Enhanced low-temperature CO-SCR denitration performance and mechanism of two-dimensional CuCoAl layered double oxide

Abstract

Pollution primarily caused by NO has a severe impact on environment and health, and researchers are now actively investigating the removal of NO using CO as a reducing agent. Catalytic removal of NO using CO usually occurs between 200 °C and 400 °C, and methods for preparing catalysts with good catalytic activity that can scavenge NO at low temperatures and their reaction mechanism remain challenging. In this study, we derived a catalyst based on two-dimensional hydrotalcite and attained 96.6% conversion of NO at only 150 °C. The CuCoAl-LDO catalyst exhibited a high specific surface area of 125.5 m2/g, and its mechanism was studied extensively via material characterization, in situ Fourier transform infrared spectroscopy, and density functional theory calculations. Results showed that Al doping could effectively augment the specific surface area of the Cu-based catalyst to expose more active sites. Furthermore, Cu+-□-Co3+ surface synergistic oxygen vacancies are formed on the surface of the catalyst owing to the synergistic effect between copper and cobalt, which can promote the redox cycle of copper and cobalt species. The presence of Cu+–CO species is essential for improving the activity of the CuCoAl-LDO catalyst at low temperatures. The proposed reaction mechanism of scavenging NO using CO on the surface of the CuCoAl-LDO catalyst offers new ideas for developing highly efficient CO-selective catalytic reduction denitrification catalysts at low temperatures.