阅读说明：本技术 一种利用双模板剂合成Silicalite-2分子筛的方法 (Method for synthesizing Silicalite-2 molecular sieve by using double templates ) 是由 林卿 杜香霖 杨芳 许建梅 何云 于 2019-11-15 设计创作，主要内容包括：本发明提供了一种利用双模板剂合成Silicalite-2分子筛的方法,包括以下步骤：步骤1、将硅源、模板剂和水按照1:0.1～0.2:25的物质的量比混合均匀得到溶液A；其中,模板剂为四丁基溴化铵和四丁基氢氧化铵按照1:2～2.1的质量比的混合物；步骤2、将步骤1得到的溶液A于130℃～150℃水热晶化；步骤3、将步骤2水热晶化的产物离心,水洗,干燥,并于空气氛围中于550℃煅烧4～4.5h,得到Silicalite-2分子筛。本发明利用四丁基溴化铵和四丁基氢氧化铵作为双模板剂合成Silicalite-2分子筛,操作简单、条件温和,成本低廉,得到的分子筛纯度较高,适用于工业化生产。(The invention provides a method for synthesizing a Silicalite-2 molecular sieve by using a dual-template agent, which comprises the following steps of: step 1, uniformly mixing a silicon source, a template agent and water according to the mass ratio of 1: 0.1-0.2: 25 to obtain a solution A; wherein the template agent is a mixture of tetrabutylammonium bromide and tetrabutylammonium hydroxide according to a mass ratio of 1: 2-2.1; step 2, carrying out hydrothermal crystallization on the solution A obtained in the step 1 at 130-150 ℃; and 3, centrifuging, washing and drying the product obtained in the step 2 through hydrothermal crystallization, and calcining for 4-4.5 hours at 550 ℃ in an air atmosphere to obtain the Silicalite-2 molecular sieve. The invention utilizes tetrabutylammonium bromide and tetrabutylammonium hydroxide as the double templates to synthesize the Silicalite-2 molecular sieve, has simple operation, mild condition and low cost, and the obtained molecular sieve has higher purity and is suitable for industrial production.)

1. A method for synthesizing a Silicalite-2 molecular sieve by using a dual-template agent is characterized by comprising the following steps:

step 1, uniformly mixing a silicon source, a template agent and water according to the mass ratio of 1: 0.1-0.2: 25 to obtain a solution A;

the template agent is a mixture of tetrabutylammonium bromide and tetrabutylammonium hydroxide according to a mass ratio of 1: 2-2.1;

step 2, carrying out hydrothermal crystallization on the solution A obtained in the step 1 at 130-150 ℃ for 36-60 h;

and 3, centrifuging the product obtained in the step 2 through hydrothermal crystallization, washing the product to be neutral, drying the product, and calcining the product for 4-4.5 hours at 550 ℃ in an air atmosphere to obtain the Silicalite-2 molecular sieve.

2. The method for synthesizing the Silicalite-2 molecular sieve by using the dual templates as claimed in claim 1, wherein the silicon source in step 1 is silica sol, tetraethoxysilane or white carbon black.

3. The method for synthesizing the Silicalite-2 molecular sieve by using the dual templates as claimed in claim 1, wherein the step 1 is carried out by uniformly mixing the templates with water by magnetic stirring, adding the silicon source, and stirring for 3-3.5 hours.

4. The method for synthesizing the Silicalite-2 molecular sieve by using the dual templates as claimed in claim 1, wherein the centrifugation rate in step 3 is 8000-10000 r/min, and the centrifugation time is 10-15 min.

5. The method for synthesizing the Silicalite-2 molecular sieve by using the dual templates as claimed in claim 1, wherein the drying temperature in step 3 is 80-100 ℃ and the drying time is 10-12 h.

6. The method for synthesizing the Silicalite-2 molecular sieve by using the dual templates as claimed in claim 1, wherein the temperature rise rate in the calcination process in the step 3 is 1-2 ℃/min.

Technical Field

The invention relates to a method for synthesizing a Silicalite-2 molecular sieve, in particular to a method for synthesizing the Silicalite-2 molecular sieve by using a dual-template agent.

Background

ZSM-11(MEL structure) was first synthesized by Kokotailot et al in 1978 using tetrabutylammonium hydroxide (TBA) as an organic Structure Directing Agent (SDA), after which it appeared that the material synthesized with TBA-directing was actually the eutectic structure of ZSM-11/ZSM-5, whereas pure phase ZSM-11 was difficult to prepare. In 1978, Nakagawa first proposed a method for synthesizing pure phase ZSM-11, i.e., ZSM-11 was synthesized from gel and a clarified solution of tetrabutylammonium hydroxide (TBAOH) using a 3, 5-dimethylpiperidine derivative as a structure directing agent. At the same time, studies have shown that TBAOH is selective for ZSM-11 and prevents the formation of molecular sieves of MFI structure. Longying et al by TBAOH-TEOS-H₂The O reaction system synthesized colloidal silicalite-2(MEL structure). Picciione et al synthesized pure phase ZSM-11 molecular sieves using 2, 2-Diethoxytrimethylammonium (DEOTA) ion as a directing agent. In 2001, nano-MEL crystals were synthesized from colloidal precursors by Mintova et al, with a chemical composition of SiO 2: 0.3 TBAOH: 4.0 EtOH: 18.0H₂O, having an average particle diameter of about 100 nm. Wu et al, 2008, synthesized a ZSM-11 molecular sieve using NaOH as a sodium source, tetrabutylammonium bromide (TBABr) and phenyltrimethyl Bromide (BTMACI) as a co-template agent, silica sol as a silicon source, and a suitable amount of deionized water.

