**Enhancing the Water Resistance of Mn-MOF-74 by Modification in Low Temperature NH3-SCR**

**Sheng Wang 1,2,**†**, Qiang Gao 1,2,**†**, Xiuqin Dong 1,2, Qianyun Wang 1,2, Ying Niu 1,2, Yifei Chen 1,2 and Haoxi Jiang 1,2,\***

1 Key Laboratory for Green Chemical Technology of Ministry of Education, R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China; shw@tju.edu.cn (S.W.); qgao@tju.edu.cn (Q.G.); xqdong@tju.edu.cn(X.D.);qywang@tju.edu.cn(Q.W.);yniu@tju.edu.cn(Y.N.);yfchen@tju.edu.cn(Y.C.)


Received: 4 November 2019; Accepted: 27 November 2019; Published: 29 November 2019

**Abstract:** In this study, Mn-MOF-74 was successfully synthesized and further modified via two paths for enhanced water resistance. The structure and morphology of the modified samples were investigated by a series of characterization methods. The results of selective catalytic reduction (SCR) performance tests showed that polyethylene oxide-polypropylene-polyethylene oxide (P123)-modified Mn-MOF-74 exhibited outstanding NO conversion of up to 92.1% in the presence of 5 vol.% water at 250 ◦C, compared to 52% for Mn-MOF-74 under the same conditions. It was concluded that the water resistance of Mn-MOF-74 was significantly promoted after the introduction of P123 and that the unmodified P123-Mn-MOF-74 was proven to be a potential low-temperature SCR catalyst.

**Keywords:** Mn-MOF-74; modification; water resistance; NH3-SCR performance
