Catalytic combustion of propane over Pt and Cu modified ZSM-5 zeolite catalysts

ZSM-5 zeolites were modified with copper and platinum by ion exchange and during the process of hydrothermal zeolite synthesis. The catalytic activity of the prepared Pt and Cu ZSM-5 zeolite catalysts was tested for complete oxidation of propane. It was observed that the mode of introduction of metals into the zeolite and the metal content influenced the catalytic activity. Copper introduced into the zeolite by ion exchange under basic conditions exhibited a high catalytic activity. Combustion efficiencies of 98.9 and 97.6% were achieved with the Cu ZSM-5 and Pt ZSM-5 catalysts containing 5.2 wt% Cu and 0.27 wt% Pt, respectively. The light-off temperature of the platinum containing catalyst was about 30 K lower than that of the 5.2 Cu ZSM-5 catalyst. The Cu ZSM-5 prepared during the process of hydrothermal synthesis exhibited a lower catalytic activity as compared to the ion exchanged Cu ZSM-5 catalysts. Temperature programmed desorption (TPD) measurements of CO and O₂ were used to interpret the catalytic activity. The results indicated the important role of the extra lattice oxygen on these catalysts.