature to 300°C, the reactor temperature to 600°C, and the pressure to atmospheric pressure;

[0061] (4) After the temperature stabilized, high-boiling methyl silicone compounds were introduced into the reactor at a rate of 0.86 ml / min;

[0062] (5) detecting product components by online gas chromatography to determine the cracking rate;

[0063] (6) Collect the reaction liquid and detect the methylchlorosilane component by gas chromatography.

[0064] Example 5

[0065] The catalyst preparation and cracking experiment of this embodiment include the following steps:

[0066] (1) 50 g of the USY molecular sieve with acid active center iron prepared in Example 1 was loaded into a fixed fluidized bed;

[0067] (2) Purge the device at 0.5 L / min for 30 min;

[0068] (3) Set the preheater temperature to 300°C, the reactor temperature to 600°C, and the pressure to atmospheric pressure;

[0069] (4) After the temperature stabilized, high-boiling methyl silicone compounds were introduced into the reactor at a rate of 0.86 ml / min and cracked hydrogen at a rate of 0.2 ml / min;

[0070] (5) detecting product components by online gas chromatography to determine the cracking rate;

[0071] (6) Collect the reaction liquid and detect the methylchlorosilane component by gas chromatography.

[0072] Example 6

[0073] The catalyst preparation and cracking experiment of this embodiment include the following steps:

[0074] (1) 50 g of the USY molecular sieve with acid active center iron prepared in Example 1 was loaded into a fixed fluidized bed;

[0075] (2) Purge the device at 0.5 L / min for 30 min;

[0076] (3) Set the preheater temperature to 300°C, the reactor temperature to 600°C, and the pressure to atmospheric pressure;

[0077] (4) After the temperature stabilized, high-boiling methyl silicone compounds were introduced into the reactor at a rate of 0.86 ml / min and cracked hydrogen chloride gas at a rate of 0.2 ml / min;

[0078] (5) detecting product components by online gas chromatography to determine the cracking rate;

[0079] (6) Collect the reaction liquid and detect the methylchlorosilane component by gas chromatography.

[0080] The catalysts in Examples 7-13 were prepared using the method in Example 4.

[0081] Example 7

[0082] The method for catalytic cracking of methyl organosilicon high boiling points of the present embodiment comprises the following steps:

[0083] (1) 100 g of HZSM-5 molecular sieve loaded with iron was loaded into a fixed fluidized bed;

[0084] (2) Purge the device at 0.5 L / min for 30 min;

[0085] (3) Set the preheater temperature to 300°C, the reactor temperature to 500°C, and the pressure to atmospheric pressure;

[0086] (4) After the temperature stabilized, high-boiling methyl silicone compounds were introduced into the reactor at a rate of 0.86 ml / min;

[0087] (5) detecting product components by online gas chromatography to determine the cracking rate;

[0088] (6) Collect the reaction liquid and detect the methylchlorosilane component by gas chromatography.

[0089] Example 8

[0090] The method for catalytic cracking of methyl organosilicon high boiling points of the present embodiment comprises the following steps:

[0091] (1) 100 g of HZSM-5 molecular sieve loaded with iron was loaded into a fixed fluidized bed;

[0092] (2) Purge the device at 0.5 L / min for 30 min;

[0093] (3) Set the preheater temperature to 300°C, the reactor temperature to 600°C, and the pressure to atmospheric pressure;

[0094] (4) After the temperature stabilized, high-boiling methyl silicone compounds were introduced into the reactor at a rate of 0.86 ml / min;

[0095] (5) detecting product components by online gas chromatography to determine the cracking rate;

[0096] (6) Collect the reaction liquid and detect the methylchlorosilane component by gas chromatography.

[0097] Example 9

[0098] The method for catalytic cracking of methyl organosilicon high boiling points of the present embodiment comprises the following steps:

[0099] (1) 100 g of HZSM-5 molecular sieve loaded with iron was loaded into a fixed fluidized bed;

[0100] (2) Purge the device at 0.5 L / min for 30 min;

[0101] (3) Set the preheater temperature to 300°C, the reactor temperature to 650°C, and the pressure to atmospheric pressure;

[0102] (4) After the temperature stabilized, high-boiling methyl silicone compounds were introduced into the reactor at a rate of 0.86 ml / min;

[0103] (5) detecting product components by online gas chromatography to determine the cracking rate;

[0104] (6) Collect the reaction liquid and detect the methylchlorosilane component by gas chromatography.

