Carbonized Nickel-Incorporated Metal-Organic Frameworks for Methane Reforming: Post-Synthetic Modification vs Impregnation

Nickel is one of the most attractive catalytically active species for methane reforming─a crucial process for producing liquid fuels and methanol, and the use of nanoporous materials to support nickel is usually necessary. Impregnation is the commonly used method to incorporate nickel into a porous support. In this work, we incorporate catalytically active nickel into a highly porous cerium(IV)-based metal-organic framework (MOF) by utilizing either the conventional impregnation or the self-limiting post-synthetic modification, and the nanosized MOF-derived ceria-supported nickel is prepared by carbonizing the nickel-incorporated Ce-based MOFs. The crystallinity, porosity, nanostructural morphology, and surface properties of each MOF and MOF-derived materials are characterized, and as a demonstration, the MOF-derived catalysts are used for the bi-reforming of methane (BRM). The catalytic activity at various temperatures is examined, and the long-term stability of MOF-derived catalysts for BRM is investigated at 600 °C. The presence of MOF-derived carbon is necessary to initiate the BRM at a lower temperature, and compared to the conventional impregnation, the use of post-synthetic modification to install the spatially separated nickel sites in the parent MOF can effectively retard the agglomeration of nickel in the final MOF-derived catalyst during the long-term BRM. Findings here suggest that the use of post-synthetic modification to install the catalytically active species in MOFs is beneficial for designing the MOF-derived catalysts that are more resistive to sintering.