Effects of dispersion and partial reduction on the catalytic properties of Rh/Al2O3 catalysts in the steam reforming of mono- and bicyclic aromatics - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal of Catalysis Année : 1989

Effects of dispersion and partial reduction on the catalytic properties of Rh/Al2O3 catalysts in the steam reforming of mono- and bicyclic aromatics

Résumé

The steam reforming of toluene, cumene, and methyl-1-naphthalene was studied on well-reduced Rh/Al2O3 catalysts of different dispersions and on partially reduced catalysts in which the dispersion of the metallic phase was maintained at 25 ± 2%. The principal reactions were dehydrogenation DH (cumene ? ?-methylstyrene), dealkylation DA (for instance, toluene ? benzene), naphthalene ring opening NRO (methylnaphthalene ? benzene + toluene), and degradations DN (total gasification of the molecules). Dispersion and partial reduction effects are shown to occur and can be summarized as follows: a partially reduced sample behaves catalytically as would dispersed and well-reduced catalysts. In this case, DN reactions are much inhibited, whereas DA and, to a lesser extent, NRO are relatively less affected by partial reduction. Moreover, DH is quite unaffected by these factors. The results may be expressed in terms of either electronic (DN favored on particles where the metal is more capable of donating electrons) or geometric effects (DN favored on a large ensemble of adjacent sites). These models are discussed on the basis of kinetic and XPS results, particularly those obtained on partially reduced Rh/Al2O3 catalyst samples. Alloy effects (selectivities modified by the presence of RhAl alloy) could also occur on a catalyst calcined and reduced at high temperatures.

Domaines

Catalyse

Dates et versions

hal-00179434 , version 1 (15-10-2007)

Identifiants

Citer

Gerard Delahay, Daniel Duprez. Effects of dispersion and partial reduction on the catalytic properties of Rh/Al2O3 catalysts in the steam reforming of mono- and bicyclic aromatics. Journal of Catalysis, 1989, 115, pp.542-550. ⟨10.1016/0021-9517(89)90056-0⟩. ⟨hal-00179434⟩

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