Catalysis Science & Engineering, Short talk
CE-025

Metal-organic frameworks as kinetic modulators for branched selectivity in hydroformylation

P. Gäumann1,5, G. Bauer1, D. Ongari2, D. Tiana3, T. Rohrbach1, G. Pareras3, M. Tarik4, B. Smit2, M. Ranocchiari1*
1Laboratory for Catalysis and Sustainable Chemistry, PSI Villigen, 2Laboratory of Molecular Simulation, Institut des Sciences et Ingénierie Chimiques, Valais, EPFL Sion, 3School of Chemistry, University College Cork, 4Laboratory for Bioenergy and Catalysis, 5Institute for Chemistry and Bioengineering, ETH Zurich

Metal-organic frameworks (MOFs) find applications in gas capture and storage, catalysis and various other fields[1]. Their application in catalysis is strongly related to how MOFs can deliver results that are very challenging to obtain with other materials.

Hydroformylation is the reaction of an olefin with syngas to form aldehydes. Since the addition of CO happens at both carbons of the olefinic bond, the product is a mixture of a linear and a branched aldehyde. The selectivity towards the linear aldehyde has been the major focus of the chemical industry. The branched products can be used in the fine chemical industry, but are not easy to obtain selectively unless olefins with directing groups and complex rhodium catalysts are employed[2].

We found by Monte Carlo and DFT simulations that microporous MOFs with UMCM-1 and MOF-74 topologies increase the density of linear liquid olefins beyond neat conditions[3]. At the same time, they reduce the local concentration of H2 and CO. Exactly these conditions favor the selective formation of the branched aldehydes in cobalt-catalyzed hydroformylation[4]. The experimental procedure consists of simply adding the MOF to the reaction mixture prior to the insertion in the autoclave. Our experiments showed that the branched aldehyde is produced with up to 90 % selectivity in unmodified Co-catalyzed hydroformylation using 1-hexene to 1-nonene as starting material. This selectivity is unreached by homogeneous catalysis making MOFs an interesting kinetic modulator in the fine chemical industry. The experimental results are supported by computational simulations, which show that the active complex has a high affinity for the MOF such that a small amount drastically changes the ratio between linear and branched product

[1] Hiroyasu Furukawa, et al., Science, 2013, 341, 1230444.
[2] Leo Iu, et al., Angew. Chem. Int. Ed., 2019, 58, 2120 –2124.
[3] Gerald Bauer, et al., Nat. Commun., 2020, 11, 1059.
[4] Raghuraj V. Gholap, Oemer M. Kut, John R. Bourne, Ind. Eng. Chem. Res., 1992, 31, 2446-2450.