NOVELTY - A thermally cracked feed stream is processed by introducing feed stream into catalytic distillation column (14) containing hydrogenation catalyst bed (15), removing portion of hydrogen and lighter hydrocarbons as vapor phase overhead, introducing portion of vapor phase overhead into vapor phase fixed bed reactor system, and removing mixed product from fixed bed reactor system.    USE - The invention is used in the processing of thermally cracked feed stream containing hydrogen, ethylene, propylene, acetylene, methyl acetylene, propadiene, and other 4-6C and heavier unsaturated hydrocarbons to generate and convert all of the acetylene in high proportion to ethylene and hydrogenate portion of methyl acetylene, propadiene, and other 4-6C and heavier unsaturated hydrocarbons to olefins and consume portion of hydrogen without hydrogenating ethylene and propylene.    ADVANTAGE - The invention is able to maintain stable high conversion of all of the 2-5C acetylenes and dienes with 100% conversion of 2C acetylene.    DETAILED DESCRIPTION - The processing of thermally cracked feed stream containing hydrogen, ethylene, propylene, acetylene, methyl acetylene, propadiene, and other 4-6C and heavier unsaturated hydrocarbons to generate and convert all of the acetylene in high proportion to ethylene and hydrogenate portion of methyl acetylene, propadiene, and other 4-6C and heavier unsaturated hydrocarbons to olefins and consume portion of hydrogen without hydrogenating ethylene and propylene, involves introducing the feed stream into catalytic distillation column containing hydrogenation catalyst bed and concurrently hydrogenating portion of acetylene to form ethylene and portions of methyl acetylene, propadiene, and 4-6C and other heavier unsaturated hydrocarbons and controlling hydrogenation conditions in which ethylene and propylene are not hydrogenated, and separating by fractional distillation the feed stream into lighter and heavier hydrocarbons; removing portion of hydrogen and lighter hydrocarbons as vapor phase overhead and the heavier hydrocarbons as bottoms from the distillation column; introducing portion of the vapor phase overhead into vapor phase fixed bed reactor system containing hydrogenation catalyst and hydrogenating the remaining portion of acetylene to form further ethylene and hydrogenating further portions of the methyl acetylene, propadiene, and 4-6C and heavier unsaturated hydrocarbons and controlling the hydrogenation; and removing the mixed product from the fixed bed reactor system.    DESCRIPTION OF DRAWING(S) - The figure is a flow diagram illustrating the inventive method.    Charge gas (10)    Distillation column (14)    Beds (15)    Rectification section (20)    Fractionation internals (22, 24)    Stripping section (26)