Activity of noble metal-promoted hydroprocessing catalysts for pyridine HDN and naphthalene hydrogenation

An important step in the upgrading of coal and coal-waste coprocessing liquids is the removal of heteroatoms, particularly nitrogen, which tend to poison the downstream cracking operations required to lower boiling points to the transportation fuels range. This requirement has motivated research to improve the activity of current hydroprocessing catalysts. In this regard we have examined the effects of Pt, Ru, and Ir promotion on three commercial Al2O3-supported catalysts (NiMo, CoMo, and NiW) using the model compounds, pyridine and naphthalene, to investigate hydrodenitrogenation and ring hydrogenation reactions, respectively. For pyridine hydrodenitrogenation (HDN), the activity of the sulfided catalysts was better than that of the oxide forms. For sulfided forms of NiMo, all noble metals tested improved the HDN activity. The activity of CoMo was improved by Pt and Ir while NiW was not improved by any noble metals promotion. For ring hydrogenation (HYD) of naphthalene, the Pt-promoted catalysts were more active than the original catalysts in the oxide forms, while the activities of both catalysts were similar after sulfidation. However for ring HYD in the presence of N, the Pt-promoted catalysts exhibited a distinct advantage.