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Al2O3-HZSM-5 compound solid acid catalyst prepared by chemical precipitation method

A composite solid acid, al2o3-hzsm-5 technology, applied in the direction of physical/chemical process catalysts, molecular sieve catalysts, chemical instruments and methods, etc., can solve the problems of many by-products, high reaction temperature, high equipment requirements, etc., to achieve high The effect of activity and stability, simple preparation process, and large external area

Inactive Publication Date: 2008-11-12
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0011] (1) The equilibrium conversion rate of the reaction is low, and a large amount of methanol needs to be recycled repeatedly, which increases the load of subsequent rectification separation;
[0012] (2) The high temperature reaction has strict requirements on the equipment, and the energy consumption of raw material pretreatment is relatively high;
[0013] (3) Under high temperature conditions, methanol dehydration is easy to generate hydrocarbons, long-chain hydrocarbons, and even carbon deposits on the surface of the catalyst, so the methanol consumption is high and the life of the catalyst is reduced
[0014] In addition, the catalyst currently used is generally a single Al 2 o 3 , HZSM-5, HY, SAPO, etc., they all have their own shortcomings; for example, although alumina has high stability, the reaction temperature is also high, and the requirements for reaction equipment are very high, resulting in high cost
Molecular sieve catalysts have strong acidity and low initial temperature, but have many by-products, easy carbon deposition, and easy deactivation

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] Weigh 13.06 grams of aluminum sulfate, add 170 grams of water, quickly add 8 grams of HZSM-5 after the aluminum sulfate is dissolved, then add saturated sodium carbonate solution dropwise to the mixed solution until the pH value of the solution is 8, and continue to stir for 2 hours. The precipitated Al 2 o 3 - The HZSM-5 composite solid acid precursor was washed with deionized water, dried in an oven at 60°C for 12 hours, and finally baked in a muffle furnace at 550°C for 4 hours.

[0028] Weigh 0.2 g of the catalyst prepared by the above method with a particle size of 40-60 mesh, and evaluate the methanol dehydration activity in a fixed-bed reactor. Reaction conditions: reaction temperature 190-270°C, reaction liquid feed flow / catalyst volume liquid air velocity 30h -1 . The conversion rates at different temperatures are shown in Table 1.

[0029] Table 1.Al 2 o 3 -HZSM-5 (CP-20%) conversion rate of methanol at different reaction temperatures

[0030] ...

Embodiment 2

[0032] Weigh 14.72 grams of aluminum nitrate, add 170 grams of water, quickly add 8 grams of HZSM-5 after the aluminum nitrate dissolves, then add ammonia solution (25-28wt%) dropwise to the mixed solution until the pH of the solution is 8, continue to stir 2 hours. The precipitated Al 2 o 3 - The HZSM-5 composite solid acid precursor was washed with deionized water, dried in an oven at 60°C for 12 hours, and finally baked in a muffle furnace at 550°C for 4 hours. The structure of the above sample is characterized by nitrogen adsorption, and the acid content is characterized by ammonia adsorption. The surface area of ​​the catalyst is 367.5m 2 / g, the external area is 247.7m 2 / g, the total acid content is 0.257mmol / g.

[0033]Weigh 0.2 g of the catalyst prepared by the above method with a particle size of 40-60 mesh, and evaluate the methanol dehydration activity in a fixed-bed reactor. Reaction conditions: reaction temperature 190-270°C, reaction liquid feed flow / cataly...

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Abstract

A process for preparing Al2O3-HZSM-5 composite solid acid catalyst by a chemical precipitation method comprises: mixing water-soluble aluminum salt and HZSM-5 molecular sieve as raw material, controlling the mass ratio of Al2O3 and the molecular sieve HZSM-5 to 1 / 20-6 / 10, adjusting PH value of the mixture solution to 8 by sodium carbonate or ammonia water, and subsequently washing, drying, baking and preforming the Al2O3-HZSM-5 composite solid acid precursor deposit to obtain the Al2O3-HZSM-5 composite solid acid catalyst. The preparation process of the invention is simple, and as the catalyst of the invention is used in the methanol dehydration reaction for producing dimethyl ether, high activity and stability at low temperature are achieved.

Description

technical field [0001] The present invention relates to a kind of preparation method of the catalyst that is used for the dehydration of methanol to prepare dimethyl ether, especially prepare Al by chemical precipitation method 2 o 3 -HZSM-5 composite solid acid catalyst. Background technique [0002] Dimethyl ether (molecular formula: CH 3 OCH 3 , Molecular weight: 46, boiling point 120-130 ° C, spontaneous ignition point 235 ° C) has a wide range of uses in chemical medicine, can be used as insecticides, polishing agents, rust inhibitors, alkylating agents, solvents, and can also be used as gas Sprays, hair sprays, air fresheners, household fuels, etc. As a green chemical, dimethyl ether has more prominent advantages in the aspect of alternative fuel for diesel engines. The cetane number of dimethyl ether is high (55-60), the combustion performance is good, and the emission of polluting tail gas can be reduced during combustion. At the same time, dimethyl ether is al...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J29/40B01J21/04C07C41/09C07C43/04
Inventor 张立伟侯昭胤吴佩金顶峰于翔费金华郑小明
Owner ZHEJIANG UNIV