Gold supported on Fe, Ce, and Al pillared bentonites for CO oxidation reaction

Abstract

A series of gold catalysts supported on Fe, Ce, and Al pillared bentonites have been prepared, characterized by means of X-ray diffraction (XRD), transmission electronic microscopy (TEM), SBET, and X-ray fluorescence spectrometry (XRF) techniques and tested in the CO oxidation reaction in the absence and in presence of water in the stream. The pillaring process of the natural bentonite results in an increase in the microporosity and surface area of the solid. In the gold samples, spherical arrangements of gold particles of 2–4nm around one central particle of 4–5nm are observed, the catalysts having an average gold particle size of 2.2nm. All the gold catalysts are very active, those modified with Fe and Ce being the best. The introduction of iron and cerium by pillaring increases the catalytic performances of the final gold solids. Introduced iron atoms are accessible and active centers for the gaseous CO oxidation reaction while the cerium ones promote the catalytic activity of Fe and gold atoms. Catalysts activity increases in the presence of water in the reactant stream at temperatures lower than 120°C. At room temperature, the catalytic activity increases continuously with the gaseous water concentration of up to 6700ppm.