Modification of zeolites usingin situ generated active species in the gas phase: II. Redox processes over the Mo5+ isolated sites in zeolites ZSM-5 and beta
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Abstract
The redox ability of isolated Mo5+ cations in model MoH-beta and MoH-ZSM-5 systems is studied byin situ ESR. The oxidation of reduced samples by nitrogen monoxide at 20°C proceeds much faster than oxidation by oxygen. The interaction between Mo5+ ions and propene at 20°C results in the formation of a complex in which the oxidizability of Mo(V) by NO is substantially enhanced. UV irradiation increases the oxidation rate for Mo5+ ions in HZSM-5 by nitrogen monoxide at 20°C, indicating the possibility for the photochemical activation of the process. The step of active site reduction during the interaction of the samples with the H2 + NO + He gas mixtures of various compositions at 500°C is fast, and the dynamic equilibrium of the redox Mo(V) ai Mo(VI) reaction is shifted to the left
Keywords
Zeolite Nitroxyl Nitrogen Monoxide Stainless Steel Capillary Chemical Transport ReactionPreview
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