Stabilization of Trivalent Vanadium in Zeotypic Systems

Abstract

Currently there is an increasing need to design and develop more environmental friendly and more effective catalytic systems for industrial chemical reactions. The need for effective catalytic systems applies strongly to the global energy challenge which we are represented in the future. This project focuses on design and development of materials for potential use in catalysis, which consists of nanoporous carrier systems that are introduced to catalytically active species within the porous cavities. Nanoporous inorganic solids with pores with pore diameters in the microporous range (0 < d < 2 nm) can be utilized as catalysts and sorption media due to high internal surface areas. In this work vanadium is attempted to be introduced into 3D- support materials termed as zeolites and zeotypes.[1] Most studies performed on vanadium in heterogeneous catalyst materials are performed with vanadium present in high oxidation states, V4+ and V5+, but vanadium has never been reported with lower oxidation states in the structures.[2] Reducing agents are introduced to the framework and the effect of different reducing agents has been investigated. In this work V2+ has been attempted to be introduced to the lattice of an AlPO-5 material, as it is supposed this may introduce acidic sites in the material. Vanadium has also been introduced as ion exchange of H-ZSM-5 and impregnated on the AlPO-5 material. The effect of tin as reducing agent is compared with zink. The synthesized materials are characterized by in- house techniques (PXRD, TGA, ICP-MS). XAS studies enables to study the vanadium species, their valency and local geometry in the support medium. Vanadium species in porous carriers are of potential interest because they are active in the selective oxidation of propene, where acrolein and acrylic acid is the desired products.[3-5]