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过程工程学报 ›› 2021, Vol. 21 ›› Issue (12): 1463-1472.DOI: 10.12034/j.issn.1009-606X.220362

• 过程与工艺 • 上一篇    下一篇

粒径对微米级氢氧化镁热解动力学的影响

陈英春1,2， 陈杭1,3*， 于建国1,2*
  

  1. 1. 华东理工大学资源过程工程教育部工程研究中心，上海 200237 2. 国家盐湖资源综合利用工程技术研究中心，上海 200237 3. 上海污染控制与生态安全研究院，上海 200092
  • 收稿日期:2020-11-09 修回日期:2021-02-03 出版日期:2021-12-28 发布日期:2022-03-28
  • 通讯作者: 陈杭 chenhang@ecust.edu.cn
  • 作者简介:陈英春(1993-)，男，山东省潍坊市人，硕士研究生，化学工程与技术专业，E-mail: Y11160219@mail.ecust.edu.cn；通讯联系人，陈杭，E-mail: chenhang@ecust.edu.cn；于建国，E-mail: jgyu@ecust.edu.cn.
  • 基金资助:
    MgCl26H2O-Mg(OH)2-MgO技术路线制备高纯镁砂过程基础研究

Effect of particle size on thermal decomposition kinetics of micron magnesium hydroxide

Yingchun CHEN1,2,  Hang CHEN1,3*,  Jianguo YU1,2*   

  1. 1. Engineering Research Center of Resource Process Engineering, Ministry of Education, East China University of Science and Technology, Shanghai 200237, China 2. National Engineering Research Center for Integrated Utilization of Salt Lake Resource, East China University of Science and Technology, Shanghai 200237, China 3. Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
  • Received:2020-11-09 Revised:2021-02-03 Online:2021-12-28 Published:2022-03-28

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摘要： 采用热重分析仪研究了氮气气氛下不同尺寸氢氧化镁颗粒(微米级)的非等温热解动力学。结果表明，氢氧化镁热解反应呈现阶段性特征，转化率达0.8以上的反应后期，其产物水蒸气扩散被氧化镁膜所阻碍，导致失重速率明显降低。针对转化率0~0.8的氢氧化镁主分解阶段，采用Starink法和联合动力学分析法拟合解析其过程动力学模型，发现颗粒尺寸对微米级氢氧化镁的热解过程动力学无显著影响，由此可知，所考察范围内的氢氧化镁热解过程为分解反应控制，颗粒热传导和产物水蒸气扩散的阻力作用弱，氢氧化镁热解主反应过程近似于均匀转化。模型拟合求解结果显示，微米级氢氧化镁热解反应活化能为129.4 kJ/mol，指前因子为1.820×1010 min?1，其热解反应过程服从随机成核和随后生长机理(A1.5)。

关键词: 氢氧化镁, 热解, 反应动力学, 热重分析法, 颗粒尺寸

Abstract: The non-isothermal pyrolysis kinetics of micron Mg(OH)2 is studied with the thermogravimetric analyzer under nitrogen atmosphere. It mainly focuses on clarifying the effects of particle size on the pyrolysis process. The measured thermogravimetric curves show a stepwise characteristic. At the main decomposition stage, the pyrolysis of Mg(OH)2 is rapid with a sudden mass loss. At the subsequent stage where conversion rate is larger than 0.8, the rate of weight loss decreases significantly because the diffusion of product water vapor is hindered by the product of MgO film. As for the main decomposition stage with conversion rate of 0~0.8, the Starink method and combined kinetic analysis are applied to fit and analyze its kinetic model. It is found that particle size has no distinct effect on the pyrolysis kinetics of micron Mg(OH)2. The model fitting results show that the pyrolysis reaction activation energy of micron Mg(OH)2 is 129.4 kJ/mol, the pre exponential factor is 1.820×1010 min?1, the pyrolysis reaction process follows the mechanism of random nucleation and growth of nuclei (A1.5). Compared to the experimental results, the thermogravimetric curves reconstructed based on these fitting parameter have the deviation less than 5%, which indicates that the kinetic model is reasonable. Meanwhile, it can be concluded that the pyrolysis process is controlled by decomposition reaction in the investigated range with the conversion rate from 0 to 0.8. The resistance effect of particle heat conduction and product water vapor diffusion is weak relatively. The main process of Mg(OH)2 weight loss is approximate to a homogeneous reaction. Considering the current investigation mainly focuses on the main decomposition stage of Mg(OH)2 with the conversion rate from 0 to 0.8, the kinetics of second stage of weight loss process remains to be studied further.

Key words: Mg(OH)2, pyrolysis, reaction kinetics, thermogravimetry, particle size