In situ Study of Structural Transformations of the Active Phase of VMoNbTeO Catalysts under Reduction Conditions


Cite item

Full Text

Open Access Open Access
Restricted Access Access granted
Restricted Access Subscription Access

Abstract

VMoNbTeO catalysts show high activity in the reactions of selective oxidation of ethane and propane. Time-resolved X-ray diffraction is used to study structural transformations of a mixed oxide with the composition (TeO)0.18(Mo0.7V0.22Nb0.08)20O56 and the structure of the active M1 phase upon heating in a hydrogen atmosphere (1% H2 in helium). It is shown that the structure of the M1 phase is destroyed in the presence of a reducing agent above 480 °C. The process is accompanied by structural distortions, diminishing of the size of crystalline blocks, elimination of tellurium (due to the reduction and sublimation), and the reduction by molybdenum and vanadium cations. As a result, VMoNb oxides with a disordered structure are formed and rapidly crystallized at T > 480 °C into the rutile-type monoclinic oxide (Mo,V,Nb)O2 with a variable composition. X-ray photoelectron spectroscopy and transmission electron microscopy data confirm heterogeneous compositions of oxides formed by the decomposition of the initial phase. The surface of the formed particles is enriched with vanadium and niobium present in the composition of the oxides with disordered structure.

About the authors

T. Yu. Kardash

Boreskov Institute of Catalysis, Siberian Branch; Novosibirsk State University

Author for correspondence.
Email: kardash@catalysis.ru
Russian Federation, Novosibirsk; Novosibirsk

A. S. Marchuk

Boreskov Institute of Catalysis, Siberian Branch; Novosibirsk State University

Email: kardash@catalysis.ru
Russian Federation, Novosibirsk; Novosibirsk

A. V. Ishchenko

Boreskov Institute of Catalysis, Siberian Branch

Email: kardash@catalysis.ru
Russian Federation, Novosibirsk

A. A. Simanenko

Boreskov Institute of Catalysis, Siberian Branch; Novosibirsk State University

Email: kardash@catalysis.ru
Russian Federation, Novosibirsk; Novosibirsk

E. V. Lazareva

Boreskov Institute of Catalysis, Siberian Branch

Email: kardash@catalysis.ru
Russian Federation, Novosibirsk

D. A. Svintsitskiy

Boreskov Institute of Catalysis, Siberian Branch; Novosibirsk State University

Email: kardash@catalysis.ru
Russian Federation, Novosibirsk; Novosibirsk

Supplementary files

Supplementary Files
Action
1. JATS XML

Copyright (c) 2019 Pleiades Publishing, Ltd.