Coadsorption and interaction of nitric oxide and carbon monoxide on Rh supported on highly dealuminated Y zeolite. Formation of mixed Rh carbonyl–nitrosyls on the surface

Abstract

The interaction of NO and CO with Rh supported on highly dealuminated zeolite Y (US-Ex) has been investigated by FTIR spectroscopy at temperatures between 300 and 573 K. The interaction of NO with oxidized or reduced Rh/US-Ex results in the formation of a well defined Rh dinitrosyl species with IR bands at 1855 and 1780 cm^–1. Other surface nitrosyl species were found to be dependent on the Rh particle size and the interaction conditions. With CO and NO in the gas phase well defined mixed surface complexes Rh^I(CO)(NO)₂(ν_CO= 2103 cm^–1; ν_NO= 1772, 1711 cm^–1) and Rh(CO)₂(NO)(ν_CO= 2162, 2128 cm^–1; ν_NO= 1786 cm^–1) were observed at room temperature in addition to Rh^I(CO)₂ and Rh^I(NO)₂. At higher temperatures, gaseous N₂O and CO₂ and isocyanate, adsorbed on the support, were observed depending on the conditions.