On the mechanism for the platinum-catalyzed reduction of rhenium in PtRe/. gamma. -Al sub 2 O sub 3

Journal Article · Wed Mar 01 04:00:00 EST 1989 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(89)90085-7· OSTI ID:6352618

Augustine, S M; Sachtler, W M.H. ^[1]

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1. Northwestern Univ., Evanston, IL (USA)

The formation of mixed PtRe clusters and of separate clusters of Re and Pt has been studied by temperature-programmed reduction (TPR) for PtRe/Al{sub 2}O{sub 3} catalysts of low metal loading. Mixed PtRe clusters are reliably detected by their specific catalytic selectivity for deep hydrogenolysis. Deuterium exchange of cyclopentane is not ensemble-specific and, therefore, useful to normalize the hydrogenolysis rates for extent of reduction and percentage metal exposed. It is concluded that formation of mixed clusters is highest if the Re precursor migrates over the support surface and becomes reduced in contact with a prereduced Pt particle. Hydrogen spillover appears to be limited to this direct contact of the reducible Re species with a Pt cluster. No catalytic effect of Pt on the reduction of Re is observed if the rhenium oxide is immobilized by the formation of a surface compound with {gamma}-Al{sub 2}O{sub 3}. Upon hydrolysis of this surface compound, Re oxide regains its surface mobility and can, again, be reduced at significantly lower temperatures.

• OSTI ID: 6352618
• Journal Information: Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 116:1; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

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