Difunctional solid acid catalyst as well as preparation method and application thereof

Abstract

The invention discloses a bifunctional solid acid catalyst as well as a preparation method and application thereof, and relates to the technical field of catalysts. According to the preparation method, the biomass raw material, the metal nitrate and the phosphoric acid aqueous solution are taken as raw materials, the introduction of the metal nitrate provides Lewis acid sites for the catalyst, and chemical bonds of the biomass raw material are broken under the action of phosphoric acid through pretreatment, so that the porous structure carbon material is formed, and subsequent sulfonation treatment is facilitated to generate more Bronsted acid sites. The bifunctional solid acid catalyst provided by the invention has dual catalytic active sites of Bronsted and Lewis, and shows very high catalytic activity and selectivity; the raw materials for preparing the catalyst belong to biomass, and have the characteristics of cheap and easily available raw materials and environmental friendliness. Besides, the bifunctional solid acid catalyst can be recycled and is applied to production of the low-molecular-weight hydrogen-containing silicone oil, and the low-molecular-weight hydrogen-containing silicone oil with high yield can be obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a bifunctional solid acid catalyst and a preparation method and application thereof. Background Art

[0002] Hydrogenated silicone oil is an important chemical raw material. Low molecular weight hydrogenated silicone oil, due to its high Si-H content, easily reacts chemically with substances containing unsaturated bonds to produce various silicone oils, silicone rubbers and silicone resin products, which are widely used in pesticides, textiles, furniture, automobiles and other fields.

[0003] In the prior art, the synthesis methods of low molecular weight hydrogenated silicone oil include halogenated silane synthesis method, ring-opening copolymerization method and high hydrogenated silicone oil telomerization method. Among them, the high hydrogenated silicone oil telomerization method has mild process conditions and high product yield, and has become the most common synthesis method. The catalysts commonly used in the high hydrogenated silicone oil telomerization method include concentrated sulfuric acid, acidic clay and ion exchange resin. Concentrated sulfuric acid is highly corrosive, and the conditions required for purchase, transportation, storage and use are very harsh, the production cost is high, and it is not environmentally friendly; acidic clay and ion exchange resin are expensive, and the catalytic activity fluctuates greatly, resulting in poor quality and stability of low molecular weight hydrogenated silicone oil.

[0004] Therefore, there is an urgent need to develop new catalysts that have high catalytic activity and selectivity, are cheap and readily available, and are environmentally friendly.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The purpose of the present invention is to provide a bifunctional solid acid catalyst and a preparation method and application thereof, aiming to provide a new catalyst with high catalytic activity and selectivity, low cost, easy availability and environmental friendliness. The catalyst is used in the production of low molecular weight hydrogenated silicone oil to obtain a high yield of low molecular weight hydrogenated silicone oil.

[0007] The present invention is achieved in that:

[0008] In a first aspect, the present invention provides a method for preparing a bifunctional solid acid catalyst, comprising: mixing a biomass raw material, a metal nitrate and an aqueous phosphoric acid solution for pretreatment to obtain a pretreatment product, and sulfonating the pretreatment product to obtain a sulfonated product;

[0009] The pretreatment includes: mixing and reacting the raw materials, followed by drying and roasting.

[0010] In an optional embodiment, the biomass raw material, metal nitrate, 80%-85% by mass phosphoric acid aqueous solution and water are mixed for pretreatment, and the mass ratio of the biomass raw material, metal nitrate, phosphoric acid aqueous solution and water is controlled to be (2-3): (1-2): 1: (10-15).

[0011] In an optional embodiment, the biomass raw material is selected from at least one of sucrose, sucralose and lignin.

[0012] In an optional embodiment, the metal nitrate is selected from at least one of Al(NO3)3·9H2O, Zn(NO3)2·6H2O and Ni(NO3)26H2O;

[0013] Preferably, in the metal nitrate, the mass ratio of Al(NO3)39H2O, Zn(NO3)2·6H2O and Ni(NO3)2·6H2O is 1:(0-0.50):(0-0.25).

[0014] In an optional embodiment, the sulfonation treatment process includes: mixing and reacting the pretreated product and a sulfonating agent;

[0015] Wherein, the mass ratio of the pretreatment product to the sulfonating agent is 1:(10-15);

[0016] Preferably, the sulfonating agent is selected from at least one of 3-methylbenzenesulfonic acid and 4-methylbenzenesulfonic acid;

[0017] Preferably, the reaction temperature of the sulfonation treatment is 70°C-100°C, and the reaction time is 18h-24h.

[0018] In an optional embodiment, the method further comprises: post-treating the sulfonated product;

[0019] Preferably, the process of post-treating the sulfonated product comprises: after the reaction between the pre-treated product and the sulfonating agent is completed and cooled, mixing the sulfonated product with water for solid-liquid separation, washing the obtained solid material with water until it is neutral, and then drying it;

[0020] Preferably, the drying treatment of the sulfonated product in the post-treatment is carried out by vacuum drying, and the drying temperature is controlled to be 100° C.-110° C., the pressure is -0.09 MPa to -0.10 MPa, and the drying time is 18 h to 24 h.

[0021] In an optional embodiment, the pretreatment includes: mixing the biomass raw material, metal nitrate, phosphoric acid aqueous solution and water, and reacting them under constant temperature reflux, followed by drying and roasting; controlling the reflux temperature to 80° C.-100° C. and the reflux time to 18 h-24 h;

[0022] Preferably, the pretreatment further comprises: cooling the calcined product, grinding it into powder, and sieving it to 80-100 mesh;

[0023] Preferably, the calcination temperature during the pretreatment process is 400°C-500°C, and the calcination time is 1h-2h;

[0024] Preferably, the drying treatment in the pretreatment process adopts a vacuum drying method, and the drying temperature is controlled to be 100° C.-110° C., the pressure is -0.09 MPa to -0.10 MPa, and the drying time is 18h-24h.

