Transient analysis of reactions between NO and H2 with Pt-Al2O3 thin film catalyst

A specially designed apparatus employing (1) pulse valves for injection of reactant molecules onto catalysts and (2) a time-of-flight mass spectrometer was used to investigate processes of NO + H2 reaction using Pt-Al2O3 thin film on Si substrate. First, the planar layer of the catalyst was located in a vacuum chamber and the reactants were supplied onto the surface by pulse valves. This process is considered to involve few consecutive reactions. There, the transient production of N2 and NH3 was observed simultaneously. Second, the reactants were supplied into the micro reactor filled with square pieces of planar catalysts spaced with SiC balls. Here, N2O was observed as well as NH3 and N2. The experiments and the numerical simulation of the NO and H2 reaction rates clearly elucidated some aspects of NO reduction passes, i.e., while N2 and NH3 were directly produced from N and H adatoms dissociated from NO and H2 admolecules, N2O was produced via consecutive process of NO reduction with NH3 molecules which were produced in transient reactions.

Transient pulse techniques using time-of-flight mass spectrometry were used to investigate the reduction of NO by H2 over Pt/Al2O3 thin film. A typical result measured at 400 °C shows different behaviors of N2, NH3 and N2O. Changing the temperature with corresponding numerical simulations, we elucidated that N2O was produced via a consecutive process of NO reduction with NH3 molecules.Figure optionsDownload as PowerPoint slide