Single column distillative separation employing bottom additives

A method for the distillative cryogenic separation of a hydrocarbon feed stream comprising CO.sub.2, C.sub.2, C.sub.3 and C.sub.4 + and employing a recycled bottom additive in a single distillative column containing vapor-liquid contacting devices, which method comprises:

• a) introducing the feed stream into a single distillative column;
• b) introducing a nonpolar liquid C.sub.4 + alkane additive agent into the upper portion of the column above the point of introduction of the feed stream;
• c) withdrawing an overhead product stream enriched in CO.sub.2 from the feed stream;
• d) condensing at least a portion of the condensed overhead product stream in a condenser and recycling a portion of the condensed overhead stream to the top portion of the distillative column;
• e) withdrawing a vapor side product stream, enriched in C.sub.2 or C.sub.3, and deficient in CO.sub.2 from the feed stream, at a point below the point of introduction of the feed stream, and substantially above the bottom of the column;
• f) withdrawing from the column bottom a bottom product stream comprising primarily C.sub.4 + alkanes;
• g) reboiling at least a portion of the withdrawn bottom product stream and recycling at least a portion of the bottom product stream to the bottom portion of the distillative column;
• and
• h) splitting the column bottom product stream into a majority, recycled bottom additive stream as in 1(b) and a minor, net heavy component recovery product stream.