Preparation Of Ionic Liquids And Palladium Catalyst Supported On Organic-Inorganic Hybrid Materials And Its Catalytic Activity

Homogeneous catalysts show high catalytic activity, but it is usually difficult to separate the catalyst from the products and recycle the catalyst. Heterogeneous catalysts have attractive advantages over homogeneous ones, including easy removal of catalysts from reaction mixtures and recycling of the catalysts. In order to combine the advantages of both the homogeneous and heterogeneous catalysts, ionic liquids and PdCl₂ catalyst was supported on the organic-inorganic hybrid materials, and the catalytic performance of the supported catalysts in liquid phase oxidative carbonylation of phenol to diphenyl carbonate (DPC) was investigated.PdCl₂/OIH were prepared as follows: 1) synthesis of the Schiff-bases fromγ-aminopropyltriethoxysilane and 2-pyridine-carboxaldehyde; 2) reduction of the Schiff-bases by NaBH₄ in methanol; 3) cogelification with tetraetyl orthosilicate to produce OIH; 4) Pd(PhCN)₂Cl₂ reacing with OIH materials. Synthesize [Bmim]BF₄ and [Bmim]PF₆ ionic liqueds, then support them on OIH materials by physical adsorption or chemical grafting to produce PdCl₂/OIH/BF₄-C,PdCl₂/OIH/BF₄-P,PdCl₂/OIH/PF₆-C,PdCl₂/OIH/PF₆-P catalysts. The strucure of the support and the heterogeneous catalysts were characterized by FT-IR, XRD, ²⁹SiNMR and AA.The resultant catalysts were used in the reaction of liquid phase oxidative carbonylation of phenol to diphenyl carbonate with PdCl₂ as main catalyst, Cu₂O and tetrahydrofuran as additives, 3A molecular sieves as dehydrating agent. It was found that the heterogeneous PdCl₂/OIH catalyst showed similar catalytic activity to the homogeneous PdCl₂ catalyst. The OIH supported ionic liquids catalysts showed higher catalytic activity than the heterogeneous PdCl₂/OIH catalyst, and PdCl₂/OIH/PF₆-C catalyst revealed good catalytic activity with DPC yield and TON of 10.5% and 52.1, respectively. The catalytic activity of different ionic liquids was also studied, and PdCl₂/OIH supported [Bmim]PF₆ catalyst prepared by chemical grafting showed the best catalytic activity...