WO2024221827A1

WO2024221827A1 - Titanium silicalite molecular sieve catalyst, preparation method therefor and use thereof

Info

Publication number: WO2024221827A1
Application number: PCT/CN2023/130326
Authority: WO
Inventors: 王聪; 袁海朋; 王元平; 李�荣; 杨克俭; 杨磊; 项天宇; 王志明; 赵文平; 杨琦武; 邴威翰; 刘大李
Original assignee: 中国天辰工程有限公司
Priority date: 2023-04-27
Filing date: 2023-11-08
Publication date: 2024-10-31
Also published as: CN116440948A

Abstract

Provided are a titanium silicalite molecular sieve catalyst, a preparation method therefor and a use thereof. R₁₁₂₁/R₈₀₀ for the titanium silicalite molecular sieve catalyst is 0.1 to 4, R₁₁₂₁ being the maximum absorption peak intensity near 1121 cm^-1 in the ultraviolet-Raman spectrum of the titanium silicalite molecular sieve catalyst, and R₈₀₀ being the maximum absorption peak intensity near 800 cm^-1 in the ultraviolet-Raman spectrum of the titanium silicalite molecular sieve catalyst; and the most probable pore size of the titanium silicalite molecular sieve catalyst is 15-36 nm. The titanium silicalite molecular sieve catalyst is characterized by high framework titanium content and a suitable most probable pore size, and has high raw material conversion rate and product selectivity. The preparation method for the titanium silicalite molecular sieve catalyst comprises two hydrothermal crystallization steps; after the first hydrothermal crystallization is completed, operations such as solid-liquid separation, drying, calcination and the like do not need to be carried out on the material subjected to the first hydrothermal crystallization, which not only simplifies the technological process of preparing the titanium silicalite molecular sieve catalyst, but can also implement adjustment of the most probable pore size by means of controlling parameters.

Description

Titanium silicon molecular sieve catalyst and its preparation method and application

Technical Field

The invention relates to the technical field of molecular sieve preparation, and in particular to a titanium silicon molecular sieve catalyst and a preparation method and application thereof.

Background Art

Titanium silicate molecular sieve catalyst TS-1 is a Pentasil type heteroatom molecular sieve containing skeleton titanium atoms. In addition to maintaining the topological structure of the original MFI molecular sieve, the titanium atoms in TS-1 are evenly distributed in the skeleton to form a skeleton Si-O-Ti bond with special properties, which makes the TS-1 molecular sieve have both catalytic oxidation activity and shape-selective catalytic performance.

Since the synthesis method of TS-1 was first disclosed in 1981 (USP4410501), the hydrothermal synthesis method of TS-1 has developed into two systems. One is to use tetrapropylammonium hydroxide (TPAOH) as a template to synthesize titanium silicon molecular sieve catalyst, also known as the classic system; the other is to use low-cost tetrapropylammonium bromide as a template to synthesize TS-1, known as the cheap system; in addition, there are many methods such as isomorphous substitution. Although the synthesis methods are diverse, since the Ti-O bond in the TS-1 structure is longer than the Si-O bond, it is difficult for titanium atoms to enter the skeleton during synthesis, so TS-1 synthesized by the existing methods will produce non-framework titanium. Non-framework titanium itself does not have catalytic oxidation activity, and it will also cause a large amount of decomposition of hydrogen peroxide, thereby reducing the catalytic performance of TS-1; further considering that it is difficult to control the content of non-framework titanium during the synthesis process, this leads to poor stability and catalytic performance of titanium silicon molecular sieve catalyst products, which restricts the industrial application of TS-1. In addition, it should be noted that in order to prepare highly active titanium silicalite catalysts, the synthesized molecular sieve raw powder needs to be acid-base modified or rearranged and crystallized in industrial production. This makes the TS-1 molecular sieve preparation process longer, increases production costs, and produces a large amount of wastewater, which restricts the increase in production capacity.

