阅读说明：本技术 偏三甲苯和甲醇烷基化合成均四甲苯催化剂的制备及其使用方法 (Preparation and application method of pseudocumene and methanol alkylation durene synthesis catalyst ) 是由 曹正国 李江华 王福 陈佳佳 殷文慧 于 2020-12-28 设计创作，主要内容包括：本发明公开了一种偏三甲苯和甲醇烷基化合成均四甲苯催化剂的制备方法,催化剂制备时包括如下步骤：(1)硅铝比100-150的ZSM-5分子筛用0.2-2.0mol/L稀盐酸交换成氢型分子筛HZSM-5；(2)加压挤条成型后,用400-600℃水蒸汽处理5-8小时；(3)用1.0-3.0mol/L稀硝酸洗去非骨架铝；再用去离子水洗涤呈中性；(4)用氯化钾溶液充分洗涤3-8次,制得钾离子改性分子筛；(5)用硝酸镁浸渍法进行镁改性,使得改性物分布均匀；(6)高温烘焙去除挥发物,烘焙温度350-550℃。其作为偏三甲苯和甲醇烷基化合成均四甲苯的催化剂。其具有催化活性高,目标产物选择性高的特点。(The invention discloses a method for preparing a catalyst for synthesizing durene by alkylating pseudocumene and methanol, which comprises the following steps: (1) exchanging the ZSM-5 molecular sieve with the silica-alumina ratio of 100-; (2) after the extrusion molding under pressure, treating for 5-8 hours by using water vapor with the temperature of 400-; (3) washing off non-framework aluminum by using 1.0-3.0mol/L dilute nitric acid; then washing the mixture by deionized water to be neutral; (4) fully washing for 3-8 times by using a potassium chloride solution to prepare a potassium ion modified molecular sieve; (5) magnesium modification is carried out by a magnesium nitrate dipping method, so that the modified substances are uniformly distributed; (6) high-temperature baking is carried out to remove the volatile matters, and the baking temperature is 350-550 ℃. It is used as the catalyst for synthesizing durene by alkylating pseudocumene and methanol. The catalyst has the characteristics of high catalytic activity and high selectivity of target products.)

1. A preparation method of a catalyst for synthesizing durene by alkylating pseudocumene and methanol is characterized by comprising the following steps:

(1) exchanging the ZSM-5 molecular sieve with the silica-alumina ratio of 100-;

(2) after the extrusion molding under pressure, treating for 5-8 hours by using water vapor with the temperature of 400-;

(3) washing off non-framework aluminum by using 1.0-3.0mol/L dilute nitric acid; then washing the mixture by deionized water to be neutral;

(4) fully washing for 3-8 times by using a potassium chloride solution to prepare a potassium ion modified molecular sieve;

(5) magnesium modification is carried out by a magnesium nitrate dipping method, so that the modified substances are uniformly distributed;

(6) and (4) removing the volatile matters by high-temperature baking, wherein the baking temperature is 350-550 ℃, and obtaining the target product.

2. The method for preparing the catalyst for synthesizing durene by alkylating pseudocumene and methanol according to claim 1, which is characterized in that: and (5) performing magnesium modification by using a magnesium nitrate solution for multiple times.

3. The method for preparing the catalyst for synthesizing durene by alkylating pseudocumene and methanol according to claim 1 or 2, which is characterized in that: in the step (4), the loading amount of the potassium chloride is 8-15%.

4. The method for preparing the catalyst for synthesizing durene by alkylating pseudocumene and methanol according to claim 1 or 2, which is characterized in that: in the step (5), the loading amount of magnesium nitrate is 5-10%.

5. The use method of the catalyst for synthesizing durene by the alkylation of pseudocumene and methanol according to claim 1 or 2, characterized by comprising the following steps:

(1) pseudocumene and methanol in a molar ratio of 1.0-3.0: 1, heating and gasifying by a preheater after the materials are fed and mixed in proportion;

(2) after the pseudocumene and the methanol are gasified, the pseudocumene and the methanol are heated by a heating furnace and then enter a reactor, the reaction temperature in the reactor is 280-420 ℃, the reaction pressure is 1.0-2.0MPa, and the mass space velocity is 0.5-1.0h^-1A catalyst bed filled with the catalyst is arranged in the reactor;

(3) after catalytic reaction in a catalytic bed, cooling, decompressing and dividing water, reducing the pressure to normal pressure, and rectifying to obtain durene and a byproduct high-boiling-point aromatic solvent;

(4) cooling again for crystallization or rectification separation to obtain durene.

