On the Active Sites for Selective Ammoxidation of Propane on Vanadium Containing Oxide Catalysts

Abstract

The development of effective catalysts for the oxidative functionalization of alkanes is one of the challenges in the research on mixed-oxide catalysts. One example reaction is the formation of acrylonitrile (ACN) by direct catalytic ammoxidation of propane. This conversion represents a technically interesting alternative route to the presently used SOHIO process [1], which bases on the reaction of propene with ammonia and oxygen. However, the obtainable yields to acrylonitrile are still low. Using modified V-Sb-oxide catalysts ACN yields of YACN = 40% are reported in literature [2]. Understanding the key factors of the surface properties of these catalysts and their relationship with the elementary steps of ammoxidation of propane is thus an important step towards the controlled design of mixed-oxides in oxidative functionalization reactions in order to achieve more appropriate catalysts of industrial interest. In consequence considerable effort was put on the investigation of the characterization of V-Sb-oxide catalysts (e.g. [3,4]) and the mechanism of ammoxidation of propane on these catalysts (e.g. [5,6,7]). However, the nature of the active sites is still a matter of discussion [3–6]. In the present work a relationship between several physico-chemical properties and the catalytic performance under stationary and transient conditions is set up. On the basis of these results the nature of the active sites in ammoxidation of propane on modified V-Sb-Al-oxides is elucidated.