Enhanced catalytic oxidation of formaldehyde over dual-site supported catalysts at ambient temperature

In the study highly active dual-site TiO2 supported Pt catalysts were prepared for catalytic oxidation of formaldehyde (HCHO) at ambient temperature. We used (3-aminopropyl)triethoxysilane to modify the TiO2 supported Pt catalysts, resulting in amino groups grafted on their surfaces and thus dual sites on supports. Characterization of the dual-site catalysts and the corresponding catalytic activity for HCHO decomposition were analyzed and evaluated. The TiO2 supported Pt catalysts featuring amino groups showed significant enhancement on the catalytic activity for HCHO removal. Compared to the supported catalyst with Pt active sites only, the presence of amino groups on the surface of the TiO2 supported Pt catalyst enhanced the catalytic oxidation of HCHO by a factor of 2.8 times at 5-ppm inlet HCHO concentration. The optimal enhancement occurred on the moderate gas hourly space velocity and low HCHO concentration. We speculate that the enhancement may result from the synergistic effect of Pt active sites and amino groups. The affinity of amino groups as capture sites to HCHO or formate molecules leads to higher localized HCHO concentration in the vicinity of Pt active sites, thereby resulting in a higher catalytic activity for the dual-site catalysts.