Effects of support on formation of active sites and hydrodesulfurization activity of rhodium phosphide catalyst

Abstract

The effects of the support on active site formation and hydrodesulfurization (HDS) activity of Rh2P catalyst were examined, using metal oxides (MO x), such as SiO 2, TiO 2, Al 2O 3, MgO and ZrO 2, as the support. Rh2P was formed on MO x support after reduction of supported rhodium and phosphorus (Rh-P) catalysts. However, differences in the formation temperatures of Rh2P were observed by changing the MO x support. Furthermore, the HDS activities of the supported Rh-P catalysts strongly changed with higher reduction temperature. The order of HDS activities of Rh-P/MO x catalysts reduced at optimal temperatures was SiO 2 ~ TiO 2 ~ Al 2O 3 MgO ZrO 2. The TOF of Rh-P/MO x catalysts was enhanced by increasing the reduction temperature to form Rh2P. The order of TOF of supported Rh2P catalysts was TiO 2 ZrO 2 Al 2O 3 SiO 2 MgO, and this order disagreed with that of thiophene conversion. The high TOF of Rh-P/TiO 2 catalyst may be explained by formation of partially sulfided TiO 2 in the HDS reaction. The low TOF of Rh-P/MgO catalyst was attributed to the basicity of the support with low sulfur tolerance.