Toluene absorption from laboratory to industrial scale: An experimental and theoretical study

[Display omitted] •Evaluation of absorption capacities for toluene on a laboratory and industrial scale.•New heat and matter exchanger successfully applied for gas purification.•Possibility to scale up the process with similar absorption capacities as the laboratory process.•The absorption mechanism was revealed at molecular level.•Water/benzyl alcohol mixture showed interesting absorption capacities, close to silicone oil. Toluene is a typical example of aromatic volatile organic compounds (VOCs), and its elimination makes a significant contribution to reducing air pollution. The treatment of gaseous effluents can be achieved by solvent absorption. This work aims to evaluate, for the first time, the removal of toluene from laboratory scale to industrial scale using a new heat and mass exchanger and to elucidate the absorption mechanism at molecular level. The vapor–liquid partition coefficient (K) and the absorption capacity were determined for three industrially available solvents, benzyl alcohol, acetic acid and propylene glycol, and their water mixtures. In addition, several absorption/desorption cycles were also used to regenerate the absorbent on a laboratory scale. An up to 488-fold lower K value was obtained for benzyl alcohol. The effect of water addition to the studied solvents on the partition coefficient confirmed a decreasing VOC absorption with increasing amount of water. However, the overall results show that the water/benzyl alcohol mixture (60:40 wt%) has interesting absorption capacities, close to some organic solvents, and therefore a high potential for the treatment of industrial air polluted with toluene. This phenomenon was further explained by COSMO-RS calculation and molecular dynamics. It was found that magnitude of interaction energy for absorbent-toluene (−63.3 kJ/mol) with 60 wt% water is slightly smaller than that of pure benzyl alcohol (−71.76 kJ/mol). Moreover, benzyl alcohol has the most negative Gibbs free energy of solvation value for toluene compared to other absorbents under study. The reason for the enhanced toluene absorption is the significant π–π interaction between benzyl alcohol and toluene. The results obtained at different scales were in good agreement with each other.