二氧化碳置换天然气水合物微观机理的理论研究

项目名称： 二氧化碳置换天然气水合物微观机理的理论研究

项目编号： No.11504133

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 数理科学和化学

项目作者： 刘金祥

作者单位： 济南大学

项目金额： 20万元

中文摘要： CO2置换天然气水合物是一种经济和环保的开采技术，但因涉及到分子吸附、扩散和交换等复杂的动力学过程，其微观机理尚不清楚。而置换微观机理的研究可为提高置换开采的安全性、置换速率和置换效率提供理论指导，目前已受到研究者越来越多的关注。本项目以sI型水合物为主要研究对象，采用量子化学计算和从头算分子动力学模拟相结合的方法，从分子和电子层次系统考察CO2分子在水合物表面的吸附和渗透、CO2分子在水笼子间的扩散转移、以及形成CH4-CO2混合水合物的热动力学性质等，从而深入认识置换微观机理；在此基础上，明确CO2水合物及其二次水合物的形成机制，澄清CO2分子的扩散和渗透行为对置换速率的影响规律，探究混合水合物中CH4分子的占有率对置换效率的影响规律。该研究可为置换开采技术的工业化应用提供基础数据和理论支持，因此具有重要意义和科学价值。

中文关键词： 二氧化碳；天然气水合物；从头算分子动力学模拟；量子化学计算；置换微观机理

英文摘要： The replacement exploitation of natural gas hydrate with CO2 has been known as an economical and environmental-friendly method. However, the replacement process is dominated by many factors such as adsorption, diffusion and intermolecular exchange, and the microscopic mechanism of the replacement process is still not well understood. Investigating replacement microscopic mechanism can be helpful to improve the replacement security, efficiency and rate, which has recently attracted wide attention. In this proposal, the micro-mechanism of sI-type hydrate replaced by CO2 is explored by the method of the quantum chemistry calculation combined with the ab initio molecular dynamics simulation. The following objectives are investigated at the molecular and electronic levels: (i) the adsorption and permeability behavior of the CO2 molecule on the hydrate surface; (ii) the diffusion and transfer processes of the CO2 molecule between the water cages; (iii) the thermal and dynamic properties of the CH4-CO2 hydrates. Through this work, we can provide detailed information about the formation of the CO2 hydrate, and have better understanding about the replacement efficiency and rate. Therefore, our work would be beneficial for the replacement method in the commercial production.

英文关键词： carbon dioxide;natural gas hydrate;ab initio molecular dynamics simulation;quantum chemistry calculation;replacement microscopic mechanism