Novel Flower-Like Ag-SiO2-MgO-Al2O3 Material: Preparation, Characterization and Catalytic Application in Methanol Dehydrogenation

Catalytic direct dehydrogenation of methanol to formaldehyde was carried out over Ag‐SiO2‐MgO‐Al2O3 catalysts prepared by sol‐gel method. The optimal preparation mass fractions were determined as 8.3% MgO, 16.5% Al2O3 and 20% silver loading. Using this optimum catalyst, excellent activity and selectivity were obtained. The conversion of methanol and the selectivity to formaldehyde both reached 100%, which were much higher than other previously reported silver supported catalysts. Based on combined characterizations, such as X‐ray diffraction (XRD), scanning electronic microscopy (SEM), diffuse reflectance ultraviolet‐visible spectroscopy (UV‐Vis, DRS), nitrogen adsorption at low temperature, temperature programmed desorption of ammonia (NH3‐TPD), desorption of CO2 (CO2‐TPD), etc., the correlation of the catalytic performance to the structural properties of the Ag‐SiO2‐ MgO‐Al2O3 catalyst was discussed in detail. This perfect catalytic performance in the direct dehydrogenation of methanol to formaldehyde without any side‐products is attributed to its unique flower‐like structure with a surface area less than 1 m2/g, and the strong interactions between neutralized support and the nano‐sized Ag particles as active centers.