铈对铜硅催化剂催化草酸二甲酯加氢反应性能的影响

Effect of Cerium on Catalytic Performance of Cu-SiO_2 in Dimethyl Oxalate Hydrogenation

采用沉淀凝胶法制备了一系列不同Ce含量的Ce-Cu-SiO2催化剂,利用N2物理吸附(BET)、X射线衍射(XRD)、N2O吸附、氢气程序升温还原(H2-TPR)和氢气程序升温脱附(H2-TPD)等方法对催化剂进行表征,并在连续流动固定床反应器中考察了催化剂催化草酸二甲酯加氢制取乙二醇的反应性能。实验结果表明,引入适量的Ce能够改善Cu-SiO2催化剂的还原性能,增加Cu0表面积,减小Cu晶粒尺寸,增加催化剂的氢吸附能力。添加适量的Ce可提高催化剂对草酸二甲酯加氢制取乙二醇的选择性和稳定性。在195℃、3 MPa和质量空速(WHSV)0.07 h-1反应条件下,0.06Ce-Cu-SiO2催化剂上草酸二甲酯转化率可达99.4%,乙二醇选择性可达99.1%,且具有良好的稳定性。

A series of Ce-promoted Cu-SiO2 catalysts with different Ce contents were prepared via a precipitation-gel method, and these catalysts were characterized by N2 adsorption-desorption （BET）, X-ray diffraction （XRD）, N2O chemisorption, hydrogen temperature-programmed reduction （H2-TPR） and hydrogen temperature-programmed desorption （H2-TPD） techniques. Their catalytic performance in dimethyl oxalate （DMO） hydrogenation to produce ethylene glycol （EG） was investigated in a fixed-bed continuous-flow reactor. The results indicate that the addition of an appropriate amount of Ce can enhance reducibility of the Cu-SiO2 catalysts, increase copper surface area and H2 adsorption capacity, and decrease copper crystal size. Therefore, the selectivity and stability of the catalysts are improved with the addition of Ce. DMO conversion of 99.4%and EG selectivity of 99.1% can be achieved with 0.06Ce-Cu-SiO2 under 195℃ and 3 MPa with WHSV （weight hourly space velocity） of 0.07 h-1, and the catalyst is stable in these studies.