CO hydrogenation over a rhodium vanadate catalyst:: Reduction and regeneration of RhVO4 on SiO2

The hydrogenation of CO over an Rh vanadate (RhVO4) catalyst supported on SiO2 (RhVO4/SiO2) has been investigated after H-2 reduction at 500 degrees C, and the results are compared with those of vanadia-promoted (V2O5-Rh/SiO2) and unpromoted Rh/SiO2 catalysts. The mean size of Rh particles, which were dispersed by the decomposition of RhVO4 after the H-2 reduction, was smaller (41 Angstrom) than those (91-101 Angstrom) of V2O5-Rh/SiO2 and Rh/SiO2 catalysts. The RhVO4/SiO2 catalyst showed higher activity and selectivity to C-2 oxygenates than the unpromoted Rh/SiO2 catalyst after the H-2 pretreatment. The CO conversion of the RhVO4/SiO2 catalyst was much higher than that of V2O5-Rh/SiO2 catalyst, and the yield of C-2 oxygenates increased. We also found that the RhVO4/SiO2 catalyst can be regenerated by calcination or O-2 treatment at high temperature after the reaction. (C) 1998 Elsevier Science B.V. All rights reserved.