基于实时直接分析质谱技术的氯铝酸及其复合离子液体分析  

Comprehensive analysis of chloroaluminate and composite ionic liquids using direct analysis in real time mass spectrometry

作　　者：韩晔华[1] 欧阳萍 张艳芬[1] 黄凌[2] 张睿[1] 史权[1] 孟祥海[1] 刘植昌[1] 徐春明[1] Yehua Han;Ping Ouyang;Yanfen Zhang;Ling Huang;Rui Zhang;Quan Shi;Xianghai Meng;Zhichang Liu;Chunming Xu(State Key Laboratory of Heavy Oil Processing,China University of Petroleum-Beijing,Beijing 102249,China;China Central Laboratory of Geological Sciences,Research Institute of Petroleum Exploration&Development(RIPED),PetroChina,Beijing 100083,China)

机构地区：[1]中国石油大学(北京)重质油国家重点实验室,北京102249 [2]中国石油勘探开发研究院石油地质实验研究中心,北京100083

出　　处：《中国科学：化学》2020年第6期720-728,共9页SCIENTIA SINICA Chimica

基　　金：国家自然科学基金(编号:218741153,21890763);中国石油大学(北京)科研基金(编号:2462017BJB09)资助项目。

摘　　要：经氯化亚铜改性的氯铝酸复合离子液体是碳四烷基化反应的优良催化剂,具有很高的催化活性和目标产物选择性.深入解析离子液体的组成、阴阳离子的形态及改性金属对酸中心结构的影响有助于烷基化反应机理的研究及催化剂的定向设计.首先,本工作开发了实时直接分析离子化方法,实现了氯铝酸及其复合离子液体的有效电离和直接分析.其次,通过与静电场轨道阱高分辨质谱联用、同位素峰法指认、多级质谱结构解析等对离子液体组成进行了准确表征,确定了酸性阴离子的存在形态,并明确鉴别出复合离子液体中Cu(Ⅰ)-Al(Ⅲ)双金属配位中心阴离子的存在.进而,借助高能碰撞解离技术对双金属配位中心阴离子[CuAlCl5]^-和[CuAl2Cl8]^-的结构进行了解析.最后,依据质谱分析结果对复合离子液体的卓越催化性能进行了构效关系分析.本研究为Cu(Ⅰ)-Al(Ⅲ)双金属配位中心对复合离子液体优异催化活性的贡献提供了可靠依据,为深入研究复合离子液体催化碳四烷基化反应机理奠定了基础.A composite chloroaluminate ionic liquid(IL)modified with copper(Ⅰ)chloride has attracted considerable attention due to its high catalytic activity and selectivity for isobutane alkylation,where the bimetallic anions of Cu(Ⅰ)-Al(Ⅲ)have been proposed to play important roles.Characterization of chloroaluminate and composite ionic liquids(CIL)is crucial for a better understanding of alkylation mechanism and catalysts design In this work,a plasma-based ion source,direct analysis in real time(DART),was introduced to achieve soft but effective ionization of chloroaluminate IL and CIL with minimized hydrolysis,fragmentation and salt effects.Combined with the isotope patterns strategy and high-energy collision dissociation(HCD)technology,this developed high resolution mass spectrometry(HRMS)method,DART-Orbitrap-HRMS,was not only able to identify the accurate chemical composition of chloroaluminate IL and CIL,but also capable of structure analysis.Based on the comparison of chloroaluminate IL and CIL,it showed that similar acidic anions in both ILs were[AlCl4]^-,[Al2Cl7]^- and [Al3Cl10]^-.The remarkable difference was the verification of Cu(Ⅰ)-Al(Ⅲ) bimetallic anions as[CuAlCl5]^- and [CuAl2Cl8]^- merely in CIL,which were proposed to count for the high catalytic activity.Moreover,Cu(Ⅰ)cation ion that might be related to the alkylation selectivity was characterized as[(Et3NH)2CuCl2]^+ in CIL.Structure analysis of the two bimetallic anions were then achieved by HCD technology.All the results have provided substantial support for the structure-activity study of CIL,setting the stage for in-depth research on IL-catalyzed isobutane alkylation.

关 键 词：氯铝酸离子液体 复合离子液体 碳四烷基化反应 实时直接分析质谱 

分 类 号：O645.1[理学—物理化学] O657.63[理学—化学]