Method for preparing ethanol and co-producing mixed solvent through acetic acid hydrogenation

Abstract

The invention provides a low-energy consumption method for preparing ethanol and co-producing a mixed solvent through acetic acid hydrogenation. The method comprises 1, gas phase hydrogenation, 2, gas-liquid separation, 3, esterification reaction and 4, product refining: feeding a liquid product B into a neutralization reactor, adding an alkaline substance into the reactor, carrying out a neutralization reaction process, feeding the neutralization product into a first rectifying tower, feeding a part of the first rectifying tower top fraction back to a gas phase hydrogenation reactor, feeding the first rectifying tower bottom fraction into a second rectifying tower, feeding a part of the second rectifying tower top fraction back to the gas phase hydrogenation reactor, collecting a part of the second rectifying tower top fraction as a mixed solvent, wherein the mixed solvent comprises ethanol, ethyl acetate and water according to an ethanol-ethyl acetate mass ratio of 1: 0.05-1.1, has water content of 1-15wt% and an acidity value of 0-30mg / L and the second rectifying tower bottom fraction contains water, acetate and butanol, feeding the second rectifying tower bottom fraction into a third rectifying tower, and carrying out separation to obtain a third rectifying tower bottom fraction containing water, acetate and butanol and a third rectifying tower top fraction containing ethanol and water, wherein the third rectifying tower top fraction has ethanol content of 85-95wt% and an acidity value of 0-25mg / L. The method can reduce energy consumption and improve ethanol product quality.

Description

technical field [0001] The present invention relates to a kind of method of producing ethanol, more specifically, relate to a kind of method of preparing highly selective ethanol product by acetic acid hydrogenation. Background technique [0002] Ethanol is the earliest and most widely used fatty alcohol, and it is also the main component of wine. At present, the industrial production methods of ethanol mainly include fermentation method and ethylene hydration method. Ethylene hydration method is developed along with the rise of petrochemical industry, including indirect hydration method and direct hydration method. Due to the increase of ethylene production cost in recent years, the ethylene process is basically in a state of suspension in my country. The main raw material of the fermentation method is crops (including corn, sugarcane, sorghum, cassava, rice, etc.), and ethanol is obtained by fermenting starch in the crops. [0003] The raw materials used by my country's...

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Problems solved by technology

In these patents, acetic acid is generally removed first by rectification, which can reduce the material requirements in the subsequent separation, thereby reducing investment costs, but there are also some problems: ethanol and ethanol, which account for the vast majority of product quality Water needs to be vaporized, so the energy consumption of rectification and deacidification is extremely high, and the deacidification tower has a large size and high material requirements, and the investment cost is extremely high; and in the actual rectification separation, there may be a very small amount of In the case of acetic acid, fuel ethanol and industrial ethanol products have strict requirements on acidity, so the product is unqualified in the case of operational fluctuations

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