Summary of the invention

In view of the deficiencies in the prior art, the present invention discloses a titanium silicate molecular sieve catalyst and a preparation method and application thereof. The titanium silicate molecular sieve catalyst has a high skeleton titanium content and a suitable most probable pore size, and the preparation process is simpler than that of the prior art. The titanium silicate molecular sieve catalyst catalyzes the propylene epoxidation to propylene oxide reaction with high raw material conversion rate and product selectivity.

In one aspect of the present invention, a titanium silicate molecular sieve catalyst is disclosed, wherein R ₁₁₂₁ /R ₈₀₀ of the titanium silicate molecular sieve catalyst is 0.1 to 4, R ₁₁₂₁ is the maximum absorption peak intensity near 1121 cm ^-1 in the ultraviolet-Raman spectrum of the titanium silicate molecular sieve catalyst, and R ₈₀₀ is the maximum absorption peak intensity near 800 cm ^-1 in the ultraviolet-Raman spectrum of the titanium silicate molecular sieve catalyst; the most probable pore size of the titanium silicate molecular sieve catalyst is 15 to 36 nm.

In the above technical scheme, the titanium silicate catalyst of the present invention has a high skeleton titanium content and a suitable most probable pore size. Combining the embodiments and comparative examples, it can be seen that the titanium silicate catalyst of the present invention is suitable for catalyzing propylene epoxidation reaction and has high raw material conversion rate and product selectivity.

Furthermore, the R ₁₁₂₁ /R ₈₀₀ of the titanium silicalite catalyst is 0.1, and the most probable pore diameter is 35.

Furthermore, the R ₁₁₂₁ /R ₈₀₀ of the titanium silicalite catalyst is 3.5, and the most probable pore diameter is 17.

Another aspect of the present invention discloses a method for preparing a titanium silicon molecular sieve catalyst, which includes two hydrothermal crystallizations; a first hydrothermal crystallization of a first silicon source and a titanium source in an aqueous solution of a first template; after the first hydrothermal crystallization is completed, a pressure relief operation is performed, and then a second silicon source, a second template and an organic amine are added to perform a second hydrothermal crystallization to obtain a secondary hydrothermal crystallization mixture.

It should be noted that the preparation process of the titanium silicon molecular sieve catalyst of the present invention is carried out in a reactor. The present invention does not limit the reactor used. The reactor used in the present invention is broadly understood as a container for physical or chemical reactions. The heating, evaporation, cooling and low-speed mixing functions required by the process are achieved through the structural design and parameter configuration of the container. Ordinary technicians in this field can select a suitable reactor through non-creative labor, and the technical solutions formed thereby are all within the scope of protection of the present invention.

In the above technical scheme, there is no need to perform solid-liquid separation, drying, calcination and other operations on the material after the first hydrothermal crystallization. The second silicon source, the second template and the organic amine can be directly added to the reactor for the second hydrothermal crystallization. This not only simplifies the process flow of titanium silicon molecular sieve catalyst preparation, but also can control the realization of the most probable pore size by controlling the parameters.

Furthermore, in the first hydrothermal crystallization, the molar ratio of Si in the first silicon source, Ti in the titanium source, the first template and water is 1: (0.01-0.5): (0.03-0.6): (1-100), and the preferred molar ratio is 1: (0.1-0.5): (0.2-0.6): (60-80).

Furthermore, in order to promote sufficient reaction, the first hydrothermal crystallization further comprises adding the first silicon source and titanium source to the aqueous solution of the template and stirring the mixture for 0.5 h to 24 h at a temperature of 0 to 60°C.

Furthermore, the temperature of the first hydrothermal crystallization is 100-300° C., and the time is 10-100 hours.

Furthermore, the gas discharged from the pressure relief operation is condensed to obtain a condensate, and the mass of the condensate accounts for 5% to 50% of the total weight of the material after the first hydrothermal crystallization is completed; preferably 10% to 49%.

