化工学报 ›› 2020, Vol. 71 ›› Issue (8): 3452-3459.DOI: 10.11949/0438-1157.20200061

• 热力学 • 上一篇    下一篇

常见钠盐的高温挥发特性及热解机理

李剑1,2(),蒲舸1,2(),陈家善1,2,刘啟文1,2   

  1. 1.重庆大学低品位能源利用技术及系统教育部重点实验室,重庆 400044
    2.重庆大学能源与动力工程学院,重庆 400044
  • 收稿日期:2020-01-15 修回日期:2020-03-10 出版日期:2020-08-05 发布日期:2020-08-05
  • 通讯作者: 蒲舸
  • 作者简介:李剑(1987—),男,硕士研究生,233759117@qq.com
  • 基金资助:
    重庆市重点产业共性关键技术创新专项(cstc2016zdcy-ztzx 0024)

High-temperature volatility characteristics and pyrolysis mechanism of common sodium salts

Jian LI1,2(),Ge PU1,2(),Jiashan CHEN1,2,Qiwen LIU1,2   

  1. 1.Key Laboratory of Low-Grade Energy Utilization Technologies & Systems of Ministry of Education, Chongqing University, Chongqing 400044, China
    2.School of Energy and Power Engineering, Chongqing University, Chongqing 400044, China
  • Received:2020-01-15 Revised:2020-03-10 Online:2020-08-05 Published:2020-08-05
  • Contact: Ge PU

摘要:

选取有机废液中常见的钠盐(氯化钠、碳酸钠、硫酸钠、甲酸钠、乙酸钠、草酸钠),通过热重分析仪,在25~1400℃考察其高温挥发特性。基于Gibbs自由能最小原理,对NaCl、Na2CO3及Na2SO4的挥发特性进行热力学计算。结果表明,在N2气氛中,NaCl在达到熔点后以气态NaCl及气态Na2Cl2的形式释放,Na2SO4升温至885℃分解生成Na2O,同时Na2O分解,并以Na单质形式释放。而有机羧酸钠盐在600℃之前均热解为Na2CO3,继续升高温度则分解为Na2O,同样最后以气态Na单质的形式释放。在空气气氛中,由于O2的存在,抑制了Na2O的分解反应,致使Na2CO3分解速率小于N2气氛。

关键词: 钠盐, 高温挥发特性, 热重分析, 热解, 热力学, 腐蚀

Abstract:

The common sodium salts (sodium chloride, sodium carbonate, sodium sulphate, sodium formate, sodium acetate, sodium oxalate) in organic wastewater were selected, and their high-temperature volatility characteristics were examined by thermogravimetric analyzer at 25—1400℃. Based on the principle of Gibbs free energy minimum, the volatility characteristics of NaCl, Na2CO3 and Na2SO4 were calculated thermodynamically. The results showed that in the N2 atmosphere, NaCl began to be released in the form of NaCl(g) and Na2Cl2(g) after reaching the melting point. Na2SO4 decomposed to form Na2O at high temperature, and it continued to decompose to form elemental sodium when the temperature raised. The organic carboxylic acid sodium salt was pyrolyzed to Na2CO3 before 600℃, then it decomposed to form Na2O when the temperature went up, and finally released as sodium vapor. In the air atmosphere, due to the presence of O2, the decomposition reaction of Na2O is suppressed, resulting in the decomposition rate of Na2CO3 is less than that of N2 atmosphere.

Key words: sodium salt, high temperature volatility characteristics, thermogravimetric analysis, pyrolysis, thermodynamic, corrosion

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