Photocatalytic decomposition of dinitrogen oxide on Cu-containing ZSM-5 catalyst

Abstract

Photodecomposition of dinitrogen oxide (N₂O) into N₂ and O₂ on Cu-exchanged ZSM-5 zeolite (ion-exchange degree, 145 %), degassed at 723 K, proceeds catalytically at 278 K. The dependence of the decomposition rate on the wavelength of the irradiated light reveals the importance of the excitation of monovalent Cu ions (<300 nm) in the photocatalytic decomposition of N₂O. The rate of decomposition can be expressed by the rate equation: r=a[N₂O]//_{([N2O]+b[O2]^½)}, where a and b are constants, and a is proportional to the light intensity.

The desorption of O₂ from the surface is not a rate-determining step in the photodecomposition or the thermal decomposition of N₂O on the zeolite which occurs with an apparent activation energy of 37 ± 3 kJ mol^–1.