Y沸石中Cu(Ⅰ)的可控构筑及其乙烯/乙烷吸附分离性能研究

Controllable construction of Cu(Ⅰ)in Y zeolite for adsorptive separation of ethylene/ethane

乙烯(C_(2)H_(4))和乙烷(C_(2)H_(6))物理性质相似,其高效分离具有挑战性。利用Cu(Ⅰ)活性位与C_(2)H_(4)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C_(2)H_(4)和C_(2)H_(6),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C_(2)H_(4)/C_(2)H_(6)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C_(2)H_(4)/C_(2)H_(6)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CO_(2)和H_(2)O。

The similarity in the physical properties of ethylene(C_(2)H_(4))and ethane(C_(2)H_(6))makes their selective separation one of the most challenging chemical separation processes.Utilizing theπ-complexation between Cu(Ⅰ)active species and C_(2)H_(4),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 C_(2)H_(4)/C_(2)H_(6)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 C_(2)H_(4)/C_(2)H_(6)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 CO_(2)and H_(2)O.