摘要
利用自发单层分散的原理制备负载氯化银的活性炭(AC),讨论氯化银在活性炭载体上的分散情况,并且采用密度泛函理论(DFT)B3LYP的方法,研究了活性炭表面AgCl活性组分的单层分散行为.结果表明:在低AgCl负载量时,AgCl可在活性炭载体表面达到单层分散,XRD测得其单层分散阈值为每克活性炭0.144 g AgCl.静态定容法测得当AgCl的负载量为每克AC0.133 gAgCl时,样品的CO的吸附容量最大.AgCl主要以银端垂直附着在活性炭表面的顶位和桥位上,作用能在46.26～47.64 kJ/mol之间.在此基础上,用不同的原子簇模型模拟计算得到其单层分散阈值为每克活性炭0.148 gAgCl,与XRD测得的结果一致.结合X衍射相定量法和密度泛函理论,同样可研究其他相似的活性组分在活性炭载体上的单层分散情况,为高效吸附剂和催化剂的研究制备提供方法的指导.
Activated carbon （AC） is the “versatile” adsorbent and catalyst carrier for some distinguished features, such as fully developed porosity, high specific surface area. Silver is an efficient active catalytic component for it＇s d^10s^0 electronic structure. So much attention has been put on the behavior of silver on AC. In this paper AgCl/AC was prepared by a thermal treatment of a mixture of AgCl and AC. The dispersions of AgCl on AC were studied by X-ray diffraction （XRD）. The results showed that AgCl dispersed uniformly on AC surface when AgCl loading was lower than the threshold, 0. 144 g AgCl/gAC measured by XRD method. The adsorbent with the highest CO adsorption capacity is 0. 133 g AgCL/gAC. Density functional theory （DFT） was applied to theoretically investigate the monolayer dispersion behavior of AgCl on AC surface. Calculations were performed with the B3LYP approach using LanL 2DZ basis set for Ag and Cl atoms, whereas 6 -31G＊ basis set was used for C and H atoms. AgCl prefers to disperse on the top site or bridge site on the AC surface with Ag-bonded iriteraction energy between 46. 26 kJ/mol and 47.64 kJ/mol. The dispersion threshold calculated by DFT is 0. 148 g AgCl/gAC, which is in agreement with the dispersion threshold measured by XRD method. By combining the experimental data obtained by XRD with the results of DFT, the proposed method in the paper can be used to the similar systems for the guidance of making and seeking high efficiency adsorbent and catalyst.
出处
《南京工业大学学报（自然科学版）》
CAS
2005年第6期6-11,共6页
Journal of Nanjing Tech University(Natural Science Edition)
基金
国家自然科学基金资助项目(20276029)
高等学校博士学科点专项科研基金资助课题(20040291005)
