Sepn. of highly pure ethylene and propylene - from gas mixts. obtd. by hydrogenation of pyrolysed petroleum distillates

摘要

The gaseous mixt. comprises H2, methane, ethylene, acetylene hydrocarbons propylene, propane and traces of satd. 4C hydrocarbons. It is first hydrogenated to remove the acetylene hydrocarbons, the residual mixt. being cooled to very low temps. to abtain a condensate and an H2/methane gas mixt. which is sepd. The condensate is demethanised by rectification to obtain a still residue contg. ethylene, ethane, propane, propylene and satd. 4C hydrocarbons. This still residue is then rectified at a still temp. of 52-60 degrees C to obtain highly pure ethylene; the still residue is further rectified to obtain ethane and the residue obtd. rectified again to obtain highly pure propylene. Sepn. of thje ethylene, ethane and propylene is effected in separate rectifying columns. A suitable plant is described. Economy in energy and cost is achieved; no compressors are needed. Ethylene and proplene are obtd. in purities of up to 99.9 vol. %.