基于COSMO-RS方法筛选离子液体用于焦油脱除

Selected ionic liquids by COSMO-RS method for tar removal

焦油的脱除是生物质气化规模化应用的难题。离子液体具有饱和蒸气压低、分子结构可设计等优势,在催化和吸收领域有广泛的应用前景,但在脱除焦油方面鲜有探索。以改进的COSMO-RS方法为基础,借助COSMOtherm软件推算离子液体对苯、甲苯、苯酚和萘等焦油模拟物的无限稀释活度系数。并进一步通过偏摩尔过量焓验证以上筛选结果。结果表明,优选的两取代基咪唑类离子液体对四种焦油模拟物的无限稀释活度系数值主要分布在0.4~1之间,预计具有良好的吸收性能。当阴离子相同时,两取代基咪唑阳离子随着R_(1)位置烷基侧链的增长吸收性能变好,其中[C_(8)MIM][NTf_(2)]表现出了较佳性能,吸收苯、甲苯和萘的γ∞分别为0.95、1.24和1.36,但此时离子液体黏度较大;对于苯酚体系,[BF_(4)]-阴离子性能较佳。

The removal of tar is a problem for the large-scale application of biomass gasification.Ionic liquids have the advantages of lower saturation vapor pressure and designable molecular structure,which are widely used in catalysis and absorption,but there is little research in the tar removal.Based on the improved COSMO-RS method,the infinite dilution activity coefficients for benzene,toluene,phenol and naphthalene are calculated by COSMOtherm software.The effects of imidazole cations and strong electronegative anions on absorption properties are further investigated by partial molar excess enthalpies.The results show that the infinite dilution activity coefficients of the preferred double substituent imidazole ionic liquids for the four tar simulants are between 0.4-1,which is expected to have excellent absorbing performance.When the anions are the same,the absorbability of the double substituent imidazole cation becomes better with the increase of alkyl side chains at R_(1) position,and[C_(8)MIM][NTf_(2)]shows a better absorbing performance.The infinite dilution activity coefficients of benzene,toluene and naphthalene are 0.95,1.24 and 1.36,respectively,but the viscosity of the ionic liquid is higher.For phenol system,[BF_(4)]-anion performance is better.