Promotional mechanism of enhanced denitration activity with Cu modification in a Ce/TiO2-ZrO2 catalyst for a low temperature NH3-SCR system

Wei Zhang; Yunhao Tang; Wei Xiao; Min Ruan; Yanshan Yin; Quanbin Song; Kang Xie; Chuan Qin; Mengyao Dong; Yunhe Zhou; Jie Li

doi:10.1039/d1ra06325a

Promotional mechanism of enhanced denitration activity with Cu modification in a Ce/TiO₂-ZrO₂ catalyst for a low temperature NH₃-SCR system

RSC Adv. 2021 Dec 21;12(1):378-388. doi: 10.1039/d1ra06325a. eCollection 2021 Dec 20.

Authors

Wei Zhang^{1

2}, Yunhao Tang^{1

2}, Wei Xiao^{1

2}, Min Ruan^{1

2}, Yanshan Yin^{1

2}, Quanbin Song^{1

2}, Kang Xie^{1

2}, Chuan Qin^{1

2}, Mengyao Dong^{1

2}, Yunhe Zhou^{1

2}, Jie Li^{1

2}

Affiliations

¹ College of Energy and Power Engineering, Changsha University of Science & Technology Changsha 410114 China weizhang@csust.edu.cn.
² Key Laboratory of Renewable Energy Electric-Technology of Hunan Province Changsha 410114 China.

Abstract

This study aims to investigate the enhanced low temperature denitration activity and promotional mechanism of a cerium-based catalyst through copper modification. In this paper, copper and cerium oxides were supported on TiO₂-ZrO₂ by an impregnation method, their catalytic activity tests of selective catalytic reduction (SCR) of NO with NH₃ were carried out and their physicochemical properties were characterized. The CuCe/TiO₂-ZrO₂ catalyst shows obviously enhanced NH₃-SCR activity at low temperature (<300 °C), which is associated with the well dispersed active ingredients and the synergistic effect between copper and cerium species (Cu²⁺ + Ce³⁺ ↔ Cu⁺ + Ce⁴⁺), and the increased ratios of surface chemisorbed oxygen and Cu⁺/Cu²⁺ lead to the enhanced low-temperature SCR activity. The denitration reaction mechanism over the CuCe/TiO₂-ZrO₂ catalyst was investigated by in situ DRIFTS and DFT studies. Results illustrate that the NH₃ is inclined to adsorb on the Cu acidic sites (Lewis acid sites), and the NH₂ and NH₂NO species are the key intermediates in the low-temperature NH₃-SCR process, which can explain the promotional effect of Cu modification on denitration activity of Ce/TiO₂-ZrO₂ at the molecular level. Finally, we have reasonably concluded a NH₃-SCR catalytic cycle involving the Eley-Rideal mechanism and Langmuir-Hinshelwood mechanism, and the former mechanism dominates in the NH₃-SCR reaction.