Experimental studies on poisoning of La0.9Ce0.1Ni5 based hydrogen purification system with CO2 as impurity

Abstract

In the present study, bed poisoning characteristics of CO2 as gaseous impurity in the La0.9Ce0.1Ni5 based, “Metal Hydride Hydrogen Purification System (MHHPS)” and regeneration of poisoned bed are reported. The study was conducted by varying impurity content of CO2 gas in the H2–CO2 mixture, in the range of 10–50% by weight and the cyclic stability of alloy was tested with 10% CO2 in H2–CO2 mixture. The study was conducted on a lab scale reactor with 6 embedded cooling tube (ECT) filled with 1.2 kg of La0.9Ce0.1Ni5. According to the experimental outcomes, the MHHPS was capable of delivery 99.99% pure hydrogen for CO2 impurity up to 20%. However, for higher impurities level (20–50%), the purity level was in the range of 97.3–99.8%. With CO2 as impurity, significant drop in the absorption capacity of the MHHPS was observed, which was in the range of 0.92 wt% to 0.67 wt% for impurity of 10–50%. However, the bed regeneration was performed, wherein the bed was desorbed and evacuated at 95 °C and 10−2 mbar, followed by absorption of pure hydrogen at 20 bar and 25 °C. Within 2-3 regeneration cycle, the alloy got regenerated and achieved storage capacity of 1.27 wt% in 200 s.