Increasing cerium dispersion favours lattice oxygen activity of cobalt oxides for CO catalytic combustion

Abstract

Removing carbon monoxide with catalytic combustion technology is an effective and economical solution. Highly efficient conversion of CO at low temperatures can be achieved by introducing a catalyst, and its application in automotive exhaust emissions and preferential oxidation of CO in fuel cells is remarkable. In this work, catalysts were prepared by mixing the prepared cerium organic framework with Co3O4, and after calcination at 400 °C, the organic framework collapsed, resulting in a uniform dispersion of Ce on the Co3O4 nano surface. Experimental results demonstrated that the required temperature of the catalyst is 101 °C when the conversion is 90 %, and it remained stable over the 75 h tested at 100 °C. High resolution transmission electron microscopy (HRTEM) revealed that Ce/Co3O4 primarily exposed 311 surface. Combined with DFT calculations, the catalysts may improve the catalytic combustion activity of CO by multiplying the oxygen vacancies and modulating the dispersion of Ce atoms. The reaction occurred on the 311 surface predominantly. Activated CO* preferred to react with the lattice oxygen at the Ce-O-Co linkage compared to the lattice oxygen at Co-O-Co. Energy barrier for the rate dictating step in the complete catalytic cycle is 0.42 eV. This work not only provides experimental support and theoretical basis for the design of low-temperature catalytic combustion CO catalysts, but also provides new ideas for the doping of metal oxides with lanthanide metals.