氮掺杂铁基催化剂的制备及其催化4-硝基苯酚加氢还原性能

Preparation of nitrogen-doped iron-based catalysts and their catalytic performance in the hydrogenation reduction of 4-nitrophenol

采用铁离子和单宁酸的配合物作为前驱体,以醋酸锌为造孔剂,双氰胺为氮源,通过高温还原方法制备了氮掺杂碳负载的铁基催化剂,评价了其催化4-硝基苯酚(4-NP)加氢还原反应的活性,筛选出活性最高的催化剂为Fe_(0.5)Zn_(2.5)-N@C(n(Fe^(3+))=0.5 mmol,n(Zn^(2+))=2.5 mmol)。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、拉曼(Raman)光谱、X射线光电子能谱(XPS)等手段对该催化剂结构进行了表征。结果表明,催化剂表面没有观察到Fe纳米颗粒,金属Fe的化学价态为+2和+3价,催化剂表面存在明显的缺陷。活性测试结果表明,催化剂Fe_(0.5)Zn_(2.5)-N@C具有较好的重复利用特性,重复使用5次后,底物4-NP的转化率仍维持在96%以上。

N-doped carbon supported iron-based catalysts have been prepared by pyrolysis reduction using a coordination complex of iron ions and tannic acid as a precursor,zinc acetate as a pore-forming agent,and dicyandiamide as a nitrogen source.The activity of the catalysts was evaluated in the hydrogenation of 4-nitrophenol(4-NP),and the catalyst Fe_(0.5)Zn_(2.5)-N@C(n(Fe^(3+))=0.5 mmol,n(Zn^(2+))=2.5 mmol)with the highest activity was selected for further study.The structure of Fe_(0.5)Zn_(2.5)-N@C was characterized using X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),Raman spectroscopy,and X-ray photoelectron spectroscopy(XPS).The chemical valence states of Fe were+2 and+3 and no Fe nanoparticles were observed on the surface of the catalyst Fe_(0.5)Zn_(2.5)-N@C.There were obvious defects on the surface of the catalyst.The activity test results showed that the catalyst Fe_(0.5)Zn_(2.5)-N@C has good reuse characteristics,and the conversion rate of the 4-NP substrate remained above 96%even after the catalyst was reused five times.