A Si-Ga nanomaterial catalyst and its preparation method and application

Abstract

The present invention provides a Si-Ga nanomaterial catalyst and its preparation method and application, which belongs to the field of catalyst technology, comprising the following steps: stirring after mixing a tetraethyl orthosilicate solution with a structure directing agent (DMF), subsequently adding a gallium nitrate solution and continuing to stir, then continuing to add a rare earth compound solution and an ethylene glycol solution and continuing to stir the reaction, calcining after freeze-drying, and obtaining the Si-Ga nanomaterial catalyst. The present invention also discloses the Si-Ga nanomaterial catalyst prepared by the above-mentioned preparation method and its application in the catalytic synthesis of tert-dodecyl mercaptan. The catalyst provided by the present invention can make the reaction react in a wider reaction temperature (60°C to 200°C) window and under low pressure, and the tert-dodecyl mercaptan yield is greater than 85%, and the stability is not less than 800h, which is suitable for industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and in particular relates to a Si-Ga nanomaterial catalyst and a preparation method and application thereof. Background Art

[0002] Tert-dodecyl mercaptan is an extremely important chemical intermediate used as a polymerization regulator for polymer materials such as synthetic rubber and fibers. Currently, commercial tert-dodecyl mercaptan is synthesized by reacting C12 olefins with hydrogen sulfide. C12 olefins are composed of tetrapropylene and its isomer, triisobutylene. Tetrapropylene and triisobutylene exhibit different molecular diffusion patterns and reaction mechanisms when reacting with hydrogen sulfide to produce TDM. Tetrapropylene, as a linear olefin, is more susceptible to cleavage of carbon-carbon double bonds and reaction with the thiol groups in hydrogen sulfide, resulting in fewer side reactions and high conversion and selectivity. This has been extensively studied, as shown in US Pat. No. 4,565,893 and US Pat. No. 4,102,931. However, due to the presence of two side chains in its molecular structure, triisobutylene is commonly used in the synthesis of TDM using commercial catalysts. This has severely hampered the industrialization of TDM production using triisobutylene as a raw material. Currently, the production of triisobutylene in the chemical industry is increasing, and with the promotion of ethanol gasoline, isobutylene is no longer suitable for gasoline blending. In addition, the reaction of trimerized isobutylene with hydrogen sulfide is an exothermic reaction, which releases a large amount of heat during the rapid reaction, causing the reaction temperature to rise. However, the traditional reported reaction, especially the zeolite catalyst, is very sensitive to temperature (the optimal temperature is 80°C). Once the temperature exceeds the reaction temperature, the conversion rate drops sharply (see Comparative Examples 7 and Figure 6 Therefore, broadening the reaction temperature window, especially the catalyst applicable window, has important practical application value for the synthesis of TDM.

[0003] Therefore, how to broaden the sources of raw materials for preparing tert-dodecyl mercaptan is a technical problem that those skilled in the art urgently need to solve. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention proposes a Si-Ga nanomaterial catalyst and a preparation method and application thereof.

[0005] To achieve the above objectives, the present invention provides the following technical solutions:

[0006] A method for preparing a Si-Ga nanomaterial catalyst comprises the following steps:

[0007] The ethyl orthosilicate solution and the dual-structure directing agent are mixed and stirred, and then the gallium nitrate solution is added and stirred continuously, and then the rare earth compound is added and stirred continuously for reaction, and the mixture is freeze-dried and calcined to obtain the Si-Ga nanomaterial catalyst.

[0008] Preferably, the dual-structure directing agent is ethylene glycol solution (EG solution) and DMF (N,N-dimethylformamide), and the volume ratio of ethylene glycol to DMF is 1: (10-20);

[0009] The volume concentration of the ethyl orthosilicate solution is 99.5%;

[0010] The concentration of the gallium nitrate solution is 0.05 g / mL.

