摘要
采用实验研究与分子模拟相结合的方法研究了低碳烷烃烯烃在超微孔柔性Cu(Qc)_(2)上的吸附热力学、动力学和吸附分离机理。用常温合成方法制备了超微孔金属-有机骨架材料Cu(Qc)_(2),测定了低碳烷烃烯烃(CH_(4)/C_(2)H_(4)/C_(2)H_(6)/C_(3)H_(6)/C_(3)H_(8))在Cu(Qc)_(2)上的吸附相平衡和吸附动力学。使用Materials Studio中的Fortcite模块模拟低碳烷烃烯烃在超微孔柔性Cu(Qc)_(2)上的吸附机理以及材料的结构形变。结果表明Cu(Qc)_(2)具有优良的C_(2)H_(6)/C_(2)H_(4)吸附选择性和吸附动力学,而对C_(3)H_(8)/C_(3)H_(6)的吸附选择性很低。273 K和0.1 MPa下,C_(2)H_(6)/C_(2)H_(4)在Cu(Qc)_(2)上的IAST选择性达4.6。298 K和0.05 MPa下C_(2)H_(6)/C_(2)H_(4)在Cu(Qc)_(2)上的扩散时间常数分别达1.42×10^(-3)和1.48×10^(-3)s^(-1),扩散活化能分别为16.62和16.43 kJ/mol。应用装填Cu(Qc)_(2)的固定床可在常温条件下实现C_(2)H_(6)/C_(2)H_(4)二元混合气的完全分离。模拟结果显示Cu(Qc)_(2)为二维堆叠结构,材料会由于吸附不同分子而发生不同程度的结构形变。甲烷易从变大的层间扩散脱附,导致其在材料上的吸附量很低;C_(2)H_(6)/C_(2)H_(4)两者都能稳定吸附在层中的孔道中,其分离推动力主要来源于两种气体在材料上明显的吸附热差异;C_(3)H_(8)/C_(3)H_(6)会分别吸附在两种不同的环境,吸附热差异小导致Cu(Qc)_(2)对C_(3)H_(8)/C_(3)H_(6)的吸附选择性低。
The adsorption thermodynamics,kinetics and separation behavior of light alkanes/alkenes(CH_(4)/C_(2) H_(4)/C_(2) H_(6)/C_(3) H_(6)/C_(3) H_(8))on ultramicroporous and flexible metal-organic frameworks(MOFs)Cu(Qc)_(2) were systematically studied by using combination of experimental and simulation methods.Ultramicroporous and flexible Cu(Qc)_(2) was synthesized using a room temperature synthesis method for alkanes/alkenes separation.The adsorption isotherms and kinetic curves of these alkanes/alkenes on Cu(Qc)_(2) were measured.The adsorption behavior of these light hydrocarbons on the Cu(Qc)_(2) and the deformation of the material structure were studied by means of the Fortcite module of the Materials Studio.The results showed that Cu(Qc)_(2) had excellent C_(2) H_(6)/C_(2) H_(4) adsorption selectivity and adsorption kinetics,while its adsorption selectivity to C_(3) H_(8)/C_(3) H_(6) was very weak.At 273 K and 0.1 MPa,the IAST selectivity of Cu(Qc)_(2) for C_(2) H_(6)/C_(2) H_(4) reached as high as 4.6.At 298 K and 0.05 MPa,the diffusion time constants of C_(2) H_(6) and C_(2) H_(4) on Cu(Qc)_(2) reached 1.42×10^(-3) and 1.48×10^(-3) s^(-1),respectively,and the activation energy of diffusion was 16.62 and 16.43 kJ/mol,respectively.The application of fixed bed packed with Cu(Qc)_(2) can realize the complete separation of C_(2) H_(6)/C_(2) H_(4) binary mixture under normal temperature conditions.The simulation results showed that Cu(Qc)_(2) was a two-dimensional stack structure,which would undergo different degrees of structural deformation when different molecules were adsorbed.Methane would be ready to diffuse and desorb from the enlarged layer,resulting in a very low adsorption capacity;both C_(2) H_(6) and C_(2) H_(4) can be stably adsorbed in the pores in the layer,and the separation driving force mainly comes from the difference in the adsorption heats of the two molecules;C_(3) H_(8) and C_(3) H_(6) would be separately adsorbed in two different environments of Cu(Qc)_(2),and the small difference in adsorption heats of these molecules makes the C_(3) H_(8)/C_(3) H_(6) adsorption selectivity low.
作者
唐瑜佞
王勋
彭俊洁
吴颖
李忠
TANG Yuning;WANG Xun;PENG Junjie;WU Ying;LI Zhong(School of Chemistry and Chemical Engineering,South China University of Technology,Guangzhou 510640,Guangdong,China)
出处
《化工学报》
EI
CAS
CSCD
北大核心
2021年第11期5664-5674,共11页
CIESC Journal
基金
国家自然科学基金项目(21436005,U1662136)。
