摘要
煤直接液化工艺中,除催化剂外,溶剂的组成和结构也是直接影响煤的转化率和液体产物油收率关键因素。近10 a稳定运行,在催化剂、操作条件无变化情况下,发现位于鄂尔多斯市伊金霍洛旗神华煤直接液化工厂的油收率与神华上海研究院中试装置的油收率结果有些许差距。为此,对分别来自神华上海研究院中试供氢溶剂(RS-S)和鄂尔多斯煤直接液化工厂供氢溶剂(RS-E)的物理化学结构,如官能团和芳香结构等,采用红外光谱、同步荧光光谱、全二维气相色谱-质谱联用仪进行了定性定量分析。在此基础上,采用密度泛函理论计算了溶剂分子中氢化芳烃的C—H键键能及化学环境对其影响的因素。结果表明,2种溶剂主要以带取代基的不饱和芳烃为主,芳环数集中在2~4环;RS-S中氢化芳烃含量要比RS-E高15.79%,环烷烃含量要比RS-E的低17.11%,说明RS-E被过度加氢,RS-S的供氢能力要高于RS-E;在一定程度上,芳环上不同取代基可以促进C—H键的断裂,当取代基取代四氢萘1位时,对C1—H键键能的影响最大,吸电子取代基比给电子取代基对四氢萘C1—H键解离能的影响更明显。C—H键键能与解离H原子后C原子上的自旋密度值呈现正相关性,H原子解离后C1的自旋密度越小,C1—H键键能越低,C1—H越容易断裂;随着芳环数的增加,C—H键键解离能降低,更容易断裂,导致稠环芳香族化合物更容易被加氢饱和。良好的供氢溶剂应该是由带取代基的、2~4环不饱和芳香烃组成的混合物。
In direct coal liquefaction, in addition to catalyst, the composition and structure of solvent are key factors that directly affect the rate of coal conversion and the oil yield in liquid product. After nearly ten years of stable operation, with no change in the catalyst and operating conditions, a slight difference was found between the oil yield of Shenhua coal direct liquefaction plant located in Ejin Horo Banner, Ordos and the oil yield results of the Shenhua Shanghai Research Institute pilot plant. Thus, the physicochemical structures of hydrogen-donor solvents from the Shenhua Shanghai Research Institute(RS-S)and the Ordos Coal Direct Liquefaction Plant(RS-E),respectively, were investigated, such as functional groups and aromatic structures, etc. Qualitative and quantitative analyses have been performed using the infrared spectroscopy and simultaneous fluorescence spectroscopy, and the group-selective two-dimensional gas chromatography-mass spectrometry/hydrogen flame-ionization detector method. Based on the above analysis, the C-H bond dissociation energy(BDE) of hydrogenated aromatics in solvent molecules and the factors influenced by the chemical environment were calculated using the density functional theory calculations. Results show that both the hydrogen-donor solvents are dominated by unsaturated aromatics with substituents, and have the condensed aromatic rings, mainly the bi-cyclic, tri-cyclic, and tetra-cyclic aromatic systems. The content of partially hydrogenated aromatics is the highest in the analyzed two hydrogen-donor solvents. The content of partially hydrogenated aromatics in RS-S is 15.79% higher than that in RS-E,and the content of cycloalkanes is 17.11% lower than that in RS-E,indicating that the liquefied solvent of RS-E is over-hydrogenated, and the hydrogen supplying capacity of RS-S is higher than that of RS-E. Different substituents can promote the dissociation of C-H bonds to some extent. When a substituent is located in the tetralin 1 position, the effect BDE,BDEvalue is strong,
作者
范欢欢
白佳凯
李旺
王兴宝
冯杰
李文英
FAN Huanhuan;BAI Jiakai;LI Wang;WANG Xingbao;FENG Jie;LI Wenying(State Key Laboratory of Clean and Efficient Coal Utilization,Taiyuan University of Technology,Taiyuan 030024,China)
出处
《煤炭学报》
EI
CAS
CSCD
北大核心
2022年第10期3805-3811,共7页
Journal of China Coal Society
基金
国家能源集团2030重大项目先导资助项目(GJNY2030XDXM-19-13.2)
国家自然科学基金资助项目(21808153)。
关键词
煤直接液化工艺
供氢溶剂
分子结构
C—H键
解离能
direct coal liquefaction
H-donor solvents
molecular structure
C—H bond
dissociation energy
