Abstract: The effect of support pre-fluorination on the physical properties and catalytic activity of MoCo/TiO2-Al2O3 was studied by XRD, N2 adsorption ,and thiophene hydrodesulfurization (HDS).Freon (CFC-12) in wet air or in NH4F solution was used as fluorinating reagents. The influences of CFC-12 content, effect of fluorination temperature and fluorinating time on the structure and hydrodesulfurization activity of the catalysts were examined systematically. The results revealed that hydrodesulfurization activity of the catalyst fluorinated by 1％ CFC-12 at 623 K was obviously improved with an increase of 20％～30 ％ as compared with that of the unfluorinated catalyst, the commercially available BY2 catalyst, and NH4F-fluorinated catalysts. Moreover, the catalyst fluorinated by the Freon gas presented excellent stability on catalytic activity and structure.

Key words: Hydrodesulfurization(HDS), Freon, Gas phase fluorination, CoMo/ TiO₂-Al₂O₃ catalyst