A method for preparing p-xylene by isomerizing m-xylene and/or o-xylene

Abstract

The invention discloses a method for preparing p-xylene by using m-xylene and / or o-xylene isomerisation. The method comprises the following steps: preparing a series of zeolite molecular sieves of different silica-alumina ratios, and preparing a zeolite molecular sieve catalyst Me / HZSM-5 modified by different metals by adopting a hydrothermal crystallization-impregnation method. The p-xylene in the mixed xylene is close to equilibrium under appropriate process conditions, and the xylene loss is lower than 2.5%. The method disclosed by the invention is less in by-products and simple in operation, effectively reduces carbon deposit on the catalyst, and is capable of prolonging the service life, stable in catalytic performance and applicable to large-scale industrial production.

Description

technical field

[0001] The invention relates to a method for isomerizing aromatic hydrocarbons, in particular to a method for preparing p-xylene by isomerizing m-xylene and / or ortho-xylene. Background technique

[0002] As a raw material for a variety of fine chemical products, my country's demand for p-xylene PX continues to grow. In order to meet market needs, the production process of toluene disproportionation and toluene methylation to p-xylene has appeared successively. Due to the demand gap for p-xylene Large, and a large amount of p-xylene still needs to be imported every year. In xylene, the content of m-xylene MX is the most, but its demand is the least. If m-xylene is isomerized into p-xylene as much as possible, it can not only make up for the insufficient production of p-xylene, but also fully Excess m-xylene is utilized. In the meta-xylene isomerization reaction, the isomerization of ortho-xylene may be involved, but mainly the isomerization of meta-xylene pro...

Examples

Embodiment 1

[0074] Example 1 SiO 2 / al 2 o 3 Molecular sieve 120HZ with a molar ratio of 120

[0075] Step (1) Preparation of gel

[0076] Weigh 5.08g of sodium chloride particles and dissolve in 50g of water, slowly add 0.96g of concentrated sulfuric acid dropwise, then add 3.23g of aluminum sulfate solid (Al 2 (SO 4 ) 3 18H 2 O), stirred evenly as A solution. Weigh 3.20g of sodium hydroxide particles and dissolve in 103.96g of water, then add 34.56g of silica gel, and stir evenly to form B solution. Slowly pour B solution into A solution, and keep stirring, slowly add 8.67g template agent n-butylamine dropwise to form a gel;

[0077] Step (2) hydrothermal crystallization

[0078] Move the gel prepared in step (1) to a synthesis kettle, stir at 30°C for 0.5h, heat up to 100°C for aging for 24h, then crystallize at a constant temperature of 170°C for 72h, and cool down to room temperature rapidly after crystallization to obtain crystal chemical products;

[0079] Step (3) ion e...

Embodiment 2

[0095] Step (1) Preparation of gel

[0096] According to SiO 2 / Al 2 o 3 Molar ratio is 120 to get the raw materials ready, takes by weighing 5.08g sodium chloride particle and is dissolved in 50g water, slowly drips the vitriol oil of 0.96g, then adds 3.23g aluminum sulfate solid (Al 2 (SO 4 ) 3 18H 2 O), stirred evenly as A solution. Weigh 3.20g of sodium hydroxide particles and dissolve in 103.96g of water, then add 34.56g of silica gel, stir evenly as solution B. Slowly pour B solution into A solution, and keep stirring, slowly add 8.67g template agent n-butylamine dropwise to form a gel;

[0097] Step (2) hydrothermal crystallization

[0098] Move the gel prepared in step (1) to a synthesis kettle, stir at 30°C for 0.5h, heat up to 100°C for aging for 24h, then crystallize at a constant temperature of 170°C for 72h, and cool down to room temperature rapidly after crystallization to obtain crystal chemical products;

[0099] Step (3) ion exchange

[0100] The cr...

Embodiment 3

[0106] Step (1) Preparation of gel

[0107] According to SiO 2 / Al 2 o 3 Molar ratio is 120 to get the raw materials ready, takes by weighing 5.08g sodium chloride particle and is dissolved in 50g water, slowly drips the vitriol oil of 0.96g, then adds 3.23g aluminum sulfate solid (Al 2 (SO 4 ) 3 18H 2 O), stirred evenly as A solution. Weigh 3.20g of sodium hydroxide particles and dissolve in 103.96g of water, then add 34.56g of silica gel, and stir evenly to form B solution. Slowly pour the B solution into the A solution, and keep stirring, slowly add 8.67g template agent n-butylamine dropwise to form a gel;

