Method for preparing dimethyl ether through methanol dehydration

Abstract

The invention discloses a method for preparing dimethyl ether (DME) through methanol dehydration. According to the method, a catalyst A and a catalyst B are subjected to graded loading. The catalyst A is composed of an active component heteropoly acid ammonium salt, an auxiliary agent lanthanum oxide and / or cerium oxide, and a carrier silicon oxide. The catalyst B is composed of an active component heteropoly acid, an auxiliary agent lanthanum oxide and / or cerium oxide, and a carrier silicon oxide. According to the invention, the two catalysts cooperate with each other, and fully perform their advantages. Under a situation with a relatively low reaction temperature, the catalysts comprehensively have relatively high activity and selectivity.

Description

technical field [0001] The invention relates to a method for preparing dimethyl ether by dehydrating methanol, in particular to a method for preparing dimethyl ether by using a combined catalyst for dehydrating methanol. Background technique [0002] Dimethyl ether (Dimethy Ether, abbreviated as DME) is a colorless, non-toxic gas at normal temperature and pressure, which can be compressed into a liquid. Dimethyl ether is an important organic chemical raw material and chemical intermediate, which can be used in aerosols, refrigerants, alkylating agents, pharmaceuticals, cosmetics, fuels and other industries. [0003] Dimethyl ether was first produced by rectification of by-products in high-pressure methanol production, and soon developed into two processes of methanol dehydration and direct synthesis of synthesis gas. The liquid-phase method of methanol dehydration to produce dimethyl ether, the reaction is carried out in the liquid phase, the main disadvantages are severe e...

AI Technical Summary

Problems solved by technology

[0004] At present, the catalyst used for methanol dehydration is generally Al 2 o 3 Or molecular sieves, among which the commonly used molecular sieves include aluminum phosphate, HZSM-5, HY, SAPO, etc., and they all have their own shortcomings: for example, although alumina has high stability, the reaction temperature is high, and the requirements for reaction equipment are very high, resulting in cost High; molecular sieve catalysts have strong acidity and low initial temperature, but they also have the disadvantages of many by-products, easy carbon deposition, and easy deactivation

Moreover, due to the equilibrium limitation of the reaction, as the bed temperature increases, the activity of the catalyst will be significantly limited, and the advantages of catalyst activity will not be exerted.

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