Purification of Hydrogen from CO with Cu/ZSM-5 Adsorbents |
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Authors: | Mihail Mihaylov Elena Ivanova Videlina Zdravkova Stanislava Andonova Nikola Drenchev Kristina Chakarova Radoslav Kefirov Rositsa Kukeva Radostina Stoyanova Konstantin Hadjiivanov |
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Affiliation: | Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria; (E.I.); (V.Z.); (S.A.); (N.D.); (K.C.); (R.K.); (R.K.); (R.S.) |
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Abstract: | The transition to a hydrogen economy requires the development of cost-effective methods for purifying hydrogen from CO. In this study, we explore the possibilities of Cu/ZSM-5 as an adsorbent for this purpose. Samples obtained by cation exchange from aqueous solution (AE) and solid-state exchange with CuCl (SE) were characterized by in situ EPR and FTIR, H2-TPR, CO-TPD, etc. The AE samples possess mainly isolated Cu2+ cations not adsorbing CO. Reduction generates Cu+ sites demonstrating different affinity to CO, with the strongest centres desorbing CO at about 350 °C. The SE samples have about twice higher Cu/Al ratios, as one H+ is exchanged with one Cu+ cation. Although some of the introduced Cu+ sites are oxidized to Cu2+ upon contact with air, they easily recover their original oxidation state after thermal treatment in vacuum or under inert gas stream. In addition, these Cu+ centres regenerate at relatively low temperatures. It is important that water does not block the CO adsorption sites because of the formation of Cu+(CO)(H2O)x complexes. Dynamic adsorption studies show that Cu/ZSM-5 selectively adsorbs CO in the presence of hydrogen. The results indicate that the SE samples are very perspective materials for purification of H2 from CO. |
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Keywords: | adsorption breakthrough curves carbon monoxide Cu/ZSM-5 FTIR spectroscopy hydrogen purification temperature-programmed desorption |
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