| 摘要 |
Ethyl alcohol is prepared by contacting a low-grade hydrocarbon mixture containing 30-40 per cent by volume of ethylene, and propylene impurity, with sulphuric acid of a concentration of 95-100 per cent by weight on a hydrocarbon-free basis at 60-100 DEG C. and a pressure of 300-500 pounds per square inch gauge to produce an acid extract containing 1.0-1.3 mols. of ethylene per mol. of H2SO4, then further contacting said extract with a higher grade substantially propylene-free hydrocarbon gas containing 60-100 per cent by volume of ethylene for 1 to 3 hours at a temperature of 80-110 DEG C. and a pressure of 300-500 pounds per square inch gauge to produce an extract containing at least 1.4 mols. of ethylene per mol. H2SO4, and hydrolysing said extract with water to produce ethyl alcohol. The contacting time of 1-3 hours in the second stage converts the propylene present in the extract into compounds not convertible into alcohols in the final hydrolysis, thus yielding a purer ethyl alcohol, and in addition, increases the amount of ethylene absorbed and so provides a higher yield of ethyl alcohol. The process is adapted to the use of low-grade ethylene-containing hydrocarbon gas mixture containing from 0.1 to 5 per cent propylene. A suitable method comprises feeding a gas mixture containing 30-40 per cent ethylene and the remainder hydrogen, methane, ethane and propylene impurity up an absorber countercurrently to a stream of 95-100 per cent sulphuric acid, a portion of the resulting extract from about midway of the absorber being circulated to the top of the absorber to counteract the corrosiveness of the fresh acid; the temperature and pressure are maintained within the respective ranges defined above. An extract containing about 1.3 mols. ethylene is led from the bottom of the absorber and conducted to a tank maintained at a pressure of 300-500 lbs./square inch gauge and, preferably, a temperature of 85-95 DEG C.; a hydrocarbon gas containing 65-80 per cent ethylene and substantially free from propylene is continuously fed into the bottom of the tank and the subsequently enriched extract is then removed to a hydrolyzer for conversion into ethyl alcohol. In an example, an initial extract prepared as above and containing 1.3 mols ethylene per mol. H2SO4 is treated in the tank with the higher grade gas (76 per cent ethylene) for 1 hour at 80 DEG C. and 500 lbs/square inch pressure, so yielding an extract containing 1.53 mols. ethylene per mol. H2SO4.
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