Corrélation entre l’activité catalytique d’un film métallique et la nature des radicaux chimisorbés. 2^e partie : évolution du catalyseur au cours de la réaction d’échange de l’hydrogène entre CH₄ et D₂

Site requirements in the kinetics of alkane transformations catalysed by metals

“…[12] and [13] Coekelbergs et al found some discrepancies in their interpretations compared to the ones of Kemball. In fact Kemball interpreted his results by a adsorptiondesorption mechanism where the slow step was desorption [14], and all his work was performed under static conditions which give much more complicated results even at initial conditions because the equilibrium is not reached.…”

“…Following these results they used CH 4 and D 2 on Mo film under dynamic conditions [13]. They wanted to understand the possible modification of the catalytic activity during the reaction.…”

“…If there are some changes, the catalytic activity will be responsible of that. Coekelbergs et al [13] observed an evolution of the different deuteromethane formed, which means that the catalytic activity was not stable with time. Such results suggested that the gas-solid system had not reached its equilibrium.…”

“…In the previous works [13,15] measurements of the catalytic activity of films of several metals were realized in a flow system, under stationary conditions. From such experiments the determination of the deuteromethanes' rates of formation, at the initial conditions were undertaken and Delaunois et al [18] developed an important work on the characterization of the metallic films to be able to compare quantitatively the results obtained on two films condensed at the same temperature.…”