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 H-2 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 H-2, 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. (C) 2012 Elsevier B. V. All rights reserved.