[0011] Preferably, the stirring temperature is room temperature and the time is 1 h;

[0012] The stirring temperature is 60°C and the stirring time is 3 hours;

[0013] The stirring reaction was carried out at a temperature of 0-10°C and for 12 hours.

[0014] Preferably, the ratio of the added amounts of ethyl orthosilicate, DMF and gallium nitrate is 14.5 mL: (0.5-1) mL: (0.8-3.4) g.

[0015] Preferably, the rare earth compound includes cerium nitrate hexahydrate and / or lanthanum nitrate hexahydrate, and the added amount of the rare earth element is 0.1-1% of the total molar mass of Si and Ga.

[0016] Beneficial effect: At the above addition amount, the unit point La can be inserted into the unsaturated Ga site, further regulating the local microenvironment of the Ga site.

[0017] Preferably, the mass concentration of the ethylene glycol solution is 99.5%, and the added amount is 2-4 times the volume of ethyl orthosilicate.

[0018] Beneficial effects: DMF and ethylene glycol dual structure directing agents. The possible principle of dual structure directing agents is that in the dual structure directing agent system of DMF and ethylene glycol, ethylene glycol can act as a structure directing agent to induce orderly arrangement of TEOS.

[0019] Preferably, the calcination temperature is 580° C. and the calcination time is 5 hours.

[0020] Beneficial effects: The catalyst provided by the present invention is a new mesoporous Si-Ga material regulated by a unit-point rare earth (La\Ce) with a tetrahedral structure. During the preparation process, DMF is used as a structure-directing agent, tetraethyl orthosilicate (TEOS) and gallium nitrate (Ga(NO3)2) are used as silicon sources and gallium sources, and a small amount of lanthanum nitrate hexahydrate (La(NO3)2·6H2O) or cerium nitrate hexahydrate (Ce(NO3)2·6H2O) is used as a rare earth element for unit-point regulation.

[0021] A Si-Ga nanomaterial catalyst is prepared by a method for preparing the Si-Ga nanomaterial catalyst.

[0022] Preferably, the molar ratio of Si to Ga is 5-20.

[0023] More preferably, the molar ratio of Si to Ga is 8-10.

[0024] The invention discloses an application of a Si-Ga nanomaterial catalyst in the catalytic synthesis of tert-dodecyl mercaptan.

[0025] Preferably, the catalytic synthesis of tert-dodecyl mercaptan specifically comprises the following steps:

[0026] The Si-Ga nanomaterial catalyst was added to the reactor, the pressure was adjusted to 1.0 MPa, and then hydrogen sulfide and tripolyisobutylene were simultaneously introduced into the reactor for reaction, wherein the molar ratio of hydrogen sulfide to olefin was 3:1 and the space velocity was 0.6 h -1 , the reaction temperature of the test is 40-300℃.

[0027] Beneficial effects: The new mesoporous Si-Ga material regulated by single-point rare earth (La\Ce) in a tetrahedral structure provided by the present invention is mainly used in the directional synthesis of tert-dodecyl mercaptan by the addition of triisobutylene to hydrogen sulfide. It mainly increases and stabilizes the number of B acids at the active sites and inhibits carbon and sulfur deposition on the catalyst during the reaction, thereby effectively improving the single-pass conversion rate and stability of the reaction.

[0028] Compared with the prior art, the present invention has the following advantages and technical effects:

[0029] 1. The catalyst prepared by the method of the present invention greatly improves the activity in the process of synthesizing tert-dodecyl mercaptan by reacting trimerized isobutylene as a raw material with hydrogen sulfide, overcoming the problems of low conversion rate, poor selectivity for tert-dodecyl mercaptan and easy deactivation of the commercial catalyst in the process of synthesizing tert-dodecyl mercaptan by reacting trimerized isobutylene as a raw material with hydrogen sulfide. Compared with the commercial Amberlyst-15 resin catalyst (the optimal conversion rate of triisobutylene is not higher than 45%, and the selectivity for tert-dodecyl mercaptan is not higher than 85%), the catalyst obtained by the present invention can enable the reaction to proceed at a mild reaction temperature (80°C to 200°C) and low pressure. The yield of tert-dodecyl mercaptan obtained is greater than 85%, the selectivity for tert-dodecyl mercaptan is greater than 98%, and the stability is not less than 800 hours, making it suitable for industrial production.