[0025] In a second aspect, the present invention provides a bifunctional solid acid catalyst prepared by any one of the preparation methods in the aforementioned embodiments.

[0026] In a third aspect, the present invention provides use of the bifunctional solid acid catalyst of the aforementioned embodiment in the preparation of low molecular weight hydrogen-containing silicone oil.

[0027] In an optional embodiment, the low molecular weight hydrogen-containing silicone oil is 1,1,1,3,5,7,7,7-octamethyltetrasiloxane, and its structural formula is:

[0028]

[0029] Preferably, the process of preparing low molecular weight hydrogenated silicone oil using a bifunctional solid acid catalyst comprises: mixing high hydrogenated silicone oil, hexamethyldisiloxane and a bifunctional solid acid catalyst for reaction; wherein the structural formula of the high hydrogenated silicone oil is:

[0030]

[0031] Wherein, m = 30-50;

[0032] Preferably, the mass ratio of high hydrogen silicone oil to hexamethyldisiloxane is (0.4-1.95):1; the amount of the bifunctional solid acid catalyst is 0.3%-0.6% of the total mass of the high hydrogen silicone oil and hexamethyldisiloxane;

[0033] Preferably, the temperature of the mixed reaction is 40°C-70°C, and the time is 2h-4h;

[0034] Preferably, after the mixing reaction is completed, the reaction product is subjected to impurity removal and distillation, and the fractions are collected to obtain low molecular weight hydrogen-containing silicone oil.

[0035] The present invention has the following beneficial effects: the present invention uses biomass raw materials, metal nitrates and phosphoric acid aqueous solution as raw materials, the introduction of metal nitrates provides Lewis acid sites for the catalyst, and the chemical bonds of the biomass raw materials are broken under the action of phosphoric acid after pretreatment, thereby forming a porous structure carbon material, which is convenient for subsequent sulfonation treatment to produce more Bronsted acid sites. The bifunctional solid acid catalyst provided by the present invention has Bronsted and Lewis dual catalytic active sites, showing high catalytic activity and selectivity; the raw materials for preparing the catalyst belong to biomass, which has the characteristics of cheap raw materials, easy to obtain and environmentally friendly. In addition, the bifunctional solid acid catalyst of the present invention can be recycled and applied to the production of low molecular weight hydrogen-containing silicone oil, and a high yield of low molecular weight hydrogen-containing silicone oil can be obtained. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0037] In view of the fact that in the prior art, the catalyst for preparing low molecular weight hydrogenated silicone oil is not environmentally friendly or has the problem of difficult to control stability, the present invention is now proposed: a novel bifunctional solid acid catalyst using biomass raw materials as carriers, which has the characteristics of being environmentally friendly and having cheap and readily available raw materials, and the prepared bifunctional solid acid catalyst is easy to separate and can be recycled. In addition, the bifunctional solid acid catalyst is applied to the production of low molecular weight hydrogenated silicone oil to obtain low molecular weight hydrogenated silicone oil with a higher yield.

[0038] The present invention provides a method for preparing a bifunctional solid acid catalyst, comprising the following steps:

[0039] S1. Preprocessing

[0040] The biomass raw material, metal nitrate and phosphoric acid aqueous solution are mixed and pretreated to obtain a pretreated product, wherein the pretreatment includes: drying and roasting in sequence after the raw materials are mixed and reacted. The chemical bonds of the biomass raw material are broken by the action of phosphoric acid through the pretreatment, thereby forming a porous structure carbon material, which is convenient for subsequent sulfonation treatment to produce more Bronsted acid sites. In addition, the introduction of metal nitrate provides Lewis acid sites for the catalyst.

[0041] In some embodiments, the pretreatment includes: mixing biomass raw materials, metal nitrates, phosphoric acid aqueous solution and water, reflux reaction at a constant temperature, and then drying and roasting. The reflux temperature is controlled to be 80°C-100°C, and the reflux time is 18h-24h. By adjusting the reaction temperature and time, the porosity of the carbon material is further improved. Specifically, the reflux temperature can be 80°C, 85°C, 90°C, 95°C, 100°C, etc.; the reflux time can be 18h, 20h, 22h, 24h, etc.

[0042] In order to improve the catalytic activity of the catalyst product, the embodiment of the present invention optimizes the amount of each raw material: in actual operation, the biomass raw material, the metal nitrate, the phosphoric acid aqueous solution with a mass fraction of 80%-85% and water are mixed for pretreatment, and the mass ratio of the biomass raw material, the metal nitrate, the phosphoric acid aqueous solution and the water is controlled to be (2-3): (1-2): 1: (10-15), such as 2.0:1.0:1:10, 2.2:1.2:1:11, 2.4:1.4:1:12, 2.6:1.6:1:13, 2.8:1.8:1:14, 3.0:2.0:1:15, etc.; the mass fraction of the phosphoric acid aqueous solution can be 80%, 81%, 82%, 83%, 84%, 85%, etc.

[0043] In some embodiments, the biomass raw material is selected from at least one of sucrose, sucralose and lignin. The biomass raw material can be any one or more of the above, all of which are suitable as a carrier of the novel bifunctional solid acid catalyst. The biomass raw material is selected as a bifunctional solid acid catalyst carrier because it has a wide range of sources and is cheap and easy to obtain.

[0044] In some embodiments, the metal nitrate is selected from at least one of Al(NO3)3·9H2O, Zn(NO3)2·6H2O and Ni(NO3)2·6H2O, and the metal nitrate may be any one or more of the above. Preferably, in the metal nitrate, the mass ratio of Al(NO3)3 9H2O, Zn(NO3)2·6H2O and Ni(NO3)2·6H2O is 1:(0-0.50):(0-0.25), such as 1:0.00:0.00, 1:0.10:0.05, 1:0.20:0.10, 1:0.30:0.15, 1:0.40:0.20, 1:0.50:0.25, etc. The ratio of each component of the metal nitrate is preferably within the above range, which can further enhance the catalytic activity.

