Dispersion and reactivity of monolayer vanadium oxide catalysts supported on zirconia: The influence of molybdena addition

• Published in: Journal of molecular catalysis. A, Chemical Vol. 258; no. 1; pp. 313 - 319
• Main Authors: Chary, Komandur V.R., Kumar, Chinthala Praveen, Rajiah, Taduri, Srikanth, Chakravartula S.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 02.10.2006; Elsevier
• Subjects: Ammoxidation; Catalysis; Chemistry; Dispersion; Exact sciences and technology; General and physical chemistry; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Vanadia–molybdena; Zirconia; Zirconia; Ammoxidation; Vanadia–molybdena; Dispersion; Monolayer; Nitrogen heterocycle; Transition element compounds; Molybdenum oxide; Supported catalyst; Pyridine derivatives; Vanadia-molybdena; Heterogeneous catalysis; Six membered ring; Vanadium oxide; Chemical reactivity; Catalyst support
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/j.molcata.2006.05.049

ZrO 2 is an interesting support to investigate the dispersion of vanadia and catalytic properties of V 2O 5–MoO 3 catalysts. This paper provides influence of MoO 3 on the dispersion and catalytic properties of vanadium oxide supported on ZrO 2. These catalysts are found to be highly active and selective for the vapour phase ammoxidation of 3-picoline to nicotinonitrile. ▪ This investigation reports the influence of MoO 3 on the dispersion of vanadium oxide on zirconia support. Samples containing various MoO 3 loadings ranging from 0.5 to 4 wt.% were prepared by impregnation of previously prepared 6 wt.% V 2O 5/ZrO 2 with requisite amounts of ammonium heptamolybdate solution. Dispersion of vanadia was determined by oxygen chemisorption at 640 K and was found to decrease with the increase of molybdena loading. The calcined catalyst samples were characterized by specific BET surface area, XRD, FT-IR, Oxygen chemisorption and TPR of H 2 techniques. The XRD results show that the intensity of tetragonal phase decreases and monoclinic phase intensity increases with the addition of MoO 3 to V 2O 5/ZrO 2 catalyst. The TPR of H 2 results reveal that the reducibility of vanadia was found to decrease with the addition of molybdena to V 2O 5/ZrO 2 catalyst. The catalytic properties were evaluated during the ammoxidation of 3-picoline to nicotinonitrile. The activity in ammoxidation reaction did not change much with the addition of molybdenum oxide. However, the selectivity of nicotinonitrile was found to increase with molybdena loading, indicates that the added molybdena created additional sites for the ammoxidation of 3-picoline reaction. The addition of molybdenum oxide inhibited the interaction between vanadium and zirconia, leading to decrease in dispersion and reducibility of vanadia.