Structural and thermal study of carbon-modified molybdenum sub-oxide catalysts

The phase composition and the physico-chemical nature of the carbon-modified molybdenum sub-oxide catalyst during the isomerization of n-heptane were studied. It was found that different phases of molybdenum sub-oxides coexist, MoO2, MoO, besides MoO3-x Our results indicate that MoO is present as dispersed nano-structures inside the bulk catalysts . The thermal oxidation study revealed that the O-2 is consumed to oxidize part of the reduced oxide as well as carbonaceous deposits simultaneously, giving an additional evidence of the mixture of oxide phases during reaction. A thermo-kinetic study of the different oxidation process is included and the results are discussed in terms of the activation energy for the oxidation of each phase. The structural and thermal characterization has revealed the complexity of the system, but has also opened a window to a new insight into the understanding of MoO3 catalyst. (c) 2007 Elsevier B.V. All rights reserved.