[0045] In some embodiments, the drying process in the pretreatment process can be carried out by vacuum drying, and the drying temperature is controlled to be 100°C-110°C, the pressure is -0.09MPa to -0.10MPa, and the drying time is 18h-24h, and the water on the surface of the solid material is fully removed by drying. Specifically, the drying temperature can be 100°C, 103°C, 105°C, 108°C, 110°C, etc., the pressure can be -0.090MPa, -0.095MPa, -0.10MPa, etc., and the drying time can be 18h, 20h, 22h, 24h, etc.

[0046] In some embodiments, the calcination temperature in the pretreatment process is 400°C-500°C, and the calcination time is 1h-2h. After calcination, the metal oxide functional catalyst is evenly loaded on the carrier. Specifically, the calcination temperature can be 400°C, 430°C, 450°C, 480°C, 500°C, etc., and the calcination time can be 1.0h, 1.3h, 1.5h, 1.8h, 2.0h, etc. The calcination process can be carried out in a muffle furnace.

[0047] In some embodiments, the pretreatment further comprises: grinding the calcined product into powder after cooling, and sieving to 80-100 mesh to obtain a pretreated product. Grinding and sieving are performed according to the particle size of the desired catalyst product to obtain solid particles with a particle size that meets the requirements and enter the next stage.

[0048] S2. Sulfonation

[0049] The pre-treated product is subjected to sulfonation treatment to obtain a sulfonated product. The sulfonation treatment is achieved by introducing sulfonic acid groups into the carrier. The pre-treated product is subjected to sulfonation treatment to enable it to have Bronsted acid sites.

[0050] In some embodiments, the sulfonation process includes: mixing the pretreatment product and the sulfonating agent to react, and introducing sulfonic acid groups into the carrier. The sulfonating agent is selected from at least one of 3-methylbenzenesulfonic acid and 4-methylbenzenesulfonic acid, and the sulfonating agent can be any one or more of the above. The mass ratio of the pretreatment product and the sulfonating agent is 1: (10-15), such as 1: 10, 1: 11, 1: 12, 1: 13, 1: 14, 1: 15, etc. It is appropriate to control the amount of the sulfonating agent within the above range, so as to introduce a sufficient amount of sulfonic acid groups and improve the catalytic activity.

[0051] Furthermore, the reaction temperature of the sulfonation treatment is 70°C-100°C, such as 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, etc.; the reaction time of the sulfonation treatment is 18h-24h, such as 18h, 20h, 22h, 24h, etc.

[0052] S3, post-processing

[0053] After the sulfonation treatment, the sulfonation product is post-treated to separate and purify the reaction product.

[0054] In some embodiments, the process of post-treating the sulfonated product includes: after the reaction of the pre-treated product and the sulfonating agent is completed and cooled, the sulfonated product and water are mixed for solid-liquid separation, the obtained solid material is repeatedly washed with water until it is neutral, and then dried. The method of solid-liquid separation is not limited, and filtering can be used; the residual acid on the surface is removed by water washing to obtain a solid material with a pH value of about 7, and then the catalyst product is obtained after drying to remove the washing water. The number of water washings is not limited, the filter cake is repeatedly washed with water until the filtrate is neutral, and the washed sulfonated product is dried to obtain a bifunctional solid acid catalyst.

[0055] It should be noted that washing the sulfonated product until the filtrate is neutral can prevent the free acidic substances from affecting the yield of the subsequent low molecular weight hydrogenated silicone oil. The water used in the washing process can be deionized water, distilled water or purified water according to actual needs.

[0056] In some embodiments, the drying treatment in the post-treatment can be carried out by vacuum drying, and the drying temperature is controlled to be 100℃-110℃, such as 100℃, 103℃, 105℃, 108℃, 110℃, etc.; the pressure is -0.09MPa~-0.10MPa, such as -0.090MPa, -0.095MPa, -0.100MPa, etc.; the drying time is 18h-24h, such as 18h, 20h, 22h, 24h, etc.

[0057] It should be noted that the drying method in the present invention is vacuum drying, which helps to reduce the drying temperature and make the catalyst have a larger specific surface area.

[0058] The embodiment of the present invention provides a bifunctional solid acid catalyst, which is prepared by the preparation method provided by the embodiment of the present invention. The bifunctional solid acid catalyst has Bronsted and Lewis dual catalytic active sites and exhibits high catalytic activity and selectivity.

[0059] The bifunctional solid acid catalyst provided in the embodiment of the present invention is applied to the production of low molecular weight hydrogen-containing silicone oil, so that a high yield of low molecular weight hydrogen-containing silicone oil can be obtained.

[0060] In some embodiments, the low molecular weight hydrogen-containing silicone oil is 1,1,1,3,5,7,7,7-octamethyltetrasiloxane, which has the structural formula:

[0061]

[0062] It should be noted that the bifunctional solid acid catalyst provided in the embodiment of the present invention is used to catalyze the preparation of 1,1,1,3,5,7,7,7-octamethyltetrasiloxane, which shows high catalytic activity and high product yield.

[0063] In some embodiments, the process of preparing low molecular weight hydrogenated silicone oil using a bifunctional solid acid catalyst comprises: mixing high hydrogenated silicone oil, hexamethyldisiloxane and a bifunctional solid acid catalyst for reaction. The structural formula of the high hydrogenated silicone oil is:

[0064]

[0065] In the formula, m=30-50. The high hydrogen-containing silicone oil with this molecular weight is particularly suitable for catalysis by the bifunctional solid acid catalyst provided by the embodiment of the present invention, and the yield of the low molecular weight hydrogen-containing silicone oil prepared is relatively high.

