Showing papers by "Preeti Aghalayam published in 2008"

Bifurcation analysis on PT and IR for the reduction of NO by CO

Abstract: Due to the importance of the NO-CO reaction in current catalytic converters, reduction of NO by CO on Pt group catalysts is important to study. Various reaction mechanisms have been proposed for the NO-CO reaction on Pt(100), which shows bifurcations, kinetic oscillations and multiple steady states under ultra high vacuum (UHV) conditions due to complex surface dynamics. Some experiments on supported Pt group catalysts reported in literature show oscillations and bistability under atmospheric conditions as well. Industrially relevant conditions require the modelling and detailed analysis of the system at atmospheric pressure. We have proposed a reaction mechanism for the NO-CO system on Pt group catalysts and coupled it with an isothermal PSR model to obtain solutions at atmospheric conditions with the continuation software CONTENT 1.5, at different operating conditions. Simulation results suggest that Pt(111) shows bifurcations at certain operating conditions while Ir(111) shows stable solutions at all the operating conditions studied here. En raison de l'importance de la reaction entre NO et CO dans les convertisseurs catalytiques habituels, il est important d'etudier la reduction de NO par le CO sur des catalyseurs du groupe Pt. Divers mecanismes de reaction ont ete proposes pour la reaction de NO-CO sur Pt(100), qui montre des bifurcations, des oscillations cinetiques et de multiples etats permanents dans des conditions de vide extreme en raison de la dynamique de surface complexe. Certaines experiences dans la litterature scientifique sur des catalyseurs de groupe Pt supportes montrent en outre des oscillations et une bi-stabilite dans des conditions atmospheriques. Des conditions industrielles pertinentes requierent la modelisation et l'analyse detaillee du systeme a la pression atmospherique. On a propose un mecanisme de reaction pour le systeme de NO-CO sur des catalyseurs de groupe Pt et on l'a couple avec un modele PSR isotherme afin d'obtenir des solutions dans des conditions atmospheriques avec le logiciel de continuation CONTENT 1.5, dans differentes conditions operatoires. Les resultats des simulations suggerent que Pt(111) montre des bifurcations a certaines conditions operatoires, tandis que l'Ir(111) montre des solutions stables a toutes les conditions operatoires etudiees ici.

Direct Methane Proton Exchange Membrane Fuel Cell

Abstract: The direct methane proton exchange membrane fuel cell was demonstrated for the first time. A Nafion membrane doped with phosphoric acid was used as the electrolyte. Pd/C, Pd-Ru/C and Pd-Au/C were studied as the anode catalysts with catalyst loading of 0.2mg/cm2. Selection of these catalysts for the studies was made based on the activation energy obtained by calculation using the UBI-QEP method. It was shown among these catalysts; Pd-Au/C anode exhibited a maximum open circuit voltage of 0.55V with current density of 30mA/cm2. It was also seen that by bleeding oxygen on anode side, open circuit voltage was 0.74V and current density was increased to 160mA/cm2.