In the above technical scheme, the water content in the material after the first hydrothermal crystallization is relatively large, so that the concentration of the newly added second template during the second hydrothermal crystallization is relatively low, which further leads to low reaction efficiency; moreover, the high water content also increases the time for the subsequent solid-liquid separation operation of the secondary hydrothermal crystallization mixture, and it is also easy to cause material loss. In addition, the condensate mainly includes water and substances produced by the decomposition of the first template during the first hydrothermal crystallization process; the substances produced by the decomposition of the first template not only affect the quality of the finished titanium silicon molecular sieve catalyst, but also float on the upper layer of the reaction material and adhere to the surface of the reactor during the subsequent crystallization process, affecting the crystallization efficiency and increasing the difficulty of cleaning the reactor. Therefore, the present invention sets a pressure relief operation after the first hydrothermal crystallization is completed, which is not only conducive to the subsequent second hydrothermal crystallization, reduces the difficulty of subsequent processing, but also improves the quality and overall preparation efficiency of the titanium silicon molecular sieve catalyst, and reduces the difficulty of equipment cleaning.

Furthermore, in the second hydrothermal crystallization, the molar ratio of the second silicon source, the second template, the organic amine and water is 1: (0.01-0.5): (0.03-0.6): (1-100).

Furthermore, in order to promote sufficient reaction, the second hydrothermal crystallization further includes stirring after adding the second silicon source, the second template and the organic amine, the stirring time is 0.5h to 24h, and the stirring temperature is 0 to 60°C.

Furthermore, the temperature of the second hydrothermal crystallization is 100-300° C., and the time is 10-100 h, preferably 60-100 h.

The first silicon source and the second silicon source are independently selected from one or more of inorganic silicon or organic silicone grease; the inorganic silicon includes silica sol, silicon dioxide, and white carbon black; the general formula of the organic silicone grease is Si(OR1)4, and R1 is an alkyl substituent having 1 to 6 carbon atoms.

Furthermore, the titanium source is one or more of an inorganic titanium source or an organic titanate; the inorganic titanium includes titanium tetrachloride and titanium sulfate; the general formula of the organic titanate is Ti(OR ² ) 4, wherein R ² is an alkyl substituent having 2 to 6 carbon atoms.

Further, the first template is one or more of a quaternary ammonium base or a quaternary ammonium salt; the quaternary ammonium base includes tetrapropylammonium hydroxide, tetraethylammonium hydroxide, tetramethylammonium hydroxide and tetrabutylammonium hydroxide; the quaternary ammonium salt includes tetrapropylammonium bromide, tetrapropylammonium chloride, tetraethylammonium bromide, tetraethylammonium chloride, tetrabutylammonium bromide and tetrabutylammonium chloride.

Furthermore, the second template is a quaternary ammonium salt; the quaternary ammonium salt includes one or more of tetrapropylammonium bromide, tetrapropylammonium chloride, tetraethylammonium bromide, tetraethylammonium chloride, tetrabutylammonium bromide, and tetrabutylammonium chloride.

Furthermore, the organic amine is one or more of aliphatic amine compounds, alcohol amine compounds or aromatic amine compounds; the aliphatic amine compounds include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, n-butylamine, isobutylamine, tert-butylamine, sec-butylamine, butylene diamine, diisobutylamine, pentylamine, isopentylamine, sec-pentylamine, cyclopentylamine, propylamine, dipropylamine, tripropylamine, isopropylamine and diisopropylamine; the alcohol amine compounds include monoethanolamine, diethanolamine, triethanolamine, isopropanolamine and butyldiethanolamine; the aromatic amine compounds include aniline, toluidine and phenylenediamine.

Furthermore, the above technical solution also includes performing solid-liquid separation on the secondary hydrothermal crystallization mixture to obtain a solid phase, and drying and baking the solid phase.

