Circumventing the wettability issue of heterogeneous metal catalysts for solvent-free organic transformations.

Substituting homogeneous metal catalysts with recyclable heterogeneous metal catalysts has long been a goal in catalysis. However, most approaches yield heterogeneous metal catalysts that often exhibit relatively low stability and diminished catalytic activity under practical reaction conditions. Herein, we present an inorganic Rh catalyst obtained by confining subnanometer Rh clusters within a self-pillared zeolite structure. This catalyst design not only stabilizes the subnanometer Rh active sites but also facilitates efficient mass transport properties during solvent-free olefin hydroformylation reaction. Owing to the unique electronic properties of the Rh clusters and the optimal morphology of the zeolite support, the optimal catalyst achieves over 1,100,000 total turnovers across a broad substrate range under solvent-free conditions. This strategy can be extended to other metals confined within self-pillared zeolite, offering a general approach to circumvent the wettability issue of heterogeneous metal catalysts for solvent-free organic transformations.