Synthesis of CrO x /C catalysts for low temperature NH3-SCR with enhanced regeneration ability in the presence of SO2

Shuohan Yu; Sheng Xu; Bowen Sun; Yiyang Lu; Lulu Li; Weixin Zou; Peng Wang; Fei Gao; Changjin Tang; Lin Dong

doi:10.1039/c7ra09680a

Synthesis of CrO _x /C catalysts for low temperature NH₃-SCR with enhanced regeneration ability in the presence of SO₂

RSC Adv. 2018 Jan 22;8(7):3858-3868. doi: 10.1039/c7ra09680a. eCollection 2018 Jan 16.

Authors

Shuohan Yu^{1

2}, Sheng Xu³, Bowen Sun^{1

2}, Yiyang Lu^{1

2}, Lulu Li^{1

2}, Weixin Zou^{1

2}, Peng Wang³, Fei Gao^{1

2}, Changjin Tang^{1

2}, Lin Dong^{1

2}

Affiliations

¹ Key Laboratory of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Nanjing University Nanjing 210093 PR China donglin@nju.edu.cn gaofei@nju.edu.cn.
² Jiangsu Key Laboratory of Vehicle Emissions Control, Center of Modern Analysis, Nanjing University Nanjing 210093 PR China.
³ National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences, Collaborative Innovation Center of Advanced Microstructures, Nanjing University Nanjing 210093 China.

Abstract

Chromium oxide nano-particles with an average diameter of 3 nm covered by amorphous carbon (CrO _x /C) were successfully synthesized. The synthesized CrO _x /C materials were used for the selective catalytic reduction of NO _x by NH₃ (NH₃-SCR), which shows superb NH₃-SCR activity and in particular, satisfactory regeneration ability in the presence of SO₂ compared with Mn-based catalysts. The as-prepared catalysts were characterized by XRD, HRTEM, Raman, FTIR, BET, TPD, TPR, XPS and in situ FTIR techniques. The results indicated presence of certain amounts of unstable lattice oxygen exposed on the surface of CrO _x nano-particles with an average size of 3 nm in the CrO _x /C samples, which led to NO being conveniently oxidized to NO₂. The formed NO₂ participated in NH₃-SCR activity, reacting with catalysts via a "fast NH₃-SCR" pathway, which enhanced th NH₃-SCR performance of the CrO _x /C catalysts. Furthermore, the stable lattice of the CrO _x species made the catalyst immune to the sulfation process, which was inferred to be the cause of its superior regeneration ability in the presence of SO₂. This study provides a simple way to synthesize stable CrO _x nano-particles with active oxygen, and sheds light on designing NH₃-SCR catalysts with highly efficient low temperature activity, SO₂ tolerance, and regeneration ability.