Relationship between Al-loading and CO oxidation activity of mesostructured silica-supported Pt-based catalysts

The supported Pt-based catalysts for CO oxidation have been extensively investigated, but to our best knowledge, no reports about the effect of the Al-incorporation on mesostructured Pt/MCM-41 catalysts can be found. The parent and Al-modified MCM-41 supports, with typical honeycomb structure, were synthesized using the liquid-crystal template mechanism, while supported Pt-catalysts were prepared by the deposition-precipitation method. The fresh samples were characterized by small- and wide-angle X-ray diffraction (SA-XRD and WA-XRD), N-2 physisorption and high-resolution transmission electron microscopy (HRTEM, only supports), while reduced catalysts were also characterized by WA-XRD, HRTEM and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of the adsorbed CO molecules at temperatures between 50 and 200 degrees C. The relationship between Al-loading with the catalytic performance were well-investigated. The MCM-41- and Al-MCM-41-supported Pt-based catalysts showed a good activity, circularity and stability in the CO oxidation reaction. The studied catalytic parameters (X-CO, E-a and T-50) were improved with the Al-incorporation and correlated with the average particles sizes. The defects formation and even the acidic features, corroborated by the formation of the Pt-carbonyl-hydride species, were also observed in the Al-modified catalysts.