[0066] In some embodiments, the mass ratio of high hydrogen silicone oil and hexamethyldisiloxane is (0.4-1.95): 1, such as 0.40: 1, 0.50: 1, 0.80: 1, 1.00: 1, 1.30: 1, 1.50: 1, 1.80: 1, 1.95: 1, etc. The amount of the bifunctional solid acid catalyst is 0.3%-0.6% of the total mass of the high hydrogen silicone oil and hexamethyldisiloxane, such as 0.3%, 0.4%, 0.5%, 0.6%, etc. By regulating the amount of high hydrogen silicone oil, hexamethyldisiloxane, and bifunctional solid acid catalyst, the yield of low molecular weight hydrogen silicone oil is further improved.

[0067] Furthermore, the temperature of the mixed reaction of high hydrogen silicone oil, hexamethyldisiloxane and bifunctional solid acid catalyst is 40°C-70°C, such as 40°C, 50°C, 60°C, 70°C, etc.; the reaction time can be 2h, 3h, 4h, etc.

[0068] Furthermore, after the mixed reaction is completed, the reaction product is subjected to impurity removal and distillation, and the fractions are collected to obtain low molecular weight hydrogenated silicone oil. Specifically, after the reaction is completed, the bifunctional solid acid catalyst is removed by filtering, and then the low boiling point substances below 160°C are removed by atmospheric distillation, and then atmospheric distillation is performed to collect the fraction of 177-180°C, which is 1,1,1,3,5,7,7,7-octamethyltetrasiloxane.

[0069] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0070] Example 1

[0071] This embodiment provides a bifunctional solid acid catalyst, and the bifunctional solid acid catalyst is used to catalyze the preparation of low molecular weight hydrogen-containing silicone oil, as follows:

[0072] (1) The preparation of the bifunctional solid acid catalyst comprises the following steps:

[0073] 10.0g sucrose, 6g Al(NO3)3·9H2O and 3.5g phosphoric acid aqueous solution (phosphoric acid mass fraction is 80%) are dissolved in 50g deionized water, refluxed at 80°C for 20h, placed in a 100°C, -0.09MPa vacuum drying oven for 20h, and then placed in a 500°C muffle furnace for calcination for 1h. After cooling, the solid product is ground into powder and sieved to 80-100 mesh to obtain a pretreated product.

[0074] 1.0 g of the pretreated product was added to 13.0 g of 4-methylbenzenesulfonic acid and sulfonated at 90° C. for 20 h. After cooling, the sulfonated product was added to deionized water, stirred and filtered. The filter cake was repeatedly washed with deionized water until the filtrate was neutral. The filter cake was placed in a vacuum drying oven at 100° C. and -0.09 MPa and dried for 24 h to obtain a bifunctional solid acid catalyst.

[0075] (2) The preparation of low molecular weight hydrogen-containing silicone oil comprises the following steps:

[0076] 65g of high hydrogen silicone oil (m=50) and 100g of hexamethyldisiloxane were reacted at 50°C for 3 hours, and the amount of bifunctional solid acid catalyst was 0.5% of the total mass of the raw materials. After the reaction was completed, the catalyst was removed by filtration to obtain a low molecular weight hydrogen silicone oil crude product. Low boiling point substances below 160°C in the crude product were first removed by atmospheric distillation, and then the fraction of 177°C-180°C was collected by atmospheric distillation to obtain 1,1,1,3,5,7,7,7-octamethyltetrasiloxane.

[0077] Example 2

[0078] This embodiment provides a bifunctional solid acid catalyst, and the bifunctional solid acid catalyst is used to catalyze the preparation of low molecular weight hydrogen-containing silicone oil, as follows:

[0079] (1) The preparation of the bifunctional solid acid catalyst comprises the following steps:

[0080] 10g sucrose, 5g Al(NO3)3·9H2O and 5g phosphoric acid aqueous solution (phosphoric acid mass fraction is 83%) are dissolved in 50g deionized water, refluxed at 90°C for 20h, placed in a 100°C, -0.09MPa vacuum drying oven for 20h, and then placed in a 400°C muffle furnace for calcination for 2h. After cooling, the solid product is ground into powder and sieved to 80-100 mesh to obtain a pretreated product.

[0081] 1 g of the pretreated product was added to 15 g of 4-methylbenzenesulfonic acid and sulfonated at 80°C for 20 h. After cooling, the sulfonated product was added to deionized water, stirred and filtered. The filter cake was repeatedly washed with deionized water until the filtrate was neutral. The filter cake was placed in a vacuum drying oven at 100°C and -0.10 MPa and dried for 20 h to obtain a bifunctional solid acid catalyst.

[0082] (2) The preparation of low molecular weight hydrogen-containing silicone oil comprises the following steps:

[0083] 79g of high hydrogen silicone oil (m=40) and 100g of hexamethyldisiloxane were reacted at 40°C for 3 hours, and the amount of bifunctional solid acid catalyst was 0.6% of the total mass of the raw materials. After the reaction was completed, the catalyst was removed by filtration to obtain a low molecular weight hydrogen silicone oil crude product. Low boiling point substances below 160°C in the crude product were first removed by atmospheric distillation, and then the fraction of 177-180°C was collected by atmospheric distillation to obtain 1,1,1,3,5,7,7,7-octamethyltetrasiloxane.

[0084] Example 3

[0085] This embodiment provides a bifunctional solid acid catalyst, and the bifunctional solid acid catalyst is used to catalyze the preparation of low molecular weight hydrogen-containing silicone oil, as follows:

[0086] (1) The preparation of the bifunctional solid acid catalyst comprises the following steps:

[0087] 10g sucrose, 5g Al(NO3)3·9H2O, 1g Ni(NO3)2·6H2O and 3.4g phosphoric acid aqueous solution (phosphoric acid mass fraction is 85%) are dissolved in 50g deionized water, refluxed at 100°C for 18h, placed in a 110°C, -0.10MPa vacuum drying oven for 18h, and then placed in a 500°C muffle furnace for calcination for 1h. After cooling, the solid product is ground into powder and sieved to 80-100 mesh to obtain a pretreated product.

