Method for preparing ethanol through acetic acid hydrogenation

Abstract

The invention provides a low-energy consumption method for preparing ethanol 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 first rectifying tower, feeding a part of the first rectifying tower top fraction containing acetaldehyde, ethyl acetate and acetone back to a gas phase hydrogenation reactor, feeding the first rectifying tower bottom fraction as a crude ethanol product containing ethanol, ethyl acetate and water into a neutralization reactor, adding an alkaline substance into the neutralization reactor, carrying out a neutralization reaction process, feeding the neutralized first rectifying tower bottom fraction into a second rectifying tower, and carrying out separation to obtain a second rectifying tower top fraction containing ethanol and water and a second rectifying tower top fraction containing water, butanol and acetate, wherein the second 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 major ethano...

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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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