Kinetics of ammonia oxidation on stepped platinum surfaces. I. Experimental results

The kinetics of ammonia oxidation with oxygen have been investigated in the 10−5 and 10−4 mbar range on Pt(5 3 3) and Pt(4 4 3). Only N2 and NO but no N2O were detected as reaction products. The dependence of product formation on temperature and on the partial pressures of the reactants has been studied under steady state conditions. The reactive sticking coefficients were determined under reaction conditions with sreac of ammonia reaching nearly 0.2. The Pt(5 3 3) surface was found to be catalytically more active than Pt(4 4 3) by a factor of 2-4.