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电化学(中英文) ›› 2021, Vol. 27 ›› Issue (5): 529-539.  doi: 10.13208/j.electrochem.200830

• 论文 • 上一篇    下一篇

对称季铵碱的烷基链长度对草酸电还原反应的影响

黄波, 张新胜, 钮东方, 胡硕真*()   

  1. 华东理工大学化学工程联合国家重点实验室,上海 200237
  • 收稿日期:2020-09-05 修回日期:2020-10-30 出版日期:2021-10-28 发布日期:2020-11-12
  • 通讯作者: 胡硕真 E-mail:shuozhen.hu@ecust.edu.cn

Effect of Alkyl Chain Length of Symmetrical Quaternary Ammonium Hydroxide on Oxalic Acid Electroreduction Reaction

Bo Huang, Xin-Sheng Zhang, Dong-Fang Niu, Shuo-Zhen Hu*()   

  1. State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, P.R. China
  • Received:2020-09-05 Revised:2020-10-30 Published:2021-10-28 Online:2020-11-12
  • Contact: Shuo-Zhen Hu E-mail:shuozhen.hu@ecust.edu.cn

摘要:

研究了四种不同烷基链长度的对称季铵碱对草酸电还原制备乙醛酸反应的影响。线性扫描测试考察了添加剂对铅电极上阴极反应的影响,结果表明对称季铵碱在电极表面的吸附对析氢反应的抑制程度大于其对草酸电还原反应的抑制程度,且随着对称季铵碱中烷基链长度的增加,添加剂抑制析氢反应效果更明显。计时安培法的结果证明添加剂可影响草酸向电极表面的扩散,随着对称季铵碱中烷基链长度的增加,草酸的扩散系数呈现出先增加后减小的趋势。恒流电解实验结果表明,添加剂能有效提高草酸电还原反应的电流效率,且提高效果随对称季铵碱所含烷基链长度的增加而增强。因此,添加剂的吸附对阴极表面析氢反应的抑制作用是草酸电还原反应电流效率提高的主要原因。本研究表明,四丁基氢氧化铵为添加剂时,草酸还原为乙醛酸的电流效率最高。

关键词: 草酸, 电解还原, 乙醛酸, 对称季铵碱添加剂, 烷基链长度

Abstract:

Glyoxylic acid with the dual characteristics of acid and aldehyde is an important chemical raw material and organic synthesis intermediate, which is extensively used in the perfumery, pharmaceutical and fine chemical industries. A family of symmetric quaternary ammonium hydroxides (QAHs) with different alkyl chain lengths was used as the additives in generating glyoxylic acid from oxalic acid electroreduction reaction (OAER). The effects of alkyl chain length on OAER and the corresponding side reaction, i.e., hydrogen evolution reaction (HER), were investigated. Linear sweep voltammetric (LSV) results showed that the adsorption of the additives suppressed more on the HER than that on OAER, resulted in improving the current efficiency of OAER. As the alkyl chain length of QAH increased, the suppression effect on HER was more obvious. The effect of additives on oxalic acid diffusion was studied by chronoamperometry (CA). With the increase in the alkyl chain length of the QAH additives, the diffusion coefficient of oxalic acid increased first and then decreased. The constant-current electrolysis results showed that the additives could effectively improve the current efficiency of the OAER, which was highly related to the alkyl chain length of QAHs. The LSV, CA and electrolysis results indicate that the suppression effect of QAHs adsorption on HER is the main reason for the improvement of current efficiency. In this study, tetrabutylammonium hydroxide (TBAH) is the best additive to increase the current efficiency of generating glyoxylic acid from oxalic acid.

Key words: oxalic acid, electroreduction, glyoxylic acid, symmetrical quaternary ammonium additive, alkyl chain length