Study Of Prepareration Of Supported Liquid Phase Catalyst And Gas-Phase Catalyzed Synthesis Of Dimethyl Carbonate On It

SLPC has effectively combined the features of homogeneous and heterogeneous catalyst. Selecting PdCl₂,CuCl₂ and KOAc as active components of SLPC, and gas-phase oxidative carbonylation of methanol to DMC on it were studied. Multiple technique including BET,XRD,XPS and SEM were used to characterize the morphological and electronic structure of the catalysts.SLPC were prepared using DEG and TetraEG as liquid-phase solvent respectively. The catalytic activity of DEG-PdCl₂-CuCl₂-KOAc/AC is better than it of TetraEG-PdCl₂-CuCl₂ -KOAc /AC. When the loading of DEG is 37.1%(wt%), STY of DMC reached to 1040g·(L-cat·h)^-1; SEM testified that DEG can make distribution of active component on surface of catalyst better, but remarkably decline of the surface area of catalyst with the increase of loading of DEG is verified by BET. The catalysts have no catalytic activity , whose supports are SiO₂ andγ-Al₂O₃, and coal activated carbon is better than coconut shell activated carbon as the supports. The main reason for this result is their chemical properties, XPS show that Cu⁺ appear on PdCl₂-CuCl₂-KOAc/AC, and the active site is Pd²⁺ and Cu⁺ in this reaction, but there is not Cu⁺ on PdCl₂- CuCl₂- KOAc /SiO₂. There are many functional groups containing oxide on the surface of activated carbon, such as carboxyl, carbonyl and quinonyl. these groups are thought the reduction site in the surface of activated carbon, however, SiO₂ andγ-Al₂O₃ don't possess this function.The effects reaction conditions on catalytic performance were studied, the optimal reaction conditions were obtained through experiment: 0.3Mpa, 160℃, 7168h^-1, molar ratio of MeOH, CO and O₂ is 3.6:2.3:1. The catalytic activity of SLPC is higher than the supported solid catalyst. The XRD pattern show that there is crystal phase of KCl on the surface of supported solid catalyst PdCl₂-CuCl₂-KOAc/AC and PdCl₂- CuCl₂- KOAc /SiO₂, but it don't appear on the surface of DEG-PdCl₂-CuCl₂-KOAc/AC, The DEG added result in this situation.