Control of the morphology and reactivity of MIL-100(Fe): effect of synthesis variables on NOx removal

Abstract

In this study, we synthesized a metal–organic framework (MOF) material, MIL-100(Fe), under various conditions and evaluated its performance as a catalyst for activating the H₂O₂/NaOH system to efficiently remove nitrogen monoxide (NO_x). However, the influence of different synthesis conditions on the NO_x removal efficiency of this material remains unclear. To investigate this, we varied the iron source, precursor ratio, solvent, hydrothermal temperature, and reaction time during catalyst synthesis to control the material's composition, crystallinity, particle size, specific surface area, and iron content. Using FeCl₂ as the iron source, a FeCl₂ to H₃BTC ratio of 1 : 2, H₂O as the solvent, and a hydrothermal temperature of 180 °C for 12 hours, the optimal MIL-100(Fe) was synthesized, which exhibited the highest NO_x removal performance. The maximum NO_x removal capacity of MIL-100(Fe) was 22.97 mmol L⁻¹, corresponding to an efficiency of 86.91%. This study offers new insights into the use of MIL-100(Fe) synthesized under different conditions as a Fenton-like catalyst for NO_x removal. We found that an efficient MIL-100(Fe) catalyst requires a combination of larger octahedral particles and irregularly shaped small particles at their boundaries, resulting in a larger specific surface area, abundant exposed iron active sites, and moderate crystallinity.