Sulfur Poisoning and Self‐Recovery of Single‐Site Rh1/Porous Organic Polymer Catalysts for Olefin Hydroformylation

Sulfur poisoning and regeneration are global challenges for metal catalysts even at the ppm level. The sulfur poisoning of single-metal-site catalysts and their regeneration is worthy of further study. Herein, sulfur poisoning and self-recovery are first presented on an industrialized single-Rh-site catalyst (Rh₁ /POPs). A decreased turnover frequency of Rh₁ /POPs from 4317 h^-1 to 318 h^-1 was observed in a 1000 ppm H₂ S co-feed for ethylene hydroformylation, but it self-recovered to 4527 h^-1 after withdrawal of H₂ S, whereas the rhodium nanoparticles demonstrated poor activity and self-recovery ability. H₂ S reduced the charge density of the single Rh atom and lowered its Gibbs free energy with the formation of inactive (SH)Rh(CO)(PPh₃ -frame)₂ , which could be regenerated to active HRh(CO)(PPh₃ -frame)₂ after withdrawing H₂ S. The mechanism and the sulfur-related structure-activity relationship were highlighted. This work provides an understanding of heterogeneous ethylene hydroformylation and sulfur-poisoned regeneration in the science of single-atom catalysts.