The Liquid-Phase Catalytic Oxidative Carbonylation Of Methanol By Cu～1 Supported Catalysts

Dimethyl carbonate (DMC) is an environmental benign chemicalcompound; The research and development of clean technology to synthesizeDMC by liquid-phase oxidative carbonylation of methanol are attracting moreand more attention all over the world. In this paper, the Cu^â… loading catalystssupported on the solid supper acid were prepared by solid-state ion-exchangemethod, and the catalytic activity on continuous stainless autoclave equipmentis also studied in detail. The catalysts have been characterized by the TPD,BET, IR, XRD and XPS analytical methods and well discussed; The conclusionsobtained are listed as following:(1) The most suitable condition for preparing catalyst of Cu(I)-H₃PO₄/ZrO₂ isas following: At the moler ratio of P/Zr was 0.05, H₃PO₄/ZrO₂ wascalcined at 400℃for 3h, The catalyst was prepared at 500℃for 4h. Underthis condition, The STY and C_m and S_m of DMC reach the maximum andare 1.60g·g^-1·h^-1, 8.90ï¼…and 99.55ï¼…, respectively.(2) The most suitable condition for preparing catalyst of Cu(I)-H₃PO₄/TiO₂ isas following: At the moler ratio ofP/Ti=0.1, H₃PO₄/TiO₂ was calcined at450℃for 3h, The catalyst was prepared at 550℃for 4h. Under thiscondition, The STY and C_m of DMC reach the maximum and are1.73g·g^-1.h^-1 and 9.93ï¼…, respectively, while the Smis 96.81ï¼…. (3) The most suitable condition for continuous reaction is as following: thereaction temperature is 120℃,the reaction time is 2h,under pressure of4MPa and CO/O₂ ratio is 2.Under this condition, The STY and C_m ofDMC reach the maximum and are 1.34g·g^-1·h^-1 and 10.26%, respectively,while the S_m is 97.04%.(4) The XRD of catalysts show that, with the temperature rising and timeincreasing, the characteristic diffraction peaks of crystalline phase ofCuCl become weaker. When the preparation temperature is over 550℃,the catalysts were without crystalline phase of CuCl. The CuCl isdispersed on the surface of the support by single layer and was exchangedwith the support. The solid-state ion-exchange become more and morecomplete with the calcining temperature rising.(5) By synthetical characterising, we notice that, because of the disactivity ofthe catalyst, the surface area of used catalyst decrease and the new phaseof Cu₂(OH)₃Cl is observed.