物理化学学报 >> 2012, Vol. 28 >> Issue (07): 16911691-1700..doi: 10.3866/PKU.WHXB201205032

理论与计算化学 上一篇    下一篇

超临界水中碳酸钠团簇成核与生长分子动力学模拟

张金利1, 何正华1, 韩优1,2, 李韡1, 武江洁星1, 甘中学3, 谷俊杰3   

  1. 1. 天津大学化工学院, 天津 300072;
    2. 天津大学, 天津市膜科学与海水淡化技术重点实验室, 天津 300072;
    3. 新奥集团煤基低碳能源国家重点实验室, 河北廊坊 065001
  • 收稿日期:2012-03-28 修回日期:2012-05-02 发布日期:2012-06-07
  • 通讯作者: 韩优, 甘中学 E-mail:yhan@tju.edu.cn; ganzhongxue@enn.cn
  • 基金资助:

    国家高技术研究发展计划项目(863) (2011AA05A201), 国家自然科学基金(21106094, 20836005)和国家重点基础研究发展规划项目(973) (2010CB736202)资助

Nucleation and Growth of Na2CO3 Clusters in Supercritical Water Using Molecular Dynamics Simulation

ZHANG Jin-Li1, HE Zheng-Hua1, HAN You1,2, LI Wei1, WU Jiang-Jie-Xing1, GAN Zhong-Xue3, GU Jun-Jie3   

  1. 1. School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, P. R. China;
    2. Tianjin Key Laboratory of Membrane Science and Desalination Technology, Tianjin University, Tianjin 300072, P. R. China;
    3. State Key Laboratory of Coal-Based Low Carbon Energy, ENN Group, Langfang 065001, Hebei Province, P. R. China
  • Received:2012-03-28 Revised:2012-05-02 Published:2012-06-07
  • Contact: HAN You, GAN Zhong-Xue E-mail:yhan@tju.edu.cn; ganzhongxue@enn.cn
  • Supported by:

    The project was supported by the National High-Tech Research and Development Program of China (863) (2011AA05A201), National Natural Science Foundation of China (21106094, 20836005), and National Key Basic Research Program of China (973) (2010CB736202).

摘要:

应用分子动力学方法研究了碳酸钠颗粒在超临界水中的成核与生长过程. 计算了温度为700-1100 K、压力在23-30 MPa下碳酸钠的团聚过程, 计算时间为1 ns. 对体系结合能与径向分布函数的分析表明, 碳酸钠成核过程主要受静电作用的影响. 在超临界态下, 水分子与Na+和CO32- 之间的静电作用降低, Na+与CO32- 能够很容易碰撞形成Na2CO3小团簇. 在Na2CO3整个成核过程中, 单个离子的碰撞在前50 ps 内完成, 同时离子碰撞速率达到1030 cm-3·s-1. 另外, 在成核阶段温度的影响比压力更加明显, 温度越高, 离子碰撞速率越快, 形成的初始团簇越多. 而压力对Na2CO3团簇的进一步生长影响较大.

关键词: 超临界水, 碳酸钠, 结合能, 碰撞速率, 分子动力学

Abstract:

The nucleation and growth of Na2CO3 particles in supercritical water were investigated using molecular dynamics simulation. The clustering process of Na2CO3 was studied for 1 ns at a series of state points, across temperature and pressure ranges of 700 to 1100 K and 23 to 30 MPa, respectively. The binding energy and radial distribution function analysis showed that the electrostatic interaction was the main factor affecting the whole Na2CO3 nucleation process. Under supercritical conditions, the electrostatic interaction of water molecules with Na+ and CO32- ions rapidly decreased, allowing Na+ and CO32- ions to readily collide with each other to form small Na2CO3 clusters. During the initial Na2CO3 nucleation process, all the single-ion collisions were complete within 50 ps and the ionic collision rates appeared to be of the order of 1030 cm-3·s-1. Furthermore, the effect of temperature was found to be more important than that of the pressure at the nucleation stage and a higher temperature led to an enhanced collision rate and the formation of more initial Na2CO3 particles. The further growth of the Na2CO3 particles was more dependent on the pressure.

Key words: Supercritical water, Sodium carbonate, Binding energy, Collision rate, Molecular dynamics

MSC2000: 

  • O641