Study of nano-structured ceria for catalyticCO oxidation

Abstract

Mesoporous, nano-structured ceria has been synthesized using a low-cost biopolymer chitosan as a template, and the same material has been studied for its CO oxidation activity. The ceria thus prepared shows low crystallite size (6.5 nm), high surface area (BET-SA 144.2 m² g⁻¹) and mesopores (32.4 Å) without ordered structure. Different ceria samples have been synthesized by manipulating the chitosan : cerium ratio and synthesis temperature. These ceria samples have been characterized using XRD, BET-SA, SEM, FTIR, UV-DRS, PL and TEM techniques. The ceria samples show fluorite structure with cubic symmetry and increased lattice volume. The nano-structured ceria thus synthesized lowers the CO oxidation temperature by 30–60 °C as compared to the commercial ceria. The improved catalytic activity primarily appears to be the effect of improved surface area and pore characteristics of nano-structured ceria. Also the expansion in lattice cell volume leads to the improvement in redox properties of ceria, thereby facilitating the formation of surface oxygen vacancies. Such mesoporous ceria without ordered structure could be useful as an oxidation catalyst as well as a support for various catalysts. The platinum incorporated mesoporous ceria also shows excellent CO oxidation.