物理化学学报 >> 2019, Vol. 35 >> Issue (7): 775-786.doi: 10.3866/PKU.WHXB201811046

论文 上一篇    

Cu2-MnOx高效催化1, 2, 3, 4-四氢喹啉氧化脱氢芳构化

陈福山1,2,赵松林1,3,杨涛2,江涛涛1,倪珺1,张群峰1,*(),李小年1,*()   

  1. 1 浙江工业大学工业催化研究所，杭州 310014
    2 九江学院江西省生态化工工程技术研究中心，江西 九江 332005
    3 台州学院医药化工学院，浙江 台州 318000
  • 收稿日期:2018-11-30 录用日期:2018-12-07 发布日期:2018-12-21
  • 通讯作者: 张群峰,李小年 E-mail:zhangqf@zjut.edu.cn;xnli@zjut.edu.cn
  • 基金资助:
    国家自然科学基金(21776258);国家自然科学基金(21476207);国家自然科学基金(21566013);国家自然科学基金(21875220);国家自然科学基金(91534113);国家自然科学基金(21406199);和浙江省科学技术厅项目(2015C31042)

Highly Efficient Oxidative Dehydrogenation Aromatization of 1, 2, 3, 4-Tetrahydroquinoline by Cu2-MnOx Catalyst

Fushan CHEN1,2,Songlin ZHAO1,3,Tao YANG2,Taotao JIANG1,Jun NI1,Qunfeng ZHANG1,*(),Xiaonian LI1,*()   

  1. 1 Institute of Industrial Catalysis, Zhejiang University of Technology, Hangzhou 310014, P. R. China
    2 Jiangxi Province Engineering Research Center of Ecological Chemical Industry, Jiujiang University, Jiujiang 332005, Jiangxi Province, P. R. China
    3 School of Pharmaceutical and Chemical Engineering, Taizhou University, Taizhou 318000, Zhejiang Province, P. R. China
  • Received:2018-11-30 Accepted:2018-12-07 Published:2018-12-21
  • Contact: Qunfeng ZHANG,Xiaonian LI E-mail:zhangqf@zjut.edu.cn;xnli@zjut.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(21776258);the National Natural Science Foundation of China(21476207);the National Natural Science Foundation of China(21566013);the National Natural Science Foundation of China(21875220);the National Natural Science Foundation of China(91534113);the National Natural Science Foundation of China(21406199);Program from Science and Technology Department of Zhejiang Province, China(2015C31042)

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摘要：

采用新型无模板草酸盐路线制备了系列不同Cu含量的MnOx催化剂(MnOx、Cu1-MnOx、Cu2-MnOx、Cu3-MnOx、Cu4-MnOx、Cu2-450及Cu2-550)，并应用于1, 2, 3, 4-四氢喹啉(THQL)氧化脱氢芳构化。通过热重和热流分析(TG-DSC)、X射线衍射(XRD)、N2物理吸附-脱附、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、能谱(EDS)、X射线光电子能谱(XPS)、H2程序升温还原(H2-TPR)、原子吸收光谱(AAS)手段对催化剂进行表征。结果显示在这七种锰氧化物中，Cu2-MnOx具有高比表面积、增大的介孔平均孔径、较低的还原温度、最高的Mn3+含量和吸附氧含量，最高的Mn3+/Mn4+。Cu2-MnOx在温和的反应条件下，以廉价的空气为氧化剂、无碱添加剂的情况下对THQL芳构化转化率和喹啉(QL)选择性分别达99.1%、97.2%。催化剂套用五次后转化率还可达95.8%，选择性随着套用次数增加略有降低，这可能是Cu元素的流失所致。催化剂无定型结构、Mn3+和吸附氧含量，Mn3+/Mn4+、晶格氧的流动性及CuO和MnOx的协同作用是高催化活性的关键因素。

关键词: 草酸盐路线, 锰氧化物, CuO掺杂, 1, 2, 3, 4-四氢喹啉, 氧化脱氢

Abstract:

A novel template-free oxalate route was applied to synthesize a series of MnOx catalysts with different Cu content (MnOx, Cu1-MnOx, Cu2-MnOx, Cu3-MnOx, Cu4-MnOx, Cu2-450, and Cu2-550), which were then used in 1, 2, 3, 4-tetrahydroquinoline (THQL) oxidative dehydrogenation aromatization. To obtain insight into the structure-activity relationships of the catalysts, the samples were characterized by thermogravimetry and heat flow analysis, X-ray diffraction (XRD), N2 physical adsorption-desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), H2 temperature programmed reduction (H2-TPR), and atomic absorption spectroscopy (AAS). The results showed that Cu2-MnOx possesses the following characteristics: amorphous nature, high specific surface area, increased mesoporous average pore diameter, lower reduction temperature, highest Mn3+ and adsorbed oxygen content, and highest Mn3+/Mn4+ ratio among the seven manganese oxide catalysts. Cu2-MnOx for the oxidative dehydrogenation aromatization of THQL showed conversion (99.1%) and selectivity (97.2%) for quinoline under mild reaction conditions, with cheap air as oxidant and no alkali additive. Cu2-MnOx was reusable and achieved 95.8% conversion even after five reuse tests. Selectivity decreased slightly with the increase in reuse time, which could be attributed to the leaching of the Cu element. Comparison of structure-activity relationships showed increased catalytic activity when Mn3+ and adsorbed oxygen content were highest among these amorphous manganese oxides. Mn4+ content was related to the formation of quinoline N-oxide by over oxidation. Despite their high Mn3+ content and Mn3+/Mn4+ ratio, Cu2-450 and Cu2-550 had reduced surface area, adsorbed oxygen content, and lattice oxygen mobility, which resulted in poor catalytic performance. Although Cu3-MnOx had the largest BET surface area, highest lattice oxygen mobility, and similar Mn3+ and adsorbed oxygen content as Cu2-MnOx, the smaller average pore diameter of Cu3-MnOx perhaps caused its conversion and selectivity to be similar to Cu2-MnOx. The amorphous nature, Mn3+ and adsorbed oxygen content, Mn3+/Mn4+ ratio, lattice oxygen mobility, and synergistic effect between CuO and MnOx were found to play key roles in catalytic performance. The absence of precious metals, the simple catalyst preparation process, the cheap air as the sole oxidant, no ligand and alkali, the mild reaction conditions, along with catalyst reusability and easy isolation of the aromatized products made our catalytic protocol both green and environmentally benign.

Key words: Oxalate route, Manganese oxide, CuO doping, 1, 2, 3, 4-Tetrahydroquinoline, Oxidative dehydrogenation