Cascade NH3 Oxidation and N2O Decomposition via Bifunctional Co and Cu Catalysts

Xuze Guan; Hiroyuki Asakura; Rong Han; Siyuan Xu; Hao-Xin Liu; Lu Chen; Zhangyi Yao; Jay Hon Cheung Yan; Tsunehiro Tanaka; Yuzheng Guo; Chun-Jiang Jia; Feng Ryan Wang

doi:10.1021/acscatal.3c02392

Cascade NH₃ Oxidation and N₂O Decomposition via Bifunctional Co and Cu Catalysts

ACS Catal. 2023 Oct 12;13(20):13816-13827. doi: 10.1021/acscatal.3c02392. eCollection 2023 Oct 20.

Authors

Xuze Guan¹, Hiroyuki Asakura^{2

3}, Rong Han⁴, Siyuan Xu⁴, Hao-Xin Liu⁵, Lu Chen¹, Zhangyi Yao¹, Jay Hon Cheung Yan¹, Tsunehiro Tanaka³, Yuzheng Guo⁴, Chun-Jiang Jia⁵, Feng Ryan Wang¹

Affiliations

¹ Department of Chemical Engineering, University College London, Roberts Building, Torrington Place, London WC1E 7JE, U.K.
² Department of Applied Chemistry, Faculty of Science and Engineering, Kindai University 3-4-1, Kowakae, Higashiosaka, Osaka 577-8502, Japan.
³ Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyotodaigaku Katsura, Nishikyo-ku, Kyoto, Kyoto 615-8510, Japan.
⁴ School of Electrical Engineering and Automation, Wuhan University, Wuhan, Hubei 430072, China.
⁵ Key Laboratory for Colloid and Interface Chemistry, Key Laboratory of Special Aggregated Materials, School of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong 250100, China.

Abstract

The selective catalytic oxidation of NH₃ (NH₃-SCO) to N₂ is an important reaction for the treatment of diesel engine exhaust. Co₃O₄ has the highest activity among non-noble metals but suffers from N₂O release. Such N₂O emissions have recently been regulated due to having a 300× higher greenhouse gas effect than CO₂. Here, we design CuO-supported Co₃O₄ as a cascade catalyst for the selective oxidation of NH₃ to N₂. The NH₃-SCO reaction on CuO-Co₃O₄ follows a de-N₂O pathway. Co₃O₄ activates gaseous oxygen to form N₂O. The high redox property of the CuO-Co₃O₄ interface promotes the breaking of the N-O bond in N₂O to form N₂. The addition of CuO-Co₃O₄ to the Pt-Al₂O₃ catalyst reduces the full NH₃ conversion temperature by 50 K and improves the N₂ selectivity by 20%. These findings provide a promising strategy for reducing N₂O emissions and will contribute to the rational design and development of non-noble metal catalysts.