M-MnCeOX derived from MOF for low temperature selective catalytic reduction of NOX by NH3: Experiments and mechanisms

Abstract

A series of M-MnCeOX catalysts using MOF (Metal-organic Framework) were prepared to apply for NH3-SCR (Selective Catalytic Reduction) of NOX. The effects of Mn/Ce molar ratio, calcination temperature and its activity including catalytic activity, H2O/SO2 resistance and stability were systematically investigated. The results showed that under the Mn/Ce molar ratio of 1 and calcination temperature of 400 ℃, the catalyst exhibited excellent catalytic activity, H2O/SO2 resistance, and stability. When the concentration of NO was 500 ppm, the gas spatiotemporal velocity (GHSV) was 36,000 h−1, and the reaction temperature was 100 ℃, the NO conversion efficiency of M-MnCeOX exceeded 90.0 %. Added 200 ppm SO2 and 3 vol% H2O simultaneously, the NO conversion efficiency was close to 80.0 %. By analyzing the physicochemical properties of the catalyst, M-MnCeOX had a large specific surface area, numerous acidic sites, and excellent redox properties. According to density functional theory (DFT), the NH3/NO adsorption energy of M-MnCeOX were −2.35 and −2.40 eV, exhibiting lower than a single MOF-derivative, promoting the adsorption of NH3 or NO. The reaction mechanism on the M-MnCeOX catalyst followed the E-R and L-H mechanisms by In situ DRIFTS.