粒度对纳米石墨燃烧热力学性质影响的量子化学研究  

Study on the effect of particle size on the combustion thermodynamic properties of graphite nanoparticles by quantum chemistry

作　　者：赵苗芝[1] 闫力[2] 薛永强[1] 

机构地区：[1]太原理工大学应用化学系,山西太原030024 [2]北京化工大学材料科学与工程系,北京100029

出　　处：《计算机与应用化学》2010年第7期853-857,共5页Computers and Applied Chemistry

基　　金：国家自然科学基金资助项目(60774079);山西省大学生创新性实验计划资助项目;太原理工大学大学生创新性实验计划资助项目(080901)

摘　　要：粒度是影响煤粉燃烧的重要内因之一,本文首次应用量子化学方法研究粒度对纳米颗粒燃烧热力学性质的影响。建模时将煤结构理想化,以结构类似的六方石墨原子簇模拟纳米煤颗粒。应用Gaussian98程序的HF方法计算不同粒度的石墨原子簇燃烧的热力学性质,并讨论粒度影响燃烧热力学性质的规律。结果表明:粒径显著影响石墨原子簇燃烧热力学性质,标准摩尔燃烧焓(Δ_cH_m~θ)、标准摩尔燃烧吉布斯函数(Δ_cG_m~θ)和标准摩尔燃烧熵(Δ_cS_m~θ)随石墨原子簇粒径的减少而减小,平衡常数的对数(lnK~θ)则随粒径减小而增大,并且Δ_cH_m~θ、Δ_cG_m~θ、Δ_cS_m~θ、lnK~θ均与粒径的倒数呈线性关系。对于原子数较多的体系,Gaussian程序计算难以进行。块状石墨的热力学性质通过外推法求得,其Δ_cH_m~θ为-353.08 kJ·mol^(-1),Δ_cG_m~θ为-362.24 kJ·mol^(-1),Δ_cS_m~θ为30.61 kJ·mol^(-1)·K^(-1),lnK~θ为146.13。这些数据与文献值比较接近。Particle size is one of the most important internal cause which influents the combustion of coal powder.The effect of particle size on the combustion thermodynamic properties of nanoparticles by quantum chemistry is studied firstly in this paper.The structures of coal is idealized,the nanoparticles of coal were simulated by hexagonal graphite clusters which are similar in structures,the thermodynamic properties of combustion of graphite clusters with different sizes were calculated by Gaussian 98 program（HF）.Size dependence of thermodynamic properties of combustion was discussed in this paper.The results show that the particle size of graphite cluster has obvious effects on the thermodynamic properties of combustion; the molar standard enthalpy of combustion,the molar standard Gibbs free energy and the molar standard entropy of combustion decrease but the standard equilibrium constant increases with the particle size of graphite clusters decreasing.The molar standard enthalpy of combustion,the molar standard Gibbs free energy,the molar standard entropy of combustion and the standard equilibrium constant have linear relationship with the reciprocal of particle size.The calculation of Gaussian program is rather difficult for the system with numerous atoms.The thermodynamic properties of combustion of block graphite were calculated by extrapolation method,the calculated value of△cHmθwas -353.08 kJ·mol-1,the calculated value of△cGm-1 was -362.24 kJ·mol-1,the calculated value of△cSmθwas 30.61 kJ·mol-1·K-1,and the calculated value of ln K~θwas 146.13.The above data were relatively close to the reported value.

关 键 词：热力学性质 粒径 量子化学 燃烧热 石墨原子簇 

分 类 号：O6-39[理学—化学] X513[环境科学与工程—环境工程]