Characterization and reactivity of molybdenum oxide catalysts supported on anatase and rutile polymorphs of titania

A comparative study on the dispersion behaviors and surface acid properties of molybdena on CeO2 and ZrO2 (Tet)

“…6. It can be seen that ZrO 2 is not reduced in this temperature scale, and a weak peak appears in the profile of CeO 2 at 508 • C. As reported elsewhere [49], reduction of bulk MoO 3 takes place when temperature is beyond 700 • C, giving rise to two peaks at 767 and 997 • C, which correspond to MoO 3 → MoO 2 and MoO 2 → Mo, respectively. Only one reduction peak is detected in the profiles of the molybdena supported samples presented in Fig.…”

Influence of Na content on behavior of NiMo catalysts supported on titania nanotubes in hydrodesulfurization

“…This may be because the reduction of Mo(VI) oxide species is a stepwise process: first Mo 6+ is reduced to Mo 4+ , and then from Mo 4+ to Mo 0 [33,34]. In addition, the exact position of the above reduction steps is influenced by a number of factors: the Mo 6+ coordination state (tetrahedral or octahedral), the degree of agglomeration, and the strength of the Mo 6+ -support interaction depending on the support's nature [35][36][37][38], among others. It can be seen in Fig.…”

“…At the same time, the TPR profiles of tetrahedrally-coordinated molybdate species clearly show the presence of two main reduction signals at 580 and 705°C for NiMoO 4 and 665 and 910°C for Na 2 MoO 4 , in addition to some smaller shoulders. In the supported NiMo catalysts, the onset of the reduction process usually occurs at lower temperatures than for the bulk compounds because of spreading and dispersion of molybdenum-containing compounds on the support's surface [32][33][34][35][36][37][38][39]. The above makes it almost impossible to exactly assign all the reduction signals observed in the TPR profiles of our NiMo catalysts supported on TNT(x), Fig.…”

Molybdenum thin film growth on a TiO2 (110) substrate

“…The elements in the middle of the 3d and 4d series display the biggest variety of oxidation states and thus their electronic and catalytic properties may change dramatically as a function of the structural and chemical environment of the metal atom. Supported molybdenum oxide is used as a catalyst for many industrially important reactions such as hydrodesulfurization, partial oxidation and metathesis of olefins and TiO 2 is one of the interesting substrates [3,4]. When elemental molybdenum is adsorbed on a TiO 2 surface at sub-monolayer coverage, it is strongly oxidized as was shown experimentally in Ref.…”