Kinetic Models for the Hydrogenolysis of Thiophene. A Comparison of Hougen‐Watson Models with Fixed and Interconverting Sites for Hydrogenolysis and Hydrogenation

Abstract

AbstractA Hougen‐Watson model with interconverting sites (H.W.‐I.S.) has been formulated to account for the influence of H2 and H2S on the number of active sites. The model assumes that the ratio of the concentration of active sites for hydrogenolysis and hydrogenation depends upon the ratio of the partial pressures of H2 and H2S. Compared to the Hougen‐Watson model with a fixed number of active sites (H.W.‐F.S.), this H.W.‐I.S. model is less satisfactory for low partial pressures of H2S. For higher Ps/PH ratios, however, the H.W.‐I.S. model can compete with the H.W.‐F.S. model. These results suggest that only a fraction of the adsorbed sulfur is converted into an active site for hydrogenation and that most of the adsorbed sulfur is desorbed as H2S, leaving an active site for hydrogenolysis on the catalyst surface.