[0105] Example 10

[0106] The method for catalytic cracking of methyl organosilicon high boiling points of the present embodiment comprises the following steps:

[0107] (1) 100 g of HZSM-5 molecular sieve loaded with iron was loaded into a fixed fluidized bed;

[0108] (2) Purge the device at 0.5 L / min for 30 min;

[0109] (3) Set the preheater temperature to 300°C, the reactor temperature to 600°C, and the pressure to atmospheric pressure;

[0110] (4) After the temperature stabilized, high-boiling methyl silicone compounds were introduced into the reactor at a rate of 0.86 ml / min and cracked hydrogen chloride gas at a rate of 0.2 ml / min;

[0111] (5) detecting product components by online gas chromatography to determine the cracking rate;

[0112] (6) Collect the reaction liquid and detect the methylchlorosilane component by gas chromatography.

[0113] Example 11

[0114] The method for catalytic cracking of methyl organosilicon high boiling points of the present embodiment comprises the following steps:

[0115] (1) 100 g of HZSM-5 molecular sieve loaded with iron was loaded into a fixed fluidized bed;

[0116] (2) Purge the device at 0.5 L / min for 30 min;

[0117] (3) Set the preheater temperature to 300°C, the reactor temperature to 600°C, and the pressure to atmospheric pressure;

[0118] (4) After the temperature stabilized, high-boiling methyl silicone compounds were introduced into the reactor at a rate of 0.86 ml / min and cracked hydrogen at a rate of 0.2 ml / min;

[0119] (5) detecting product components by online gas chromatography to determine the cracking rate;

[0120] (6) Collect the reaction liquid and detect the methylchlorosilane component by gas chromatography.

[0121] Example 12

[0122] The method for catalytic cracking of methyl organosilicon high boiling points of the present embodiment comprises the following steps:

[0123] (1) 100 g of HZSM-5 molecular sieve loaded with iron was loaded into a fixed fluidized bed;

[0124] (2) Purge the device at 0.5 L / min for 30 min;

[0125] (3) Set the preheater temperature to 300°C, the reactor temperature to 600°C, and the pressure to atmospheric pressure;

[0126] (4) After the temperature stabilized, high-boiling methyl silicone compounds were introduced into the reactor at a rate of 0.86 ml / min and cracked methane at a rate of 0.2 ml / min;

[0127] (5) detecting product components by online gas chromatography to determine the cracking rate;

[0128] (6) Collect the reaction liquid and detect the methylchlorosilane component by gas chromatography.

[0129] Example 13

[0130] The method for catalytic cracking of methyl organosilicon high boiling points of the present embodiment comprises the following steps:

[0131] (1) 100 g of HZSM-5 molecular sieve loaded with iron was loaded into a fixed fluidized bed;

[0132] (2) Purge the device at 0.5 L / min for 30 min;

[0133] (3) Set the preheater temperature to 300°C, the reactor temperature to 600°C, and the pressure to atmospheric pressure;

[0134] (4) After the temperature stabilized, high-boiling methyl silicone compounds were introduced into the reactor at a rate of 0.86 ml / min and cracked ethane at a rate of 0.2 ml / min;

[0135] (5) detecting product components by online gas chromatography to determine the cracking rate;

[0136] (6) Collect the reaction liquid and detect the methylchlorosilane component by gas chromatography.

[0137] Comparative Example 1

[0138] The method for catalytic cracking of methyl organosilicon high boiling points of the comparative example comprises the following steps:

[0139] (1) Purge the device at 0.5 l / min for 30 min;

[0140] (2) Set the preheater temperature to 300°C, the reactor temperature to 600°C, and the pressure to atmospheric pressure;

[0141] (3) After the temperature stabilized, high-boiling methyl silicone compounds were introduced into the reactor at a rate of 0.86 ml / min;

[0142] (4) detecting product components by online gas chromatography to determine the cracking rate;

[0143] (5) Collect the reaction liquid and detect the methylchlorosilane component by gas chromatography.

