Effect of the nature of TiO2 support over the performances of Rh/TiO2 catalysts in the partial oxidation of methane

The effect of TiO2 phase composition on the catalytic and physico-chemical properties of supported Rh catalysts in the partial oxidation of methane were studied. Two types of TiO2 with different rutile/anatase crystalline phase compositions were used as support. The performance of supported Rh catalysts depends on the nature of the TiO2 support. CH4 conversion and selectivity towards H2 and CO are improved when using an anatase-rich TiO2 support, probably because it improves dispersion and reducibility of rhodium particles compared with the rutile-rich carrier. Both Rh/TiO2 catalysts produced more CO than H2, which suggests the involvement of other reactions such as dry reforming, steam reforming and water gas shift reactions. The anatase-rich catalyst is remarkably stable but its rutile-rich counterpart becomes deactivated after a few hours. This loss of activity is attributed to the oxidation of rhodium. With anatase-rich TiO2 catalyst the dispersion of rhodium is stabilized and its oxidation is avoided.