[0108] Step (2) hydrothermal crystallization

[0109] Move the gel prepared in step (1) to a synthesis kettle, stir at 30°C for 0.5h, heat up to 100°C for aging for 24h, then crystallize at a constant temperature of 170°C for 72h, and cool down to room temperature rapidly after crystallization to obtain crystal chemical products;

[0110] Step (3) ion exchange...

technical field

[0001] The invention relates to a method for isomerizing aromatic hydrocarbons, in particular to a method for preparing p-xylene by isomerizing m-xylene and / or ortho-xylene. Background technique

[0002] As a raw material for a variety of fine chemical products, my country's demand for p-xylene PX continues to grow. In order to meet market needs, the production process of toluene disproportionation and toluene methylation to p-xylene has appeared successively. Due to the demand gap for p-xylene Large, and a large amount of p-xylene still needs to be imported every year. In xylene, the content of m-xylene MX is the most, but its demand is the least. If m-xylene is isomerized into p-xylene as much as possible, it can not only make up for the insufficient production of p-xylene, but also fully Excess m-xylene is utilized. In the meta-xylene isomerization reaction, the isomerization of ortho-xylene may be involved, but mainly the isomerization of meta-xylene pro...

Examples

Embodiment 1

[0074] Example 1 SiO 2 / al 2 o 3 Molecular sieve 120HZ with a molar ratio of 120

[0075] Step (1) Preparation of gel

[0076] Weigh 5.08g of sodium chloride particles and dissolve in 50g of water, slowly add 0.96g of concentrated sulfuric acid dropwise, then add 3.23g of aluminum sulfate solid (Al 2 (SO 4 ) 3 18H 2 O), stirred evenly as A solution. Weigh 3.20g of sodium hydroxide particles and dissolve in 103.96g of water, then add 34.56g of silica gel, and stir evenly to form B solution. Slowly pour B solution into A solution, and keep stirring, slowly add 8.67g template agent n-butylamine dropwise to form a gel;

[0077] Step (2) hydrothermal crystallization

[0078] Move the gel prepared in step (1) to a synthesis kettle, stir at 30°C for 0.5h, heat up to 100°C for aging for 24h, then crystallize at a constant temperature of 170°C for 72h, and cool down to room temperature rapidly after crystallization to obtain crystal chemical products;

[0079] Step (3) ion e...

Embodiment 2

[0095] Step (1) Preparation of gel

[0096] According to SiO 2 / Al 2 o 3 Molar ratio is 120 to get the raw materials ready, takes by weighing 5.08g sodium chloride particle and is dissolved in 50g water, slowly drips the vitriol oil of 0.96g, then adds 3.23g aluminum sulfate solid (Al 2 (SO 4 ) 3 18H 2 O), stirred evenly as A solution. Weigh 3.20g of sodium hydroxide particles and dissolve in 103.96g of water, then add 34.56g of silica gel, stir evenly as solution B. Slowly pour B solution into A solution, and keep stirring, slowly add 8.67g template agent n-butylamine dropwise to form a gel;

[0097] Step (2) hydrothermal crystallization

[0098] Move the gel prepared in step (1) to a synthesis kettle, stir at 30°C for 0.5h, heat up to 100°C for aging for 24h, then crystallize at a constant temperature of 170°C for 72h, and cool down to room temperature rapidly after crystallization to obtain crystal chemical products;

[0099] Step (3) ion exchange

[0100] The cr...

Embodiment 3

[0106] Step (1) Preparation of gel

[0107] According to SiO 2 / Al 2 o 3 Molar ratio is 120 to get the raw materials ready, takes by weighing 5.08g sodium chloride particle and is dissolved in 50g water, slowly drips the vitriol oil of 0.96g, then adds 3.23g aluminum sulfate solid (Al 2 (SO 4 ) 3 18H 2 O), stirred evenly as A solution. Weigh 3.20g of sodium hydroxide particles and dissolve in 103.96g of water, then add 34.56g of silica gel, and stir evenly to form B solution. Slowly pour the B solution into the A solution, and keep stirring, slowly add 8.67g template agent n-butylamine dropwise to form a gel;

[0108] Step (2) hydrothermal crystallization

[0109] Move the gel prepared in step (1) to a synthesis kettle, stir at 30°C for 0.5h, heat up to 100°C for aging for 24h, then crystallize at a constant temperature of 170°C for 72h, and cool down to room temperature rapidly after crystallization to obtain crystal chemical products;

[0110] Step (3) ion exchange...

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