Method for industrial preparation of ethanol

In industry, ethanol is usually produced by starch fermentation or direct hydration of ethylene:

1. Fermentation method

Fermentation to produce ethanol was developed on the basis of wine making, and it was the only industrial method to produce ethanol for a long period of time. The raw material of fermentation method can be agricultural products containing starch, such as cereals, potatoes or fruits of wild plants. You can also use waste molasses from sugar factories; Or use sawdust containing cellulose, plant straw, etc. After some pretreatment, these substances are hydrolyzed (using waste honey as raw material) and fermented to produce ethanol.

The mass fraction of fermentation broth is about 6%~ 10%, and it contains some other organic impurities. After rectification, 95% industrial ethanol can be obtained.

2. Ethylene hydration method

Direct hydration of ethylene means heating.

In the presence of pressure and catalyst, ethylene directly reacts with water to produce ethanol;

ch2═ch2

+

h─oh→c2h5oh

(The reaction is carried out in two steps. The first step is to react with mercury salts such as mercury acetate in water-tetrahydrofuran solution to generate organic mercury compounds, and then reduce them with sodium borohydride. )

. The raw material ethylene in this method can be taken from petroleum pyrolysis gas in large quantities, with low cost and large output, which can save a lot of grain, so it develops rapidly.