Technical Field

The invention relates to a preparation method and application of an alkylation catalyst, in particular to a preparation method and application of a catalyst for synthesizing durene by alkylating pseudocumene and methanol.

Background

Durene is an important organic chemical raw material and is mainly used for producing pyromellitic dianhydride (PMDA). PMDA is an important raw material for synthesizing polyimide polymers. The polyimide has excellent electrical insulation performance, high temperature resistance and radiation resistance and can be widely applied to aerospace industry, atomic energy industry and electromechanical industry. PMDA is also an important raw material for high quality plasticizers, curing agents and powder coating matting agents.

The synthetic route of durene mainly includes two kinds of separation and purification method and chemical synthesis method, one is separation and purification method, and uses by-product in the course of petroleum and coal processing, mainly C₁₀Separating and purifying heavy aromatics as raw materials; the other is a chemical synthesis method which mainly comprises alkylation, disproportionation reaction and the like. The alkylation method has the advantages of low cost, no corrosion to equipment, large product scale and the like, and is widely concerned. The current alkylation process has mainly focused on the development of highly efficient, stable, long-lived catalysts. A molecular sieve catalyst for synthesizing durene from methanol is prepared from ZSM-5 molecular sieve with Si-Al ratio of 13-50, assistant and nitric acid through mixing, pugging, press shaping, baking, pulverizing, calcining, immersing in nitric acid, baking and calcining. After the methanol is converted, the content of durene in the oil phase product can reach 20 percent. However, the invention only discloses the preparation of the catalystThe method does not mention the corresponding processing technology for synthesizing durene from methanol. The process is prone to sintering, carbon deposition and corrosion.

Disclosure of Invention

The invention aims to provide a preparation method of a catalyst for synthesizing durene by alkylating pseudocumene and methanol.

The purpose of the invention is realized as follows: a method for preparing a catalyst for synthesizing durene by alkylating pseudocumene and methanol comprises the following steps:

(1) exchanging the ZSM-5 molecular sieve with the silica-alumina ratio of 100-;

(2) after the extrusion molding under pressure, treating for 5-8 hours by using water vapor with the temperature of 400-;

(3) washing off non-framework aluminum by using 1.0-3.0mol/L dilute nitric acid; then washing the mixture by deionized water to be neutral; the aim is to improve the stability of the catalyst. Because framework aluminum refers to aluminum present in the molecular sieve framework in the form of aluminotetrahedra, non-framework aluminum refers to aluminum present in the molecular sieve due to defects, charge adsorption, and the like, without forming chemical bonds in the form of Si-O-Al.

(4) Fully washing for 3-8 times by using a potassium chloride solution to prepare a potassium ion modified molecular sieve; the purpose is to reduce the pore volume, narrow the pore channel, increase the shape-selective effect and improve the selectivity.

(5) Magnesium modification is carried out by a magnesium nitrate dipping method, so that the modified substances are uniformly distributed; the aim is to cover partial outer surface acidity and reduce the occurrence of side reactions such as disproportionation, isomerization and deep alkylation.

(6) And (4) removing the volatile matters by high-temperature baking, wherein the baking temperature is 350-550 ℃, and obtaining the target product.

Further, the step (5) is carried out magnesium modification with magnesium nitrate solution for a plurality of times.

Further, in the step (4), the loading amount of potassium chloride is 8-15%.

Further, in the step (5), the loading amount of magnesium nitrate is 5-10%.

