Impact of barium and lanthanum incorporation to supported Pt and Rh on α-Al2O3 in the dry reforming of methane

The dry reforming of CH4 by CO2 has been studied, between 300 and 900 °C, over monometallic platinum and rhodium based catalysts supported on α-Al2O3 doped with La2O3 and BaO. Those catalysts were prepared by conventional wet impregnation and characterized by various physicochemical techniques (nitrogen adsorption, X-ray diffraction, XPS analysis and H2-temperature-programmed experiments). It was found that Pt and Rh incorporation leads to different types of interactions with La and Ba-modified α-Al2O3. As observed, Pt would preferentially interact with Ba inducing an inhibiting effect on the rate of the CH4/CO2 reaction reflected by a significant increase in the apparent activation energy. On the other hand, the preferential interaction of Rh with lanthanum oxide after Ba incorporation leads to the preservation of the catalyst activity. Such changes in catalytic properties have been discussed in the light of surface characterization and previous mechanistic information related to the occurrence of a bi-functional mechanism involving the metal/support interface.