Enhancing resistance to CaO&PbO poisoning of CeO2/TiO2 NH3-SCR catalyst via hybrid with SO42−/ZrO2: Dual functions of SO42−/ZrO2
Chenguang Zhang, Shuo Feng, Peng Yuan, Peng Zhao, Pei Gao, Shuhao Li, Qiqi Shi, Dongrui Kang, Yuye Xing, Boxiong Shen
Abstract
Catalyst deactivation caused by the co-poisoning of alkaline earth metals (CaO) and heavy metals (PbO) is still a problem in the NH 3 selective catalytic reduction (SCR) of NO x in flue gas. In this work, a hybrid catalyst (Hybrid-CT) was being synthesized by grinding CeO 2 /TiO 2 (CT) catalyst and SO 4 2− /ZrO 2 to evaluate the poisoning tolerance. It shown that Hybrid-CT exhibited a higher tolerance against CaO&PbO poisoning compared with CT. Under the co-poisoning of 2.5 wt% CaO and 2.5 wt% PbO, the NO x conversion of Hybrid-CT catalyst could approach to 100 % at 350 °C. Whereas, the NO x conversion of CT was only 66.3 % under the same condition. A series of characterizations suggested that the SO 4 2− /ZrO 2 could inhibit the CaO&PbO poisoning. Once the CaO&PbO present on the surface of Hybrid-CT catalyst, SO 4 2− could convert CaO&PbO into CaSO 4 &PbSO 4 with less toxic, which could protect the redox site and acid site of the CeO 2 /TiO 2 . Furthermore, the ZrO 2 released from SO 4 2− /ZrO 2 could serve as a promoter, enhancing the acid performance of CeO 2 /TiO 2 catalysts. Moreover, SO 4 2− /ZrO 2 could also reduce the passive effect of CaO&PbO on nitrate oxide. This work provides a simple and novel way to improve the resistance to CaO&PbO of Ce-based SCR catalysts.