Redox and carbonylation chemistry of iridium species in the channels of H-ZSM-5 zeolite

Autor:	T.V. Voskobojnikov, H. Landmesser, Günter Schulz-Ekloff, Nils I. Jaeger, Efim S. Shpiro
Rok vydání:	1996
Předmět:	Chemistry Process Chemistry and Technology Inorganic chemistry Water gas chemistry.chemical_element Infrared spectroscopy Photochemistry Redox Catalysis Water-gas shift reaction chemistry.chemical_compound Iridium Physical and Theoretical Chemistry Carbonylation Carbon monoxide
Zdroj:	Journal of Molecular Catalysis A: Chemical. 104:299-309
ISSN:	1381-1169
DOI:	10.1016/1381-1169(95)00185-9
Popis:	Reduction of IrH-ZSM-5 by hydrogen yields Ir0 clusters exhibiting a large positive XPS shift (1.4 eV) and an upward IR shift (25–30 cm−1) of linearly bonded CO, both suggesting a strong electron deficiency. Ir clusters (< 1 nm) can be readily and rapidly reoxidised by the highly acidic hydroxyls (protons) with subsequent formation of Ir+ (CO)2 gem-dicarbonyl even with residual CO. Reductive carbonylation of Ir+ (CO)2 in the presence of larger amounts of CO and H2O results in the formation of an iridium cluster carbonyl species, most likely tetra-Ir carbonyl, Ir4(CO)12 which is unstable and can be reversibly transformed into a precursor compound Ir+ (CO)2. Displacement of NH3 ligands originally coordinated to unreduced Ir3+ cations yields the formation of Ir3+ (CO)2. This species undergoes stepwise reduction to Ir+ (CO)2 and Ir0CO via the water-gas shift reaction.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::54cf6730c60c73d883be9ed22b31f926 https://doi.org/10.1016/1381-1169(95)00185-9 Zobrazit plný text záznamu Full Text from ScienceDirect