MODE OF ARRANGEMENT OF COMPONENTS IN MIXED VANADIA CATALYST AND ITS BEARING FOR OXIDATION CATALYSIS

Vanadium oxide or V-containing systems are extensively used as compone nts of various catalysts used in mild oxidation, ammoxidation and dehy drogenation of hydrocarbons and other organic compounds. The discussed examples are the definite phases (V-P-O, butene and butane oxidations ), supported bulk and monolayers (V-Ti-O, o-xylene oxidation), and mix ed oxides (V-Mo-Nb-O, ethane oxidation). The common structural feature s are commented. Heteropolyacids, which can be stabilized either on st ructurally related heteropolysalts or on silica doped with potassium, are also considered as they contain similar molecular sites. The model of coherent interfaces, proposed to explain the synergic effects exhi bited by most of these catalysts, is discussed and compared with conce pts of other authors.