For the selective production of propylene from an olefinic C4 fraction,
a process is implemented that successively comprises:
- 1) the selective hydrogenation of butadiene with isomerization of butene-1
into butene-2;
- 2) the separation by distillation of a mixture that is rich in isobutene
and butene-1 at the top and a fraction that is rich in butene-2 at the bottom;
- 3) the skeletal isomerization of isobutene into n-butenes on the top
fraction, with recycling in stage 1; and
- 4) the metathesis of the butene-2-rich fraction with ethylene.
The advantage of this process is to produce in a very selective way polymerization-quality
propylene from all of the olefinic compounds of a C
4 fraction, including isobutene.
