Abstract:

The similarity in the physical properties of ethylene (C₂H₄) and ethane (C₂H₆) makes their selective separation one of the most challenging chemical separation processes. Utilizing the π-complexation between Cu(Ⅰ) active species and C₂H₄, Cu(Ⅰ)-based adsorbents can achieve their selective separation, significantly reducing the cost and environmental impact resulting from the high energy consumption of traditional distillation processes. Cu(Ⅰ)-based adsorbents are prepared by reducing Cu(Ⅱ)-containing samples, but the uncontrollable Cu(Ⅱ) reduction, low Cu(Ⅰ) yields, and high energy consumption have been the obstacles to the application of Cu(Ⅰ)-based materials. Here, a selective reduction strategy has been successfully employed to selectively construct Cu(Ⅰ) active sites in Y zeolite, enabling the selective separation of C₂H₄/C₂H₆ under mild conditions. Using formaldehyde (HCHO) vapor diffusion transfer to react with Cu(Ⅱ) in zeolite, the selective construction of Cu(Ⅰ) at low temperature (140℃) was achieved. Compared to the original Cu(Ⅱ)Y, Cu(Ⅰ)Y exhibits excellent C₂H₄/C₂H₆ selective separation performance. Cu(Ⅰ)Y achieves a selectivity of 16.3, far higher than the selectivity of Cu(Ⅱ) of 3.2. Finally, the formation mechanism of Cu(Ⅱ) is revealed, in which Cu(Ⅱ) in the zeolite is selectively converted to Cu(Ⅰ) along with the production of CO₂ and H₂O.

Key words: adsorption, ethylene/ethane separation, selectivity, Cu(Ⅰ), selective reduction strategy, zeolite

摘要：

乙烯（C₂H₄）和乙烷（C₂H₆）物理性质相似，其高效分离具有挑战性。利用Cu（Ⅰ）活性位与C₂H₄间的π络合作用，Cu（Ⅰ）基吸附剂能在温和条件下选择性地分离C₂H₄和C₂H₆，显著降低传统低温精馏分离过程的能耗。Cu（Ⅰ）由Cu（Ⅱ）还原制得，但Cu（Ⅱ）还原的不可控、能耗高且Cu（Ⅰ）收率低一直是Cu（Ⅰ）基吸附剂应用的障碍。采用选择性还原策略（SRS）成功在Y型沸石中选择性地构筑了Cu（Ⅰ）活性位，实现了温和条件下C₂H₄/C₂H₆的吸附分离。利用甲醛（HCHO）蒸气扩散传递，与沸石中的Cu（Ⅱ）反应，实现了低温（140℃）下Cu（Ⅰ）的选择性构筑；制得的Cu（Ⅰ）Y具有优异的C₂H₄/C₂H₆吸附分离性能，Cu（Ⅰ）Y的选择性达16.3，远高于Cu（Ⅱ）Y的3.2。机理研究表明，HCHO与Y沸石中的Cu（Ⅱ）发生氧化还原反应，在得到Cu（Ⅰ）的同时生成CO₂和H₂O。

关键词: 吸附, 乙烯/乙烷分离, 选择性, 一价铜, 选择性还原策略, 沸石