[0030] 2. The catalyst provided by the present invention greatly improves the problem of poor stability in the process of synthesizing tert-dodecyl mercaptan by reacting trimerized isobutylene as a raw material with hydrogen sulfide. Compared with the commercial Amberlyst-15 resin catalyst (after 120 hours, the conversion rate of triisobutylene gradually decreases and drops to below 20% after 180 hours), the catalyst obtained by the present invention still maintains a conversion rate of triisobutylene above 80% after 800 hours of reaction.

[0031] 3. The preparation method provided by the present invention has a simple synthesis process, a high catalyst yield, and the obtained catalyst has a special morphology, a quadrangular pyramid structure composed of nano-Si-Ga microstructures, which significantly exposes the catalytic sites of the catalyst.

[0032] 4. The catalyst provided by the present invention is regulated by the unit-site rare earth La (Ce) element and has good resistance to carbon deposition and sulfur deposition. At the same time, compared with the traditional Si-Ga catalyst, the Ga ions in the Si-Ga catalyst synthesized by this method are not easily lost, and the active sites required for catalyzing the reaction are stabilized, thereby having higher catalytic stability.

[0033] 5. Compared with the traditional hydrothermal autoclave synthesis, the method provided by the present invention produces less three wastes during the synthesis of the catalyst and can be produced on a large scale. At the same time, the catalyst regeneration is simple, and only requires air calcination at 550°C for 5 hours, which is suitable for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. In the accompanying drawings:

[0035] Figure 1 This is a SEM scanning photograph of the 0.5Ce / Si-Ga-10 catalyst obtained in Example 1 of the present invention;

[0036] Figure 2 The effect of reaction temperature on the performance of synthesizing tert-dodecyl mercaptan over the 0.5La / Si-Ga-10 catalyst obtained in Example 1;

[0037] Figure 3 The stability results of the synthesis of tert-dodecyl mercaptan over the catalysts of Example 1 and Comparative Example 20.5 are shown;

[0038] Figure 4 The effect of reaction temperature on the performance of synthesizing tert-dodecyl mercaptan over the 0.5Ce / Si-Ga-10 catalyst obtained in Example 3;

[0039] Figure 5The effect of reaction temperature on the performance of synthesizing tert-dodecyl mercaptan on the 0.5La / Si-Ga-10-C catalyst obtained in Comparative Example 4;

[0040] Figure 6 The effect of reaction temperature on the performance of synthesizing tert-dodecyl mercaptan on the Zeolite catalyst obtained in Comparative Example 7 is shown. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0042] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] 1. Sources of some raw materials:

[0044] Tripolyisobutylene was purchased from Aladdin with a purity greater than 96%;

[0045] Hydrogen sulfide was purchased from Dalian Date Gas Co., Ltd. with a purity greater than 99%;

[0046] High-purity nitrogen, argon, and helium were purchased from Kunming Guangruida Gas Co., Ltd., with purities greater than 99.99%.

[0047] The DMF in the examples of the present invention was purchased from Aladdin. The other raw materials in the examples of the present invention were purchased from Shanghai Macklin Co., Ltd.

[0048] 2. Analysis methods:

[0049] instrument Manufacturer Analytical methods Gas chromatography Zhejiang Fuli Normalization method

[0050] Gas chromatography analysis method: column temperature 50°C, maintain for 5 min, increase to 220°C at 10°C / min; detection by FID detector, injection volume 0.5 μL.

[0051] The present invention is further described in detail below with reference to specific examples. A series of catalysts prepared in the examples of the present invention are named xLa / Si-Ga-y (x represents the amount of rare earth element Ce added, and y represents the molar ratio of Si to Ga).

