Activity promotion of Rh 1 Ca x /Al 2 O 3 single-atom catalyst in 1-octene hydroformylation: a volcano curve exists between Ca adding ratio and catalytic activity

Single-atom catalysts (SACs) are considered the best candidates for olefin hydroformylation due to their combined advantages of homogeneous and heterogeneous catalysts. Unlike conventional organo-phosphine modification, Rh SAC is modified by introducing Ca, resulting in a significant increase in activity (maximum ∼5.7-fold) and stability. Furthermore, a volcano curve between Ca addition ratio and catalytic activity is found. Introducing Ca significantly increases activity by decreasing the energy barrier, but excessive Ca decreases activity due to hindering substrate adsorption and reaction.