V2O5/TiO2 catalysts for the vapor-phase oxidation of β-picoline:: Influence of the TiO2-carrier

The heterogeneously catalyzed vapor-phase oxidation of beta-picoline to nicotinic acid over a series of V2O5/TiO2 was investigated, Characterizations of the catalysts were carried out using X-ray diffraction, temperature-programmed desorption, and N-2-adsorption, It was found that the use of an anatase type of TiO2-carrier with a higher BET surface area enhances the activity of the V/Ti-oxide catalyst enormously. TiO2-materials with different BET surface areas (between 10 and 270 m(2)/g) were used. Since these different materials originate from different processes, namely, the chloride and the sulfate process, the influence of the sulfate content was investigated. Additionally, the use of different TiO2 crystalline structures (anatase vs rutile) was evaluated, and a sulfate-free TiO2-material was modified with sulfate and cerium oxide during vanadia impregnation. The results of these experiments verified that the sulfate content itself did not have a strong influence on the catalyst activity. XRD-characterization of the catalysts demonstrated that only the TiO2 and the V2O5 phase could be detected. This corresponds with other investigations in the literature and strengthens the assumption that there is a synergetic effect of a V2O5 layer supported by TiO2 as a catalyst carrier. Therefore the increase of the interface between these two crystalline phases is the determining factor to improve the catalyst's activity. (C) 2000 Academic Press.