[0052] Example 1

[0053] A method for preparing a Si-Ga nanomaterial catalyst comprises the following steps:

[0054] (1) Dissolve 14.5 mL of ethyl orthosilicate in 50 mL of deionized water and ultrasonicate for 10 min to obtain a ethyl orthosilicate solution;

[0055] (2) Dissolve 1.6 g of gallium nitrate in 10 mL of deionized water and sonicate for 10 min to obtain a gallium nitrate solution;

[0056] (3) Add 1 mL of DMF to 72 mL of deionized water to obtain a diluted DMF solution;

[0057] (4) Add the ethyl orthosilicate solution dropwise to the DMF solution, stir at room temperature for 1 h, then quickly pour in the gallium nitrate solution to obtain a sol-like substance, and stir at 60 ° C for 3 h;

[0058] (5) After stirring for 2 hours in step (4), lanthanum nitrate hexahydrate aqueous solution (the ratio of lanthanum nitrate hexahydrate aqueous solution is 0.043 g dissolved in 5 mL of water) and 30 mL of ethylene glycol solution (99.5% concentration) are added dropwise. After stirring evenly, stirring vigorously at 0-10°C for 12 hours, and then freeze-dried to obtain a solid powder. The muffle furnace is heated to 580°C at a heating rate of 2°C / min, and the solid powder is then placed in a muffle furnace and calcined at 580°C for 5 hours. The obtained powder material is recorded as 0.5La / Si-Ga-10.

[0059] The SEM image of the 0.5La / Si-Ga-10 catalyst after synthesis is shown in Figure 2. Figure 1 As shown in the figure, the obtained catalyst presents a regular tetrahedral structure. And the enlarged image shows that the regular tetrahedral pyramid is composed of Si-Ga nanoparticles, which can better expose the active sites.

[0060] The catalyst obtained in this embodiment is applied to the synthesis reaction of tert-dodecyl mercaptan, and the specific reaction conditions are as follows:

[0061] 30 mL of the above catalyst was placed in a 316 stainless steel reactor with an inner diameter of 16 mm and a length of 354 mm. The pressure was adjusted to 1.0 MPa. Hydrogen sulfide and tripolyisobutylene were then introduced into the reactor simultaneously for reaction. The molar ratio of hydrogen sulfide to olefin was 3:1, and the space velocity was 0.6 h / min. -1 The reaction temperature is in the range of 40-300 degrees and stabilized at 120°C.

[0062] The final activity results are as follows Figure 2As shown, the conversion rate initially increases with increasing temperature, then reaches over 90% between 80°C and 200°C, then gradually decreases with further temperature increases. A wide temperature window of 80°C to 200°C is maintained. Stable 0.5Ce / Si-Ga-10 achieves an initial TIB conversion of 93% and a TDM selectivity of >99% at 120°C. After 500 hours of continuous operation, the conversion rate reaches 90% and the selectivity reaches 100%. After 800 hours of continuous operation, the conversion rate reaches 86% and the selectivity reaches 100%.

[0063] Comparative Example 1

[0064] A method for preparing a Si-Ga nanomaterial catalyst is different from that of Example 1 in that in step (2), 0.25 g of gallium nitrate is added to 10 mL of deionized water to prepare a gallium nitrate solution, and the resulting catalyst is recorded as 0.5Ce / Si-Ga-5.

[0065] Comparative Example 2

[0066] A method for preparing a Si-Ga nanomaterial catalyst is different from that of Example 1 in that in step (2), 1 g of gallium nitrate is added to 10 mL of deionized water to prepare a gallium nitrate solution, and the resulting catalyst is recorded as 0.5Ce / Si-Ga-20.

[0067] The catalyst obtained in Comparative Example 1-2 was applied to the synthesis reaction of tert-dodecyl mercaptan, and the steps were the same as in Example 1. The results were as follows: Figure 3 As shown, it was finally found that the stability of 0.5La / Si-Ga-5 and 0.5La / Si-Ga-20 catalysts was poor.

