Presented is an improvement to a previous invention involving the catalytichydrogenation of the C2 to C5 and heavier acetylenes and dienes in a thermallycracked feed stream without significantly hydrogenating the C2 and C3 olefins.The improvement involves the use of a fixed bed hydrogenation reactor systemin combination with a modified version of the catalytic distillation unit usedin the prior art. The modification to the catalytic distillation unit involvesimprovement of the liquid recycle scheme. The fixed bed reactors combined withthe modified catalytic distillation allows for 100% conversion of acetyleneand helps to maintain high conversion of the other dienes and acetylenes withno ethylene or propylene conversion under a variety of conditions. Thesecondition variations include but are not limited to the feed diene andacetylene composition, the mol% carbon monoxide in the feed, and catalystdeactivation. With catalytic distillation alone, complete conversion of theacetylene as stated above can not be achieved without ethylene loss, nor wouldsatisfactory operation and control be possible under the variety of conditionsexperienced during a commercial operation.
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