Surface electronic structure and isomerization reactions of alkanes on some transition metal oxides

Surface studies and catalytic properties of the bifunctional bulk MoO2 system

“…Hydroisomerization of alkanes C 4 -C 6 is an important process in order to increase the gasoline octane number in the oil industry. The widely used catalysts for the isomerization of alkanes consist mainly of platinum deposited on acidic alumina.…”

“…The metallic function is assured by the delocalized -electrons above the metal atoms located along the C-axis of the deformed rutile structure, and observed by UPS/XPS in terms of density of states at the Fermi level. 6,8,9 The Brønsted acidic function is attributed to the formation of M-OH at the surface as a result of hydrogen atoms bonding to the surface oxygen atoms following hydrogen dissociation, which is present as a reducing agent. This leads to the formation of a surface layer of MoO 2 phase in which O-H Brønsted acidic functions are present at the surface.…”

New insights into the reaction mechanism and the rate-determining step of n-butane hydroisomerisation over reduced MoO3 catalystsElectronic supplementary information (ESI) available: experimental details. See http://www.rsc.org/suppdata/cc/b3/b304978g/

“…6 Other experiments (to be reported elsewhere) have shown that a pure MoO 2 phase leads to the same equilibrium concentration of linear butenes, without any iso-butene being formed. Regarding this last point, Wehrer et al have also shown that a pure MoO 2 phase is not active for n-hexane and hex-1-ene skeletal isomerisation.…”

“…5 Further catalyst development has been hampered by the structural complexity of the material and by contradictory statements regarding the associated mechanism of reaction. Katrib et al 6 and Matsuda et al 5 have proposed that a traditional bifunctional mechanism operates, whereas Bouchy et al 7 have proposed a metallacyclobutane intermediate-based mechanism. In the case of the isomerisation of C 5 -C 7 alkanes over reduced MoO 3 , Matsuda et al 5 proposed that the dehydrogenation/hydrogenation process was the rate-determining step.…”

n-Heptane isomerization over mesoporous MoOx and Ni–MoOx catalysts

“…active for n-heptane isomerization than the MoO 2 phase. In some previous investigations [17,18], this has to be noticed, it seems that the role of the MoO 2 phase in alkane isomerization has been strongly emphasized by the researchers.…”