[0068] Example 2

[0069] A method for preparing a Si-Ga nanomaterial catalyst comprises the following steps:

[0070] (1) Dissolve 14.5 mL of ethyl orthosilicate in 50 mL of deionized water and ultrasonicate for 10 min to obtain a ethyl orthosilicate solution;

[0071] (2) Dissolve 1.6 g of gallium nitrate in 10 mL of deionized water and sonicate for 10 min to obtain a gallium nitrate solution;

[0072] (3) Add 1 mL of DMF to 72 mL of deionized water to obtain a diluted DMF solution;

[0073] (4) Add the ethyl orthosilicate solution dropwise to the DMF solution, stir at room temperature for 1 h, then quickly pour in the gallium nitrate solution to obtain a sol-like substance, and stir at 60 ° C for 3 h;

[0074] (5) After stirring for 2 h in step (4), lanthanum nitrate hexahydrate aqueous solution (the ratio of lanthanum nitrate hexahydrate aqueous solution is 0.086 g dissolved in 5 mL of water) and 30 mL of ethylene glycol solution (99.5% concentration) are added dropwise. After stirring evenly, stirring vigorously at 0-10 ° C for 12 h, and then freeze-dried to obtain a solid powder. The muffle furnace is heated to 580 ° C at a heating rate of 2 ° C / min, and then the solid powder is placed in a muffle furnace and calcined at 580 ° C for 5 h. The obtained powder material is recorded as 0.5La / Si-Ga-10.

[0075] Comparative Example 3

[0076] A method for preparing a Si-Ga nanomaterial catalyst is different from that of Example 1 in that no cerium nitrate hexahydrate aqueous solution is added in step (5). The obtained catalyst is recorded as Si-Ga-10.

[0077] The catalysts obtained in Examples 1-2 and Comparative Example 3 were applied to the synthesis reaction of tert-dodecyl mercaptan, and the specific reaction conditions were as follows:

[0078] 30 mL of the above catalyst was placed in a 316 stainless steel reactor with an inner diameter of 16 mm and a length of 354 mm. The pressure was 1.0 MPa. Hydrogen sulfide and tripolyisobutylene were simultaneously introduced into the reactor for reaction. The molar ratio of hydrogen sulfide to olefin was 3:1, and the space velocity was 0.6 h / min. -1 , the reaction temperature is 90℃.

[0079] The results show that the addition of single-site rare earth elements effectively improves the catalyst's resistance to carbon and sulfur deposition. The activity of the 0.5Ce / Si-Ga-10 catalyst with 0.5% Ce addition remained unchanged, with the conversion of dodecene remaining at 86% after 800 hours of stable operation, showing almost no loss. However, the activity of the Si-Ga-10 catalyst without Ce addition gradually decreased during stable operation, dropping from an initial 84% to 33% after 800 hours of operation. The stability of the 1Ce / Si-Ga-10 catalyst with 1% Ce addition was significantly improved compared to the Si-Ga-10 without Ce addition, but the activity decreased slightly, likely due to the excessive Ce addition covering some active sites.

[0080] Example 3

[0081] A method for preparing a Si-Ga nanomaterial catalyst is different from that of Example 1 in that the lanthanum nitrate hexahydrate solution in step (5) is replaced by an equal amount of cerium nitrate hexahydrate solution of equal concentration, and the obtained catalyst is recorded as 0.5Ce / Si-Ga-10.

[0082] The catalyst obtained in Example 3 was applied to the synthesis reaction of tert-dodecyl mercaptan, and the specific steps and parameters were the same as in Example 1. The results are as follows: Figure 4 As shown, it can be seen that the conversion rate of trimerized isobutylene and the selectivity of the target product tert-dodecyl mercaptan over the 0.5Ce / Si-Ga-10 catalyst in the temperature range of 80-200°C are both higher than 90%.

