Investigation of Cu(I)-Y zeolites with different Cu/Al ratios towards the ultra-deep adsorption desulfurization: Discrimination and role of the specific adsorption active sites
Investigation of Cu(I)-Y zeolites with different Cu/Al ratios towards the ultra-deep adsorption desulfurization: Discrimination and role of the specific adsorption active sites
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DOI：
10.1016/j.cej.2019.122319
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发表时间：
2020-01
影响因子：
15.1
通讯作者：
Yun Zu;Guo Zhongsen;Jian Zheng;Y. Hui;Sihua Wang;Yucai Qin;Li Zhang;Hong-hai Liu;Xiong-hou Gao
中科院分区：
文献类型：
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作者：
Yun Zu;Guo Zhongsen;Jian Zheng;Y. Hui;Sihua Wang;Yucai Qin;Li Zhang;Hong-hai Liu;Xiong-hou Gao
含铜材料因其优异的硫吸附性能而成为吸附脱硫研究的热点。然而，吸附剂中吸附活性中心的化学性质和吸附脱硫机理仍不明确，阻碍了潜在脱硫吸附剂的开发。本工作旨在通过液相离子交换法制备Cu（I）-Y分子筛来解决上述挑战。研究了Cu/Al比对活性中心化学性质、吸附脱硫性能及机理的影响。脱硫实验结果表明，Cu（I）-Y-0.28具有显著的硫穿透吸附容量（约0.95 mmol S/g），是文献报道的最佳吸附容量的约2.0倍。本文提出了一个新的观点，即除了B ronsted酸中心和Cu+物种外，位于Cu（I）-Y吸附剂超笼中的二聚体[Cu-O-Cu]2+和[Cu-O 2-Cu]2+物种可以被认为是有效的脱硫活性中心。此外，我们还发现，噻吩分子可以独立地吸附在上述吸附活性位，而不是噻吩齐聚，即使在存在的Brønsted酸中心。DFT计算进一步揭示了[Cu-O-Cu]2+和[Cu-O2-Cu]2+在噻吩捕获中的作用，这是由于其不同的吸附模式[（η1C）和（O-μ1-C，η1C，O-μ1-S）].本研究对Cu（I）-Y分子筛中有效吸附活性位的识别，对开发性能优良的脱硫吸附剂，提高脱硫能力乃至吸附选择性具有指导意义。
Cu-containing materials attracted much attentions to adsorption desulfurization due to their excellent sulfur adsorption capacities. The chemical properties of adsorption active sites in the adsorbents and adsorption desulfurization mechanism, however, still remained ambiguous, which had impeded the development of a potential desulfurization adsorbent. This work aimed to address the aforementioned challenges by using Cu(I)-Y zeolites obtainedvialiquid phase ion exchange method. The implication of Cu/Al ratios on the chemical properties of active sites, the adsorption desulfurization performance and the mechanism was the major focus of this work. The desulfurization experimental results indicate that the remarkable sulfur breakthrough adsorption capacity (ca.0.95 mmol S/g) can be achieved by the sample Cu(I)-Y-0.28, which is aboutca.2.0 folds as high as the best one reported. In this work, a new insight is put forward that except for the Brønsted acid sites and Cu+species, the dimeric [Cu-O-Cu]2+and [Cu-O2-Cu]2+species located in the supercages of Cu(I)-Y adsorbents are identified and can be considered as the effective desulfurization active sites by employingin situFTIR spectroscopy, IGA, XPS, and H2-TPR techniques. Furthermore, we also discover that the thiophene molecules can be independently adsorbed on the abovementioned adsorption active sites, rather than the thiophene oligomerization even if in the presence of Brønsted acid sites. DFT calculation further reveals the respective role of dimeric [Cu-O-Cu]2+and [Cu-O2-Cu]2+species for the thiophene capture, due to its different adsorption modes [(η1C) and (O-μ1-C, η1C, O-μ1-S)]. This study to distinguish effective adsorption active sites in the Cu(I)-Y zeolites should play an instructive role in the development of excellent desulfurization adsorbents in aspects of sulfur adsorption capacity and even adsorption selectivity.