Absorption of poisoned hydrogen from metal hydride under CO+H₂ mixture gas for the production of clean, high purity hydrogen

The properties of metal hydride materials will be significantly degenerated by the poisoning effect of impurity gases such as CO, O₂, H₂S, etc. However, there are few reports on the poisoning kinetic model of metal hydride, which is important for the high-purity hydrogen purification and production from industry H₂-contained waste gas. Hence, in this work, a novel poisoning hydrogen absorption kinetic model for metal hydride running in the CO + H₂ mixture gas is developed, which considers the effect of poisoning on the volume growth rate of the product phase based on classical Johnson-Mehl-Avrami model. The novel model is also validated by comparison with experimental data of hydrogen absorption of LaNi_4.3Al_0.7 in a hydrogen atmosphere containing CO (∼0.1% v/v). The comparison results showed good agreement between model and experiment in the temperature range of 323–403 K. Based on experimental data and model, the reaction mechanism and rate-controlling steps of LaNi_4.3Al_0.7 hydrogenation process with 0.1%v/v CO were further uncovered.