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Title: Active states of rhodium in rhodium exchanged Y zeolite catalysts for hydrogenation of ethylene and acetylene and dimerization of ethylene studied with X-ray photoelectron spectroscopy

Journal Article · · J. Catal.; (United States)

ESCA and ESR spectroscopic studies of 18 and 50Vertical Bar3< rhodium-exchanged Y zeolites, activated under vacuum at 100/sup 0/-600/sup 0/C, and activity tests for ethylene hydrogenation and dimerization and acetylene hydrogenation in a static reactor at 20/sup 0/C and 76-100 mm Hg provided evidence that during reduction under vacuum of the rhodium(III) in the zeolite, part of the rhodium formed stable rhodium(I) ions, possibly partly associated with residual chlorine or hydride ions. The bare rhodium(I) cations were coordinatively unsaturated, were more stable at the lower rhodium exchange levels, and were active in ethylene hydrogenation and dimerization. The formation of atomically dispersed and clustered rhodium(0) was also observed during the heat treatment; it was active for acetylene hydrogenation and ethylene dimerization. The results were similar to results obtained with chloro tris(triphenylphosphine) rhodium(I) and various other homogeneous catalysts, and similar mechanisms apparently apply to the two types of catalysts.

Research Organization:
Osaka Univ.
OSTI ID:
6675595
Journal Information:
J. Catal.; (United States), Vol. 58:1
Country of Publication:
United States
Language:
English