硝化甘油在α-Al2O3(0001)和γ-Al2O3(110)表面吸附的理论计算

摘要

Nitroglycerin(NG) and alumina were used as the models of energetic plasticizers and the surface of fuels in propellants to investigate the microscopic mechanism of interactions between materials containing nitrate ester group and combustion agent surface.First-principles calculations based on density functional theory with the all-electron double numerical polarized basis sets were employed to study the adsorption of NG on the α-Al2O3(0001) and γ-Al2O3 (110) surfaces.The results indicate that strong chemical adsorption exists between NG and the α-Al2O3(0001) as well as γ-Al2O3 (110) surfaces, which results in significant elongation and breakage of corresponding O-NO2 bond of NG.The dissociation which produces NO2 free radical is barrierless and releases a large amount of heat.The adsorption energy is about 175.7 kJ/mol.The interaction of NG and the fully hydroxylated surfaces comes from H-bonding interactions mainly.The adsorption energy decreases significantly and is about 50.0 kJ/mol.For partly hydroxylated surfaces, it is found that both chemical and physical adsorption would occur on the surfaces and no obvious synergy or catalysis exist for both mechanisms.The present theoretical work is useful to gain some new insights on the compatibility of materials containing nitrate ester group and the other components in propellants.%选取硝化甘油(NG)和氧化铝(Al2O3)分别作为推进剂中的含能增塑剂和燃料表面的模型, 研究了含硝酸酯类增塑剂与推进剂中燃烧剂表面的微观作用机理.采用基于密度泛函理论的第一性原理方法和全电子双数值基组研究了NG在α-Al2O3(0001)和γ-Al2O3(110)表面的吸附作用.计算结果表明, NG可以在α-Al2O3(0001) 和γ-Al2O3(110)表面发生强烈化学吸附;吸附导致相应的O-NO2键被明显拉长并断裂, 无能垒自发产生NO2自由基, 该解离过程放出大量的热, 吸附能高达约175.7 kJ/mol;NG在完全羟基化的α-Al2O3(0001)和γ-Al2O3(110)表面上的吸附明显减弱, 从强烈的化学吸附转变成以氢键作用为主的物理吸附, 吸附能只有约50.0 kJ/mol;而在部分羟基化的α-Al2O3(0001) 和γ-Al2O3(110)表面上可以同时发生物理吸附和化学吸附, 且两种机制并不存在明显的协同或催化作用.