复杂混合气体组分在低温活性炭表面的吸附特性

为实现大体积气体中微量放射性气体Kr、Xe同位素的测量，须将混合气体进行浓集并将目标气体吸附于10 mL左右的活性炭源盒中。本实验对混合气体中各组分在活性炭分离柱上的吸附性能进行研究，建立了通过去除其他杂质气体、浓集大体积气体制备放射性Kr和Xe活度源的方法。根据反应堆流出气体和核爆可能生成的气体组分，配制了模拟气体，使用活化的4A分子筛对其中的水和CO₂进行模拟去除，获得了流程中去除水和CO₂的实验条件；选择5个低温点(273、264、255、246、238 K)，在低温活性炭柱上对H₂、CO、CH₄、Kr和Xe的吸附特性进行研究，测定了各气体在不同温度下的吸附穿透曲线。结果表明，室温下4A分子筛对水和CO₂有较好的吸附效果。低温下，H₂、CO不易在活性炭表面吸附；CH₄、Kr吸附性质相似；Xe吸附能力较强。低温下难以去除的CH₄可在高温下氧化去除。因此，可根据混合气体中各组分性质的不同实现杂质气体的去除和目标气体Kr、Xe的回收测量。

Adsorption Characteristics of Component in Complex Mixed Gas on Activated Carbon

In order to measure the Kr and Xe isotopes of trace-level radioactive gases in large volume gas, the mixed gas must be concentrated and adsorbed in the activated carbon source box of about 10 mL. In this experiment, the adsorption properties of components in the mixed gas on the activated carbon column were studied. The method of the separation of other impurity gases and the concentration of large volume gas was established. According to the understanding of possible gas composition of effluent gas from reactor and nuclear explosion, the simulated gas containing water, CO₂, H₂, CO, CH₄, Kr and Xe was prepared. The activated 4A molecular sieve was used to remove the water and CO₂. The adsorption characteristics of H₂, CO, CH₄, Kr and Xe were studied on the fully cooled activated carbon column. The breakthrough curves of H₂, CO, CH₄, Kr and Xe gases at different temperatures were measured. The results show that 4A molecular sieve has large adsorption capacity for water and CO₂ at room temperature. At low temperature, H₂ and CO are not easily adsorbed on the surface of activated carbon. CH₄ and Kr have similar adsorption properties, and Xe has strong adsorption capacity. CH₄ which is difficult to remove at low temperature can be oxidized and removed at high temperature. Therefore, according to the different properties of each component in the mixed gases, the removal of impurity gases and the recovery and measurement of target gases Kr and Xe can be realized.