MICROCALORIMETRIC AND INFRARED SPECTROSCOPIC STUDIES OF CO, C2H4, N2O, AND O-2 ADSORPTION ON CU-Y ZEOLITE

Microcalorimetric and infrared spectroscopic techniques were used to probe the interactions of carbon monoxide, ethylene, oxygen, and nitrous oxide with Cu-Y zeolite and Cu/SiO2. Treatment of Cu-Y zeolite in hydrogen produces Cu1+ cations that adsorb carbon monoxide and ethylene at 313 K with initial heats of 80 and 90 kJ/mol, respectively. Carbon monoxide is linearly adsorbed on Cu1+ cations, and ethylene is pi-adsorbed on these cations. The corresponding heats of adsorption of these molecules at 313 K on silica-supported metallic copper are lower than on Cu1+ cations, equal to 64 and 60 kJ/mol, respectively. Cuprous cations in Y zeolite do not decompose N2O and adsorb oxygen more weakly than metallic copper at temperatures up to 473 K. The heat of O-2 adsorption on Cu1+ cations is equal to 95-170 kJ/mol, and this value is considerably lower than the value of 400 kJ/mol for metallic copper estimated from results of N2O decomposition.