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Kinetics of Phase-Transfer Catalyzed Disproportionation of Elemental Sulfur

Deng Tong and Chen Jiayong(Chia-Yung Chen) (Institute of Chemical Metallurgy, Academia Sinica, Beijing)   

  • Online:1988-10-25 Published:1988-10-25

相转移催化元素硫歧化反应的动力学

邓彤,陈家镛   

  1. 中国科学院化工冶金研究所,中国科学院化工冶金研究所 北京 ,北京

Abstract: Disproportionate of elemental sulfur in tetrachloroethylene with aqueous hydroxide was found to be catalyzed by tetrabutylammonium hydroxide, and its reaction kinetics was investigated at a hydroxide concentration of 0.02-0.14 mol and within a temperature of 45-70℃. The linear dependence of the observed volumetric reaction rate Rsa on the rate of agitation within the range from 1.1.3 to 21.2 s-1 (680 to 1270 rpm), indicates the typical characteristics of a interfacial reaction, and within the range studied, Rsa can be expressed as The apparent activation energy was derived from experimental data as 79 kJ/ mol. The results of this kinetic study can be explained satisfactorily by a mathematical model of mass transfer with fast chemical reaction in liquid-liquid system. It indicated that disproportionation of elemental sulfur was first order with respect to both the hydroxide ion in the aqueous phase and sulfur in the organic phase. The reaction was supposed to be initiated at the interface and completed within the diffusion film in the organic side. Evidence of PTC from the experimental results was given, and a reaction mechanism was proposed and discussed.

摘要: 在45—70℃、氢氧离子浓度为0.02—0.14mol/l范围内研究了四氯乙烯/水体系中氢氧化四丁铵相转移催化元素硫歧化反应初始阶段的动力学.实验得到表观速度表达式:R_(?)a=k~(?)[Q~+]_(aq)[OH~-]_(aq)[S]_(org)~(1/2),并导得表观活化能为79kJ/mol.用液液体系伴有快速化学反应的传质模型成功地解释了本体系动力学.推测了元素硫的歧化反应机理,从动力学上提出了本体系相转移催化的证据.