Method for preparing dimethyl ether from methanol

Abstract

This invention relates to a preparation method for dimethyl ether by dehydrating methanol under liquid phase or gas-liquid mixing state in a catalytic distillation tower loaded with a solid acid catalyst in reaction section, wherein the methanol has a content of 5~99.99 wt.%. Catalytic distillation tower operating conditions include pressure of 0.6~5.0 MPa, column top temperature of 30~124DEG C, reaction section central temperature of 120~220DEG C, column reactor temperature of 160~270DEG C, the reflux ratio at 3~50, and feed volume space velocity of 0.1-10 ml methanol / ml catalyst, Or the reactions are carried out in one fixed bed rector or 2~4 fixed bed reactors in series with reaction conditions of temperature 120~220DEG C, pressure 0.6~8.0 MPa, and feed volume space velocity 0.1-10 ml methanol / ml catalyst.

Description

technical field [0001] The invention relates to a method for producing dimethyl ether from methanol, specifically, in the presence of a solid acid catalyst, dehydrating methanol in a liquid phase or in a gas-liquid mixed state to produce dimethyl ether, in particular to A catalytic distillation method for producing dimethyl ether from methanol dehydration. Background technique [0002] Chinese patent CN 1036199A discloses a method for producing dimethyl ether from methanol. Methanol vapor is dehydrated on a γ-alumina catalyst containing a small amount of silicon dioxide, and the dehydrated product is sent to a rectification tower for rectification. Pure dimethyl ether Ether and impurities are withdrawn as side products on certain trays of the tower. [0003] Chinese patent CN 1125216 discloses a method for producing dimethyl ether from methanol. After methanol with a content of 72-99.9% is removed from high boilers and impurities in a gasification separation tower, gas-phas...

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Problems solved by technology

[0008] In the above inventions, the use of liquid acids such as sulfuric acid as catalysts will cause equipment corrosion and environmental pollution problems, and it is difficult to obtain high-purity dimethyl ether products by directly synthesizing dimethyl ether from synthesis gas

Using a solid acid catalyst to produce dimethyl ether from methanol gas-phase dehydration can obtain dimethyl ether with a purity of 99.9%, but the reaction temperature is relatively high, generally 200-380°C, and the single-pass conversion rate is about 70-80%, which has a great impact on the purity of methanol raw materials. There are also certain requirements. When the methanol reaction raw material has a high water content, it will inevitably lead to a decrease in the conversion rate per pass, and a high reaction temperature is not good for the stability of the catalyst.