Abstract
The modular structure of metal-organic frameworks (MOFs) makes them promising platforms for catalyst design and for elucidating structure/performance relationships in catalysis. In this work, we systematically varied the composition of the metal nodes (Fe2M) of the MOF PCN-250 and used density functional theory (DFT) to identify promising catalysts for light alkane C-H bond activation. Oxidative dehydrogenation (ODH) of alkanes was studied using N2O as the oxidant to understand the reactivity of the oxocentered Fe2M nodes found in PCN-250, where the Fe ions are in the +3 oxidation state and M is a metal with the oxidation state of +2. We show that the N2O activation barrier is positively correlated with the oxygen-binding energy at the metal center, and the C-H activation barrier is negatively correlated with this same quantity. For clusters containing early transition metals, oxygen binds strongly, facilitating N2O activation but hindering C-H activation. To validate the DFT predictions, we synthesized and tested PCN-250(Fe2M) with M = Mn, Fe, Co, and Ni and found that PCN-250(Fe2Mn) and PCN-250(Fe3) are more active than PCN-250(Fe2Co) and PCN-250(Fe2Ni) in agreement with the DFT predictions, demonstrating the power of DFT calculations to predict and identify promising MOF catalysts for alkane C-H bond activation in advance of experiments.
Original language | English (US) |
---|---|
Pages (from-to) | 1460-1469 |
Number of pages | 10 |
Journal | ACS Catalysis |
Volume | 10 |
Issue number | 2 |
DOIs | |
State | Published - Jan 17 2020 |
Keywords
- C-H bond activation
- PCN-250
- density functional theory
- metal-organic frameworks
- oxidation catalysis
- oxidative dehydrogenation
- structure-function relationships
ASJC Scopus subject areas
- Catalysis
- Chemistry(all)