Method for preparing high-quality ethanol through hydrogenating acetic acid

Abstract

The invention discloses a method for preparing ethanol through hydrogenating acetic acid. The method comprises the steps of directly carrying out gas phase hydrogenation on acetic acid so as to prepare a crude ethanol product, separating a liquid phase by a gas-liquid separation tank, and then, carrying out liquid phase hydrogenation, thereby obtaining high-selectivity ethanol. The method has the advantages that the quality of the final ethanol product can be improved, and the energy consumption of a subsequent separation process can be effectively lowered.

Description

technical field [0001] The invention belongs to the field of catalytic hydrogenation, in particular to a method for preparing ethanol through hydrogenation of acetic acid. Background technique [0002] 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 hydration method in my country is basically in a state of suspension. The main raw material of the fermentation method is crops (including corn, sugarcane, sorghum, cassava, rice, etc.), and ethanol is obtained by fermenting the starch in the crops. The raw materials used by my country's main ethanol production enterprises are corn, wheat and cassava (mainly rely on imports). In fact, the cost of food has risen sharply in recent...

AI Technical Summary

Problems solved by technology

[0010] The present inventor has also carried out careful research on the direct gas-phase hydrogenation of acetic acid. After research, it is found that it is relatively difficult to achieve a higher ethanol selectivity (98mol%), because it requires extremely high selectivity to achieve such a selectivity. The molar ratio of hydrogen to acetic acid (>30), because hydrogen needs to be recycled, such a high molar ratio of hydrogen to acetic acid will greatly increase the energy consumption of the compressor, and the energy consumption of the entire system will also be very high

[0011] The direct hydrogenation of acetic acid liquid phase discloses few documents and patents, and this is because acetic acid is a highly corrosive organic acid, and the corrosiveness of its liquid phase is particularly serious. Therefore, as described in European Patent US EP0198681, in In liquid phase direct hydrogenation of acetic acid, the catalysts used are rapidly deactivated, which makes the process not commercially viable

Images