The invention also discloses a using method of the catalyst for synthesizing durene by alkylating pseudocumene and methanol, which comprises the following steps:

(1) pseudocumene and methanol in a molar ratio of 1.0-3.0: 1, heating and gasifying by a preheater after the materials are fed and mixed in proportion;

(2) after the pseudocumene and the methanol are gasified, the pseudocumene and the methanol are heated by a heating furnace and then enter a reactor, the reaction temperature in the reactor is 280-420 ℃, the reaction pressure is 1.0-2.0MPa, and the mass space velocity (the volume of fed material per hour/the loading volume of a catalyst) is 0.5-1.0h^-1A catalyst bed filled with the catalyst is arranged in the reactor;

(3) after catalytic reaction in a catalytic bed, cooling, decompressing and dividing water, reducing the pressure to normal pressure, and rectifying to obtain durene and a byproduct high-boiling-point aromatic solvent;

(4) cooling again for crystallization or rectification separation to obtain durene.

Compared with the prior art, the invention has the beneficial effects that: covering the outer surface of the acid sites and reducing the number of strong acid sites is critical to increasing the alkylation selectivity of the ZSM-5 molecular sieve. The modified double-metal ion catalyst reduces the deposition in the ZSM-5 molecular sieve pores and maintains the smoothness of the pore channels; so that the modified molecular sieve catalyst can keep high activity; the potassium modification can selectively remove strong acid centers, and the magnesium modification further improves the selectivity of the alkylation reaction; the combination of the three can prepare the alkylation catalyst with high performance.

Detailed Description

Example 1

A catalyst for synthesizing durene by alkylating pseudocumene and methanol is a modified ZSM-5 molecular sieve catalyst and is prepared by the following specific steps:

(1) exchanging a ZSM-5 molecular sieve with the silica-alumina ratio of 100 into a hydrogen type molecular sieve HZSM-5 by using 0.2mol/L HCl;

(2) pressurizing, extruding and molding, and treating for 6 hours by using high-temperature water vapor at 400 ℃;

(3) washing off non-framework aluminum by using 1.0mol/L dilute nitric acid, and then washing the molecular sieve by using deionized water until the washing liquid is neutral;

(4) then washing the molecular sieve for 6 times by using a KCl solution, wherein the KCl loading is 15%, and preparing the potassium ion modified molecular sieve;

(5) magnesium modification by magnesium nitrate impregnation method, Mg (NO)₃)₂The loading capacity is 10%, and the magnesium modification can be carried out for multiple times, so that the distribution of the modified substances is more uniform;

(6) and finally, baking at the high temperature of 370 ℃ for 6 hours, and removing volatile matters to obtain the catalyst for synthesizing durene by alkylating pseudocumene and methanol.

The catalyst is used for synthesizing durene by alkylating pseudocumene and methanol, and the synthesis steps are as follows:

(1) pseudocumene and methanol in a molar ratio of 1: 1, heating by a preheater at 270-300 ℃ for gasification;

(2) after the pseudocumene and the methanol are gasified, the pseudocumene and the methanol are heated by a heating furnace and then enter a reactor, the reaction temperature in the reactor is 280-420 ℃, the reaction pressure is 1.0-2.0MPa, and the mass space velocity is 0.5-1.0h^-1A catalyst bed filled with the catalyst is arranged in the reactor;

(3) after catalytic reaction in a catalytic bed, cooling, decompressing and dividing water, reducing the pressure to normal pressure, and rectifying to obtain durene and a byproduct high-boiling-point aromatic solvent; the durene content of the product was analyzed by gas chromatography to be 28.9%;

(4) cooling again for crystallization or rectification separation to obtain durene.

Example 2

A catalyst for synthesizing durene by alkylating pseudocumene and methanol is a modified ZSM-5 molecular sieve catalyst and is prepared by the following specific steps:

(1) exchanging a ZSM-5 molecular sieve with the silica-alumina ratio of 150 into a hydrogen type molecular sieve HZSM-5 by using 2mol/L HCl;

(2) pressing, extruding and forming, and treating with 600 ℃ high-temperature water vapor for 5 hours;

(3) washing off non-framework aluminum by using 3.0mol/L dilute nitric acid, and then washing the molecular sieve by using deionized water until the washing liquid is neutral;

(4) then washing for 3 times by using a KCl solution, wherein the KCl loading capacity is 8 percent, and preparing the potassium ion modified molecular sieve;

(5) magnesium modification by magnesium nitrate impregnation method, Mg (NO)₃)₂The loading amount is 5%, and the magnesium modification can be carried out for multiple times, so that the distribution of the modified substances is more uniform;

(6) and finally, baking at a high temperature of 350 ℃, removing volatile matters, and obtaining the catalyst for synthesizing durene by alkylating pseudocumene and methanol.

