Recovery of 1,3-butadiene from a C.sub.4 -hydrocarbon mixture

A process for the recovery of 1,3-butadiene, using a selective solvent, from a C.sub.4 -hydrocarbon mixture containing 1,3-butadiene, hydrocarbons which are more soluble in the selective solvent than 1,3-butadiene, including higher acetylenes and hydrocarbons which are less soluble in the selective solvent than 1,3-butadiene, which comprises:

• separating the C.sub.4 -hydrocarbon mixture in a first extractive distillation zone into a distillate containing the less soluble hydrocarbons and an extract of 1,3-butadiene, the more soluble hydrocarbons and the selective solvent;
• removing the selective solvent from the extract to obtain a mixture of 1,3-butadiene and the more soluble hydrocarbons;
• passing the mixture of 1,3-butadiene and the more soluble hydrocarbons through a second extractive distillation zone to obtain 1,3-butadiene as a distillate and an extract containing the more soluble hydrocarbons including the higher acetylenes and a residue of 1,3-butadiene and the selective solvent;
• recovering from the extract a stream containing the more soluble hydrocarbons including the higher acetylenes and 1,3-butadiene having a content of acetylenes of from 10 to 60% by weight;
• subjecting the acetylenes-containing stream to selective catalytic hydrogenation in the presence of hydrogen and a hydrogenation catalyst to selectively hydrogenate the acetylenes;
• and adding the hydrocarbon stream obtained after hydrogenation to the starting C.sub.4 -hydrocarbon mixture.