EFFECT OF CALCINATION TEMPERATURE ON THE STRUCTURE AND CATALYTIC PERFORMANCE OF THE CU-MCM-41 CATALYSTS FOR THE SYNTHESIS OF DIMETHYL CARBONATE

A series of Cu-MCM-41 catalysts were synthesized through in-situ hydrothermal preparation method, calcinated at different temperatures and characterized by thermogravimetric and differential scanning calorimetry (TG-DSC), N2 adsorption-desorption, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FI-IR), transmission electron microscopy (TEM) and hydrogen temperature-programmed (H2-TPR). The effect of calcination temperature on the structural properties and selective oxidation of dimethoxymethane (DMM) to dimethyl carbonate (DMC) were discussed in detail. The results showed that the calcination temperature played important role on the microstructure and catalytic activity of the Cu-MCM-41 catalysts. At the calcination temperature 550 °C, the Cu-MCM-41 catalyst possessed higher surface area, smaller pore diameter, stronger metal-support interaction, and better CuO dispersion compared the other catalysts, and the corresponding catalyst exhibited excellent activity and stability for the DMC synthesis. Under the reaction conditions at 2.0 MPa and 130 °C, the highest DMM conversion was 99.47% with the best DMC selectivity of 85.01%. In addition, the catalyst was reused four times without significant loss of performance.本研究通过原位水热合成法（in-situ hydrothermal preparation method）制备了一系列Cu-MCM-41催化剂，经不同温度焙烧处理后，采用热重-差示扫描量热法（thermogravimetric and differential scanning calorimetry, TG-DSC）、N₂吸附-脱附（N₂ adsorption-desorption）、X射线衍射（X-ray diffraction, XRD）、傅里叶变换红外光谱（Fourier transform infrared spectroscopy, FI-IR）、透射电子显微镜（transmission electron microscopy, TEM）以及氢气程序升温还原（hydrogen temperature-programmed, H₂-TPR）对其进行了系统表征。本文详细探讨了焙烧温度对Cu-MCM-41催化剂结构性能，以及甲缩醛（dimethoxymethane, DMM）选择性氧化制备碳酸二甲酯（dimethyl carbonate, DMC）反应的影响。结果表明，焙烧温度对Cu-MCM-41催化剂的微观结构与催化活性具有显著调控作用。当焙烧温度为550℃时，相较于其余催化剂，该Cu-MCM-41催化剂具备更高的比表面积、更小的孔径、更强的金属-载体相互作用以及更均匀的CuO分散性，对应的催化剂在DMC合成反应中表现出优异的催化活性与稳定性。在2.0 MPa、130℃的反应条件下，该催化剂的DMM最高转化率可达99.47%，对应的DMC最优选择性为85.01%。此外，该催化剂经四次循环使用后，其催化性能无明显衰减。