Synthesis Of Anion-Functionalized Materials For The Separation Of Phenols And Hydrocarbons

Separation of structurally similar compounds such as olefins,alkynes,dienes,and natural active compounds is a great challenge in the chemical industry due to their similar structure and properties.The purity of olefins,alkynes and natural active compounds is the key to the market share.Therefore,it is necessary to explore efficient and environmentally friendly separation materials and technologies for the purity of structural similar compounds,which can solve the problems of high energy consumption,high cost and secondary pollution brought by traditional separation methods.Ionic liquids(ILs)are room temperature molten salts composed of anion and cation,which have great application prospects in separation because of the advantages of structural adjustment and strong molecular recognition ability.In this dissertation,carboxylate ILs,which are capable of efficiently identifying molecules,were designed for the absorption and separation of C4 olefins.Friedel-Crafts alkylation reaction was used to introduce the carboxylate ILs into the hypercrosslinked polymers.Microstructure of these materials was explored and the separation performance of ethylene/acetylene(C2H4/C2H2)and natural active compounds was investigatedCarboxylate ILs with large free volume and strong hydrogen bond basicities were designed by reasonably adjusting the structure of anion and cation.The absorbtion and separation performance of these ILs for C4 gases such as 1,3-butadiene(1,3-C4H6)and n-butene(n-C4H8)was investigated.The relationship between free volume of unit mass(FVUM)/hydrogen bond basicities(? values)and mass solubility were established.And the potential reasons of excellent separation performance in these ILs were explored by quantitative calculation.The results showed that the tributylethylphosphonium-based carboxylate ILs had large FVUM(0.2026-0.2327 cm3/g),strong hydrogen bond basicities(1.265-1.506),lower viscosity(<315.6 mPa s,298.1 K),excellent thermal stability(Tonset>540.0 K)and wide liquidus range.At 308.1 K and 100 kPa,the solubility of 1,3-C4H6 in tributylethylphosphonium formate([P4442][HCOO])was 0.663 mmol/g while the selectivity of 1,3-C4H6/n-C4H8 wasl.83,which made[P4442][HCOO]an excellent material for gases separation.The relationship between FVUM/? values and the mass solubility indicated that large FVUM and high ? values could improve the solubility of 1,3-C4H6 in ILs.Quantitative calculations demonstrated that two hydrogen bonding sites could be formed between[HCOO]-and 1,3-C4H6 while only one was formed with n-C4H8,which resulted in lower interaction energy of the former(-43.25 kJ/mol),thus explaining the reason why[P4442][HCOO]could dissolve more 1,3-C4H6 than n-C4H8.The IL-based hypercrosslinked polymers(HCPs)were prepared using aromatic hydrocarbon containing halogens as crosslinkers.The effect of species and contents of ILs on pore structure of the materials and separation performance of C2H4/C2H2 was investigated.The results showed that the specific surface area of carboxylate IL-based HCPs was 323-516 m2/g and the total pore volume was 0.281-0.340 cm3/g,and they both decreased with the increasement of IL content in the polymers.These IL-based HCPs exhibited a high gas adsorption capacity of C2H2 and the selectivity of C2H2/C2H4 is significantly improved compared to HP-DBX(DBX:?,?'-dibromo-p-xylene)which contained no IL.The adsorption and separation performance of tocopherol homologues and phenolic structurally similar compounds in IL-based HCPs were studied and the influence of IL content was explored.The results showed that in the separation of tocopherol homologues,HP-[BzMIm][C5H11COO]-DBX,which was prepared by hypercrosslinking 1-benzyl-3-methylimidazolium caproate([BzMIm][C5H11COO])and ?,?'-dibromo-p-xylene,had the best separation performance.The total adsorption capacity of tocopherols in HP-[BzMIm][C5HiiCOO]-DBX was 103.6 mg/g,and the selectivity of ?/?-tocopherol to?-tocopherol and ?-tocopherol to ?-tocopherol were 4.26 and 3.19,respectively,which was significantly better than the commercial adsorbents.The total adsorption capacity of phenolic structurally similar compounds in HP-[BzMIm][C5H11COO]-DBX was 264.0 mg/g and the selectivity of phenol to 2,6-dimethylphenol and p-methylphenol to 2,6-dimethylphenol were 5.62 and 4.86,respectively.The adsorption capacity and selectivity of phenolic structurally similar compounds could improve as the increasement of IL content in the materials.