Equation of state for CO and CO2 fluids and their application on decarbonation reactions at high pressure and temperature
Equation of state for CO and CO2 fluids and their application on decarbonation reactions at high pressure and temperature
复制标题
DOI：
10.1016/j.chemgeo.2020.119918
复制
发表时间：
2021-01
期刊：
影响因子：
3.9
通讯作者：
Yunguo Li;L. Vočadlo;A. Edgington;J. Brodholt
中科院分区：
文献类型：
--
作者：
Yunguo Li;L. Vočadlo;A. Edgington;J. Brodholt
在压力和温度高达160 GPa和4000 K下进行了从头算分子动力学模拟，以获得CO和CO2流体的状态方程（EOS）。我们发现，CO和CO2流体的聚合在低压下开始，并且包括聚合的影响对于精确的EOS是必不可少的。从使用实验数据的方法确定的CO和CO2的EOS，或忽略形态变化的经典电位，当外推超出检查的压力和温度时，应谨慎对待。对于CO和CO2流体，将获得的数据拟合到修改后的Lee和Kesler EOS。用导出的CO_2状态方程对MgCO_3和CaCO_3的脱碳酸反应进行热力学计算，结果与实验数据和理论计算相符。MgCO3和CaCO3纯相被发现是稳定的上地幔相比，CO2。然而，当接近下地幔条件时，它们都变得不稳定。
Ab initiomolecular dynamics simulations were performed at pressures and temperatures up to 160 GPa and 4000 K, in order to obtain equations of state (EOS) for CO and CO2fluids. We found that polymerisation of CO and CO2fluids starts at low pressures, and that including the effect of polymerisation is essential for accurate EOS. EOSs for CO and CO2determined from methods using experimental data, or classical potentials that ignore the changes in speciation, should be treated with caution when extrapolated beyond the examined pressures and temperatures. The obtained data was fitted to a modified Lee and Kesler EOS for both CO and CO2fluids. The thermodynamic calculations for the decarbonation reactions of both MgCO3and CaCO3using the derived CO2EOS reproduced the experimental data and theoretical calculations at low pressures. Both MgCO3and CaCO3pure phases are found to be stable in the upper mantle compared to CO2. However, they both become destabilised when approaching lower mantle conditions.