Process method for producing dimethyl ether by dehydrating methanol in liquid phase

Abstract

The invention provides a method for producing dimethyl ether by dehydrating methanol. The method comprises the following steps: firstly performing two-stage heat exchange on methanol, further heating to 120-160 DEG C, and then dehydrating to generate a mixture of dimethyl ether, methanol and water under the action of a catalyst; directly separating and purifying the generated dimethyl ether mixture to obtain a qualified dimethyl ether product and alcohol-containing process water; directly separating and purifying the obtained alcohol-containing process water to obtain qualified methanol and qualified wastewater; heating obtained qualified methanol to 120-160 DEG C, further performing dehydration reaction, and further separating and purifying the obtained mixture of dimethyl ether and the water to obtain the qualified dimethyl ether product and qualified wastewater. The method has the following advantages: (1) the process flow is simple, devices are few, the occupied area is saved and the investment is low; (2) the reaction temperature is low, the conversion rate is high, the selectivity is good, side effects are avoided, and material consumption and energy consumption are low.

Description

technical field [0001] The invention relates to the technical field of chemical production, in particular to a process for producing dimethyl ether by liquid-phase methanol dehydration. Background technique [0002] Dimethyl ether is also called methyl ether, or DME for short. As a basic chemical raw material, dimethyl ether can be widely used in industry, agriculture, medical treatment, daily life and other fields due to its good characteristics of easy compression, condensation and vaporization. In the future, DME will be mainly used to replace automobile fuel, liquefied petroleum gas, city gas, etc., and the market prospect is extremely broad. [0003] The methanol dehydration method was the first to use the sulfuric acid method for dehydration, and the reaction was carried out in the liquid phase. The main disadvantages were severe equipment corrosion, harsh operating conditions, and serious environmental pollution. At present, the production methods of dimethyl ether ...

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Problems solved by technology

[0003] The sulfuric acid dehydration method was first used in the methanol dehydration method, and the reaction was carried out in the liquid phase. The main disadvantages were serious equipment corrosion, harsh operating conditions, and serious environmental pollution.

At present, the production methods of dimethyl ether mainly include: (1) using methanol vapor phase dehydration to produce dimethyl ether, advantages: the purity of dimethyl ether can reach 99.9%, disadvantages: the reaction temperature of methanol dehydration is relatively high, generally 200-380 ° C, and methanol The purity of raw materials also has certain requirements; (2) DME is produced by catalytic distillation. Advantages: methanol dehydration reaction and product separation are carried out in a catalytic distillation tower at the same time. Disadvantages: more plates, higher equipment investment, and flexible operation smaller

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