The 2V-P,N polymer supported palladium catalyst for methoxycarbonylation of acetylene

• 2-PyPPh2 ligand based porous organic polymer (POL-2V-P,N) was successfully synthesized.
• The Pd/POL-2V-P,N catalyst exhibits higher activity than the corresponding homogeneous complex.
• The reused catalyst exhibited similar activity as that of the fresh catalyst.

Heterogenization of homogeneous catalyst by immobilizing complex on the surface of polymer supports promotes the design of the catalysts which combine the advantages of heterogeneous and homogeneous catalysts. The porous 2-vinyl-functional diphenyl-2-pyridylphosphine (2V-P,N) polymer (POL-2V-P,N) was successfully synthesized under solvothermal conditions. The POL-2V-P,N polymer was characterized by nitrogen physisorption, thermogravimetry (TG), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The heterogenized homogeneous Pd/POL-2V-P,N catalyst was synthesized by immobilizing Pd(OAc)2 on the POL-2V-P,N, which was used as not only support but also as ligands. The catalyst was investigated by means of 31P NMR, X-ray absorption fine structure (EXAFS), X-ray photoelectron spectroscopic (XPS) and FT-IR and tested for the methoxycarbonylation of acetylene. According to the results of 31P NMR, XPS and EXAFS, there existed coordination bonds between palladium and the exposed phosphorous and nitrogen atoms of the porous POL-2V-P,N support. The XPS and FT-IR results showed that Pd0 species were present on the Pd/POL-2V-P,N catalyst. The heterogenized Pd/POL-2V-P,N palladium complex catalyst with high surface area and large pore volume displayed excellent activity for the methoxycarbonylation of acetylene as compared with the corresponding homogeneous palladium diphenyl-2-pyridylphosphine complex (Pd-P,N) under the same conditions. The used Pd/POL-2V-P,N catalyst also exhibited excellent activity under the same conditions. In addition, the hot filtration tests indicated that the reaction occurred in a heterogeneous way.

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