Reforming of methane with carbon dioxide over supported bimetallic catalysts containing Ni and noble metal -: I.: Characterization and activity of SiO2 supported Ni-Rh catalysts

The activity and stability of silica supported monometallic Ni, Rh and bimetallic Ni-Rh catalysts have been studied towards the carbon dioxide reforming of methane. The catalysts were prepared by incipient wetness impregnation with different contents of Rh and Ni and they were characterized by H-2 chemisorption, TPRH2, XRD and FF-IR methods. SiO2 supported monometallic Ni, Rh and bimetallic Ni-Rh catalysts are comparably good catalysts for carbon dioxide reforming of methane and Rh-rich catalysts are resistant to deactivation and carbon formation. Temperature-programmed hydrogen assisted decomposition of bimetallic Ni-Rh/SiO2 catalyst precursors leads to formation of Ni-Rh alloys. Segregation of metals leads to the formation of Ni-rich surface alloy. TG-DTA-MS, TPSRH2, TPO, TPSRCO2, TOC and SEM methods were used in order to characterize the carbonaceous deposits. At least two types of carbon deposit with different reactivity have been detected on the surface of bimetallic catalysts. The results suggest a significant metal-metal interaction in the bimetallic systems. (C) 2004 Elsevier B.V. All rights reserved.