Confining Molecular rhodium phosphine catalysts within liquid-solid hybrid microreactor for olefin hydroformylation

Abstract

The concept of liquid-solid hybrid catalyst that featuring a truly homogeneous liquid microenvironment together with insoluble solid characteristics has been established recently by our group, which enables us to conveniently bridge the gap between homo- and heterogeneous catalysis. In this study, we extend this general concept to the confinement of molecular rhodium phosphine complexes, including Rh-TPPTS, Rh-TPPMS and Rh-SXP, for olefin hydroformylation reactions. A series of hybrid catalyst materials consisting a modulated liquid interior ([BMIM]NTf₂, [BMIM]PF₆, [BMIM]BF₄ or H₂O) and a permeable silica crust were fabricated through our developed Pickering emulsion-based method, showing 9.4–24.2-fold activity enhancement and significantly improved aldehyde selectivity (from 72.2%, 61.8% to 86.6%) compared to their biphasic counterparts or traditional supported liquid phase system in the hydroformylation of 1-dodecene. Interestingly, the catalytic efficiency was demonstrated to be tunable by rationally engineering the thickness of porous crust and dimensions of the liquid pool. The thus-attained hybrid catalyst could also successfully catalyze the hydroformylation of a variety of olefin substrates and be recycled without a significant loss of activity for at least seven times.