Method for preparing dimethyl ether by dehydration of methanol

Abstract

The invention discloses a manufacturing method of dimethyl ether hydrated by carbinol, which comprises the following steps: introducing raw material with carbinol into catalytic distilling tower; hydrating at least partial carbinol to produce dimethyl ether and water; guiding partial steam from the top of catalytic distilling tower into autoclave of second distilling tower; using liquid-phased material in the second distilling tower as reflux liquid to lead into top of catalytic distilling tower; obtaining the mass with dimethyl ether as main component of top of second distilling tower; introducing liquid-phased mass of catalytic distilling tower into the third distilling tower; obtaining the mass with carbinol as main component of third distilling tower to lead into top of catalytic distilling tower or autoclave of second distilling tower; draining water mass as main component from the autoclave of third distilling tower.

Description

technical field [0001] The invention relates to a method for producing dimethyl ether from methanol, in particular, the invention relates to dehydration and separation of methanol in a catalytic distillation tower in the presence of a solid acid catalyst, and combined with a simplified distillation A method for producing dimethyl ether by combining a distillation column with a conventional distillation column. Background technique [0002] Dimethyl ether is a widely used chemical product, which can be synthesized by one-step synthesis of methanol dehydration and synthesis gas. The methanol dehydration method first used sulfuric acid as a catalyst, and the reaction was carried out in the liquid phase. The main disadvantages were equipment corrosion and serious environmental pollution. In the current industrial production, the method of producing dimethyl ether by gas-phase dehydration of methanol using solid acid catalyst has become the main production method. [0003] U.S....

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Problems solved by technology

[0011] 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 vapor 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%. 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.

In the disclosed catalytic distillation method, since the separation of the reaction and the product is completely completed in a catalytic distillation tower, the relative volatility between the components is small under high temperature and high pressure, thus requiring a large number of trays and relatively low equipment investment. High, and the operation of the catalytic distillation tower needs to take into account the optimization of the reaction conditions and the requirements of the purity of the product dimethyl ether and the content of methanol in the waste water, and the operation flexibility is small

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