AN FTIR STUDY OF THE INFLUENCE OF ENVIRONMENT CONDITIONS ON THE SUCCESSIVE HY-DROGENATIONS OF CO

\underline{C. PIRIM}, L. KRIM, UPMC Univ Paris 06, UMR 7075, Laboratoire de Dynamique, Interactions et Réactivité (LADIR), F-75005, Paris, France.

In a preliminary study, the reaction of CO successive hydrogenation has been performed at 3 and 10 K using a co-injection technique. A H/H_{2} mixture and CO molecules are codeposited on a cold mirror and hydrogen atoms are reacting step by step with CO as follows : CO → HCO → H_{2}CO → H_{3}CO → CH_{3}OH At 3 K, CO hydrogenation is limited to the first step of the reaction. However, when the reaction is performed at 10 K, CO hydrogenation is total and all intermediates are observed in the IR spectra. The aim of this present work is to understand the influence of the environment in wich the reaction takes place, in order to determine the best conditions promoting CO hydrogenation. Indeed, the catalytic potential of water molecules on CO hydrogenation has been more specifically studied. In this experiment, mixtures of (CO,H_{2}O) and H/H_{2} are co-injected at various concentrations and in a temperature range between 3 and 20 K. It is clear that water environnements induce noticeable changes by increasing the chemical reaction rate and promoting HCO conversion into H_{2}CO.