Phosphorus-containing polymeric ionic liquids-supported rhodium catalyst for hydroformylation of dihydrofurans

Abstract

By immobilizing complexes on the surface of phosphorus-containing polymeric ionic liquids (PILs-PPh3), heterogenization of homogeneous catalysts was realized, which promoted the design combination of the advantages of heterogeneous and homogeneous catalysts. Furthermore, the addition of ionic liquid can increase the designability of the phosphine ligand, ranging from the pore structure to acid-base adjustability. In this study, a series of PILs-PPh3 were successfully prepared by copolymerization. The PILs-PPh3 were characterized by scanning electron microscopy, thermogravimetry, and N2 adsorption-desorption isotherms. Heterogenized homogeneous Rh@PILs-PPh3 catalysts were synthesized by immobilizing Rh(CO)2(acac) on PILs-PPh3, which was used not only as a support but also as a ligand. Furthermore, the Rh@VIMBtDVB-PPh3 catalyst was characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma spectroscopy. The FT-IR and XPS results showed that Rh1 species were present on the Rh@VIMBtDVB-PPh3 catalyst. Moreover, the catalytic performance of Rh@VIMBtDVB-PPh3 was investigated for the hydroformylation of 2,5-dihydrofuran. The effects of the amount of catalyst, mole ratio of reactants, and partial pressure ratio on the reaction were investigated. Undoubtedly, the prepared supported catalyst exhibited good thermal stability and potential applications.