Transient kinetic experiments were performed in order to study the catalytic reduction of NO by CO over a polycrystalline platinum surface. The experiments were performed by preadsorbing one reactant on the Pt surface at the reaction temperature and then rapidly introducing the second reactant in a pressure jump while monitoring the transient production of CO2. The CO2 production rate, RCO2, was modeled as a function of NO and CO coverages (θNOand θCO). When NO was preadsorbed, the reaction rate can be described by RCO2 = kθNOθCO (for the onset of the reaction) and RCO2 = k′θNOθfree sites (for the final portion). The onset of CO2 production showed no detectable induction period in these experiments. When CO was preadsorbed, the reaction rate is described by RCO2 = k″θNOθfree sites (for the onset of the reaction) and RCO2 = k″′(gqCO)2 (for the final portion). For CO preadsorption, a time delay in the onset of CO2 production which varied with temperature and the initial amount of preadsorbed CO was observed. Our transient kinetic results indicate that the reaction proceeds over a wide range of reaction conditions via a dissociative mechanism in which NO(a) first dissociates into N(a) and O(a), and then O(a) reacts with CO(a) to form CO2.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry