Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
Molecules. 2021 Dec 24;27(1):96. doi: 10.3390/molecules27010096.
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, H-TPR, CO-TPD, etc. The AE samples possess mainly isolated Cu 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 Cu 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)(HO) 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 H from CO.
向氢能经济的转变需要开发从 CO 中有效且经济地纯化氢气的方法。在这项研究中，我们探索了 Cu/ZSM-5 作为吸附剂的可能性。通过从水溶液（AE）中的阳离子交换和与 CuCl 的固态交换获得的样品通过原位 EPR 和 FTIR、H-TPR、CO-TPD 等进行了表征。AE 样品主要含有不吸附 CO 的孤立 Cu 阳离子。还原生成表现出对 CO 不同亲和力的 Cu 位，最强的中心在约 350°C 下解吸 CO。SE 样品的 Cu/Al 比约高两倍，因为一个 H 与一个 Cu 阳离子交换。尽管一些引入的 Cu 位在与空气接触时会被氧化为 Cu，但它们在真空或惰性气流下进行热处理后很容易恢复其原始氧化态。此外，这些 Cu 中心在相对较低的温度下再生。重要的是，由于形成了 Cu(CO)(HO) 配合物，水不会堵塞 CO 吸附位。动态吸附研究表明，Cu/ZSM-5 在氢气存在下选择性地吸附 CO。结果表明，SE 样品是从 CO 中纯化 H 的很有前途的材料。
