The Influence of Fe Substitution in GdFeO 3 on Redox and Catalytic Properties
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VI INTERNATIONAL CONFERENCE ON THERMAL ANALYSIS AND CALORIMETRY IN RUSSIA
The Influence of Fe Substitution in GdFeO3 on Redox and Catalytic Properties L. V. Yafarovaa,*, O. I. Silyukova, T. A. Kryuchkovab, T. F. Sheshkob, and I. A. Zverevaa a St.
b People’s
Petersburg State University, St. Petersburg, 198504 Russia Friendship University of Russia (RUDN University), Moscow, 117198 Russia * e-mail: [email protected] Received April 15, 2020; revised April 22, 2020; accepted April 24, 2020
Abstract—GdMn1 – xFexO3 (x = 0, 0.2, 0.5, 0.8, 1) perovskite oxides were prepared by a sol–gel method. The catalytic activity in dry reforming of methane was examined. XRD, BET, TPR, and TGA techniques have been used to characterize structural properties, reducibility and carbonization of the catalyst. The H2-TPR data show that an increase in the Mn content in the series of GdMn1 – xFexO3 compounds (x = 0, 0.2, 0.5, 0.8, 1) leads to a decrease in the reduction temperature. The study of the catalytic properties in the reaction of dry reforming of methane (DRM) showed that the catalytic activity of the studied compounds depends on the Fe content and increases in the series: GdMnO3 < GdMn0.8Fe0.2O3 < GdMn0.2Fe0.8O3 < GdFeO3. Keywords: perovskites, thermal analysis, temperature-programmed reduction, catalysts, dry reforming of methane DOI: 10.1134/S0036024420130324
INTRODUCTION Dry (carbon dioxide) reforming of methane (DRM) is of great interest to researchers, due to the possibility of producing synthesis gas, which can be used as a raw material for the production of environmentally friendly fuels, alcohols and dimethyl ether [1]. Noble metals (Ru, Rh, Pd, Ir, and Pt) and transition metals (Ni, Co, Mn, and Fe) are used as DRM catalysts; however, the use of high temperatures during the process leads to rapid deactivation of the catalysts due to sintering and carbonization of their surface [2]. Thus, one of the ways to improve the process is the development of catalysts with high thermal stability, activity and resistance to coke formation. Perovskite oxides are solid crystalline compounds with composition ABO3 (where A = alkaline, alkaline earth or rare earth elements, B = transition metal) with a structure close to the structure of the perovskite mineral. They are characterized by high thermal and chemical stability [3]. The possibility of partial substitution of cation A and/or B allows one to control the stability of the structure, electronic and/or ionic conductivity, and the redox and surface properties of perovskites, which makes it possible to create catalysts for various processes with directed selectivity [4]. This work aims to study the effect of the complete and partial substitution of Fe for Mn in GdFeO3 on the redox properties and catalytic characteristics of DRM.
EXPERIMENTAL A series of GdMnxFe1 – xO3 (x = 0, 0.2,0.5, 0.8, 1) perovskite-type oxides were prepared by the sol–gel citrate method, described in the previous article [5, 6]. Gd(NO3)3 ⋅ 6H2O (99.9 wt %, Vekton), Fe(NO3)3 ⋅ 9H2O (99.9 wt %, Vekton) and Mn
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