XPS Characterization of Carbon Nanotube Supported CoMo Hydrodesulfurization Catalysts

• 来源期刊: 中国化学（英文版）
• 年，卷（期）: 2004,（11）
• 页码范围: 1250-1256
• 页数: 7页
• 语种: 英文

摘要

In this paper, the effect of catalytic support and sulfiding method on the chemical state of supported Co-Mo catalysts is studied by XPS. After sulfidation with in-situ method, the majority of molybdenum in CNT supported CoMo catalyst is transferred to a species with a formal chemical state Mo(Ⅳ) in MoS2 phase, and the rest to Mo(Ⅴ)which consists of Mo coordinated both to O and S, such as MoO2S22- and MoO3S2-. In case of CoMo/γ-Al2O3 catalyst sulfided with in-situ method, a fraction of molybdenum is transferred to formal state Mo(Ⅳ) in the form of MoS2, but there is still a mount of unreduced Mo(Ⅵ) phase which is difficult to be sulfided. In CoMo/CNT catalytic system sulfided with ex-situ method, Mo(Ⅳ) in the form of MoS2 is detected along with a portion of unreduced Mo(Ⅵ) phase, suggesting that not all the Mo phases are reduced and sulfided by ex-situ method. As for CoMo/γ-Al2O3, a portion of molybdenum is sulfided to intermediate reduced state Mo(Ⅴ) which consists of Mo coordinated both to O and S, such as MoO2S22- and MoO3S2-, in addition, there is still a fraction of unreduced Mo(Ⅵ)phase. XPS analyses results suggest that CNT support facilitates the reduction and sulfidation of active species to a large extent, and that alumina support strongly interacts with active species, hereby producing a fraction of phase which resists complete sulfiding. Catalytic measurements of catalysts in the HDS of dibenzothiophene (DBT) show that CoMo/CNT catalysts are of higher HDS activity and selectivity than CoMo/γ-Al2O3 catalyst, which is in good relation with the sulfiding behavior of the corresponding catalyst.