Enhanced Hydroformylation in a Continuous-Flow Microreactor with a Water-Soluble Phosphine Rhodium Catalyst

A packed tube microreactor with stainless steel springs was engineered to enhance mass transfer in the hydroformylation of Fischer-Tropsch 1-octene catalyzed by a water-soluble phosphine rhodium complex. Remarkably, within just 10 min of the reaction, 82% 1-octene was converted, resulting in a space-time yield of 140 kg<middle dot>m(-3)<middle dot>h(-1) for nonanal and a linear-to-branched aldehyde ratio of 27. In contrast to traditional stirred-tank reactors, the packed tube microreactor offered a higher surface-to-volume ratio and improved heat and mass transfer efficiency while eliminating sealing issues associated with mechanical stirring. This ensured the safety and stability of the production process. Moreover, compared to homogeneous catalytic systems, the water-soluble rhodium-catalyzed hydroformylation of olefins into aldehydes presented distinct advantages. It enabled facile separation and recycling of the catalyst from the reaction mixture, with minimal rhodium loss, evidenced by only 50 ppb detected in the crude aldehyde products. The catalytic performance remained stable during continuous running in the microreactor over 150 h, achieving a total turnover number of 71,731 without additional rhodium and ligand required.