摘要
电石法制备的乙炔(C2H2)中会混入氮气、氧气和二氧化碳等杂质组分,为获得高纯度乙炔,相应的纯化分离研究十分必要.金属有机框架(metal organic framework,MOF)材料是一种具有超高孔隙率和易于功能化的多孔材料.基于特殊的孔腔特点,该类材料在气体吸附分离领域展现出优异的性能.本研究以一水合乙酸铜和5-(4-吡啶基)-1H-四唑为原料,制备了一种新的MOF材料——Cu(Hptz),命名为TYUT-15.该材料基于特殊的方形孔腔结构和多氮吸附位点触发了孔中乙炔分子间的偶极矩协同吸附,在主客体的共同作用下极大地提高了乙炔的吸附容量.采用单晶X射线衍射、同步热重分析、单组分气体吸附及混合气体穿透测试等对样品的结构及气体吸附分离性能进行了表征.分离实验表明,该材料可以从C2H2/CO2/N2/O2四组分混合气体中直接捕集C2H2.
Abstract
Acetylene(C2H2)production using the calcium carbide method produces several impurities,such as nitrogen,oxygen,and carbon dioxide.To obtain high-purity acetylene,research regarding the corresponding purification and separation is vital.Metal organic framework(MOF)materials have ultrahigh porosity and easy functionalization.Based on the specific characteristics of their pores,these materials typically possess large surface areas,abundant functional sites,and flexible and tunable pore structures.Thus,these materials demonstrate excellent performance in gas adsorption and separation.This study is based on MOF material construction using multiple nitrogen-containing imidazole ligands.A novel MOF material(Cu(Hptz)),named TYUT-15,was successfully synthesized using copper acetate monohydrate and 5-(4-pyridyl)-lH-tetrazole as raw materials.TYUT-15 has a basic structural unit comprising five-coordinated copper atoms linked to three different ligand units and two bridging oxygen atoms.Moreover,these units form a one-dimensional square channel structure with pore openings of approximately 6.0A×6.0Å and have a BET(Brunauer,Emmett and Teller)specific surface area of approximately 416 m2/g.Considering the unique square-shaped pore structures and multiple nitrogen adsorption sites,TYUT-15 triggers the dipole moment synergistic adsorption among acetylene molecules in the pores,and it improves the adsorption capacity of acetylene under the joint action of host and guest.Single-crystal X-ray diffraction,thermogravimetric analysis,single-component gas adsorption,and a breakthrough test were performed to characterize the sample structure and gas adsorption/separation performance.The results indicate that TYUT-15 is structurally stable and possesses numerous microporous structures.The single-component gas adsorption test reveals that this material has a high C2H2 adsorption capacity.The desorption isotherm of C2H2 exhibits certain hysteresis compared to the desorption isotherms of other gases,indicating a stronger interaction between TYUT-15 and C2H2.GCMC simulation calculations also support this observation by demonstrating that the adsorption heat of C2H2 is higher than that of CO2,providing further evidence of the stronger interaction between TYUT-15 and C2H2.Furthermore,TYUT-15 exhibits remarkably better adsorption capacity for C2H2 compared to CO2/N2/O2,and its adsorption capacity surpasses those of many previously reported MOF materials,including BSF-1(52.6 cm3/g),PCPs-mal(56.4 cm3/g),NTU-72(41 cm3/g),andNbOFFIVE-l-Ni(53.8 cm3/g).The IAST selectivity calculation results for TYUT-15 at 298 K and 1 bar for the equimolar gas mixture of C2H2/CO2(V/V=1/1)show that this material exhibits excellent C2H2/CO2 selectivity(11.3).Moreover,the selectivity is superior to that of most C2H2/CO2 separation materials,such as JNU-1(3.6),UTSA-74(9),DZU-11(3.6),FJU-112(4.2),and Ni-pz(10.3).The separation experiment results of the multicomponent mixed gas(C2H2/CO2/N2/O2)show that the retention time of C2H2 is approximately twice that of CO2,indicating that TYUT-15 can directly capture C2H2 from the four-component mixed gas of C2H2/CO2/N2/O2.Based on the structure construction of TYUT-15,this study utilizes the material's special square-shaped cavity characteristics and multiple nitrogen adsorption sites to achieve efficient C2H2 separation from mixed gases.This study proves that using multiazole ligands is feasible for building MOF materials for C2H2 recognition and separation.
基金项目
国家自然科学基金(22278287)
山西省基础研究计划(202203021224005)
山西省回国留学人员科研资助项目(2021-053)
NETL
NSTL
万方数据