CO2 absorption and diffusion in ionic liquid [P66614][Triz] modified molecular sieves SBA-15 with various pore lengths

Abstract

Mesoporous molecular sieves SBA-15 with four pore structures were loaded with an ionic liquid [P66614][Triz] to adsorb CO2 from raw biohythane. The hybrid sorbents of SBA-15 loaded with [P66614][Triz] were characterized by using N2 adsorption analyzer, thermogravimetric analyzer, scanning electron microscopy, and high-resolution transmission electron microscopy. The molecular sieve SBA-15 (with the most probable pore size of 4.3nm) loaded with 50% ionic liquid (IL), which was called SBA-15 (4.3) −50% IL, exhibited the fastest CO2 absorption rate and the shortest equilibrium time, which was approximately one-third of the equilibrium times of the other three hybrid sorbents. An intraparticle diffusion model was used to clarify that SBA-15 (4.3) −50% IL (with the shortest pore length of 120nm) executed a two-stage CO2 absorption process, which reduced the CO2 absorption time. The rate constant kI in the first stage of the CO2 absorption of SBA-15 (4.3) −50% IL was approximately four times as much as those of the other three hybrid sorbents because the cross-section area of its total pores was approximately three times higher than those of the other three hybrid sorbents. Results showed that pore length had significant effect on CO2 absorption performance.