Selected ionic liquids by COSMO-RS method for tar removal

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 R1 position, and [C8MIM][NTf2] 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, [BF4]- anion performance is better. © 2022, Editorial Board of CIESC Journal. All right reserved.