Comments on the HDS, HDM and HDN activities of commercial catalysts in the hydrotreating of heavy crude oils

Abstract

The influence of pretreatment conditions on the hydrodesulfurization (HDS), hydrodemetallization (HDM) and hydrodenitrogenation (HDN) activities of heavy crude oils was studied under industrial conditions. Sulfidation enhances both the HDS and HDM activities. The initial deactivation of sulfided catalysts is best interpreted in terms of sulfiding degree adjustment of the catalyst surface rather than by carbon or metal poisoning. Catalyst subject to different chemical pretreatments exhibits a similar evolution of HDS and HDM activities. A correlation between HDS, HDM and HDN is observed when commercial catalysts are tested under similar conditions. This correlation is not explained by intraparticle diffusion limitations or by degradation of asphaltene-type molecules. Results are interpreted assuming that HDM is a catalytic reaction for which the active phase is also involved in HDS and HDN.