Effects of surface orientation of alumina supports on the catalytic functionality of molybdenum sulfide catalysts

• Published in: Applied catalysis. A, General General, 2001-07, Vol.215 (1), p.101-110
• Main Authors: Sakashita, Yukio, Araki, Yasuhiro, Shimada, Hiromichi
• Format: Article
• Language: English
• Subjects: Catalysis; Catalysts: preparations and properties; Catalytic functionality; Chemistry; Exact sciences and technology; General and physical chemistry; Model catalysts; Molybdenum sulfide catalysts; Surface orientation; TEM observation; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; γ-Al 2O 3 powders
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/S0926-860X(01)00524-5

Two kinds of γ-Al 2O 3 powders with different surface orientation ratios were used as supports of MoS 2 catalysts. After Mo was loaded on the γ-Al 2O 3 catalyst, we characterized the microstructures of the catalysts by using transmission electron microscopy (TEM) and then evaluated the catalytic functionality, such as hydrogenation (HYD) and hydrodesulfurization (HDS), by using model test reactions. Our results showed that relatively large (3–5 nm) basal-bonding MoS 2 clusters with single layers were formed on the plate-like (PL) alumina, whose surface orientation was mainly {1 1 0} planes. The PL alumina-supported catalyst exhibited HYD-oriented functionality. Stacked basal-bonding or highly dispersed MoS 2 clusters were formed on the spherical (SP) alumina, whose surface orientation was mainly {1 1 1} and {1 0 0} planes. Compared to the PL alumina-supported catalyst, the SP alumina-supported catalyst exhibited higher HYD and HDS activities and higher HDS-oriented functionality. Our results on the effects of surface orientation of alumina supports on the microstructure of MoS 2 clusters obtained for alumina powders were consistent with those previously obtained for alumina single crystal thin films. This consistency indicates that our results obtained by using model catalysts can be applied to the designing of industrial catalysts. Our results also show that the catalytic activity and selectivity of MoS 2 catalysts depended on the microstructures of MoS 2 clusters that were affected by the surface orientation of γ-Al 2O 3. Thus, the surface properties of γ-Al 2O 3 support are important factors in controlling the catalytic functionality of MoS 2-based catalysts. Our results indicate that the microstructure of MoS 2 clusters can be controlled by tailoring the surface orientation of alumina supports.