Carbon Coated Silica Doped With Cerium/Zirconium Mixed Oxides as NO2 Adsorbent at Ambient Conditions

Abstract

Silica gel (Si-60) was modified by carbon grafting to produce carbon coated silica composites. The resulting materials were doped with cerium zirconium mixed oxide and tested as NO2 adsorbents at ambient conditions. The textural and chemical features were characterized using SEM-EDX, adsorption of nitrogen, potentiometirc titration, thermal analysis and FT-IR. Modification with mixed oxides enhanced the adsorption of NO2. While the composites with the lowest content of carbon exhibited the best performance in dry conditions, the composites with the highest carbon content showed the best performance in moist conditions. This trend is linked to the hydrophobic nature of the carbonaceous phase, which repels water but allows NO2 accessibility to reactive sites introduced in the form of mixed oxides. Moreover, with an increase in the carbon content homogeneity of mixed oxide deposition on the surface increases. The release of NO is governed by the ability of the carbon surface to reduce nitrate species. Weakly...