CN104607238B - A kind of composite catalyst containing modified montmorillonite used and ZSM-8 and preparation method thereof - Google Patents

Abstract

The invention provides a composite catalyst containing modified montmorillonite and ZSM-8 and a preparation method thereof. The catalyst adopts La modified montmorillonite as a binder, and simultaneously uses Ga and Zn modified ZSM-8 The catalyst thus obtained has higher paraffin conversion rate and higher aromatic hydrocarbon yield than conventional catalysts in the prior art, and the deactivation rate of the catalyst is greatly reduced, and the service life is effectively extended.

Description

A kind of composite catalyst containing modified montmorillonite and ZSM-8 and preparation method thereof

technical field

The present invention relates to a catalyst composition comprising ZSM-8 and modified montmorillonite.

Background technique

The conversion of saturated low-alkanes into aromatics that can be directly used in chemical industry has been a subject of widespread concern. In the past several years, a method of aromatizing light hydrocarbons to aromatics using zeolite-based catalysts has been developed successively. However, the conversion of light hydrocarbons to aromatics on catalysts is a complex process involving multiple reactions. The control of catalytic activity and selectivity has always been the focus of attention in this field.

Catalysts known in the prior art that can be used as catalysts for the conversion of lower paraffins to aromatics usually contain rare earth metals and are optionally bonded with a suitable binder. Alumina and silica are commonly used binders in such catalysts. In addition, zeolite is commonly used as the main component in this type of catalyst, and the modification of zeolite is mainly through impregnation, ion exchange, and mechanical mixing to introduce modifying elements into molecular sieves.

Contents of the invention

The purpose of this invention is to provide a composite catalyst composition containing modified montmorillonite and ZSM-8, used La modified montmorillonite as binding agent in this catalyst, and combined Ga and Zn modified ZSM -8, due to the use of this special component, the catalyst has a good conversion rate of paraffins and a good total yield of aromatics.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A method for preparing a composite catalyst containing modified montmorillonite and ZSM-8, characterized in that it comprises the steps:

a) Preparation of La-modified montmorillonite: Take 0.20 g of lanthanum nitrate, dissolve it in 140 ml of deionized water, heat the solution to 70 ° C, then add 15 g of montmorillonite with a particle size of 500 mesh, and continue stirring for 30 minutes. After the montmorillonite is dispersed, heat up to 110°C, stir at this temperature for 10h, filter, wash with deionized water for 3 times, dry the solid product, and place the dried solid powder in a muffle furnace in an air atmosphere for 550 ℃ roasting for 5 hours to obtain La modified montmorillonite;

b) Preparation of Ga/Zn-ZSM-8: Dissolve gallium nitrate and zinc nitrate in 250ml of deionized water, wherein the total weight of gallium nitrate and zinc nitrate is 0.825g, stir and dissolve for later use; disperse ZSM-8 in In the ammonium nitrate aqueous solution, keep at 100°C for 5 hours, filter and dry, add 15g of dry powder to the above solution of gallium nitrate and zinc nitrate, then raise the temperature to 100°C, stir at constant temperature for 20 hours, filter and dry the solid matter to obtain Ga and Zn-modified ZSM-8;

c) Catalyst preparation: take Ga/Zn-ZSM-8 and La modified montmorillonite with a mass ratio of 3:1, add them to the mixer, then add appropriate amount of silica sol and distilled water, beat, filter and dry at 450°C After roasting for 0.5h, crush and sieve, and take 20-100 mesh particles as the finished catalyst.

The stirring rate in the step a) is 400 rpm.

The heating rate in the step b) is 10°C/min.

The heating rate in step c) is 10°C/min.

Beneficial effect

Compared with the prior art, the present invention has the following beneficial effects due to the adoption of the above-mentioned technical scheme: the catalyst of the present invention adopts La modified montmorillonite as the binding agent, and simultaneously adopts Ga and Zn modified ZSM-8, The catalyst thus obtained has higher paraffin conversion rate and higher aromatic hydrocarbon yield than conventional catalysts in the prior art, and the deactivation rate of the catalyst is greatly reduced, and the service life is effectively extended.

Detailed ways

Below by embodiment the present invention will be further described.

