碘硫循环制氢中 HI 的电解渗析浓缩工艺研究

为应对碘硫循环制氢工艺中浓缩 HI 的要求,采用石墨、活性炭纤维布为电极,Nation117CS 为质子交换膜构成电解渗析(EED)池,对Bunsen反应 Hix相的模拟溶液进行了HI 的 EED浓缩实验.实验结果表明,EED操作能够对 HI 起到有效的浓缩作用.在所考察的 2.5～20.0 A/dm2 电流密度范围内未发生浓差极化,随电流密度的提高,阴极液 HI 浓缩速率逐渐增大.在连续运行实验中,当电流密度为 20.0 A/dm2 时,对初始m(HI)为 8.8 mol/kg 的 HH-H2O-I2溶液进行2 h 的 EED处理,即可使m(HI)超越恒沸点.采用石墨电极时的浓缩效果优于采用活性炭纤维布,但采用后者时EED槽电压明显低于前者,可使EED操作能耗有效降低.提高操作温度会使HI的浓缩效率下降,但可显著降低槽电压.

HI Concentration of HIx (HI-H2O-I2) Solution in Iodine-Sulfur Water-Splitting Cycle by Electro-Electrodialysis

Nafion 117CS membrane and electrodes of graphite or activated carbon fiber cloth are adopted to establish electro-electrodialysis(EED) apparatus for concentration of hydriodic acid in HIx phase of IS cycle.The effects of different electrodes,current density,operating time and temperature on the efficiency of EED process are investigated.The concentration effect of HI is strengthened with the increasing current densities in range of 5-20 A/dm2.When graphite plates are adopted as electrodes,the molality of HI in catholyte increases faster than activated carbon fiber cloth to lead to a quite low cell voltage.The increasing EED temperature brings out a lower efficiency of HI concentration,while significantly drops the cell voltage.