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 (SL=0.88). The surface composition of silica-alumina catalysts is apparently not affected by thermal treatments whether in argon or in CO/H2 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. © 1993.