Metal-organic frameworks (MOFs) are porous materials that are formed by nodes of metal ions or metal oxide clusters linked by organic ligands; this modularity results in a large set of diverse pore networks useful in various applications, including wastewater treatment, gas capture and separations, energy storage, sensing, and catalysis. Here, we investigate MOFs as catalysts and catalyst precursors for oxidation, dehydrogenation, and reduction reactions, respectively. First, we probe the kinetic mechanism and recyclability of MIL-101, one of the more thermochemically tenable MOFs, for styrene oxidation with hydrogen peroxide, an oxidant with primarily benign byproducts (i.e. water). Specifically, we assess the intrinsic reactivity and stability differences between MIL-101 in its Cr and Fe forms. Oxygenate production rates are constant across all cycles for MIL-101(Fe), whereas MIL-101(Cr) resulted in increased rates and a different product distribution after the first cycle; the presence of solvated Cr(III) complexes was observed via UV-VIS, indicating that chromium leaching dominates cycling inefficiencies. Second, we utilize MOFs as catalysts precursors that result in unique nanomaterials upon high temperature treatment or under an applied potential. The efficacy of these MOF-derived catalysts, in monometallic Fe and Cu forms, was tested for propane dehydrogenation and CO<sub>2</sub> electrocatalytic reduction, respectively. The effect of external applied on the phase and/or structure of the catalysts, as determined from various characterization techniques, was evaluated along with their catalytic performances. The work shown here provides examples of using MOFs as catalysts and as precursors to synthesize unique, stable catalyst structures with desired rates and selectivities for hydrocarbon processes.

Survive and advance: A study of metal-organic frameworks deactivation mechanisms for small-molecule conversions

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.