Green Oxidation of n‐Octanol on Supported Nanogold Catalysts: Formation of Gold Active Sites under Combined Effect of Gold Content, Additive Nature and Redox Pretreatment. Issue 6 (11th February 2019)

• Record Type: Journal Article
• Authors: Pakrieva, E.; Kolobova, E.; Mamontov, G.; Bogdanchikova, N.; Farias, M. H.; Pascual, L.; Cortés Corberán, V.; Martinez Gonzalez, S.; Carabineiro, S. A. C.; Pestryakov, A.
• Is Part Of: ChemCatChem. Volume 11:Issue 6(2019)
• Page Start: 1615
• Page End: 1624
• Publication Date: 2019-02-11
• Subjects: effect of pretreatments -- gold catalyst active sites -- gold loading -- n-octanol selective oxidation -- support modifiers; Catalysis -- Periodicals; 541.39505
• DOI: 10.1002/cctc.201801566
• Languages: English
• ISSNs: 1867-3880

Abstract

Abstract: The combined influence of gold content (0.5 or 4 wt. %), modifying additives (La or Ce oxides) and redox pretreatments (H2 or O2 ) on catalytic properties and formation of active sites of Au/TiO2 in the selective oxidation of n‐octanol under mild conditions was studied. Samples were characterized by BET, XRD, EDX, ICP, TEM, STEM‐HAADF, CO2 ‐TPD, H2‐TPR and XPS methods. The order of catalytic activity depended on the support nature for all treated samples, as follows: Au/La2 O3 /TiO2 >Au/CeO2 /TiO2 >Au/TiO2 . The catalytic activity enhanced with the increase of gold loading in the samples with hydrogen pretreatment, while after the oxidative pretreatment of the catalysts the opposite dependence of the activity with the gold content was found. This catalytic behavior was explained by a change in the surface concentration of monovalent gold ions, which seemed to be the active sites. The most active catalyst, 0.5 % Au/La2 O3 /TiO2, pretreated in oxidative atmosphere, had the highest surface concentration of monovalent gold ions. Abstract : The highest concentration of stable Au + sites – the best catalytic properties . The combined influence of gold content (0.5 or 4 % wt.), modifying additives (La or Ce oxides) and redox pretreatments (H2 or O2 ) on catalytic properties and formation of active sites of Au/Mex Oy TiO2 in selective oxidation of n‐octanol under mild conditions has been studied. The best promoting effects of lanthanum oxide as modifying additive, 0.5 wt. % of Au on support surface and O2 pretreatment of the catalysts were established. Cationic Au + species are active sites in liquid phase n‐octanol oxidation.