Olefin plant recovery system employing a combination of catalytic distillation and fixed bed catalytic steps

A method of processing a thermally cracked feed stream containing hydrogen, ethylene, propylene, acetylene, methyl acetylene, propadiene and other C4, C5, C6 and heavier unsaturated hydrocarbons to hydrogenate and convert essentially all of said acetylene in high proportion to ethylene and hydrogenate at least a portion of the methyl acetylene, propadiene and other C4, C5, C6 and heavier unsaturated hydrocarbons to olefins and to thereby consume a portion of said hydrogen without hydrogenating ethylene and propylene comprising the steps of:

• a. introducing said feed stream into a catalytic distillation column containing at least one hydrogenation catalyst bed and concurrently:
• (i) selectively hydrogenating a portion of said acetylene to form ethylene and hydrogenating portions of said methyl acetylene, propadiene and C4, C5, C6 and heavier unsaturated hydrocarbons and controlling the hydrogenation conditions whereby said ethylene and propylene are not hydrogenated;
• and
• (ii) separating by fractional distillation said feed stream into lighter hydrocarbons and heavier hydrocarbons;
• b. removing substantially all of the remaining portion of said hydrogen and said lighter hydrocarbons as a vapor phase overhead and substantially all of said heavier hydrocarbons as bottoms from said catalytic distillation column;
• c. introducing at least a portion of said vapor phase overhead into a vapor phase fixed bed reactor system containing a hydrogenation catalyst and hydrogenating the remaining portion of said acetylene to form further ethylene and hydrogenating further portions of said methyl acetylene, propadiene and C4, C5, C6 and heavier unsaturated hydrocarbons and controlling the hydrogenation conditions whereby said ethylene and propylene are not hydrogenated;
• and
• d. removing mixed product from said fixed bed reactor system.