The van Bokhoven Group

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Single Site Catalysis

For dehydrogenation of formic acid:

Metal–organic frameworks (MOFs) are ideal hosts for incorporation of molecular complexes without altering their original ligand environment; molecular catalysts can thus be easily synthesized and used in gas- and vapor-phase reactions operated in continuous mode.

We report the immobilization of a molecular ruthenium complex in a phosphine-functionalized MOF that is highly efficient in the vapor-phase dehydrogenation of formic acid.

Enlarged view: Ru-LSK-15
(a) General representation of the MIL-101 pore system (green = aluminum, red = oxygen, gray = carbon). (b) Molecular representation of the local environment in Ru-LSK-15 with phosphine and amine linkers (pink = phosphorus, blue = nitrogen, orange = ruthenium, light green = chloride). Hydrogen atoms are omitted for clarity. (c) Schematic representation of the ruthenium, phosphine, and amine functionalities present in the MOF cages.

The catalyst exhibited exclusive selectivity to hydrogen and carbon dioxide with outstanding stability at 145 °C (TON > 1 290 000).

Our results represent a noteworthy improvement over heterogeneous ruthenium systems in terms of selectivity in the gas-phase, while reaching a productivity level higher than that of state-of-the-art homogeneous catalysts.

Enlarged view: Selectivity
(a) Formic acid conversion and (b) selectivity to hydrogen and carbon monoxide with time while switching the reaction temperature between 125, 145, and 165 °C. Error bars represent the standard deviation of four consecutive measurements.

This research is published by: A. B. Redondo, F. L. Morel, M. Ranocchiari, and J. A. van Bokhoven, Functionalized Ruthenium–Phosphine Metal–Organic Framework for Continuous Vapor-Phase Dehydrogenation of Formic Acid, ACS Catal., 2015, 5 (12), pp 7099–7103

external pageDOI:10.1021/acscatal.5b01987

 

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