Bioinspired microenvironment modulation of metal-organic framework-based catalysts for selective methane oxidation.

Inspiration from natural enzymes enabling creationary catalyst design is appealing yet remains extremely challenging for selective methane (CH) oxidation. This study presents the construction of a biomimetic catalyst platform for CH oxidation, which is constructed by incorporating Fe-porphyrin into a robust metal-organic framework, UiO-66, furnished with saturated monocarboxylic fatty acid bearing different long alkyl chains. The catalysts demonstrate the high efficiency in the CH to methanol (CHOH) conversion at 50 °C. Moreover, the selectivity to CHOH can be effectively regulated and promoted through a fine-tuned microenvironment by hydrophobic modification around the Fe-porphyrin. The long-chain fatty acids anchored on the Zr-oxo cluster of UiO-66 can not only tune the electronic state of the Fe sites to improve CH adsorption, but also restrict the amount of HO around the Fe sites to reduce the overoxidation. This behavior resembles the microenvironment regulation in methane monooxygenase, resulting in high CHOH selectivity.