[0088] 1 g of the pretreated product was added to 10 g of 4-methylbenzenesulfonic acid and sulfonated at 100° C. for 18 h. After cooling, the sulfonated product was added to deionized water, stirred and filtered. The filter cake was repeatedly washed with deionized water until the filtrate was neutral. The filter cake was placed in a vacuum drying oven at 110° C. and -0.10 MPa and dried for 18 h to obtain a bifunctional solid acid catalyst.

[0089] (2) The preparation of low molecular weight hydrogen-containing silicone oil comprises the following steps:

[0090] 40g of high hydrogen silicone oil (m=30) and 100g of hexamethyldisiloxane were reacted at 50°C for 2 hours, and the amount of bifunctional solid acid catalyst was 0.5% of the total mass of the raw materials. After the reaction was completed, the catalyst was removed by filtration to obtain a low molecular weight hydrogen silicone oil crude product. Low boiling point substances below 160°C in the crude product were first removed by atmospheric distillation, and then the fraction of 177°C-180°C was collected by atmospheric distillation to obtain 1,1,1,3,5,7,7,7-octamethyltetrasiloxane.

[0091] Example 4

[0092] This embodiment provides a bifunctional solid acid catalyst, and the bifunctional solid acid catalyst is used to catalyze the preparation of low molecular weight hydrogen-containing silicone oil, as follows:

[0093] (1) The preparation of the bifunctional solid acid catalyst comprises the following steps:

[0094] 10g sucrose, 4g Al(NO3)3·9H2O, 1.5g Zn(NO3)2·6H2O and 4g phosphoric acid aqueous solution (phosphoric acid mass fraction is 83%) are dissolved in 50g deionized water, refluxed at 90°C for 24h, placed in a 100°C, -0.09MPa vacuum drying oven for 24h, and then placed in a 400°C muffle furnace for calcination for 2h. After cooling, the solid product is ground into powder and sieved to 80-100 mesh to obtain a pretreated product.

[0095] 1 g of the pretreated product was added to 10 g of 4-methylbenzenesulfonic acid and sulfonated at 90°C for 24 h. After cooling, the sulfonated product was added to deionized water, stirred and filtered. The filter cake was repeatedly washed with deionized water until the filtrate was neutral. The filter cake was placed in a vacuum drying oven at 100°C and -0.09 MPa and dried for 24 h to obtain a bifunctional solid acid catalyst.

[0096] (2) The preparation of low molecular weight hydrogen-containing silicone oil comprises the following steps:

[0097] 121g of high hydrogen silicone oil (m=40) and 100g of hexamethyldisiloxane were reacted at 60°C for 3 hours, and the amount of bifunctional solid acid catalyst was 0.5% of the total mass of the raw materials. After the reaction was completed, the catalyst was removed by filtration to obtain a low molecular weight hydrogen silicone oil crude product. Low boiling point substances below 160°C in the crude product were first removed by atmospheric distillation, and then the fraction of 177-180°C was collected by atmospheric distillation to obtain 1,1,1,3,5,7,7,7-octamethyltetrasiloxane.

[0098] Example 5

[0099] This embodiment provides a bifunctional solid acid catalyst, and the bifunctional solid acid catalyst is used to catalyze the preparation of low molecular weight hydrogen-containing silicone oil, as follows:

[0100] (1) The preparation of the bifunctional solid acid catalyst comprises the following steps:

[0101] 10g sucrose, 3g Al(NO3)3·9H2O, 1g Zn(NO3)2·6H2O, 0.5g Ni(NO3)2·6H2O and 4g phosphoric acid aqueous solution (phosphoric acid mass fraction is 80%) are dissolved in 50g deionized water, refluxed at 100°C for 24h, placed in a 100°C, -0.10MPa vacuum drying oven for 24h, and then placed in a 500°C muffle furnace for calcination for 2h. After cooling, the solid product is ground into powder and sieved to 80-100 mesh to obtain a pretreated product.

[0102] 1 g of the pretreated product was added to 15 g of 4-methylbenzenesulfonic acid and sulfonated at 90°C for 24 h. After cooling, the sulfonated product was added to deionized water, stirred and filtered. The filter cake was repeatedly washed with deionized water until the filtrate was neutral. The filter cake was placed in a vacuum drying oven at 100°C and -0.10 MPa and dried for 24 h to obtain a bifunctional solid acid catalyst.

[0103] (2) The preparation of low molecular weight hydrogen-containing silicone oil comprises the following steps:

[0104] 195g of high hydrogen silicone oil (m=50) and 100g of hexamethyldisiloxane were reacted at 70°C for 2 hours, and the amount of bifunctional solid acid catalyst was 0.4% of the total mass of the raw materials. After the reaction was completed, the catalyst was removed by filtration to obtain a low molecular weight hydrogen silicone oil crude product. Low boiling point substances below 160°C in the crude product were first removed by atmospheric distillation, and then the fraction of 177-180°C was collected by atmospheric distillation to obtain 1,1,1,3,5,7,7,7-octamethyltetrasiloxane.

[0105] Example 6

[0106] This embodiment provides a bifunctional solid acid catalyst, and the bifunctional solid acid catalyst is used to catalyze the preparation of low molecular weight hydrogen-containing silicone oil, as follows:

[0107] (1) The preparation of the bifunctional solid acid catalyst comprises the following steps:

[0108] 10g sucrose, 4g Al(NO3)3·9H2O, 2g Zn(NO3)2·6H2O, 1g Ni(NO3)2·6H2O and 3.5g phosphoric acid aqueous solution (phosphoric acid mass fraction is 83%) are dissolved in 50g deionized water, refluxed at 80°C for 24h, placed in a 110°C, -0.10MPa vacuum drying oven for 24h, and then placed in a 400°C muffle furnace for calcination for 2h. After cooling, the solid product is ground into powder and sieved to 80-100 mesh to obtain a pretreated product.