The catalyst is used for synthesizing durene by alkylating pseudocumene and methanol, and the synthesis steps are as follows:

(1) pseudocumene and methanol in a molar ratio of 3: 1, heating by a preheater at 300-320 ℃ for gasification;

(2) after the pseudocumene and the methanol are gasified, the pseudocumene and the methanol are heated by a heating furnace and then enter a reactor, the reaction temperature in the reactor is 280-420 ℃, the reaction pressure is 1.0-2.0MPa, and the mass space velocity is 0.5-1.0h^-1A catalyst bed filled with the catalyst is arranged in the reactor;

(3) after catalytic reaction in a catalytic bed, cooling, decompressing and dividing water, reducing the pressure to normal pressure, and rectifying to obtain durene and a byproduct high-boiling-point aromatic solvent; the durene content of the product was analyzed by gas chromatography to be 26.7%;

(4) cooling again for crystallization or rectification separation to obtain durene.

Example 3

A catalyst for synthesizing durene by alkylating pseudocumene and methanol is a modified ZSM-5 molecular sieve catalyst and is prepared by the following specific steps:

(1) exchanging a ZSM-5 molecular sieve with the silica-alumina ratio of 120 into a hydrogen type molecular sieve HZSM-5 by using 1.0mol/L HCl;

(2) pressurizing, extruding and molding, and treating for 8 hours by using high-temperature water vapor at 400 ℃;

(3) washing off non-framework aluminum by using 2.0mol/L dilute nitric acid, and then washing the molecular sieve by using deionized water until the washing liquid is neutral;

(4) then washing the molecular sieve for 8 times by using a KCl solution, wherein the KCl loading is 12 percent, and preparing the potassium ion modified molecular sieve;

(5) magnesium modification by magnesium nitrate impregnation method, Mg (NO)₃)₂The loading capacity is 8%, and the magnesium modification can be carried out for multiple times, so that the distribution of the modified substances is more uniform;

(6) and finally, baking at the high temperature of 550 ℃, removing volatile matters, and obtaining the catalyst for synthesizing durene by alkylating pseudocumene and methanol.

The catalyst is used for synthesizing durene by alkylating pseudocumene and methanol, and the synthesis steps are as follows:

(1) pseudocumene and methanol in a molar ratio of 2: 1, heating by a preheater at 320-350 ℃ for gasification;

(2) after the pseudocumene and the methanol are gasified, the pseudocumene and the methanol are heated by a heating furnace and then enter a reactor, the reaction temperature in the reactor is 280-420 ℃, the reaction pressure is 1.0-2.0MPa, and the mass space velocity is 0.5-1.0h^-1A catalyst bed filled with the catalyst is arranged in the reactor;

(3) after catalytic reaction in a catalytic bed, cooling, decompressing and dividing water, reducing the pressure to normal pressure, and rectifying to obtain durene and a byproduct high-boiling-point aromatic solvent; the product durene content was analyzed by gas chromatography to be 29.4%;

(4) cooling again for crystallization or rectification separation to obtain durene.

Example 4

Screening of Potassium chloride load

Varying the potassium chloride loading alone on the basis of example 1, the following table can be obtained:

in the above table, the loading amount of potassium chloride is preferably 8 to 15%, and the selectivity of durene is better.

Example 5

Screening of magnesium nitrate load

On the basis of example 1, varying the magnesium nitrate loading alone, the following table can be obtained:

in the table above, when the loading of magnesium nitrate is 5-10%, the selectivity of durene is good. When the content of durene is less than 5%, the durene content is rapidly reduced, and when the content of durene is more than 10%, the durene content is not obviously changed, so that the loading amount of magnesium nitrate is preferably 5-10%.

The present invention is not limited to the above-mentioned embodiments, and based on the technical solutions disclosed in the present invention, those skilled in the art can make some substitutions and modifications to some technical features without creative efforts according to the disclosed technical contents, and these substitutions and modifications are all within the protection scope of the present invention.