Drifts study of selective CO oxidation on Au/Al2O3 catalyst

Abstract

The aim of this study was to investigate the surface species formed during the selective CO oxidation over 1 wt. % Au/Al2O3 catalyst prepared by homogeneous deposition-precipitation method. The surface analyses were carried out using a DRIFTS (Diffuse Reflectance Infrared Fourier Transform Spectroscopy) system while the CO conversions were measured with MS (Mass Spectroscopy). First, the most appropriate conditions for sampling such as amount of sample, the particle size and KBr dilution were determined. Then the effects of reaction temperature on the formation of surface species were examined at the range of 25oC to 150oC in the presence of CO and O2 and in balance helium. Afterwards, the concentrations of the feed components (CO, O2, CO2, H2, and H2O) were changed systematically at 110oC to see the effects of these species on the formation of the surface intermediates. The peaks in the DRIFTS spectra obtained were analyzed with the help of similar studies in the literature. It was found that the carbonates, bicarbonate, carboxyl and hydroxyl like surface species formed with varying amounts depending on the reaction conditions used. Finally the possible contributions of these surface species to the mechanisms suggested in the literature for the CO oxidation over the Au based catalyst were discussed.