摘要
构建高性能吸附剂分离沼气中的CO_(2)是提升沼气利用经济效率的重要途径。针对当前吸附法中胺固载多孔材料存在的气体分离选择性较低、脱附能耗高的问题,本工作通过动态亚胺组装将对苯二甲醛和三乙烯四胺组装形成大尺寸超分子亚胺聚合物,进而负载于一种沸石咪唑酯骨架材料ZIF-8外表面,构建了ZIF-8@TP-X核壳金属有机框架复合材料。研究发现,TP在ZIF-8外表面形成了厚度为10 nm的完整包覆层,且未堵塞ZIF-8孔道。亚胺壳层提供大量的CO_(2)氢键吸附位点,耦合ZIF-8良好的孔隙率和大比表面积,使得CO_(2)吸附容量达29.3 cm^(3)/g,明显高于ZIF-8的15.3 cm^(3)/g;CO_(2)/CH_(4)分离选择性达到130,约为ZIF-8的45倍。TP中亚胺键上N原子相较于有机胺基中N原子的电子云密度更低,使得该材料具有较低的CO_(2)吸附热(36.5 kJ/mol)。该材料展现出优异的循环稳定性,具有较高的应用潜力。
The design and development of high-performance adsorbent materials capable of selectively separating CO_(2)from biogas are of paramount importance for improving the overall economic viability and sustainability of biogas utilization as a renewable energy source.However,conventional amine-functionalized porous materials for CO_(2)capture suffer from inherent drawbacks,such as low gas separation selectivity and high regeneration energy requirements,which limit their large-scale industrial applications.To overcome these challenges,dynamic imine assembly was used to assemble p-phenylenedialdehyde and triethylenetetramine into large-sized supramolecular imine polymers network that cannot enter the pores of MOFs.Then,these networks can be uniformly deposited on the outer surface of zeolite imidazolate framework(ZIF-8)through a simple impregnation method,ensuring uniform coating formation while maintaining the inherent porosity of the underlying MOF structure.Finally,a core-shell metal-organic framework(MOF)composite,designated as ZIF-8@TP-X was constructed.The innovative approach enables the precise functionalization of MOFs with an imine-based shell,significantly improving CO_(2)adsorption performance while maintaining excellent structural stability.The material was characterized in terms of morphology and structure,including scanning electron microscopy(SEM),transmission electron microscopy(TEM),Fourier transform infrared(FT-IR)spectroscopy,and nitrogen adsorption-desorption analysis,which confirmed the successful formation of a uniform and continuous TP coating layer on the ZIF-8 surface,with a thickness of approximately 10 nm.Notably,this imine-based shell did not compromise the intrinsic porosity of the MOF core,as evidenced by the preservation of its high surface area and well-defined microporous structure.This well-orchestrated core-shell interaction led to a significantly enhanced CO_(2)adsorption capacity of 29.3 cm^(3)/g,nearly doubling that of pristine ZIF-8(15.3 cm^(3)/g).Furthermore,the CO_(2)/CH_(4)separation selectivity reached 130,representing an extraordinary 45-fold enhancement compared to unmodified ZIF-8.The introduction of the imine-functionalized outer shell is equivalent to the incorporation of a high density of CO_(2)-specific hydrogen-bonding adsorption sites,thereby enhancing CO_(2)selectivity and adsorption capacity.Meanwhile,the ZIF-8 core retained its exceptional porosity and large specific surface area,ensuring a synergistic balance between adsorption selectivity and material stability.This drastic improvement highlights the potential of imine-functionalized MOFs as highly efficient adsorbents for biogas upgrading and methane purification.Compared to conventional organic amine groups,the nitrogen atoms in the imine bonds of TP have a lower electron cloud density,which results in a reduced CO_(2)adsorption enthalpy of 36.5 kJ/mol.The lower adsorption enthalpy effectively decreases the energy required for CO_(2)desorption and enhances the material's reusability in cyclic adsorption-desorption processes.The cyclic test results demonstrated that the material retained excellent stability after five adsorption-desorption cycles,with virtually no capacity degradation.This exceptional durability further validates the material's strong potential for large-scale biogas purification and industrial CO_(2)capture,laying a solid foundation for the development of next-generation sustainable gas separation materials.
作者
何苗
孙德贇
徐洪雪
易群
马倩
史利娟
HE Miao;SUN Deyun;XU Hongxue;YI Qun;MA Qian;SHI Lijuan(School of Chemical Engineering and Pharmacy,Wuhan Institute of Technology,Wuhan 430205,China)
出处
《燃料化学学报(中英文)》
北大核心
2025年第8期1203-1211,共9页
Journal of Fuel Chemistry and Technology
基金
国家自然科学基金(22272125,22478309)
海南省重点研发计划(ZDYF2024GXJS005)
山西-浙大先进材料与化工学院(2022SX-TD015)
武汉市科技局自然科学基金(2024040801020325)资助。
