Process and installation for the conversion of C4 and C5 olefinic fractions into ethers and propylene

The conversion of a 4-5C olefinic cut into an ether and propylene is claimed, the cut contg. di-olefins,alpha-olefins,iso-olefins, and acetylenic impurities. Process comprises the following stages: (1) selective hydrogenation of the di-olefins and acetylenic impurities with simultaneous isomerisation of alpha- into internal olefins, by passing the cut over a metallic catalyst (Ni, Pd or Pt) on a support, at 20-200 deg., 1.5MPa and VVH of 0.5-5 (pref. 1-3). An effluent contg. mainly internal and isoolefins is obtd. and no di-olefins or acetylenics; (2) the iso-olefins are etherified with an alcohol in the presence of an acid catalyst at 30-130 deg.C and a pressure such that the reactive mixt. is liq., sepn. of the ether and alcohol taking place simultaneously or after etherification. The effluent obtd. comprises mainly internal olefins and oxygenated impurities; (3) the oxygenated impurities are separated from stage (2); (4) the effluent from stage (3) is subjected to metathesis with ethylene in the presence of a Rh oxide catalyst on a support at 0-100 deg.C and at a pressure equal to the vapour pressure of the reaction mixt. at the reaction temp., so as to produce an effluent contg. propylene, which is then separated. Also claimed is the appts. for effecting this process.