MOF as Solid Ligands of Organometallic Catalysts – Unrivalled performances !
Résumé
For specific acid-base type catalytic reactions, MOF have shown superior performances than commercial catalysts [1]. However, the intrinsic acidity of MOFs is usually too weak for acid reactions such as those applied in the refinery industry which represent more than 80% of catalytic processes.
On the other hand, there is strong incentive to develop greener catalytic processes based on heterogeneous catalysis. However, the grafting of molecular catalyst at the surface of support such as mesoporous silica is not obvious. More importantly, the hydroxylated surface strongly interacts with the catalytic moiety denaturing its structure and thus yielding poor catalytic performances.
MOFs are ideal platforms for the immobilization of molecular catalysts.
-the vast chemical tool-box, ranging from Polymer Science to Bio-chemistry, can be applied for grafting catalyst moiety [2],
-site isolation and high pore volume offer unlimited access to substrates,
-the hydrophobic environment allows preserving the nature of the catalytic center,
-the confinement of substrates shall increase chemo-, regio- or enenatioselectivity.
The superiority of MOF as ligand will be demonstrated on three examples:
-greater activity and selectivity for ethylene oligomerization on MIL-101 and UiO-67,
-greater selectivity of MOF-supported (arene)metal-based catalyst for the asymmetric reduction of ketones on MIL-101,
-highly efficient photochemical reduction of CO2 utilizing UiO-67as ligand.
[1] C. Chizallet et al., JACS, 2010; L. Wee et al., ChemCatChem, 2013
[2] M. Savonnet et al. Dalton Trans, 2012 ; J. Canivet et al., ChemComm 2011, JACS, 2013