Furthermore, the drying is carried out at a temperature of 50 to 200°C. The present invention does not limit the drying time. A person skilled in the art can set a suitable solid phase drying time in combination with a calcination operation as needed. Under certain working conditions, no drying operation is required, and the separated solid phase can be directly calcined. The calcination is carried out at a temperature of 350 to 700°C, and the calcination time is 1 to 8 hours.

Another aspect of the present invention discloses an application of the above-mentioned titanium silicalite catalyst or the titanium silicalite catalyst prepared by the above-mentioned preparation method in a propylene epoxidation reaction; further, the propylene epoxidation reaction is a reaction of propylene epoxidation to prepare propylene oxide.

Compared with the prior art, the titanium silicalite catalyst of the present invention has a high skeleton titanium content and a suitable most probable pore size, is suitable for propylene epoxidation reaction, and has a high raw material conversion rate and product selectivity. The preparation method of the titanium silicalite catalyst of the present invention performs a pressure relief operation after the first hydrothermal crystallization is completed, and then adds the second silicon source, the second template and the organic amine directly for the second hydrothermal crystallization without the need for solid-liquid separation, drying, calcination and other operations on the material after the first hydrothermal crystallization, which not only simplifies the process flow of the titanium silicalite catalyst preparation, but also can control the realization of the most probable pore size by controlling the parameters.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

FIG1 is an electron microscope morphology image of the titanium silicon molecular sieve catalyst prepared in Example 6;

FIG2 is a UV-Raman spectrum of the titanium silicon molecular sieve catalyst prepared in Example 3;

FIG3 is a comparison diagram of the mesopore sizes of the titanium silicon molecular sieve catalysts prepared in Example 6 and Comparative Example 1.

DETAILED DESCRIPTION

In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively below, and preferred embodiments of the present invention are given. However, it should be understood that these embodiments are only used for more detailed description, and should not be understood as limiting the present invention in any form, that is, they are not intended to limit the scope of protection of the present invention. Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by technicians in the field to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods, unless otherwise specified, are all conventional methods.

It should be noted that in this embodiment, relational terms such as "first time", "second time", etc. are only used to distinguish one component with the same name from another, and do not necessarily require or imply any actual relationship or order between these components. Features defined as "first time", "second time", etc. may explicitly or implicitly include one or more of the features.

Example 1

This embodiment is carried out in a reactor and includes the following operations:

(1) Methyl orthosilicate and titanium tetrachloride are mixed and added to an aqueous solution of tetramethylammonium hydroxide, and the mixture is stirred thoroughly at 0°C for 24 hours to obtain a hydrolysis solution of a silicon source and a titanium source, wherein the molar ratio of Si, Ti, tetramethylammonium hydroxide and water is 1:0.01:0.03:1; and then the first hydrothermal crystallization is carried out at 150°C for 96 hours.

(2) After the first hydrothermal crystallization is completed, the reactor is depressurized; then silica sol, tetrapropylammonium bromide, n-butylamine and water are added and stirred at 0°C for 24 hours. The molar ratio of silica sol, tetrapropylammonium bromide, n-butylamine and water is 1:0.01:0.03:1, and the second hydrothermal crystallization is carried out at a temperature of 100°C for 100 hours to obtain a secondary hydrothermal crystallization mixture. The mass of the condensate obtained after the output gas is condensed after the pressure is released accounts for 5% of the total amount of the material after the first hydrothermal crystallization is completed.

(3) After the second hydrothermal crystallization, solid-liquid separation was performed to obtain a solid phase; the obtained solid phase was dried at 50° C., and then calcined at 700° C. for 1 h to obtain titanium silicon molecular sieve catalyst A1.

