Synthesis Of Polystyrene-grafted Phenanthroline/CuCl₂ Complex And Its Catalytic Activity In Oxidative Carbonylation

Homogeneous catalytic systems often have disadvantages, such as difficult separation of the products and corrosive effect of the catalyst on the reactor materials. Heterogeneous catalytic systems have attractive advantages over homogeneous counterparts in liquid-phase reactions, including easy removal of catalysts from reaction mixtures and recycling of the reuse of catalysts. This thesis deals with the preparation, characterization and catalytic reactivity in the liquid phase oxidative carbonylation of polystyrene-supported catalysts (PS-Phen/CuCl₂). CuCl₂ has been successfully immobilized on NH2-Phen modified polystyrene. The resultant materials were characterized with various techniques such as FTIR, X-ray photoelectron spectroscopy (XPS), Element Analysis (EA), Thermal Gravimetric Analysis (TGA), Atomic Absorption Spectrometry (AAS) and Field Emission Scanning Electron Microscope (FESEM). AAS and EA gave the results that the concentration of CuCl₂ and ligand were 1.67mmol/gcat, 1.54mmol/gcat respectively. FESXEM result showed that the pore size of the modified polystyrene decreased. TGA result showed that PS-Phen/CuCl₂ was stable under reaction conditions. TGA and FTIR data showed that NH2-Phen immobilized on polystyrene successfully. XPS results suggested that there was coordination bond between N-donor ligand and Cu(II). The PS-Phen/CuCl₂ materials were good catalysts for liquid phase oxidative carbonylation of methanol to form Dimethyl Carbonate (DMC). The catalyst (PS-Phen/CuCl₂) exhibited higher activity and selectivity than the unsupported CuCl₂ and Phen/CuCl₂ catalysts. PS-Phen/CuCl₂ could be separated easily and be reused several times, with slight loss of the active components. After recycling 7 times, the catalyst still showed high catalytic activity and selectivity, with the average conversion of methanol of 10.6% and the average selectivity of 94.5%, respectively, under the reaction conditions of [Cu(II)]=0.2mol/L, 3.0MPa(PCO:PO2=9:1), 2h, 120 ℃.