Pd-Rh promoted Co/HPS catalysts for heavy oil upgrading

This paper reports the promotional effects of Pd and Rh on hydrocracking (HC) and hydrodesulfurization (HDS) activity of Co/HPS catalyst. The catalysts were prepared by loading of noble metal followed by cobalt on the high porous saponite (HPS) support. The incipient impregnation technique was adapted for the loading of noble metal(s) while an ion exchange method was followed for cobalt loading on HPS. The catalysts were characterized by temperature-programmed reduction (TPR). Results showed that the reducibility of the catalysts was significantly improved in presence of the noble metals (Pd, Rh). The activity of the catalysts was tested in a batch autoclave reactor using vacuum gas oil as feedstock. Both the HC and HDS activity of noble metal-promoted Co/HPS catalysts were found to be higher than that of plain Co/HPS: catalysts. Rh displayed higher promotional effects as compared to Pd in both HC and HDS purpose. This higher activity is consistent with the TPR results, which showed superior reducibility of Rh promoted catalysts. The most interesting part of this study pertained the effects of bi-noble (Pd-Rh) metal on Co/HPS. A trace amount of Rh along with Pd exhibited a significant enhancement of the catalytic activity of Co/HPS, which was comparable to what Rh alone did with a higher amount. The coke deposition on Pd-Rh promoted catalyst was also found lower than that of the plain and single noble metal promoted Co/HPS. (C) 2004 Elsevier B.V. All rights reserved.