The influence of the preparation methods and pretreatment conditions on the properties of Ag-MCM-41 catalysts

Silver doped mesoporous silica materials MCM-41 were prepared by the direct hydrothermal (DHT) and template ion exchange (TIE) methods. The properties of materials were investigated by the adsorption/desorption of nitrogen, X-ray diffraction (XRD), and photoacoustic infrared spectroscopy (FT-IR/PAS). Redox properties were studied by the temperature programmed reduction method and temperature programmed CO oxidation test reaction. It was found that the introduction of small amounts of silver caused structural changes of the silica materials. Silver species in the catalysts obtained by the TIE method were strongly dispersed on the silica support. XRD and TPR studies of the catalysts prepared by the DHT method indicated co-existence of the large crystallites and isolated silver ions in the silica material. Studies revealed the strong influence of the pretreatment and reaction conditions on the performance of catalysts in the oxidation of CO. Reduction of catalysts was necessary to obtain high activity at low temperatures. Complex deactivation processes were recorded above 300 °C.

The structural, surface, redox and catalytic properties of the Ag-MCM-41 materials obtained by the direct hydrothermal synthesis and template ion-exchange methods were compared. It was stated strong influence of the pretreatment and reaction conditions on the performance of catalysts in the CO oxidation reaction. The catalysts showed high activity at low temperatures after reduction.Figure optionsDownload as PowerPoint slide