物理化学学报 >> 2005, Vol. 21 >> Issue (02): 218-220.doi: 10.3866/PKU.WHXB20050222

研究简报 上一篇    下一篇

铬酸铵钠复盐结晶的热分解

刘昌见;张懿   

  1. 中国科学院过程工程研究所,北京 100080; 石油大学(北京)中国石油天然气集团公司催化重点实验室,北京 102249
  • 收稿日期:2004-06-10 修回日期:2004-09-08 发布日期:2005-02-15
  • 通讯作者: 刘昌见 E-mail:chjliu@bjpeu.edu.cn

Thermal Decomposition of NaNH4CrO4•2H2O

LIU Chang-Jian;ZHANG Yi   

  1. InstituteProcessEngineering,ChineseAcademyofSciences,Beijing 100080;TheKeyLaboratoryofCatalysis,ChinaNationalPetroleumCo.,UniversityofPetroleum,Beijing 102249
  • Received:2004-06-10 Revised:2004-09-08 Published:2005-02-15
  • Contact: LIU Chang-Jian E-mail:chjliu@bjpeu.edu.cn

摘要: 采用TG-DTG、DTA和XRD对铬酸铵钠复盐结晶(NaNH4CrO4•2H2O)的热分解过程进行研究,结果表明NaNH4CrO4•2H2O的热分解过程分为三步进行,第一步是在50~95 ℃温度范围结晶水的脱除,第二步是在100~180 ℃的温度范围铵的初步热分解,产物为铬酸钠和重铬酸铵,第三步是215~385 ℃进行的铵的完全分解.存在生成重铬酸钠与生成三氧化二铬的竞争反应.在氨不易扩散的条件下,最终分解产物为三氧化二铬、重铬酸钠和铬酸钠的混合物;在流动气氛中,400~790 ℃温度范围,NaNH4CrO4•2H2O热分解产物为重铬酸钠.与传统的铬酸钠硫酸酸化生产重铬酸钠工艺相比,该方法无副产物产生,是一清洁工艺.

关键词: NaNH4CrO4•, 2H2O, 热分解, 清洁工艺

Abstract: Thermal decomposition of NaNH4CrO4•2H2O was studied by means of thermogravimetric analysis (TG),differential thermogravimetric (DTG), differential thermal analysis (DTA) and X-ray diffraction (XRD). The results showed that the thermal decomposition of NaNH4CrO4•2H2O proceeds in three steps, i.e., the release of crystal water at temperature from 50 ℃ to 95 ℃ at first, the formation of the intermediates sodium chromate and ammonium dichromate with the partial release of ammonia at temperature from 100 ℃ to 180 ℃,and the complete elimination of ammonia from 215 ℃ to 385 ℃ .In flowing ambient and suitable temperature(400~790 ℃),the final decomposition product was mostly sodium dichromate. This leads to a cleaner process for sodium dichromate production.

Key words: NaNH4CrO4•, 2H2O, Thermal decomposition, Cleaner process