Modification of the catalytic properties of MoO2−x(OH)y dispersed on TiO2 by Pt and Cs additives Original Research Article

Addition of 5% Pt or alkali metals such as K or Cs each separately to the bifunctional MoO2−x(OH)y catalyst results in modification of the chemical structure of this system, especially in the case of alkali metals. A new MoO2−x(OA)y, Adouble bond; length as m-dashK, Cs, monofunctional structure having only metallic properties is formed. In the case of Cs for example, the Mosingle bondOCs bond formation takes place in the course of the reduction process of MoO3 to MoO2 by hydrogen hinders the acidic BrØnsted Mosingle bondOH formation, which usually is formed in this system. Characterization by surface XPS–UPS, ISS and FT-IR spectroscopic techniques as well as catalytic activity carried out at the same experimental conditions confirm the presence of this monofunctional MoO2−x(OCs)y system. On the contrary, platinum addition enhances the metallic character of the MoO2−x(OH)y bifunctional system in terms of slight improvement in the conversion of 1-heptene and n-heptane as well as dehydrogenation of methylcyclohexane to toluene.