丙二酸二甲酯加氢制备1,3-丙二醇铜催化剂载体效应研究

Effect of the Support Material on Structure and Reactivity of Copper Catalysts for the Hydrogenation of Dimethyl Malonate to 1,3-Propanediol

分别采用Al_2O_3、Mg O、HMS和Si O2为载体通过尿素水解均相沉淀法制备了四种铜催化剂,并利用傅里叶变换红外光谱(FT-IR)、X射线衍射(XRD)、程序升温还原(TPR)、H2程序升温脱附(H2-TPD)、X射线光电子能谱(XPS)和CO吸附原位红外等表征手段研究了催化剂的结构,在固定床反应器中考察了其在丙二酸二甲酯(DMM)加氢制备1,3-丙二醇(1,3-PDO)反应中的催化性能。研究表明,铜和载体之间的相互作用越强,越有利于活性组分的表面积以及Cu^+/Cu^0比例提高,促进催化剂活性增加。最优的载体为SiO_2,在反应温度453 K,反应压力5.0 MPa,DMM液时空速为0.3 g/(g-cat×h),氢酯比为300的条件下,DMM转化率为92.7%,1,3-PDO的选择性可达39.5%。此外,Al2O3、Mg O为载体的催化剂由于载体表面较强的酸、碱性,DMM自分解较严重,1,3-PDO选择性降低。催化剂稳定性考评表明,Cu/SiO_2催化剂的催化稳定性良好,具有较好的工业应用前景。

The influence of the type of support (Al2O3, MgO, HMS, and SiO2) on the structure and catalytic performance of copper catalysts for the heterogeneous synthesis of 1,3-propanediol (1,3-PDO) from the hydrogenation of dimethyl malonate (DMM) was investigated. The supported copper catalysts prepared via a urea-assisted homogeneous depiction-precipitation method have been characterized by multiple characterizations including Fourier-transform infrared spectroscopy, X-ray diffraction, temperature-programmed reduction, temperature-programmed desorption of hydrogen, X-ray photoelectron spectroscopy, and in-situ infrared spectroscopy study of CO adsorption. These results revealed that a synergistic effect linked to the copper-support interactions of the catalysts play crucial roles in the surface Cu0 area and surface Cu+ concentration, thereby determining the catalytic activity of Cu catalysts for DMM hydrogenation. The following activity order was obtained: Cu/SiO2 > Cu/HMS > Cu/MgO > Cu/Al2O3. Cu/SiO2 exhibited a highest reactivity of DMM conversion of 92.7% with 39.5% selectivity to 1,3-PDO, which is attributed the catalyst having a favorable Cu0 surface (26.2 m2/g-cat) and surface ratio of Cu+/(Cu0 + Cu+)(~0.32). The Cu/SiO2 catalyst showed a good stability and a promising industrial application in DMM hydrogenation.