Effect of the preparation method on the catalytic activity and stability of Au/Fe2O3 catalysts in the low-temperature water–gas shift reaction

• Published in: Applied catalysis. A, General General, 2014, Vol.470, p.45-55
• Main Authors: Soria, M.A., Pérez, P., Carabineiro, S.A.C., Maldonado-Hódar, F.J., Mendes, A., Madeira, Luis M.
• Format: Article
• Language: English
• Subjects: Au catalyst; Catalysis; Catalysts; Catalytic activity; Chemistry; Deposition; Dispersions; Exact sciences and technology; Fe2O3; General and physical chemistry; Gold; HRTEM; Hydrogen; Low temperature; Nanostructure; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; TPR; Water–gas shift; X-rays; XRD
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2013.10.034

•Three different synthesis methods of nanosized Au-based catalysts are reported.•Gold promotes the reducibility of the Fe2O3 support.•Activity strongly depends on both Au dispersion and reducibility of the support.•The Au/Fe2O3 catalysts prepared by deposition–precipitation method are more active. The low temperature water–gas-shift reaction has been studied over a series of nanosized Au/Fe2O3 catalysts. The effect of the synthesis method on the catalytic activity has been analysed. A series of catalysts with different Au loadings has been prepared by different methods: deposition–precipitation (DP), liquid phase reductive deposition (LPRD) and double impregnation method (DIM). The Au/Fe2O3 catalysts prepared by DP showed the highest CO conversion. The catalysts were characterised by hydrogen temperature programmed reduction (TPR-H2), high-resolution transmission electron microscopy (HRTEM), X-ray powder diffraction and X-ray photoelectron spectroscopy. TPR-H2 analysis revealed that gold promotes the reducibility of the Fe2O3 support, which is crucial in this redox reaction. HRTEM evidences a very good dispersion of gold over the iron support, with nanoparticles in the range 2.2–3.1nm for the DP and LPRD series, and a negligible increase in the average particle size of the used samples. For the DIM series, much larger Au particles (∼6.6nm) were obtained.