The Silicalite-2 molecular sieve is in an MEL type pure silicon form, and the Silicalite-2 molecular sieve is used as a catalyst carrier, so that the Silicalite-1 and ZSM-5 molecular sieve has higher selectivity on low-carbon olefins, and the Silicalite-2 molecular sieve does not contain Al, so that the isomerization of an intermediate product and the occurrence of secondary hydrogenation reaction are inhibited to a certain extent. The Silicalite-2 molecular sieve has good catalytic performance, but the existing process for synthesizing the Silicalite-2 molecular sieve is relatively complex, and the obtained molecular sieve has low crystallinity and contains mixed crystals.

Disclosure of Invention

The invention aims to solve the technical defects and provides a method for synthesizing the Silicalite-2 molecular sieve by using a dual-template agent, wherein the Silicalite-2 molecular sieve is prepared by using tetrabutylammonium bromide and tetrabutylammonium hydroxide as the dual-template agent, and the preparation process has mild conditions, is simple to operate and low in cost, and is suitable for industrial production.

In order to achieve the purpose, the invention adopts the technical scheme that:

a method for synthesizing a Silicalite-2 molecular sieve by using a dual-template method comprises the following steps:

step 1, uniformly mixing a silicon source, a template agent and water according to the mass ratio of 1: 0.1-0.2: 25 to obtain a solution A;

the template agent is a mixture of tetrabutylammonium bromide and tetrabutylammonium hydroxide according to a mass ratio of 1: 2-2.1;

step 2, carrying out hydrothermal crystallization on the solution A obtained in the step 1 at 130-150 ℃ for 36-60 h;

and 3, centrifuging the product obtained in the step 2 through hydrothermal crystallization, washing the product to be neutral, drying the product, and calcining the product for 4 hours at 550 ℃ in an air atmosphere to obtain the Silicalite-2 molecular sieve.

Preferably, the silicon source in step 1 is silica sol, ethyl orthosilicate or white carbon black.

Preferably, magnetic stirring is adopted for uniform mixing in the step 1, the template agent and water are uniformly mixed, and then the silicon source is added for stirring for 3-3.5 hours.

Preferably, the centrifugation speed in the step 3 is 8000-10000 r/min, and the centrifugation time is 10-15 min.

Preferably, the drying temperature in the step 3 is 80-100 ℃, and the drying time is 10-12 h.

Preferably, the heating rate of the calcining process in the step 3 is 1-2 ℃/min.

Compared with the prior art, the invention has the following beneficial effects:

1. according to the invention, the dual-template agent is used for synthesizing the Silicalite-2 molecular sieve, tetrabutylammonium bromide and tetrabutylammonium hydroxide are used as the dual-template agent, the synthesis cost is effectively reduced, the operation is simple, the condition is mild, the crystallinity of the obtained Silicalite-2 molecular sieve is higher, no heterocrystal phase is generated, and the method is suitable for working production.

Drawings

FIG. 1 is an XRD pattern of a Silicalite-2 molecular sieve prepared in example 1;

FIG. 2 is a nitrogen adsorption desorption isotherm of the Silicalite-2 molecular sieve prepared in example 1;

FIG. 3 is a nitrogen adsorption desorption pore size distribution plot for the Silicalite-2 molecular sieve prepared in example 1;

FIG. 4 is an XRD pattern of the Silicalite-2 molecular sieve prepared in example 2;

FIG. 5 is a nitrogen adsorption desorption isotherm of the Silicalite-2 molecular sieve prepared in example 2;

FIG. 6 is a nitrogen adsorption desorption pore size distribution plot for the Silicalite-2 molecular sieve prepared in example 2;

FIG. 7 is an XRD pattern of the Silicalite-2 molecular sieve prepared in example 3;

FIG. 8 is a nitrogen adsorption desorption isotherm of the Silicalite-2 molecular sieve prepared in example 3;

FIG. 9 is a nitrogen adsorption desorption pore size distribution plot for the Silicalite-2 molecular sieve prepared in example 3;

FIG. 10 is an XRD pattern of the Silicalite-2 molecular sieve prepared in example 4;

FIG. 11 is a nitrogen adsorption desorption isotherm of the Silicalite-2 molecular sieve prepared in example 4;

FIG. 12 is a nitrogen adsorption desorption pore size distribution plot for the Silicalite-2 molecular sieve prepared in example 4;

FIG. 13 is an XRD pattern of the Silicalite-2 molecular sieve prepared in example 5;

FIG. 14 is a nitrogen adsorption desorption isotherm of the Silicalite-2 molecular sieve prepared in example 5;

FIG. 15 is a nitrogen adsorption desorption pore size distribution plot for the Silicalite-2 molecular sieve prepared in example 5;

FIG. 16 is an XRD pattern of the Silicalite-2 molecular sieve prepared in example 6;

FIG. 17 is a nitrogen adsorption desorption isotherm of the Silicalite-2 molecular sieve prepared in example 6;

FIG. 18 is a nitrogen adsorption desorption pore size distribution plot for the Silicalite-2 molecular sieve prepared in example 6.

Detailed Description

The present invention will be described in detail below with reference to specific examples. The scope of the invention is not limited to the specific embodiments.

Test methods in which specific conditions are not specified in the following examples are generally carried out under conventional conditions or under conditions recommended by the respective manufacturers.

Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention. Unless otherwise specifically stated, the various starting materials, reagents, instruments and equipment used in the following examples of the present invention are either commercially available or prepared by conventional methods.

It should be noted that the temperatures referred to in the following examples of the present invention are room temperature; the stirrer used in the present invention was Oenhenwa DF-101 s.