[0083] Comparative Example 4

[0084] A method for preparing a Si-Ga nanomaterial catalyst is different from Example 1 in that the dual-structure directing agent DMF and ethylene glycol solution are not added in steps (3) and (5), and the obtained catalyst is recorded as 0.5Ce / Si-Ga-10-C catalyst.

[0085] The catalyst obtained in Comparative Example 4 was applied to the synthesis reaction of tert-dodecyl mercaptan, and the specific steps and parameters were the same as those in Example 1. The results are as follows: Figure 5 As shown in the figure, it can be seen that the conversion of trimerized isobutylene and the selectivity of the target product tert-dodecyl mercaptan over the 0.5Ce / Si-Ga-10-C catalyst are both above 90% only in the temperature range of 100-120°C. Once the temperature is below 100°C or above 120°C, the conversion of trimerized isobutylene decreases significantly.

[0086] Comparative Example 5

[0087] The commercial catalyst Amberlyst-15 resin catalyst was used in the synthesis reaction of tert-dodecyl mercaptan. The specific reaction conditions are as follows:

[0088] A 316 stainless steel reactor with an inner diameter of 16 mm and a length of 354 mm was charged with 30 mL of Amberlyst-15 resin catalyst at a pressure of 1.0 MPa. Hydrogen sulfide and tripolyisobutylene were simultaneously introduced into the reactor for reaction at a molar ratio of hydrogen sulfide to olefin of 3:1 and a space velocity of 0.6 h / min. -1 , change the reaction temperature to 100 degrees.

[0089] The results showed that using triisobutylene as raw material and commercial Amberlyst-15 catalyst, the initial TIB conversion was 52% and the TDM selectivity was 63%. After 168 hours of continuous operation, the TIB conversion decreased to 11% and the TDM selectivity was 91%.

[0090] Comparative Example 6

[0091] The catalyst obtained in US Pat. No. 4,565,893 was used in the synthesis of tert-dodecyl mercaptan under the same reaction conditions as in Example 5. The results showed that the conversion rate was low.

[0092] Comparative Example 7

[0093] The catalyst obtained in US4102931 was used in the synthesis reaction of tert-dodecyl mercaptan, and the specific reaction conditions were the same as in Example 1 to obtain Zeolite catalyst. Figure 6 As shown, it can be seen that the zeolite catalyst is very sensitive to temperature (the optimal temperature is 80°C). Once the temperature is higher than the reaction temperature, the conversion rate drops sharply.

[0094] The above are merely preferred embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. An application of a Si-Ga nanomaterial catalyst in the catalytic synthesis of tert-dodecyl mercaptan, characterized in that: The preparation method of the Si-Ga nanomaterial catalyst comprises the following steps: The ethyl orthosilicate solution was added dropwise to the DMF solution and stirred at room temperature for 1 h. Then, the gallium nitrate solution was quickly poured into the obtained sol-like substance and stirred at 60 °C for 3 h. After stirring the above system for 2 hours, the aqueous solution of the rare earth compound and 30 mL of ethylene glycol solution were added dropwise, and after stirring evenly, the mixture was vigorously stirred at 0-10° C. for 12 hours, and then freeze-dried and calcined to obtain the Si-Ga nanomaterial catalyst; The rare earth compound is cerium nitrate hexahydrate or lanthanum nitrate hexahydrate.

2. The use according to claim 1, characterized in that The ratio of the added amounts of ethyl orthosilicate, DMF and gallium nitrate is 14.5 mL: (0.5-1) mL: (0.8-3.4) g.

3. The use according to claim 1, characterized in that The added amount of the ethylene glycol solution is 2-4 times the volume of the ethyl orthosilicate.

4. The use according to claim 1, characterized in that The calcination temperature is 580° C. and the calcination time is 5 h.

5. The use according to claim 1, characterized in that The molar ratio of Si to Ga in the Si-Ga nanomaterial catalyst is 5-20.

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