Insight into the regulating effect of phosphorylation on the NH3-SCR activity and properties of thiourea modified CeO2-TA catalyst

Abstract

Herein, three qualities of ammonium phosphate were used to investigate the influence of phosphorylation on the NH3-SCR activity of the CeO2-TA catalyst synthesized via the thiourea hydrothermal method. The results demonstrated that when the molar ratio of P/Ce was 0.1, the introduced ammonium phosphate was beneficial to the formation of highly disperse amorphous sulfates and active CePO4 on CeO2-TA surface, thus enhanced the surface total oxygen/adsorbed oxygen concentrations, the redox properties and the intermediate-strong acid sites of catalyst, which might be responsible for the better NH3-SCR activity of P0.1-CeO2-TA than CeO2-TA. However, the introduction of excessive ammonium phosphate promoted the formation of monoclinic CePO4 and reduced the formed quantity of amorphous sulfates on CeO2-TA surface, which were harmful to the redox properties and acid sites of catalyst. Therefore, the introduced ammonium phosphate decreased the NH3-SCR activity of CeO2-TA when the P/Ce molar ratio increased from 0.1 to 1.0.