Example 2

The preparation process of the titanium silicon molecular sieve catalyst in this embodiment is the same as the steps shown in Example 1, except that:

In step (1), the first silicon source, the titanium source and the first template are respectively tetraethyl orthosilicate, titanium sulfate and tetrapropylammonium hydroxide, the stirring temperature is 60°C, and the stirring time is 0.5h; wherein the molar ratio of Si:Ti:tetrapropylammonium hydroxide:water is 1:0.5:0.6:100; the temperature of the first hydrothermal crystallization is 100°C, and the time is 100h.

In step (2), the second silicon source, the second template and the organic amine added after the pressure release are silica sol, tetrapropylammonium bromide and diethanolamine, and the stirring time is 30°C and 15h. The molar ratio of silica sol, tetrapropylammonium bromide, diethanolamine and water is 1:0.5:0.6:100. The temperature of the second hydrothermal crystallization is 300°C and the time is 10h. The mass of the condensate accounts for 50% of the total amount of the material after the first hydrothermal crystallization is completed.

In step (3), after the second hydrothermal crystallization is completed, solid-liquid separation is performed to obtain a solid phase; the obtained solid phase is dried at 200° C. and then calcined at 350° C. for 8 h to obtain titanium silicon molecular sieve catalyst A2.

Example 3

In step (1), the first silicon source, titanium source and first template are ethyl orthosilicate, titanium sulfate and tetrapropylammonium hydroxide respectively, the stirring temperature is 20°C, and the stirring time is 12 hours; wherein the molar ratio of Si, Ti, tetrapropylammonium hydroxide and water is 1:0.2:0.05:1. The temperature of the first hydrothermal crystallization is 300°C, and the time is 10 hours.

In step (2), the second silicon source, the second template and the organic amine added after the pressure release are methyl orthosilicate, tetrapropyl ammonium bromide and aniline, and the stirring time is 20°C and 12h. The molar ratio of methyl orthosilicate, tetrapropyl ammonium bromide, aniline and water is 1:0.4:0.5:80. The temperature of the second hydrothermal crystallization is 150°C and the time is 72h. The mass of the condensate accounts for 40% of the total amount of the material after the first hydrothermal crystallization is completed.

In step (3), after the second hydrothermal crystallization is completed, solid-liquid separation is performed to obtain a solid phase; the obtained solid phase is dried at 50°C, and then calcined at 700°C for 1h to obtain titanium silicon molecular sieve catalyst A3. The UV-Raman spectrum of A3 is shown in Figure 2.

Example 4

In step (1), the first silicon source, titanium source and first template are propyl orthosilicate, methyl titanate and tetrabutylammonium hydroxide respectively. The stirring temperature is 40°C and the stirring time is 24 hours. The molar ratio of Si, Ti, tetrabutylammonium hydroxide and water is 1:0.4:0.05:1. The temperature of the first hydrothermal crystallization is 100°C and the time is 72 hours.

In step (2), the second silicon source, the second template and the organic amine added after the pressure release are butyl orthosilicate, tetrapropylammonium chloride and tri-n-propylamine, and the stirring time is 60°C and 0.5h. The molar ratio of butyl orthosilicate, tetrapropylammonium chloride, tri-n-propylamine and water is 1:0.1:0.5:100. The temperature of the second hydrothermal crystallization is 170°C and the time is 100h. The mass of the condensate accounts for 5% of the total amount of the material after the first hydrothermal crystallization is completed.

In step (3), after the second hydrothermal crystallization is completed, solid-liquid separation is performed to obtain a solid phase; the obtained solid phase is dried at 50° C. and then calcined at 700° C. for 1 h to obtain titanium silicon molecular sieve catalyst A4.

Example 5

In step (1), the first silicon source, titanium source and first template are ethyl orthosilicate, butyl titanate and tetramethylammonium hydroxide respectively. The stirring temperature is 10°C and the stirring time is 12 hours. The molar ratio of Si, Ti, tetramethylammonium hydroxide and water is 1:0.5:0.6:80. The temperature of the first hydrothermal crystallization is 150°C and the time is 96 hours.

