Catalysts for Alkylbenzene and Alkylpyridine Ammoxidation
D.Kh. Sembaev, F.A. Ivanovskaya, V.M. Pochtennaya
Institute of Chemical Sciences of Ministry of Education and Science of the Republic of Kazakstan
106 Walikhanov str., 480100 Almaty, Kazakhstan
An increase of effectivity of binary and ternary vanadium containing oxide catalysts can be achieved by a regulation of chemical and phase catalyst composition during their preparation. Activity and selectivity of V-Ti catalysts depend on the ratio of V2O5 to VO2 in the succession of substitutional solid solutions VO2-TiO2, as well as on the crystal modification of TiO2. It was investigated the influence of vanadium oxides over the rate of the polymorfous conversion from anatase to rutile and the kind of TiO2crystal modification over V2O5 reduction degree during the thermal treatment of V-Ti catalysts. The synthesized catalysts offered producing nicotinonitrile from 3-methylpyridine with 93-95% mol. yield. Modifying of V-Ti catalysts by SnO2 increased their activity. The reason is V=O bond weakening under the influence of SnO2. That was verified by increasing of V2O5 dissociation rate almost by an order in comparison with V-Ti catalysts. SnO2 in the ternary catalysts exists as individual phase and acts as a donor of oxygen for the lower vanadium oxides. It provides the high stability of V-Ti-Sn catalysts and possibility of obtaining isonicotinonitrile with 95-97% mol. yield from 4-methylpyridine. The investigation of the mutual influence of starting components in the ternary V-Ti-Zr catalysts showed that ZrO2 prevented the polymorphous transformation from anatase into rutile. In its turn, anatase stabilized baddeleyite, which has a higher catalytic activity than ruffite. Taking into account the mutual influence of the components, it was able to prepare the selective V-Ti-Zr catalyst. It offered obtaining nicotininitrile from 3-methylpyridine with 92-96% mol. yield.