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

• 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 2.2–3.1 nm 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 (∼6.6 nm) were obtained.

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