KINETIC-ANALYSIS OF THE DECOMPOSITION OF NITROUS-OXIDE OVER ZSM-5 CATALYSTS

A detailed comparative kinetic analysis has been made of the N2O decom position over Co-, Fe-, and Cu-ZSM-5. The effect of partial pressure o f N2O, O-2, CO, and NO, the space time, and temperature have been inve stigated. The decomposition is first order in N2O over Fe- and Co-ZSM- 5 and has a slightly lower order over the Cu sample. Inhibition of oxy gen observed for Cu-ZSM-5 is absent for Co and for Fe at the lower tem peratures. N2O destruction is enhanced by CO for all catalysts and by NO for Fe-ZSM-5 only. In the presence of NO, NO2 is produced over Fe- and Co-ZSM-5. Over Cu-ZSM-5 the enhancement by CO passes through a max imum as a function of CO pressure due to the strong adsorption at redu ced sites. A detailed kinetic model that accounts quantitatively for t he observed dependencies and which deviates from the classical model f or oxidic systems is advanced. Estimates of the maximum turnover rates for the various model steps range from 10(-4) to 1 s(-1). (C) 1997 Ac ademic Press.