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

Abstract

We report the use of Zr-based metal−organic frameworks (MOFs) as supports to prepare catalysts with uniformly and highly dispersed Ni nanoparticles (NPs) for CO 2 hydrogenation into CH 4 . In the first step, we studied the MOF support under catalytic conditions using operando diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, ex situ characterizations (PXRD, XPS, TEM, and EDX-element mapping), and DFT calculations. We showed that the high-temperature conditions undoubtedly confer a potential for catalytic functionality to the solids toward CH 4 production, while no role of the Cu could be evidenced. The MOF was shown to be transformed into a catalytically active material, amorphized but still structured with dehydroxylated Zr-oxoclusters, in line with DFT calculations. In the second step, Ni@MOF-545 catalysts were prepared using either impregnation (IM) or double solvent (DS) methods, followed by a dry reduction (R) route under H 2 to immobilize Ni NPs. The highest catalytic activity was obtained with the Ni@MOF-545 DS R catalyst (595 mmol CH4 g Ni −1 h −1 ) with 100% CH 4 selectivity and 60% CO 2 conversion after ∼3 h. The higher catalytic activity of Ni@MOF-545 DS R is a result of much smaller (∼5 nm) and better dispersed Ni NPs than in the IM sample (20−40 nm), the latter exhibiting sintering. The advantages of the encapsulation of Ni NPs by the DS method and of the use of a MOF-545-based support are discussed, highlighting the interest of designing yetunexplored Zr-based MOFs loaded with Ni NPs for CO 2 hydrogenation.

Ionic Liquid Modified Fe-Porphyrinic Metal–Organic Frameworks as Efficient and Selective Photocatalysts for CO2 Reduction

“…Metal–organic frameworks (MOFs) are versatile materials due to their large surface areas, high porosity, tunable pore size and shape, with potential applications in gas storage and separation, drug delivery, purification, catalysis, sensors, and batteries . Porous MOF materials are hybrid networks created by coordinating metal nodes with organic ligands. − The textural and structural properties can be adjusted by varying the combination of metals and ligands to fit specific applications. − Several new approaches were presented to modify MOF structures for different applications along with tunable metal nodes and ligands. These techniques include the functionalization of ligands and open metal sites, , the combination of mixed metals or mixed ligands, and the engineering of defects .…”