In step (2), the second silicon source, the second template and the organic amine added after the pressure release are tetraethyl orthosilicate, tetrapropyl ammonium bromide, aniline + triethylamine, and the stirring time is 40°C and 12h. The molar ratio of tetraethyl orthosilicate, tetrapropyl ammonium bromide, aniline + triethylamine and water is 1:0.5:0.6:100. The temperature of the second hydrothermal crystallization is 200°C and the time is 60h. The mass of the condensate accounts for 5% of the total amount of the material after the first hydrothermal crystallization is completed.

In step (3), after the second hydrothermal crystallization is completed, solid-liquid separation is performed to obtain a solid phase; the obtained solid phase is dried at 100° C. and then calcined at 600° C. for 4 h to obtain titanium silicon molecular sieve catalyst A5.

Example 6

In step (1), the first silicon source, the titanium source and the first template are silicon source, titanium source and tetrapropylammonium hydroxide respectively. The stirring temperature is 20°C and the stirring time is 6 hours. The molar ratio of Si, Ti, tetrapropylammonium hydroxide and water is 1:0.1:0.2:60. The temperature of the first hydrothermal crystallization is 150°C and the time is 96 hours.

In step (2), the second silicon source, the second template and the organic amine added after the pressure release are tetraethyl orthosilicate, tetrapropyl ammonium bromide, n-butylamine + triethanolamine, and the stirring time temperature is 20°C and the stirring time is 6 hours. Among them, the molar ratio of tetraethyl orthosilicate, tetrapropyl ammonium bromide, n-butylamine + triethanolamine and water is 1:0.5:0.6:100. The temperature of the second hydrothermal crystallization is 100°C and the time is 100 hours. The mass of the condensate accounts for 25% of the total amount of the material after the first hydrothermal crystallization is completed.

In step (3), after the second hydrothermal crystallization is completed, solid-liquid separation is performed to obtain a solid phase; the obtained solid phase is dried at 50°C, and then calcined at 700°C for 1h to obtain titanium silicon molecular sieve catalyst A6. The electron microscope morphology of A6 is shown in Figure 1.

Comparative Example 1

The preparation process of this comparative example is carried out in a reactor and comprises the following steps:

(1) A silicon source and a titanium source are mixed and added to an aqueous solution of tetrabutylammonium hydroxide and stirred thoroughly, wherein the molar ratio of Si:Ti:tetrapropylammonium hydroxide:water is 1:0.4:0.05:1; the mixed solution is subjected to hydrothermal crystallization in a reactor at a temperature of 100°C for 96 hours.

(2) After the crystallization, solid-liquid separation was performed to obtain a solid phase, which was then dried at 50°C and subsequently calcined at 700°C for 1 h to obtain the titanium silicate molecular sieve catalyst B1. The comparison of the mesopore sizes of A6 and B1 is shown in FIG3 .

Comparative Example 2

The preparation process of this comparative example is the same as that of comparative example 1, except that:

In step (1), the silicon source, titanium source and template are tetraethyl orthosilicate, titanium sulfate and tetrapropylammonium hydroxide, and the molar ratio of tetraethyl orthosilicate, titanium sulfate, tetrapropylammonium hydroxide and water is 1:0.5:0.6:100. The temperature of hydrothermal crystallization is 200°C and the time is 24h.

In step (2), after the crystallization is completed, solid-liquid separation is performed to obtain a solid phase, which is then dried at 200° C. and subsequently calcined at 550° C. for 8 h to obtain the titanium silicon molecular sieve catalyst B2.

Test Example 1-8

In order to further verify the catalytic performance of the titanium silicalite catalyst of the present invention, a test example of propylene epoxidation to propylene oxide was set up to evaluate the performance of the titanium silicalite catalysts prepared in Examples 1-6 and Comparative Examples 1-2.

