Isomerization of n-Alkanes under Supercritical Conditions over Al-promoted Sulfated Zirconia

Effect of Citric Acid Addition on Co−Mo/B2O3/Al2O3Catalysts Prepared by a Post-Treatment Method

“…In our previous study, we showed that Co-CA and Mo-CA surface complexes are formed at CA/Mo > 1 by a simultaneous-impregnation method [CoMo-CA/(B/)Al]. It was reported that the formation of Mo-CA and Co-CA surface complexes reduces the interaction between metal precursors and the support and thus increases the sulfidation degree of Mo and/or the sulfidation temperature of Co. − In the present study, these surface complexes are also observed to form by the post-treatment method with citric acid (CA/Mo mole ratio = 2). The present EXAFS results clearly show a predominant formation of Mo-CA complexes on the surface (Figure ).…”

“…They showed that the addition of citric acid improves the Co coverage on the edges of MoS 2 particles, because citric acid forms a complex with Co. Bergwerff et al also showed that the Mo dispersion is kept high throughout the preparation process, resulting in an increase in the HDS activity through use of citric acid in the impregnation solution. Funamoto and Segawa also used XPS to show that the sulfidation degree of Mo improved upon addition of citric acid. In a previous study, we showed that the addition of citric acid by simultaneous impregnation enhances the HDS activity of Co−Mo/B 2 O 3 /Al 2 O 3 catalysts.…”