Process for selective production of propylene from hydrocarbon fractions with four carbon atoms

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. By this process, it is possible to produce in a very selective way polymerization-quality propylene from all of the olefinic compounds of a C4 fraction, including isobutene.