Effect of citric acid addition on Co-Mo/(B)/Al₂O₃ catalysts prepared by a post-treatment method

Abstract

The effect of citric acid addition on a series of Co-Mo/(B)/Alumina catalysts prepared by a post-treatment method was studied for the HDS activity of thiophene. The catalysts were also prepared by a chemical vapor deposition (CVD) technique using Co(CO)₃NO as a precursor of Co. The prepared catalysts were characterized by means of NO and N₂ adsorption, LRS, EXAFS and UV-vis spectra. With a series of post-treated Co-Mo/(B)/Alumina catalysts, the HDS activity reached the maximum activity at the CA/Mo mole ratio of around 2. The addition of citric acid by the post-treatment significantly increased the HDS activity than by a simultaneous impregnation method, in particular at a 4 wt% Co-Mo/(B)/Alumina catalyst.