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Mn^3+含量和吸附氧含量,最高的Mn^3+/Mn^4+。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、Mn^3+和吸附氧含量,Mn^3+/Mn^4+、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。
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 Mn^3+ and adsorbed oxygen content, and highest Mn^3+/Mn^4+ 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 Mn^3+ and adsorbed oxygen content were highest among these amorphous manganese oxides. Mn^4+ content was related to the formation of quinoline N-oxide by over oxidation. Despite their high Mn^3+ content and Mn^3+/Mn^4+ 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 Mn^3+ and adsorbed oxyge
作者
陈福山
赵松林
杨涛
江涛涛
倪珺
张群峰
李小年
CHEN Fushan;ZHAO Songlin;YANG Tao;JIANG Taotao;NI Jun;ZHANG Qunfeng;LI Xiaonian(Institute of Industrial Catalysis,Zhejiang University of Technology,Hangzhou 310014,P.R.China;Jiangxi Province Engineering Research Center of Ecological Chemical Industry,Jiujiang University,Jiujiang 332005,Jiangxi Province,P.R.China;School of Pharmaceutical and Chemical Engineering,Taizhou University,Taizhou 318000,Zhejiang Province,P.R.China)
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2019年第7期775-786,共12页
Acta Physico-Chimica Sinica
基金
国家自然科学基金(21776258,21476207,21566013,21875220,91534113,21406199)
浙江省科学技术厅项目(2015C31042)资助~~
