CO2对Pd8Y0.23Ru合金膜氢渗透性能的影响

Effect of CO2 on Hydrogen Permeation through Pd8Y0.23Ru Alloy Membrane

摘要:

在300~450 ℃范围内，研究氢中加入CO2对Pd8Y0.23Ru合金膜氢渗透性能的影响。结果表明，CO2的加入会大大降低膜的氢渗透率，CO2浓度越高，氢渗透率降低越多；CO2对Pd8Y0.23Ru合金膜存在一定的毒化作用，使氢渗透率下降，450 ℃下的毒化作用明显强于300 ℃，但随着时间的延长，渗透率降低速率趋缓。CO2降低氢渗透率还有另外2个因素：当CO2浓度较高 (>3%，摩尔分数)时，聚集在膜表面附近的CO2对氢气传质的阻塞作用是氢渗透率降低的主要因素；当CO2浓度较低 (<1%)时, CO2在膜表面吸附，占据氢的活性点位，是氢渗透率降低的主要因素。

Abstract:

Hydrogen permeation through a Pd8Y0.23Ru alloy membrane at 300 oC~450 oC has been investigated in the presence of CO2. The results show that the hydrogen permeability is greatly decreased by CO2 addition. The higher the CO2 concentration is, the more significant the reduction of hydrogen permeation will be. The coexisting CO2 gas has a poison effect on Pd8Y0.23Ru alloy membrane. The poison effect at 450 oC is stronger than at 300 oC. The reduction rate of hydrogen permeation decreases with the permeation duration. Besides poison effect, the negative effects of CO2 on H2 permeation are also caused by two other factors. Firstly, for higher concentration of CO2 (>3%), mass transfer of H2 ?is blocked by CO2 barrier layer near the membrane surface, which is the main reason for hydrogen permeation reduction. Secondly for lower concentrations (<1%), the main reason is the effects of CO2 adsorbing on the membrane and occupying active dissociation sites of hydrogen.