H2-reduction of Pt/MoO3 to MoOx with a large surface area and its catalytic activities for the conversions of heptane and propan-2-ol

The surface area of H2-reduced 0.01 mol.% Pt/MoO3 increased in proportion to the extent of reduction, and reached the maximum value of 250 m2 g−1 at a reduction degree of 60–70%. In the case of H2-reduced MoO3, the relationship between the surface area and the reduction degree was dependent on reduction temperature. MoO3 reduced at 673 K exhibited a much smaller surface area than that at 623 K even when the reduction degree was comparable. XRD studies showed that reduction of Pt/MoO3 proceeded ia the formation of HxMoO3 phase, irrespective of reduction temperature. In the reduction of MoO3 without Pt, however, the HxMoO3 phase was formed at temperature below 623 K. The heptane isomerization activity of H2-reduced MoO3 and Pt/MoO3 was similarly dependent on the reduction degree as the surface area. H2-reduced MoO3 and Pt/MoO3 catalyzed the dehydrogenation and dehydration of propan-2-ol simultaneously, indicating the presence of dual sites. There were good relationships between the isomerization activity and the dehydration activity. We suggest from these results that the surface area and the catalytic activities can be enlarged when reduction of MoO3 proceeds through the formation of a HxMoO3 phase.