It should be noted that before testing, the titanium silicalite catalyst needs to be pretreated, that is: the titanium silicalite catalyst prepared in Examples 1-6 or Comparative Examples 1-2, silica sol, and water are mixed in a certain proportion and kneaded, dyed red, and put into an extruder for extrusion; after extrusion, it is dried and calcined to obtain a shaped titanium silicalite catalyst.

The specific test process includes adding 20g of pre-treated titanium silicon molecular sieve catalyst into a fixed bed reactor, heating to 40-50°C and reaction pressure of 2MPaG; introducing raw materials methanol, propylene and hydrogen peroxide in a molar ratio of 9:2:1 and a mass space velocity of 0.1-1h ^-1 ; separating the product after reaction into gas and liquid, and collecting the liquid phase for chromatographic analysis.

The reaction product is titrated with hydrogen peroxide residue using the national standard method, and the conversion rate of the raw material hydrogen peroxide and the selectivity of the product propylene oxide are calculated. The specific calculation method is as follows:

Hydrogen peroxide conversion rate = (amount of hydrogen peroxide added - amount of hydrogen peroxide remaining) / amount of hydrogen peroxide added × 100%;

Propylene oxide selectivity = amount of propylene consumed for conversion into propylene oxide / amount of propylene converted × 100%.

In addition, UV-Raman spectroscopy measurements were performed on the above 8 molecular sieves, and the most probable pore size of each molecular sieve was measured using a physical adsorption instrument. The test results are shown in Table 1, Figure 2 and Figure 3.

Table 1

Table 1 shows that the titanium silicon molecular sieve catalysts shown in Examples 1-6 have suitable most probable pore sizes, and the UV-Raman spectrum test results show that R ₁₁₂₁ /R ₈₀₀ is between 0.1 and 4, reflecting a high skeleton titanium content. The test examples using the titanium silicon molecular sieve catalysts shown in Examples 1-6 have high raw material conversion rates and product selectivity.

It should be noted that the above contents are further detailed descriptions of the present invention in combination with specific implementation methods, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions; the dimensional data of this embodiment does not necessarily limit the technical solution, but only shows one of the specific working conditions. For ordinary technicians in the technical field to which the present invention belongs, several simple improvements and modifications can be made without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

