Improving the K resistance effectively of CeO2-TiO2 catalyst by Nb doping for NH3-SCR reaction

The role of Nb doping in improving anti-K poisoning ability of CeO2-TiO2 catalyst was investigated by SCR activity evaluation, BET, XRD, XPS, NH3-TPD, H-2-TPR and in situ DRIFTs. The catalytic activity of the Nbmodified CeO2-TiO2 catalyst was vastly superior to that of the CeO2-TiO2 catalyst in the presence of K. The doping of Nb could enhance the BET surface area and alleviate the surface crystallinity of the CeO2-TiO2 catalyst both before and after the introduction of K. In addition, the smaller decrease in the ratio of Ce3+/ Ce4+, surface chemisorbed oxygen, Bronsted acidity and redox property was observed on the Nb-modified CeO2-TiO2 catalyst in the presence of K. The results of in situ DRIFTs indicated that all of the reactions were controlled by combined E-R and L-H mechanisms on the fresh and K-poisoned catalysts. The addition of Nb could enhance the adsorption of NO and NH3, but not all NOx adsorbed species were reactive in the NH3-SCR reaction for K-poisoned CeO2-TiO2. All the above factors contributed to enhance its K-poisoning resistance of CeO2-TiO2 due to the doping of Nb. (c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.

Automated summary

The role of Nb doping in improving the anti-K poisoning ability of CeO2-TiO2 catalyst was investigated in this study. It was found that the Nb-modified catalyst exhibited significantly enhanced catalytic activity in the presence of K. The doping of Nb improved the BET surface area and reduced the surface crystallinity of the catalyst. In addition, the Nb-modified catalyst showed a smaller decrease in the ratio of Ce3+/Ce4+, surface chemisorbed oxygen, Bronsted acidity, and redox property in the presence of K. The results of in situ DRIFTs indicated that the reactions on both fresh and K-poisoned catalysts were controlled by combined E-R and L-H mechanisms. The addition of Nb enhanced the adsorption of NO and NH3, contributing to the improved K-poisoning resistance of CeO2-TiO2.