Kinetics of NO Decomposition on Silica-Supported Rhodium

Article abstract of DOI:10.1021/j100242a025

Temperature programmed desorption (TPD) spectroscopy was used to study the desorption and decomposition of NO adsorbed on a Rh/SiO2 catalyst.At room temperature, less than about 9percent of the NO is adsorbed dissociatively, and hence associative adsorption predominates.Upon heating the catalyst, tha adsorbed NO undergoes extensive decomposition to form N2 and O2, as well as small amounts of N2O.The TPD spectra show two peaks for N2, but only single peaks for NO, N2O, and O2.It is suggested that the two N2 peaks are attributable to the following processes:N_s + NO_s -> N2 + O_s + S and 2N_s -> N2 + 2S.N2O is taken to be formed by the process N_s + NO_s -> N2O + 2S.Rate parameters for the elementary processes involved in NO desorption and decomposition were determined by forcing agreement between simulated and observed TPD spectra.The preexponential factor and activation energy for NO desorption determined this way are 1E-15 s^-1 and 23.7 kcal/mol, respectively.