A titanium silicate molecular sieve catalyst, characterized in that R 1121 /R 800 of the titanium silicate molecular sieve catalyst is 0.1-4, R 1121 is the maximum absorption peak intensity near 1121 cm -1 in the ultraviolet-Raman spectrum of the titanium silicate molecular sieve catalyst, and R 800 is the maximum absorption peak intensity near 800 cm -1 in the ultraviolet-Raman spectrum of the titanium silicate molecular sieve catalyst; the most probable pore size of the titanium silicate molecular sieve catalyst is 15-36 nm.
The titanium silicate molecular sieve catalyst according to claim 1, characterized in that R 1121 /R 800 of the titanium silicate molecular sieve catalyst is 0.1 and the most probable pore diameter is 35.
The titanium silicate molecular sieve catalyst according to claim 1, characterized in that the R 1121 /R 800 of the titanium silicate molecular sieve catalyst is 3.5 and the most probable pore diameter is 17.
A method for preparing a titanium silicon molecular sieve catalyst is characterized by comprising two hydrothermal crystallizations; a first hydrothermal crystallization is performed on a first silicon source and a titanium source in an aqueous solution of a first template; after the first hydrothermal crystallization is completed, a pressure relief operation is performed, and then a second silicon source, a second template and an organic amine are added to perform a second hydrothermal crystallization to obtain a secondary hydrothermal crystallization mixture.
The method for preparing a titanium silicon molecular sieve catalyst according to claim 4 is characterized in that, in the first hydrothermal crystallization, the molar ratio of Si in the first silicon source, Ti in the titanium source, the first template and water is 1: (0.01-0.5): (0.03-0.6): (1-100).
The preparation method according to claim 4 is characterized in that the first hydrothermal crystallization also includes adding the first silicon source and titanium source to the aqueous solution of the template and stirring, the stirring time is 0.5h to 24h, and the stirring temperature is 0 to 60°C.
The preparation method according to claim 4 is characterized in that the temperature of the first hydrothermal crystallization is 100-300°C and the time is 10-100 hours.
The preparation method according to claim 4 is characterized in that the gas discharged from the pressure relief operation is condensed to obtain a condensate, and the mass of the condensate accounts for 5% to 50% of the total weight of the material after the first hydrothermal crystallization is completed.
The preparation method according to claim 4 is characterized in that the molar ratio of the second silicon source, the second template, the organic amine and water in the second hydrothermal crystallization is 1: (0.01-0.5): (0.03-0.6): (1-100).
The preparation method according to claim 4 is characterized in that the second hydrothermal crystallization also includes stirring after adding the second silicon source, the second template and the organic amine, the stirring time is 0.5h to 24h, and the stirring temperature is 0 to 60°C.
The preparation method according to claim 4 is characterized in that the temperature of the second hydrothermal crystallization is 100-300°C and the time is 10-100h.
The preparation method according to claim 4 is characterized in that the first silicon source and the second silicon source are independently selected from one or more of inorganic silicon or organic silicone grease; the inorganic silicon includes silica sol, silicon dioxide, and white carbon black; the general formula of the organic silicone grease is Si(OR 1 ) 4 , and R 1 is an alkyl substituent having 1 to 6 carbon atoms.
The preparation method according to claim 4 is characterized in that the titanium source is one or more of an inorganic titanium source or an organic titanate; the inorganic titanium includes titanium tetrachloride and titanium sulfate; the general formula of the organic titanate is Ti(OR 2 ) 4 , wherein R 2 is an alkyl substituent having 2 to 6 carbon atoms.
The preparation method according to claim 4, characterized in that the first template is one or more of a quaternary ammonium base or a quaternary ammonium salt; the quaternary ammonium base includes tetrapropylammonium hydroxide, tetraethylammonium hydroxide, tetramethylammonium hydroxide and tetrabutylammonium hydroxide; the quaternary ammonium salt includes tetrapropylammonium bromide, tetrapropylammonium chloride, tetraethylammonium bromide, tetraethylammonium chloride, tetrabutylammonium bromide and tetrabutylammonium chloride.
The preparation method according to claim 4 is characterized in that the second template is a quaternary ammonium salt; the quaternary ammonium salt includes one or more of tetrapropylammonium bromide, tetrapropylammonium chloride, tetraethylammonium bromide, tetraethylammonium chloride, tetrabutylammonium bromide, and tetrabutylammonium chloride.
The preparation method according to claim 4 is characterized in that the organic amine is one or more of aliphatic amine compounds, alcoholamine compounds or aromatic amine compounds; the aliphatic amine compounds include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, n-butylamine, isobutylamine, tert-butylamine, sec-butylamine, butylene diamine, diisobutylamine, pentylamine, isopentylamine, sec-pentylamine, cyclopentylamine, propylamine, dipropylamine, tripropylamine, isopropylamine, diisopropylamine, tri-n-propylamine; the alcoholamine compounds include monoethanolamine, diethanolamine, triethanolamine, isopropanolamine, butyldiethanolamine; the aromatic amine compounds include aniline, toluidine, and phenylenediamine.
The preparation method according to claim 4 is characterized in that it also includes solid-liquid separation of the secondary hydrothermal crystallization mixture to obtain a solid phase, and drying and baking the solid phase.
The preparation method according to claim 17 is characterized in that the drying is carried out at a temperature of 50 to 200° C.; the roasting is carried out at a temperature of 350 to 700° C., and the roasting time is 1 to 8 hours.
Use of the titanium silicon molecular sieve catalyst according to any one of claims 1 to 3 or the titanium silicon molecular sieve catalyst prepared by the preparation method according to any one of claims 4 to 18 in propylene epoxidation reaction.