Marked Effect of Various Supports and Additives Upon Liquid Phase Methanol Reforming with Water over Supported Group 8–10 Metal Catalysts

Abstract

The support effects (SiO2, TiO2, Al2O3, MgO, CeO2 and ZrO2) as well as addition effect of group 6b and 7b elements were studied over various supported group 8–10 metal catalysts. Basic oxide support improved the selectivity to CO2 and acidic support suppressed the catalytic activity and selectivity. Among the investigated catalysts Pt–Mo/TiO2 was the most active catalysts, whereas Ir–Re/SiO2 was the most selective catalysts for H2 and CO2 formation. The mechanism of the liquid phase methanol reforming reaction over silica supported Pt–Ru catalyst was studied by kinetic investigations. The rate of H2 formation over Pt–Ru/SiO2 catalysts was more than 20 times faster than that over Pt/SiO2 catalysts with high selectivity for CO2 (72.3%), indicating a marked addition effect of Ru. In the case of HCHO–H2O reaction over Pt–Ru/SiO2, the H2 formation rate was five times larger than that in the CH3OH–H2O reaction but selectivity to CO2 was only 4%. On the contrary, in the HCOOCH3–H2O and HCOOH–H2O reactions, both high activity and selectivity were observed over Pt–Ru/SiO2. These results clearly indicate that the CO2 formation does not proceed via HCHO decomposition and following water gas shift reaction.