Analysis of the performance of the industrial Co-Mo catalyst for hydrotreatment

Abstract

The process of hydrotreatment of diesel fuel (fraction 180–320 °C) over fresh and spent (after two-year operation in an industrial reactor) Co-Mo catalyst was studied. It was established that the sulfur contents were rather close to one another in the diesel fuel samples treated using the fresh and spent catalysts, even though the specific surface area was 40 % smaller in the spent catalyst compared to that in the fresh sample. Dependence of effective constant keff of hydrodesulfurization on the temperature of low-temperature hydrotreatment (below 320–330 °C) was characteristic of the kinetic range of heterogeneous catalysis complicated by external diffusion resistance. When the temperature was elevated up to 420 °C, the process of diesel hydrotreatment transferred to the external diffusion region. Activation energies of hydrodesulfurization were comparable over the spent and fresh catalysts (81.1 and 80.5 kJ/mol, respectively). A hypothesis of the specific catalyst deactivation was discussed.