[0109] 1 g of the pretreated product was added to 13 g of 4-methylbenzenesulfonic acid and sulfonated at 70°C for 24 h. After cooling, the sulfonated product was added to deionized water, stirred and filtered. The filter cake was repeatedly washed with deionized water until the filtrate was neutral. The filter cake was placed in a vacuum drying oven at 110°C and -0.10 MPa and dried for 24 h to obtain a bifunctional solid acid catalyst.

[0110] (2) The preparation of low molecular weight hydrogen-containing silicone oil comprises the following steps:

[0111] 53g of high hydrogen silicone oil (m=40) and 100g of hexamethyldisiloxane were reacted at 40°C for 4 hours, and the amount of bifunctional solid acid catalyst was 0.4% of the total mass of the raw materials. After the reaction was completed, the catalyst was removed by filtration to obtain a low molecular weight hydrogen silicone oil crude product. Low boiling point substances below 160°C in the crude product were first removed by atmospheric distillation, and then the fraction of 177-180°C was collected by atmospheric distillation to obtain 1,1,1,3,5,7,7,7-octamethyltetrasiloxane.

[0112] Comparative Example 1

[0113] This comparative example provides a bifunctional solid acid catalyst and a low molecular weight hydrogen-containing silicone oil, which differs from Example 1 in that no metal nitrate is added during the preparation of the bifunctional solid acid catalyst, and specifically comprises:

[0114] 10g of sucrose and 3.5g of phosphoric acid aqueous solution (phosphoric acid mass fraction is 80%) are dissolved in 50g of deionized water, refluxed at 80°C for 20h, placed in a 100°C, -0.09MPa vacuum drying oven for 20h, and then placed in a 500°C muffle furnace for calcination for 1h. After cooling, the solid product is ground into powder and sieved to 80-100 mesh to obtain a pretreated product.

[0115] 1 g of the pretreated product was added to 13 g of 4-methylbenzenesulfonic acid and sulfonated at 90°C for 20 h. After cooling, the sulfonated product was added to deionized water, stirred and filtered. The filter cake was repeatedly washed with deionized water until the filtrate was neutral. The filter cake was placed in a vacuum drying oven at 100°C and -0.09 MPa and dried for 24 h to obtain a bifunctional solid acid catalyst.

[0116] Comparative Example 2

[0117] This comparative example provides a bifunctional solid acid catalyst and a low molecular weight hydrogen-containing silicone oil, which differs from Example 1 in that no phosphoric acid aqueous solution is added during the preparation of the bifunctional solid acid catalyst, and specifically comprises:

[0118] 10g sucrose and 6g Al(NO3)3·9H2O were dissolved in 50g deionized water, refluxed at 80°C for 20h, dried in a 100°C, -0.09MPa vacuum drying oven for 20h, and then calcined in a 500°C muffle furnace for 1h. After cooling, the solid product was ground into powder and sieved to 80-100 mesh to obtain a pretreated product.

[0119] 1 g of the pretreated product was added to 13 g of 4-methylbenzenesulfonic acid and sulfonated at 90°C for 20 h. After cooling, the sulfonated product was added to deionized water, stirred and filtered. The filter cake was repeatedly washed with deionized water until the filtrate was neutral. The filter cake was placed in a vacuum drying oven at 100°C and -0.09 MPa and dried for 24 h to obtain a bifunctional solid acid catalyst.

[0120] Comparative Example 3

[0121] This comparative example provides a bifunctional solid acid catalyst and a low molecular weight hydrogen-containing silicone oil, which differs from Example 1 in that the type of nitrate in the preparation process of the bifunctional solid acid catalyst is not within the range, specifically including:

[0122] 10g sucrose, 6g Mg(NO3)2·6H2O and 3.5g phosphoric acid aqueous solution (phosphoric acid mass fraction is 80%) are dissolved in 50g deionized water, refluxed at 80°C for 20h, placed in a 100°C, -0.09MPa vacuum drying oven for 20h, and then placed in a 500°C muffle furnace for calcination for 1h. After cooling, the solid product is ground into powder and sieved to 80-100 mesh to obtain a pretreated product.

[0123] 1 g of the pretreated product was added to 13 g of 4-methylbenzenesulfonic acid and sulfonated at 90°C for 20 h. After cooling, the sulfonated product was added to deionized water, stirred and filtered. The filter cake was repeatedly washed with deionized water until the filtrate was neutral. The filter cake was placed in a vacuum drying oven at 100°C and -0.09 MPa and dried for 24 h to obtain a bifunctional solid acid catalyst.

[0124] Comparative Example 4

[0125] This comparative example provides a bifunctional solid acid catalyst and a low molecular weight hydrogen-containing silicone oil, which differs from Example 1 in that the biomass raw materials in the preparation process of the bifunctional solid acid catalyst are not within the range, and specifically include:

[0126] 10g starch, 6g Al(NO3)3·9H2O and 3.5g phosphoric acid aqueous solution (phosphoric acid mass fraction is 80%) are dissolved in 50g deionized water, refluxed at 80°C for 20h, placed in a 100°C, -0.09MPa vacuum drying oven for 20h, and then placed in a 500°C muffle furnace for calcination for 1h. After cooling, the solid product is ground into powder and sieved to 80-100 mesh to obtain a pretreated product.

[0127] 1 g of the pretreated product was added to 13 g of 4-methylbenzenesulfonic acid and sulfonated at 90°C for 20 h. After cooling, the sulfonated product was added to deionized water, stirred and filtered. The filter cake was repeatedly washed with deionized water until the filtrate was neutral. The filter cake was placed in a vacuum drying oven at 100°C and -0.09 MPa and dried for 24 h to obtain a bifunctional solid acid catalyst.

[0128] Comparative Example 5

[0129] This comparative example provides a bifunctional solid acid catalyst and a low molecular weight hydrogen-containing silicone oil, which differs from Example 1 in that the mass ratio of the pretreated product to 4-methylbenzenesulfonic acid in the preparation process of the bifunctional solid acid catalyst is not within the range, specifically including:

[0130] 10g sucrose, 6g Al(NO3)3·9H2O and 3.5g phosphoric acid aqueous solution (phosphoric acid mass fraction is 80%) are dissolved in 50g deionized water, refluxed at 80°C for 20h, placed in a 100°C, -0.09MPa vacuum drying oven for 20h, and then placed in a 500°C muffle furnace for calcination for 1h. After cooling, the solid product is ground into powder and sieved to 80-100 mesh to obtain a pretreated product.

