N2O catalytic reduction over different porous SiO2 materials functionalized with copper

Abstract

A N2O reduction study in the presence of CO, used as a scavenging agent, was carried out in order to understand the role played by the SiO2 morphology and mesoporosity order. Physicochemical properties were characterized by means of low angle X-ray diffraction, N2 physisorption, FESEM, HRTEM and HAADF microscopies. Highly ordered mesoporous SiO2 was obtained by the Stöber modified method. On the other hand, disordered-pore-amorphous SiO2 with broad pore-size distribution was synthesized by the sol–gel method. The CuO functionalization of SiO2 materials was carried out by incipient impregnation using citric acid. The role played by the Cu wt.% during the reduction of the greenhouse gas was examined in the N2O reduction. The ordered mesoporosity with a sharp pore size distribution results to be crucial for enhancing the N2O reduction from 200°C; the copper functionalized xerogel and commercial materials started the N2O conversion at 350°C. Low-temperature reduction was exhibited when the CuO functionalization percentage was 10wt.%, and total conversion was achieved from 200 to 400°C, also showing good stability for 21h. CuO—supported on highly ordered mesoporous SiO2 is comparable with other Rh and Pd systems reported in the literature.