Zr-Based MOF-545 Metal-Organic Framework Loaded with Highly Dispersed Small Size Ni Nanoparticles for CO₂ Methanation

Area of Science:

• Materials Science
• Catalysis
• Nanotechnology

Background:

• Metal-organic frameworks (MOFs) offer tunable structures for catalytic applications.
• CO2 hydrogenation to methane is a key process for carbon utilization and renewable energy storage.

Purpose of the Study:

• To synthesize and characterize Ni nanoparticles (NPs) supported on Zr-based MOF-545 for CO2 hydrogenation.
• To investigate the structural transformation of MOF-545 under reaction conditions.
• To evaluate the catalytic performance of Ni@MOF-545 catalysts prepared by different methods.

Main Methods:

• Operando DRIFT spectroscopy, ex situ characterizations (PXRD, XPS, TEM, EDX), and DFT calculations were used to study the MOF support.
• Ni NPs were immobilized on MOF-545 using impregnation (IM) and double solvent (DS) methods, followed by dry reduction (R).
• Catalytic activity for CO2 hydrogenation was assessed by monitoring CH4 production and CO2 conversion.

Main Results:

• MOF-545 transformed into an amorphized, catalytically active material with dehydroxylated Zr-oxoclusters under high-temperature conditions.
• The Ni@MOF-545 DS R catalyst exhibited the highest activity (595 mmolCH4 gNi−1 h−1) with 100% CH4 selectivity and 60% CO2 conversion.
• The superior performance of Ni@MOF-545 DS R is attributed to smaller (∼5 nm) and better-dispersed Ni NPs compared to the IM method, which suffered from sintering.

Conclusions:

• Zr-based MOFs, like MOF-545, can serve as effective supports for Ni NPs in CO2 hydrogenation.
• The double solvent method followed by reduction is advantageous for preparing highly dispersed Ni NPs, enhancing catalytic efficiency.
• Further exploration of novel Zr-based MOFs for Ni NP catalysts in CO2 hydrogenation is warranted.