Modelling of hydrotreating catalysis based on the remote control: HYD and HDS

The remote control theory was used to construct a comprehensive kinetic model of hydrodesulfurization (HDS) and hydrogenation (HYD) on sulfided catalysts. The work makes an attempt to reflect in a more precise way the structure of the active sites. By considering available information on the HYD and HDS catalysis over promoted MoS2 type catalysts, several new kinetic models were developed. They were inserted into a continuous stirred tank reactor (CSTR) model to simulate both the steady states and the dynamic trends of the hydrodesulfurization and hydrogenation of model feeds represented by a mixture of thiophene and unsaturated hydrocarbons. These trends are qualitatively compared with the experimental observations in order to discriminate these slightly different models. It is found that the interconversion of HYD sites to HDS sites necessitates spillover hydrogen rather than the adsorption of hydrogen sulfide. The models based on the remote control are able to predict synergetic behaviors observed in experiments. (C) 1997 Elsevier Science B.V.