Application of concepts in heterogeneous oxidation of hydrocarbons: Mo, V-based oxide catalysts for oxidation of ethane and of n- and i-butanes

Abstract

The V and Mo-containing oxides are versatile catalysts used in a large number of reactions aiming at producing organic chemicals and intermediates like acids, anhydrides, nitriles, etc. The solid oxide catalyst is viewed as a catalytic reagent which is regenerated at each redox cycle, this principle being explicitely used in redox decoupling reactors like circulating fluid bed and catalytic membrane reactors. The selectivity to the product depends on the surface crystal field exerted by the exposed faces onto the organic molecule to be transformed. It is directly related to the structural chemistry of the solid, from its preparation up to its ageing through its use in reactors. In this paper the author, whose scientific life was dedicated to demonstrate its usefulness, wishes to illustrate the main concepts which are now agreed by the scientific community. Among them are the “seven pillars of catalysis” as put forward by R.K. Grasselli, and few others which are complementary. The differences in V-O and Mo-O systems are first evoked, before telling the story of the selective oxidations of n-butane to maleic anhydride, ethane to acetic acid, and isobutane to methacrylic acid on V-P-O, Mo-V-O systems and heteropolyvanadomolybdates, respectively.