载银蒙脱石的制备及其对对硝基苯酚还原反应的催化性能

Preparation and Characterization of Silver-based Montmorillonite Nanocomposites and Catalytic Activity for 4–Nitrophenol Reduction

以硝酸银为银源,蒙脱石为载体,采用离子交换和化学还原法,成功制备了载银量为0.5%～3.0%的负载型银系催化剂。通过X射线衍射、固体紫外吸收、Zeta电位分析、扫描电子显微镜分析对所制备的催化剂的结构、粒径分布、形貌等进行了表征。结果表明：用该方法制备的银系催化剂粒径小、形貌好,纳米银的载入未破坏蒙脱石的层状结构。以对硝基苯酚的还原反应为模板反应考查此催化剂在常温常压下对硝基类化合物的催化还原性能,结果表明,催化剂催化活性较高,反应迅速,反应过程符合准一级动力学过程,且此催化剂可重复使用23次,稳定性好。

Silver-loaded montmorillonite was prepared via an ion exchange method and a chemical reduction method with silver ni- trate and montmoriUonite as a silver precursor and a carrier, respectively. The silver content range in Ag/MMT determined by Molar method is 0.5%-3.0%. The morphology and structure of as-synthesized specimens were characterized by X-ray diffraction, solid UV （UV-visible） absorbent scanning electron microscopy, and Zeta potential analysis, respectively. The results show that silver nanopartitles are inserted into the interlayer space of montmoriUonite, and the structure of MMT does not change. Moreover, the samples exhibit effective catalytic and high selectivity for the reduction of 4-nitrophenol （4-NP） in the presence of excess NaBH4 in water. The reaction process accords with the pseudo-first-order kinetics. In addition, the degradation rate is approximately 100% within 15 rain. The Ag-deposited MMT catalyst nanoparticles still remain active even after they are reused for 23 cycles.