[0131] 1 g of the pretreated product was added to 5 g of 4-methylbenzenesulfonic acid and sulfonated at 90°C for 20 h. After cooling, the sulfonated product was added to deionized water, stirred and filtered. The filter cake was repeatedly washed with deionized water until the filtrate was neutral. The filter cake was placed in a vacuum drying oven at 100°C and -0.09 MPa and dried for 24 h to obtain a bifunctional solid acid catalyst.

[0132] Comparative Example 6

[0133] This comparative example provides a bifunctional solid acid catalyst and a low molecular weight hydrogenated silicone oil, which differs from Example 1 in that the sulfonation treatment temperature during the preparation of the bifunctional solid acid catalyst is not within the range, specifically including:

[0134] 10g sucrose, 6g Al(NO3)3·9H2O and 3.5g phosphoric acid aqueous solution (phosphoric acid mass fraction is 80%) are dissolved in 50g deionized water, refluxed at 80°C for 20h, placed in a 100°C, -0.09MPa vacuum drying oven for 20h, and then placed in a 500°C muffle furnace for calcination for 1h. After cooling, the solid product is ground into powder and sieved to 80-100 mesh to obtain a pretreated product.

[0135] 1 g of the pretreated product was added to 13 g of 4-methylbenzenesulfonic acid and sulfonated at 50°C for 20 h. After cooling, the sulfonated product was added to deionized water, stirred and filtered. The filter cake was repeatedly washed with deionized water until the filtrate was neutral. The filter cake was placed in a vacuum drying oven at 100°C and -0.09 MPa and dried for 24 h to obtain a bifunctional solid acid catalyst.

[0136] Comparative Example 7

[0137] This comparative example provides a bifunctional solid acid catalyst and a low molecular weight hydrogen-containing silicone oil, which differs from Example 1 in that the carrier of the bifunctional solid acid catalyst is changed from the pretreated product to γ-Al2O3, specifically comprising:

[0138] 1 g of γ-Al2O3 was added to 13 g of 4-methylbenzenesulfonic acid, and the mixture was sulfonated at 90°C for 20 h. After cooling, the sulfonated product was added to deionized water, stirred, and filtered. The filter cake was repeatedly washed with deionized water until the filtrate was neutral. The filter cake was placed in a vacuum drying oven at 100°C and -0.09 MPa and dried for 24 h to obtain a bifunctional solid acid catalyst.

[0139] Comparative Example 8

[0140] This comparative example provides a low molecular weight hydrogen-containing silicone oil, which differs from Example 1 in that the bifunctional solid acid catalyst in the preparation of the low molecular weight hydrogen-containing silicone oil is replaced with acidic clay, specifically comprising:

[0141] The preparation of low molecular weight hydrogenated silicone oil comprises the following steps: 65g high hydrogenated silicone oil (m=50) and 100g hexamethyldisiloxane are reacted at 50°C for 3 hours, the amount of acidic clay catalyst used is 0.5% of the total weight of the raw materials, and after the reaction is completed, the catalyst is removed by filtration to obtain a low molecular weight hydrogenated silicone oil crude product. Low boiling point substances below 160°C in the crude product are first removed by atmospheric distillation, and then the fraction of 177-180°C is collected by atmospheric distillation to obtain 1,1,1,3,5,7,7,7-octamethyltetrasiloxane.

[0142] Test Example 1

[0143] In this test example, the purity X of 1,1,1,3,5,7,7,7-octamethyltetrasiloxane in the distillation fractions of Examples 1-6 and Comparative Examples 1-8 was tested by an Agilent 7820A gas chromatograph, and the yield Y of 1,1,1,3,5,7,7,7-octamethyltetrasiloxane was calculated according to the formula: yield Y = (fraction mass × purity X / total raw material mass) × 100%. The relevant data are shown in Table 1.

[0144] Table 1 Gas chromatography test data results

[0145] X / ％ Y / ％ Remark Example 1 99.2 26.1 Example 2 98.9 24.6 Example 3 98.6 23.9 Example 4 99.4 25.4 Example 5 98.8 25.1 Example 6 99.1 24.4 Comparative Example 1 92.4 16.4 No metal nitrate is added during the preparation of bifunctional solid acid catalyst Comparative Example 2 91.3 14.7 No phosphoric acid aqueous solution is added during the preparation of the bifunctional solid acid catalyst Comparative Example 3 83.5 8.8 Nitrate type not in the range Comparative Example 4 89.8 11.4 Biomass raw materials are not included in the scope Comparative Example 5 91.9 16.1 The mass ratio of the pretreated product to 4-methylbenzenesulfonic acid is not within the range Comparative Example 6 90.8 13.6 The sulfonation temperature is not within the stated range. Comparative Example 7 90.3 11.9 <![CDATA[The support of the bifunctional solid acid catalyst is changed from the said pretreated product to γ-Al2O3]]> Comparative Example 8 88.4 10.3 The bifunctional solid acid catalyst was replaced with acid clay

[0146] As can be seen from Table 1, in Examples 1-6 provided in the embodiments of the present invention, when the preparation method of the bifunctional solid acid catalyst and the low molecular weight hydrogen-containing silicone oil is within the range provided in the embodiments of the present invention, the purity and yield of the obtained 1,1,1,3,5,7,7,7-octamethyltetrasiloxane are relatively high.

[0147] Comparative Examples 1-2 do not add metal nitrate and phosphoric acid aqueous solution during the preparation of the bifunctional solid acid catalyst. The results show that the purity and yield of the prepared 1,1,1,3,5,7,7,7-octamethyltetrasiloxane are reduced.