[0144] Comparative Example 2

[0145] The method for catalytic cracking of methyl organosilicon high boiling points of the comparative example comprises the following steps:

[0146] (1) 50 g of USY molecular sieve with silica-alumina support was loaded into a fixed fluidized bed;

[0147] (1) Purge the device at 0.5 L / min for 30 minutes;

[0148] (2) Set the preheater temperature to 300°C, the reactor temperature to 600°C, and the pressure to atmospheric pressure;

[0149] (3) After the temperature stabilizes, high-boiling methyl silicone compounds are introduced into the reactor at a rate of 0.86 ml / min; (4) product components are detected by online gas chromatography to determine the cracking rate;

[0150] (5) Collect the reaction liquid and detect the methylchlorosilane component by gas chromatography.

[0151] Comparative Example 3

[0152] The method for catalytic cracking of methyl organosilicon high boiling points in this comparative example comprises the following steps:

[0153] (1) 100 g of HZSM-5 molecular sieve on a silica-alumina carrier was loaded into a fixed fluidized bed;

[0154] (1) Purge the device at 0.5 L / min for 30 minutes;

[0155] (2) Set the preheater temperature to 300°C, the reactor temperature to 600°C, and the pressure to atmospheric pressure;

[0156] (3) After the temperature stabilizes, high-boiling methyl silicone compounds are introduced into the reactor at a rate of 0.86 ml / min; (4) product components are detected by online gas chromatography to determine the cracking rate;

[0157] (5) Collect the reaction liquid and detect the methylchlorosilane component by gas chromatography.

[0158] Table 1 Comparison of the effects of Examples 1-13 and Comparative Examples 1-3

[0159]

[0160]

[0161] Remark:

[0162] 1. Cracking rate = 100% - high boiling point content in liquid product / high boiling point content in raw material × 100%;

[0163] 2. The content of each component is the content detected by gas chromatography.

[0164] As can be seen from the above table, the methyl organosilicon high-boiling-point cracking catalyst with disproportionation cracking provided by the present invention can crack methyl organosilicon high-boiling-point points and convert them into methyl organosilicon monomers. The cracking rate can reach 90%, and the selectivity of methyl organosilicon monomers can reach 75%. It is a catalyst with high cracking rate and good selectivity.

[0165] The above describes the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A method for cracking high-boiling methyl organosilicon products, characterized in that: At a reaction temperature of 500-650°C and a reaction pressure of 0-0.3 MPa, a molecular sieve with disproportionation properties and loaded with a Lewis acidic active center element is used as a cracking catalyst, and cracking gas is introduced to catalytically crack high-boiling methyl organosilicon products into methyl organosilicon monomers; the high-boiling methyl organosilicon products are byproducts with a boiling range of 80-215°C generated during the direct process for producing methylchlorosilane; The molecular sieve with disproportionation performance is HZSM-5 molecular sieve; the Lewis acidic active center element is iron, zinc and / or molybdenum; the preparation method of the cracking catalyst comprises: preparing a water-soluble salt of the Lewis acidic active center element into an aqueous solution of appropriate concentration, impregnating the molecular sieve therein, removing it, drying it, and then calcining it to obtain a molecular sieve loaded with the corresponding Lewis acidic active center element; The cracking gas is hydrogen chloride, hydrogen and / or C 1-6 Alkanes; The cracking method is carried out in a fixed bed or fluidized bed reactor.

2. The cracking method according to claim 1, wherein The fluidized bed reactor is an MTO fluidized bed or a DMTO fluidized bed.

3. The cracking method according to claim 1 or 2, wherein: The reactor is connected to a dust filter device to separate solid particles entrained by the reaction gas.

4. The cracking method according to claim 1 or 2, wherein: The cracking product is separated by a separation device to obtain a methyl organosilicon component.

5. The cracking method according to claim 4, wherein: The separation device is a distillation device.

6. The cracking method according to claim 1 or 2, wherein: The high-boiling methyl silicone is preheated and vaporized before entering the cracking catalytic reaction.

Images