XPS and catalytic properties of the bifunctional supported MoO2(Hx)ac• on TiO2 for the hydroisomerization reactions of hexanes and 1-hexene

XPS measurements of the reduction by hydrogen of equivalent five layers of MoO3 deposited on TiO2 in function of time and temperature enabled to identify the presence of Mo2O5 and MoO2. Most of the deposited MoO3 is reduced to MoO2 after 8 h of reduction at 673 K. The MoO2 has been identified on the basis of the Mo (3d) binding energies as well as the presence of a density of states at the Fermi-level characteristic of the metallic properties of this phase. A catalytically active MO2(H-x)(ac). phase is formed on the sample surface as a result of hydrogen bonding to surface oxygen atoms. The formation of the Bronsted Mo-O(H-x)(ac). acidic groups beside the metallic function inherits a bifunctional catalytic character of MO2(H-x)(ac). in similar way to the supported bifunctional Pt catalysts. Catalytic reactions were studied for n-hexane (nH), 2-methylpentane (2MP), 3-methylpentane (3MP) and 1-hexene at temperatures less than or equal to673 K. A selectivity of more than 90% in isomerization products was obtained at reaction temperatures less than or equal to600 K. (C) 2002 Elsevier Science B.V All rights reserved.