CATALYSIS BY THE RH/B SYSTEM: Part 2. HIGHLY REGIOSELECTIVE VAPOUR PHASE HYDROFORMYLATION OF PROPENE AT ATMOSPHERIC PRESSURE ON RH/B ON SILICA AND SILICA-ALUMINA

A Rh/B catalyst prepared by reducing rhodium trichloride supported on silica and silica-alumina with NaBH4 at low temperature is used after thermal treatments in the vapour phase, propene hydroformylation in a flow reactor at atmospheric pressure. A good regioselectivity toward normal isomers, that remains constant at increasing temperatures, is detected (S(L) = 0.88). The surface composition of silica-alumina catalysts is apparently not affected by thermal treatments whether in argon or in CO/H-2 or in hydroformylation mixture flow. The geometrical arrangements of the active sites appear to play an important role in controlling the regioselectivity of the catalytic system.