Design of Cu-based MIL-100(Fe) catalyst for propylene-selective catalytic reduction of NOx: Combination of activity, characterizations and mechanism

The hydrothermal technique was applied to prepare a new metal–organic framework, MIL-100(Fe), which was modified by ultrasonic impregnation with different wt % of copper. The results showed that the NO x conversion over 2.3Cu-MIL-100(Fe) was 100 % at 275 °C and maintained at ≥ 85 %, with N 2 selectivity ≥ 90 % in the temperature range of 275–400 °C and high SO 2 resistance. An increase in the Cu content up to 2.3 wt% showed the highest surface area (1206 m 2 /g) observed in N 2 adsorption–desorption. The results show that the introduction of Cu increased the oxygen vacancies on the catalyst surface. Electron transfer and a synergistic effect were observed between Cu and Fe. The shift of the reduction peaks to lower temperatures after the addition of Cu confirmed that Cu improved the reducibility of the catalysts. The 2.3Cu-MIL-100(Fe) exhibited the highest Lewis content (44.97 μmol/g), which functions as an active site for the selective catalytic reduction (SCR) reaction. By precisely controlling the acid-base properties of the catalyst, the specificity for the desired products can be increased in complicated reaction systems, especially in hydrocarbon-SCR technology.