| Adsorption plays an important role in the chemical industries.The key to the efficient adsorption is the adsorbent with high selectivity and capacity.Novel porous materials likes metal organic frameworks(MOFs)and covalent organic frameworks(COFs),have potential to gradually weed out the traditional technologies for their favorable gas adsorption and separation properties with their advantages of large specific surface area,acceptable stability,adjustable pore sizes and controllable properties.By comparison,another newly found adsorbent,namely supramolecular organic frameworks(SOFs),are easy to depurate and regenerate,meanwhile,possess low density,high specific surface area and high flexibility.However,they were found hard to exist and further to be applied in gas separation for their fragile non-covalent frameworks.By introducing organometallic complexes into the SOFs,SOFs with adenine moieties could possess admirable properties of MOFs and SOFs.This work focused on the study of the design and preparation of SOFs with adenine moieties,and their feasibilities in gas adsorption processes were investigated further as well.The results may have significant scientific research value,as well as offer a new idea and reference for light hydrocarbon separation.Firstly,porous hydrogen-bonded supramolecular organic frameworks MPM-1-Br,MPM-1-Cl and MPM-1-TIFSIX were prepared by slow diffusion method.MPM-1-Br MPM-1-CI and MPM-1-TIFSIX were first characterized by SEM,PXRD,TGA and specific surface area analysis,and then their adsorption isotherm of acetylene and carbon dioxide were measured on these three materials.It was found that under 240 ?,both MPM-1-Br and MPM-1-Cl remained stable with the specific surface area of 373 m2·g-1 and 417 m2·g-1,respectively,while under 200 ?,MPM-1-TIFSIX maintained its porous structure with the specific surface area of 1020 m2·g-1.IAST selectivity calculations for binary equimolar mixture of C2H2 and CO2 at 298 K and 100 kPa revealed the adsorption selectivity of MPM-1-Br and MPM-1-Cl to be 3.8 and 3.0,comparable to MOFs likes HKUST-1(4.7)and UTSA-30(3.3).Secondly,by changing anion,we synthesized a new porous hydrogen-bonded SOFs,IPM-SIFSIX-1.IPM-SIFSIX-1 were first characterized by SXRD,PXRD,microscope,TGA and specific surface area analysis,and then their adsorption isotherm of several gases were measured.It was found that IPM-SIFSIX-1 qualified with thermal and water stability with specific surface area of 339 m2·g-1.IAST calculations of the component loadings for 50:50 C2H2/C2H4,50:50 C2H2/CO2 and 10:90 CO2/N2 at 298 K and 100 kPa revealed the adsorption selectivity to be 7.1,4.9 and 97,respectively.The adsorption selectivity of 50:50 C2H2/C2H4 was found to be the highest among SOFs ever reported,except HOF-1(7.4).High-resolution neutron powder diffraction measurements on C2D2-loaded samples reveals that high adsorption selectivity for C2H2/C2H4 of IPM-SIFSIX-1a was related to the relative stronge hydrogen bond between SiF62-and C2H2.Furthermore,by simply emersing collaped IPM-SIFSIX-1a into water or(NH4)2SiF6 solution,we surprisely found that IPM-SIFSIX-1a could be restored.Thirdly,as IPM-SIFSIX-1a possesed great property for gases separations,we further decorated adenine to synthesize new porous hydrogen-bonded SOFs,IPM-SIFSIX-2.IPM-SIFSIX-2 was first characterized by FT-IR,PXRD,TGA and specific surface area analysis,and then its adsorption isotherms of several gases including acetylene,ethylene,methane and carbon diociede were collected.IAST calculations of the component loadings for 50:50 C2H2/C2H4,50:50 C2H2/CO2,50:50 CO2/CH4 and 10:90 CO2/N2 at 298 K and 100 kPa revealed the adsorption selectivity to be 8.3,5.3,62.3 and 72.4,respectively.The adsorption selectivities of C2H2/C2H4 and CO2/CH4 were found to be the highest among SOFs ever reported.Beside,compared to IPM-SIFSIX-1 a,IPM-SIFSIX-2a has lower initial value of isosteric adsorption heats of C2H2(15.3 kJ/mol),which means IPM-SIFSIX-2a needs less energy for regeneration when it was used for practical gas separations. |
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