MIL-53(Fe)-based catalysts: CO2 hydrogenation performance and three-dimensional structures

Transition based metal–organic frameworks (MOFs) demonstrate significant potential for thermal catalysis owing to their high density of active metal sites, and tunable porous structure. Especially understanding the correlation between the three-dimensional (3D) structure and its catalytic performance is pivotal for designing highly efficient, stable, and selectively active thermal catalysts. Here, based on MIL-53(Fe) and its derivatives heat-treated at varying temperatures, we comprehensively investigated their 3D structures and properties using 3D reconstruction techniques in transmission electron microscopy. The specimen, pyrolysis at 800 °C in air, exhibits optimal performance used as the catalyst for CO₂ hydrogenation, achieving 21.4 % CO₂ conversion and 100 % CO selectivity. Additionally, it presents exceptionally high activity and thermal stability after reaction for 120 h. Detailed insights into the morphology, composition, pore, and surface crystallography of an individual MIL-53(Fe) and its pyrolysis product particle, respectively, are provided by 3D reconstruction at nanoscale to correlate these structural features with their catalytic performance. This research contributes valuable experimental data and theoretical insights for the structural modulation and performance enhancement of MOF-based catalysts.