Fe、Co组成对Cu-Fe-Co基混合醇催化剂合成性能的影响

Effect of Fe/Co Mass Ratio on Catalytic Performances of Cu-Fe-Co Based Catalysts for Mixed Alcohols Synthesis

采用共浸渍法制备了一系列不同Fe、Co组成的Cu-Fe-Co基混合醇催化剂,对其CO加氢合成混合醇反应性能进行了考察,并采用BET比表面积分析、X射线衍射(XRD)、X射线光电子能谱(XPS)、场发射扫描电子显微镜(FE-SEM)及H_2程序升温还原(H_2-TPR)等手段对其进行了表征.结果表明:Cu-Fe二元催化剂添加适量的Co可以明显提高催化剂醇的明空收率(STY)、CO转化率,而总醇选择性不变.当活性组分Cu、Fe及助剂Co的质量分数分别为25%、22%、3%时,催化剂醇的时空收率高达205.6 g·kg^(-1)·h^(-1),CO转化率为56.6%.XRD、XPS和TPR结果表明:在Cu组分含量不变时,少量Co组分的引入使催化剂表面形成微量的CuFe_2O_4相,促进了Cu-Fe组分间相互作用的增强,改善了催化剂活性组分的分散度,有利于提高催化剂活性及醇的时空收率;随Co含量的增大,催化剂中金属组分间的相互作用发生转变,形成了Cu-Co尖晶石相,导致催化剂的醇选择性有所下降.

A series of Cu-Fe-Co based catalysts with different mass fractions of Fe and Co were prepared by co-impregnation method.The catalytic performances of the catalysts for mixed alcohols synthesis from carbon monoxide hydrogenation were investigated in a fixed bed flow reactor.The samples were characterized by Brunauer-Emmett-Teller（BET）,X-ray diffraction（XRD）,X-ray photoelectron spectroscopy （XPS）,field-emission scanning electron microscope（FE-SEM）,and H_2 temperature-programmed reduction （H_2-TPR）.The results showed that the addition of a suitable content of Co to the Cu-Fe based catalyst significantly improved the space-time yield（STY） and CO conversion while alcohol selectivity was constant.For the catalyst with a mass fraction of Cu,Fe,and Co of 25%,22%,and 3%,respectively,a STY of 205.6 g·kg^（-1）·h^（-1） and CO conversion of 56.6%were obtained.The XRD,XPS,and TPR results showed that when the Cu content was unchanged,the introduction of some Co contributed to the formation of a small quantity of the CuFe_2O_4 phase on the surface of catalysts,which promoted the interaction between Cu and Fe,improved the dispersion of active components and enhanced the catalytic activity and STY of the mixed alcohols.With an increase of the Co content in the catalyst,the interaction between the metallic components was transformed and the Cu-Co spinel phase was generated,leading to a slight decrease of alcohol selectivity.