基于流通式金属氢化物反应器的氢高效分离提纯实验研究

The metal hydride (MH) method is viewed as one of the promising methods for hydrogen purification. The properties of MH materials will be significantly degenerated by the poisoning effect of impurity gases, especially for CO with strong effect. However, the present work in MH reactor level mainly focuses on some impurities with relatively insignificant effect yet, such as CH₄, CO₂, N₂, etc. To gain further insight into the reaction-separation behaviours of MH reactor running in by-product mixture, a flow-through type MH reactor filled with LaNi_4.3Al_0.7 is designed to separate hydrogen from mixture containing 0.1%CO and 39.9%CO₂. The effects of operating parameters such as temperature and pressure are systematically investigated for performance optimization. The optimum temperature of heat transfer fluids during hydrogen absorption process is found to be about 120℃, which keeps a balance between better anti-poisoning ability in high temperature and greater reaction driving force in low temperature. The experimental results also indicate that the optimum hydrogen partial pressure in the mixture gas should be about 0.84 MPa, due to the insignificant improvement of higher pressure. In addition, self-produce hydrogen purging is conducted to remove the impurity. The results of the experiment found clear support for the superiority of self-produce hydrogen purging for the MH reactor running in by-product mixture. Unexpectedly, purging the MH reactor with pure hydrogen for impurity replacement only leads to negligible improvement for impurity remove. A possible explanation is that molecular diffusion and desorption of impurities on the MH surface play a more important role for impurity transport and separation in MH reactor, rather than the viscous flow. The final hydrogen purity can reach 99.999% through self-produced hydrogen purge, and the hydrogen recovery rate can reach 77.6%, which shows the broad application prospects of metal hydride absorption separation method in the field of hydrogen separation and purification.