[0148] In Comparative Examples 3-4, the metal nitrate type and the biomass raw material were not within the range during the preparation of the bifunctional solid acid catalyst. The results showed that the purity and yield of the prepared 1,1,1,3,5,7,7,7-octamethyltetrasiloxane were reduced.

[0149] In Comparative Examples 5-6, the mass ratio of the pretreated product in Example 1 to 4-methylbenzenesulfonic acid was increased and the sulfonation treatment temperature was decreased. The results showed that the yield of the obtained 1,1,1,3,5,7,7,7-octamethyltetrasiloxane was reduced.

[0150] In Comparative Example 7, the bifunctional solid acid catalyst carrier in Example 1 was changed from the pretreated product to γ-Al2O3. The results showed that the yield of the prepared 1,1,1,3,5,7,7,7-octamethyltetrasiloxane was reduced.

[0151] In Comparative Example 8, the bifunctional solid acid catalyst used in the preparation of the low molecular weight hydrogenated silicone oil in Example 1 was replaced with acidic clay. The results showed that the yield of the prepared 1,1,1,3,5,7,7,7-octamethyltetrasiloxane was reduced.

[0152] In summary, the present invention provides a bifunctional solid acid catalyst and a preparation method and application thereof. The bifunctional solid acid catalyst provided has high catalytic activity and an environmentally friendly preparation process. The bifunctional solid acid catalyst is applied to the production of low molecular weight hydrogenated silicone oil to obtain a high purity and yield of the low molecular weight hydrogenated silicone oil. In addition, the low boiling point byproducts produced by the preparation process have a high added value.

[0153] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a bifunctional solid acid catalyst, characterized in that: include: The biomass raw material, the metal nitrate and the phosphoric acid aqueous solution are mixed and pretreated to obtain a pretreated product, and the pretreated product is sulfonated to obtain a sulfonated product; The pretreatment comprises: mixing and reacting the raw materials, followed by drying and roasting.

2. The preparation method according to claim 1, characterized in that: The biomass raw material, the metal nitrate, a phosphoric acid aqueous solution with a mass fraction of 80%-85% and water are mixed for pretreatment, and the mass ratio of the biomass raw material, the metal nitrate, the phosphoric acid aqueous solution and water is controlled to be (2-3): (1-2): 1: (10-15).

3. The preparation method according to claim 1 or 2, characterized in that: The biomass raw material is selected from at least one of sucrose, sucralose and lignin.

4. The preparation method according to claim 1 or 2, characterized in that: The metal nitrate is selected from at least one of Al(NO3)3·9H2O, Zn(NO3)2·6H2O and Ni(NO3)2 6H2O; Preferably, in the metal nitrate, the mass ratio of Al(NO3)39H2O, Zn(NO3)2·6H2O and Ni(NO3)2·6H2O is 1:(0-0.50):(0-0.25).

5. The preparation method according to claim 1, characterized in that: The sulfonation treatment process comprises: mixing the pre-treated product and a sulfonating agent for reaction; Wherein, the mass ratio of the pretreatment product to the sulfonating agent is 1:(10-15); Preferably, the sulfonating agent is selected from at least one of 3-methylbenzenesulfonic acid and 4-methylbenzenesulfonic acid; Preferably, the reaction temperature of the sulfonation treatment is 70°C-100°C, and the reaction time is 18h-24h.

6. The preparation method according to claim 5, characterized in that: Also includes: post-treating the sulfonated product; Preferably, the process of post-treating the sulfonated product comprises: after the reaction between the pre-treated product and the sulfonating agent is completed and cooled, mixing the sulfonated product with water for solid-liquid separation, washing the obtained solid material with water until it is neutral, and then drying it; Preferably, the drying treatment in the post-treatment of the sulfonated product is carried out by vacuum drying, with the drying temperature controlled to be 100° C.-110° C., the pressure to be -0.09 MPa to -0.10 MPa, and the drying time to be 18 h to 24 h.

7. The preparation method according to claim 1, characterized in that: The pretreatment comprises: mixing the biomass raw material, the metal nitrate, the phosphoric acid aqueous solution and water, performing a constant temperature reflux reaction, and then drying and roasting; controlling the reflux temperature to be 80° C.-100° C. and the reflux time to be 18h-24h; Preferably, the pretreatment further comprises: cooling the calcined product, grinding it into powder, and sieving it to 80-100 mesh; Preferably, the calcination temperature in the pretreatment process is 400°C-500°C, and the calcination time is 1h-2h; Preferably, the drying treatment in the pretreatment process adopts a vacuum drying method, and the drying temperature is controlled to be 100° C.-110° C., the pressure is -0.09 MPa to -0.10 MPa, and the drying time is 18h-24h.

8. A bifunctional solid acid catalyst, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the bifunctional solid acid catalyst according to claim 8 in the preparation of low molecular weight hydrogen-containing silicone oil.

10. The use according to claim 9, characterized in that: The low molecular weight hydrogen-containing silicone oil is 1,1,1,3,5,7,7,7-octamethyltetrasiloxane, and its structural formula is: Preferably, the process of preparing low molecular weight hydrogenated silicone oil using a bifunctional solid acid catalyst comprises: mixing high hydrogenated silicone oil, hexamethyldisiloxane and the bifunctional solid acid catalyst for reaction; wherein the structural formula of the high hydrogenated silicone oil is: Wherein, m = 30-50; Preferably, the mass ratio of the high hydrogen silicone oil to hexamethyldisiloxane is (0.4-1.95):1; The dosage of the bifunctional solid acid catalyst is 0.3%-0.6% of the total weight of the high hydrogen silicone oil and hexamethyldisiloxane; Preferably, the temperature of the mixed reaction is 40°C-70°C, and the time is 2h-4h; Preferably, after the mixing reaction is completed, the reaction product is subjected to impurity removal and distillation, and the fractions are collected to obtain low molecular weight hydrogen-containing silicone oil.

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