Influence of lattice oxygen on properties of Ce–Fe composite in NO+CO reduction system

Abstract

Ce–Fe composite was prepared by hydrothermal method to simulate the ore facies with Ce–Fe coatingembedded structure in rare earth tailings. Fe2O3 is used as the carrier and cerium nitrate is used as active component. We studied the effect of lattice oxygen on the performance of Ce–Fe composites in the NO+CO reduction system. The results show that the peak of CeO2 in the sample prepared by the hydrothermal method of nitric acid moves at a high angle, the lattice constant becomes smaller, and the diffraction peak corresponding to CeO2 in Raman is red-shifted. It indicated that the hydrothermal method can form Ce–O–Fe solid solution. In TEM, nanoscale Fe2O3 particles caused by the decomposition of ferric nitrate were observed on the surface of the sample. In the whole reaction process, a large amount of lattice oxygen provided by Fe2O3 as a carrier, the presence of Ce–O–Fe solid solution and free Fe2O3 fine particles determine the high catalytic activity of the composite catalyst. The presence of CeO2 can improve the surface reduction of Fe2O3, and also promote the conversion of Fe3+ to Fe2+, Ce4+ to Ce3+. The conversion of lattice oxygen to adsorbed oxygen reflects the combined action of the composite catalysts Ce and Fe. The denitration rate of the Ce–Fe composite NO+CO reduction system exceeded 92.24% at 700 °C. Lattice oxygen can promote the performance of Ce–Fe composites in NO+CO reduction system.