Catalysis of the water gas shift reaction by cis-[Rh(CO)2(AMINE)2](PF6) complexes in an aqueous tetrabutylammonium hydrogensulfate solution

Gascon, German; Ortega, M.; Suárez, José D.; Pardey, Alvaro J.; Longo, Clementina

doi:10.1007/s11144-008-5281-y

Cited by 2 publications

(1 citation statement)

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“…While aqua complexes of Rh are well-known in solution chemistrywith some of these aqua carbonyl complexes actually catalyzing the water–gas shift reaction − limited information related to interactions of H 2 O molecules with supported Rh carbonyl complexes is available. It has been reported, for example, that water facilitates reductive carbonylation of zeolite- and alumina-supported Rh(CO) 2 species at elevated temperatures to yield Rh 6 (CO) 16 or Rh 4 (CO) 12 clusters. − At room temperature, however, this reaction does not proceed at any measurable rate, and Rh(CO) 2 (H 2 O) x complexes are formed instead following exposure of Rh(CO) 2 to H 2 O. , …”

Section: Resultsmentioning

confidence: 99%

Effect of Si/Al Ratio on the Nature and Reactivity of HY Zeolite-Supported Rhodium Dicarbonyl Complexes

et al. 2014

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Fourier transform infrared (FTIR), extended Xray absorption fine structure (EXAFS), X-ray photoelectron spectroscopy (XPS) measurements, and DFT calculations were used to characterize the species formed following reaction of a Rh(CO) 2 (acac) precursor with dealuminated HY zeolites with different Si/Al ratios. The results indicate the formation of two types of Rh(CO) 2 species with characteristic ν CO bands at 2117/2053 and 2110/2043 cm −1 . Both species are attached to the zeolite framework and have similar structural properties. However, their thermal stabilities are different, and the fraction of each species formed strongly depends on the Si/Al ratio of the zeolite. The carbonyl ligands in both types of these zeolite-bound Rh(CO) 2 complexes can react with gas-phase C 2 H 4 to form Rh(CO)(C 2 H 4 ) species. However, the reaction rate is substantially higher for the Rh(CO) 2 complex with the ν CO bands at 2117/2053 cm −1 , suggesting that the electronic properties of the Rh site affect the reactivity of the carbonyl ligands. The results further indicate that the two types of Rh(CO) 2 species are not associated with unreacted or partially reacted Rh(CO) 2 (acac) complexes or with the formation of a hydrated Rh(CO) 2 (H 2 O) x -type species. Instead, the results of the DFT calculations suggest that the differences observed can be attributed to differences in the structure of the binding sites in the dealuminated faujasites framework.

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