Cu-Mn/γ-Al_2O_3催化剂上二甲醚水蒸气重整制氢

DIMETHYL ETHER STEAM REFORMING FOR HYDROGEN PRODUCTION OVER Cu-Mn/γ-Al_2O_3 CATALYST

采用草酸盐胶态共沉淀-机械混合法制备了一系列Cu-Mn/γ-Al_2O_3催化剂,考察了CuMn摩尔比及助剂La、Al、Fe、Zn等对Cu-Mn/γ-Al_2O_3催化剂上二甲醚水蒸气重整制氢的催化性能的影响,并结合热重-差热扫描量热分析(TG-DSC)、N_2吸附-脱附(BET)、X射线衍射(XRD)、H_2程序升温还原(H_2-TPR)等表征手段研究了助剂La的添加对Cu-Mn/γ-Al_2O_3催化剂微观结构的影响。研究表明:当Cu-Mn/γ-Al_2O_3催化剂中Cu/Mn摩尔比为1/2时,催化剂具有较高的初始活性;添加La、Al、Fe、Zn等助剂均不同程度地提高了Cu-Mn/γ-Al_2O_3催化剂的稳定性,其提高顺序为:La>Al>Fe>Zn;适量La的添加可以起到隔离和分散铜的作用,能阻碍活性组分的聚集长大,有助于活性组分细化,并增加表面高分散CuO的量,同时增强Cu-Mn以及金属铜和载体之间的相互作用,防止铜的团聚,从而提高催化剂的活性及稳定性。

Cu-Mn/γ-Al2O3 catalyst was prepared by gel oxalate precipitation-mechanical mixing method, and the effects of Cu-Mn ratio and La, Al, Fe, Zn promoters on dimethyl ether steam reforming for hydrogen production over Cu-Mn/γ-Al2O3 were studied. Additionally, differences in microstructure between Cu-Mn/γ-Al2O3 and Cu-Mn-La/γ-Al2O3 catalysts were discussed with reference to thermogravimetric and differential scanning thermometric analysis （TG-DSC）, nitrogen adsoorption-desorption （BET）, X-ray diffraction （XRD） and H2 temperature-programmed reduction （H2-TPR） analyses. The results show that the best Cu-Mn molar ratio is 1/2. The promoters of La, Al, Fe, Zn all can improve the stability of the Cu-Mn/γ-Al2O3 catalyst, and the improving order is La 〉 Al 〉 Fe 〉 Zn. The addition of La is favorable to the separation of copper and enhancing interaction between Cu and Mn, so as to prevent aggregation of Cu and increase copper amounts on catalyst surface. By this means, the activity and stability of the catalyst are all improved.