Characteristics of MoO3 reduced with H2 at the different flow rates of H2

MoO3 was treated with H-2 at 623 K for 12 h. The degree of reduction and the specific surface area of H-2-reduced MoO3 were dependent on the flow rate of H-2 in the reduction process. MoO3 with a surface area of about 5 m(2) g(-1) was transformed to a porous MoOx with a surface area of 180 m(2) g(-1) after reduction at a flow rate of H-2 larger than 600 mi min(-1) g(-1). The MoOx was found to be stable at 623 K, even in the presence of H2O vapor. A study of reduction with a mixture of H-2 and H2O showed that the degree of reduction and the surface area decreased with increasing partial pressure of H2O in the reduction process. We conclude from these results that the reduction of MoO3 to porous MoOx with a large surface area was prohibited by the action of H2O produced by the reduction.