Synthesis of Cu/Mn bimetallic organic framework material and their catalytic performance for NH3-SCR

Highly efficient MOF-based catalysts are attractive alternatives to traditional catalysts for the removal of NOx by the NH3-SCR. In this study, we prepared the Mn nanoparticle-supported Cu/Mn bimetallic organic framework (Mn-Cu-BTC) catalyst material by a rotary-evaporation impregnation method without calcination. The Mn nanoparticles were highly dispersed in the Cu-BTC pore structure through strong active-component-support interactions. This gives the catalyst abundant reactive oxygen species and acidic sites showing excellent catalytic activity, but it has little effect on the phase structure and crystal shape. Excessive Mn element doping blocked the Cu2+/Cu+ redox pair and inhibited the redox sites on the Cu-BTC catalyst. The acidic and redox sites on the surface of the Mn-Cu-BTC catalyst were balanced by adjusting the Mn/Cu-BTC mass ratio. When the mass ratio of MnCl2/Cu-BTC was 1/1 (Mn-Cu-BTC-500), it can provide the best catalytic activity. The acid amount of the weak acid site of the Mn-Cu-BTC-500 catalyst is about 22.2 mu mol g(-1), and the ratio of adsorbed oxygen (O alpha) was as high as 47 %, which is 3.3 times and 4.9 times that of the original Cu-BTC, respectively. The results demonstrated that the NO conversion of Mn-Cu-BTC-500 reached 92.7 %, which was increased by 1.32 times at 240 degrees C. Importantly, Mn-Cu-BTC-500 satisfied stability in NH3-SCR reaction, and its resistance to SO2 poisoning is increased by 142 %, which made it to be a potential and promising low-temperature SCR catalyst. This study provides a feasible method for adjusting the acidity and redox sites of bimetallic MOF-based catalysts, and provides technical and theoretical support for the design of new catalysts.