Example 1

Preparation of La modified montmorillonite: Take 0.20g of lanthanum nitrate, dissolve it in 140ml of deionized water, heat the solution to 70°C, then add 15g of montmorillonite with a particle size of 500 mesh, and continue to stir for 30 minutes. After the montmorillonite is dispersed, raise the temperature to 110°C, stir at this temperature for 10 h at a stirring rate of 400 rpm, filter, wash 3 times with deionized water, dry the solid product, and dry The final solid powder is placed in a muffle furnace in an air atmosphere at 550° C. for 5 hours and calcined to obtain La modified montmorillonite;

Preparation of Ga/Zn-ZSM-8: Dissolve gallium nitrate and zinc nitrate in 250ml of deionized water, wherein the total weight of gallium nitrate and zinc nitrate is 0.825g, stir and dissolve for later use; disperse ZSM-8 in ammonium nitrate In the aqueous solution, the heating rate is 10°C/min, kept at 100°C for 5 hours, filtered and dried, and 15g of dry powder is added to the above solution of gallium nitrate and zinc nitrate, and then the temperature is raised to 100°C, the heating rate is 10°C/min, constant temperature Stir for 20 hours, filter and dry the solid matter to obtain Ga and Zn modified ZSM-8;

Catalyst preparation: Take Ga/Zn-ZSM-8 and La modified montmorillonite with a mass ratio of 3:1, add them to the mixer, then add appropriate amount of silica sol and distilled water, beat, filter and dry, the heating rate is 10°C After roasting at 450°C for 0.5h, crush and sieve, and take 20-100 mesh particles as the finished catalyst.

Comparative example 1

Take the Ga/Zn-ZSM-8 and ordinary clay prepared in Example 1 with a mass ratio of 3:1, add them to the mixer, and then add an appropriate amount of silica sol and distilled water, beat, filter, and dry, at a heating rate of 10°C/min Raise to 450°C, roast for 0.5h, crush and sieve, and take 20-100 mesh particles as the finished catalyst.

Comparative example 2

Take ZSM-8 and La modified montmorillonite with a mass ratio of 3:1, add them to the mixer, then add appropriate amount of silica sol and distilled water, beat, filter and dry, and raise the temperature to 450°C at a heating rate of 10°C/min. After roasting for 0.5h, crush and sieve, and take 20-100 mesh particles as the finished catalyst.

Claims (4)

1. a preparation method containing a composite catalyst of modified montmorillonite and ZSM-8, is characterized in that, comprises the steps: a) Preparation of La-modified montmorillonite: Take 0.20 g of lanthanum nitrate, dissolve it in 140 ml of deionized water, heat the solution to 70 ° C, then add 15 g of montmorillonite with a particle size of 500 mesh, and continue stirring for 30 minutes. After the montmorillonite is dispersed, heat up to 110°C, stir at this temperature for 10h, filter, wash with deionized water for 3 times, dry the solid product, and place the dried solid powder in a muffle furnace in an air atmosphere for 550 ℃ roasting for 5 hours to obtain La modified montmorillonite; b) Preparation of Ga/Zn-ZSM-8: Dissolve gallium nitrate and zinc nitrate in 250ml of deionized water, wherein the total weight of gallium nitrate and zinc nitrate is 0.825g, stir and dissolve for later use; disperse ZSM-8 in In the ammonium nitrate aqueous solution, keep at 100°C for 5 hours, filter and dry, add 15g of dry powder to the above solution of gallium nitrate and zinc nitrate, then raise the temperature to 100°C, stir at constant temperature for 20 hours, filter and dry the solid matter to obtain Ga and Zn-modified ZSM-8; c) Catalyst preparation: take Ga/Zn-ZSM-8 and La modified montmorillonite with a mass ratio of 3:1, add them to the mixer, then add appropriate amount of silica sol and distilled water, beat, filter and dry at 450°C After roasting for 0.5h, crush and sieve, and take 20-100 mesh particles as the finished catalyst. 2. The preparation method according to claim 1, characterized in that: the stirring speed in step a) is about 400-500 rpm. 3. The preparation method according to claim 1, characterized in that: the heating rate in step b) is 10°C/min. 4. The preparation method according to claim 1, characterized in that: the heating rate in step c) is 10°C/min.