Synthesis and separation performance of direct hydrogen adsorbent at moderate temperature

Hydrogen enriched natural gas (HENG) transportation through pipeline networks is one of the effective approaches to address the challenges of hydrogen storage and transportation at this stage.Thus, it is a hot spot to research the efficient separation and purification of hydrogen at the terminals of HENG pipeline network at present.In order to achieve the rapid separation of hydrogen and natural gas in the HENG and overcome the pulverization of direct hydrogen adsorbents, a series of modified lanthanum-nickel-based direct hydrogen adsorbent materials were prepared using the vacuum induction melting method, and the direct hydrogen adsorbent particles were fabricated by granulating the adsorption alloy powder.Then, SEM, XRD and ICP detection were conducted with three kinds of adsorption alloys, namely, LaNi_4.3Al_0.7, LaNi₃Al₁ and LaNi₄Al₁ respectively.The LaNi_4.3Al_0.7 alloy was selected preferably to make the direct hydrogen absorbent.On this basis, tests were carried out for the hydrogen adsorption capacity of the prepared direct hydrogen adsorbent under different pressures and temperatures, as well as the decay of adsorption capacity at 80℃.Besides, a direct hydrogen adsorption purification process at moderate temperature was developed, which successfully realized the separation of hydrogen and natural gas in HENG under the simulated conditions of pressure and hydrogen blending ratio.The results show that the purity of separated hydrogen could reach 99.9% and above.The direct hydrogen adsorbent has almost no decrease in adsorption capacity after 3 000 cycles and shows no pulverization after the cumulative operation over 900 hours.Generally, these findings lay a solid research foundation for the"hydrogen into end-user households"science and technology demonstration project.