Patent ID: 7935855

Claim:
A process for treating a feed comprising C4 acetylenic compounds, butadiene and a C5+ fraction comprising diethylenic and/or acetylenic compounds, including but not limited to pentadiene and/or cyclopentadiene, in which: i) the feed is sent to a step for distillation carried out in a distillation column, to separate a C4 cut that comprises substantially all of the butadiene in the feed and is recovered from the head of said column, a cut that is enriched in C5+ is recovered from a bottom zone of the column and a drawn fraction comprising C4 acetylenic compounds is withdrawn from a side stream of the column; ii) at least a portion of said drawn fraction is treated in at least one hydrogenation step; and iii) an effluent that is depleted in acetylenic compounds from the hydrogenation step is recycled to the distillation step; wherein the distillation step comprises: an initial step for pre-fractionation of the feed, which latter is supplied to a pre-fractionation zone ( 4 a , 4 b , 6 , 7 ) included in a distillation column, comprising a feed plate and lower plates, to obtain at least one intermediate stream with a reduced C5+ content at one or more intermediate levels of the column; and at least one step for fractionation by distillation of the intermediate stream or streams, carried out in a complementary fractionation zone at least a portion A ( 5 ) of which is distinct from and not adjacent to portion B ( 4 b , 7 ) of the pre-fractionation zone constituted by the feed supply plate and the lower plates, to withdraw the drawn fraction from a point in A located at a level in the column that is higher than the feed supply point and for which the mole ratio [C4/C5+] is higher than that of the feed; and in that recycling said effluent which is depleted in acetylenic compounds from the hydrogenation step is carried out to a level in the distillation column located above the level from which said drawn fraction is withdrawn and above said portions A and B.