title: CO₂ sorption kinetics of scaled-up polyethylenimine-functionalized mesoporous silica sorbent.
abstract: Two CO2 solid sorbents based on polyethylenimine, PEI (M(n) ∼ 423 and 10K), impregnated into mesoporous silica (MPS) foam prepared in kilogram quantities via a scale-up process were synthesized and systematically characterized by a range of analytical and surface techniques. The mesoporous silica sorbent impregnated with lower molecular weight PEI, PEI-423/MPS, showed higher capacity toward CO2 sorption than the sorbent functionalized with the higher molecular weight PEI (PEI-10K/MPS). On the other hand, PEI-10K/MPS exhibited higher thermal stability than PEI-423/MPS. The kinetics of CO2 adsorption on both PEI/MPS fitted well with a double-exponential model. According to this model CO2 adsorption can be divided into two steps: the first is fast and is attributed to CO2 adsorption on the sorbent surface; the second is slower and can be related to the diffusion of CO2 within and between the mesoporous particles. In contrast, the desorption process obeyed first-order kinetics with activation energies of 64.3 and 140.7 kJ mol(-1) for PEI-423/MPS and PEI-10K/MPS, respectively. These studies suggest that the selection of amine is critical as it affects not only sorbent capacity and stability but also the energy penalty associated with sorbent regeneration.
authors.affiliation: †Gas Processing Center, College of Engineering, Qatar University, P.O. Box 2713, Doha, Qatar.
authors.forename: M J
authors.initials: MJ
authors.lastname: Al-Marri
authors.affiliation: †Gas Processing Center, College of Engineering, Qatar University, P.O. Box 2713, Doha, Qatar.
authors.forename: M M
authors.initials: MM
authors.lastname: Khader
authors.affiliation: †Gas Processing Center, College of Engineering, Qatar University, P.O. Box 2713, Doha, Qatar.
authors.forename: M
authors.initials: M
authors.lastname: Tawfik
authors.affiliation: ‡Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, United States.
authors.forename: G
authors.initials: G
authors.lastname: Qi
authors.affiliation: ‡Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, United States.
authors.forename: E P
authors.initials: EP
authors.lastname: Giannelis