Patent ID: 6916448

Claim:
An apparatus for the conversion of an olefinic C 4 fraction into isobutene and into propylene, successively comprising: 1) a selective hydrogenation zone with isomerization of butene-1 into butene-2, whereby said zone comprises at least one means ( 5 ) for introducing the C 4 fraction that is to be converted, at least one means ( 7 ) for the output of the effluent and at least one means ( 6 ) for the introduction of hydrogen, whereby said selective hydrogenation zone ( 1 ) also comprises at least one catalyst bed; 2) a separation that comprises at least one means ( 7 ) for introducing the effluent that is obtained from zone ( 1 ), at least one means ( 9 ) for the output of isobutene and butene-1, at least one means ( 8 ) for the output of butene-2 and n-butane; and 4) a metathesis zone that contains at least one catalyst bed and that comprises at least one means ( 8 ) for introducing output of butene-2 and n-butane that is obtained from zone ( 2 ), at least one means ( 11 ) for introducing ethylene and at least one means ( 12 ) for the output of propylene, whereby said apparatus also comprises a skeletal-isomerization zone ( 3 ) that comprises at least one means ( 9 ) for introducing the output of isobutane and butene-1 obtained from zone ( 2 ), at least one means ( 10 ) for recycling from the outlet of zone ( 3 ) to the inlet of zone ( 1 ) and at least one means ( 13 ) for purging the optionally present isobutane, whereby said skeletal-isomerization zone ( 3 ) also comprises at least one catalyst bed.