Rhenium Effect on the Performance of CoMoNi/γ-Al2O3 Catalyst in Thiophene Hydrodesulphurization. Performance Evaluation and Process Kinetics

The rhenium effect on the performance of CoMoNi/gamma-Al2O3 catalyst was studied in thiophene hydrodesulphurization. The unsulfided and freshly sulfided catalysts were characterized by N-2 adsorption-desorption, IR spectroscopy, X-ray photoelectron spectroscopy (XPS) and total acidity. The effects of reaction temperature, pressure, and liquid hourly space velocity (LHSV) on thiophene HDS performance shown that the activity of the CoMoNiRe/gamma-Al2O3 catalyst for thiophene HDS was superior to that of the CoMoNi/gamma-Al2O catalyst, which was mainly ascribed to the higher acidic functional groups. Based on Langmuir-Hinshelwood approach, a kinetic model for thiophene HDS over both catalysts have been developed. In this respect, two mechanisms have been considered, one hypothesizing that hydrogen is adsorbed on different active centers than thiophene (two-centers mechanism) and the other considering one type of active centers. Based on statistical reasons, the kinetic model considering two types of active centers proved to be more adequate in representing the experimental results.