欢迎访问过程工程学报, 今天是

›› 2002, Vol. 2 ›› Issue (1): 0-0.

• 1 •    

超声对钼酸铵溶液结晶过程的影响机制

吴争平，尹周澜，陈启元，张平民，李洁(   

  1. 中南大学化学化工学院，湖南 长沙 410083
  • 出版日期:2002-02-20 发布日期:2002-02-20

Characteristics and Active Energy for the Precursor of Lithium Manganese Oxides

ZHAO Ming-shu1, SONG Xiao-ping1, ZHAI Yu-chun2, TIAN Yan-wen2   

  1. College of Chemistry and Chemical Engineering, Central South University, Changsha,Hunan 410083, China
  • Online:2002-02-20 Published:2002-02-20

PDF

摘要： 揭示了超声对3种不同结晶形态四钼酸铵结晶的晶型和热化学性质的影响规律. 对于生成b型四钼酸铵的反应体系，无超声作用下需1~2 d制得产物，而在超声作用下只需十几分钟即可完成，并且发生晶型的改变，生成了微粉型四钼酸铵. 用量子化学从头计算方法，在RHF/3–21G和STO–3G 水平上，对超声作用下可能发生的离子形态转变中所涉及到的H2Mo7O244–, [(MoO2) ( MoO3)x–1]2+ (x=1, 2, 3)等进行计算，得到各研究体系的总能量和集居数. pH值为2.3~2.5时超声作用下所产生的高能环境可能是使钼酸铵溶液中的H2Mo7O244– 变成[(MoO2)(MoO3) x–1]2+ (x=1, 2, 3)，从而生成微粉型四钼酸铵的原因.

关键词: 超声, 钼酸铵, 晶型, 量子化学从头计算

Abstract: The effect of ultrasonic wave on the crystallization of ammonium molybdate aqueous solution was studied. The crystalline and thermochemical property under ultrasonic effect were discussed. It is indicated that ultrasonic has a great effect on the reaction system of preparing b-type ammonium tetramolybdate. The crystallization time was shortened from 1~2 d to 10~20 min under ultrasonic and the crystalline form became microcrystal-type under ultrasonic. The total energy and condensation of atoms of H2Mo7O244– and [(MoO2)(MoO3)x–1]2+(x=1, 2, 3) were computed at the HF/ 3–21G, STO–3G level, and their geometrical structures were optimized using the molecular mechanics optimization method. The calculation results show that the reason of transformation from H2Mo7O244– to [(MoO2)(MoO3)x–1]2+ at pH 2.3~2.5 is the effect of ultrasonic. All ab initio calculations were performed with the Gaussian–98 program.

Key words: lithium manganese oxides precursor, characteristics, decomposition kinetics

中图分类号: