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过程工程学报 ›› 2022, Vol. 22 ›› Issue (8): 1103-1114.DOI: 10.12034/j.issn.1009-606X.221348

• 研究论文 • 上一篇    下一篇

碳酸铈在NaCl-H2O体系中的相平衡热力学模型

栾峰1,4， 王道广2,3,4， 王均凤2,3,4*， 张建伟1， 崔朋蕾2,3,4
  

  1. 1. 沈阳化工大学机械与动力工程学院，辽宁 沈阳 110142 2. 中国科学院过程工程研究所多相复杂系统国家重点实验室，北京 100190 3. 中国科学院绿色制造创新研究院，北京 100190 4. 中国科学院离子液体清洁过程北京市重点实验室，北京 100190
  • 收稿日期:2021-11-03 修回日期:2021-12-15 出版日期:2022-08-28 发布日期:2022-08-28
  • 通讯作者: 王均凤 junfwang@ipe.ac.cn
  • 作者简介:栾峰(1995-)，男，吉林省四平市人，硕士研究生，动力工程专业，E-mail: luanfeng7558@163.com；通讯联系人，王均凤，E-mail: junfwang@ipe.ac.cn.
  • 基金资助:
    国家自然科学基金项目;中国科学院国际合作项目资助;中国科学院绿色制造创新研究院

Thermodynamic model for the phase equilibrium of cerium carbonates in the NaCl-H2O system

Feng LUAN1,4,  Daoguang WANG2,3,4,  Junfeng WANG2,3,4*,  Jianwei ZHANG1,  Penglei CUI2,3,4   

  1. 1. School of Mechanical and Power Engineering, Shenyang University of Chemical Technology, Shenyang, Liaoning 110142, China 2. State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China 3. Innovation Academy for Green Manufacture, Chinese Academy of Sciences, Beijing 100190, China 4. Beijing Key Laboratory of Ionic Liquids Clean Process, Chinese Academy of Sciences, Beijing 100190, China
  • Received:2021-11-03 Revised:2021-12-15 Online:2022-08-28 Published:2022-08-28

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摘要： 碳酸铈是生产CeO2的重要前驱体，对其性质具有决定性影响。碳酸铈的结晶特征取决于反应结晶过程中过饱和度的控制，其在NaCl-H2O体系中的相平衡数据是关键基础数据。本工作首先在298.15~363.15 K温度范围内合成了碳酸铈，XRD分析结果显示，323.15 K及以下得到的产品为八水碳酸铈[Ce2(CO3)3?8H2O]，343.15 K及以上得到的产品为碱式碳酸铈[CeCO3OH]。本工作采用经典等温法测定了这两种碳酸铈化合物在NaCl-H2O体系中的相平衡数据，并利用Aspen Plus平台的ELEC-NRTL方程建立了可准确预测Ce2(CO3)3?8H2O和CeCO3OH在NaCl-H2O体系中相平衡数据的热力学模型。在无限稀释假设的基础上，通过回归Ce2(CO3)3?8H2O和CeCO3OH在水中的溶解度数据，确定了这两种化合物的溶度积。采用赋存形态分析方法，将CeCO3+, CeOH2+, CeHCO32+等组分引入热力学模型。利用实验数据获得了新的离子对(Ce3+-HCO3-和Ce3+-Cl-)参数，提高了新模型的预测能力，所建立的热力学模型预测值与实验数据吻合较好。

关键词: 碳酸铈, 相平衡, 溶解度, 热力学模型

Abstract: Cerium carbonates are important precursors for the production of CeO2, which have a decisive effect on the properties of CeO2. The crystal characteristics of cerium carbonate compounds depend on the control of supersaturating in reactive crystallization, and the solubility of cerium carbonate compounds in the NaCl-H2O system are important basic data. In this work, cerium carbonates were synthesized by homogeneous precipitation method at the temperature range of 298.15~363.15 K. The generated solids were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM) and thermogravimetric analyzer (TG). The results showed that Ce2(CO3)3?8H2O was obtained below 323.15 K and transferred to CeCO3OH above 343.15 K. The solubility of the two cerium carbonate compounds in the NaCl-H2O system were determined by the classical isothermal method. The results showed that the solubility of Ce2(CO3)3?8H2O increased with the increase of temperature and concentration of NaCl, while the solubility of CeCO3OH increased with the increase of concentration of NaCl, and decreased with the increase of temperature. The solubility of Ce2(CO3)3?8H2O in water at 298.15 K was 4.08×10-6 mol/kg, which was of the same order of magnitude as the solubility of cerium carbonate [Ce2(CO3)3] that was 2.17×10-7~2.17×10-6 mol/kg at 298.15 K. The results indicated the reliability of the experimental data measured in this work. A thermodynamic model for predicting the solubility of Ce2(CO3)3?8H2O and CeCO3OH in the NaCl-H2O system was finally established by using the ELEC-NRTL equation embedded in the Aspen Plus platform. The solubility products of Ce2(CO3)3?8H2O and CeCO3OH were obtained by regression of their solubility data in water on the basis of an infinite dilution assumption. The species such as CeCO3+, CeOH2+, CeHCO32+ were introduced into the thermodynamic model on basis of the speciation method and their equilibrium constants were calculated by Van't Hoff isothermal formula. The new ion pair parameters of Ce3+-HCO3- and Ce3+-Cl- were obtained by regression of the experimental data to improve the predictive ability of the new model. The predicted values of the established thermodynamic model were well in agreement with the experimental data.

Key words: Cerium carbonate, Phase equilibrium, Solubility, Thermodynamics model