Adsorption of CO₂ on a micro-/mesoporous polyimine modified with tris(2-aminoethyl)amine

Abstract

5Amine-modified sorbents are relevant to the capturing of dilute carbon dioxide from gas mixtures, and micro-/mesoporous polymers are promising substrates due to their rich chemistry. Here, we prepared an aldehyde-rich polyimine with micro-and mesopores with a Schiff-base condensation of 1,3,5-tris(4aminophenyl)benzene and 1,3,5-benzenetricarboxaldehyde using an excess of aldehydes. The micropores were crucial to the physisorption of CO 2 , while the mesopores provided space for the post-modification 10 with tris(2-aminoethyl)amine (tren) that induced the chemisorption of CO 2 . The amine modified polymer showed a high uptake of CO 2 at low pressures (1.13 mmol/g at 0.05 bar and 273 K) and a high estimated CO 2 -over-N 2 selectivity (1.04×10 3 at 273 K for 5v%/95v% CO 2 /N 2 mixture). CO 2 both physisorbed and chemisorbed on the amine-modified polyimine, which we confirmed by studying the CO 2 -amine chemistry using in situ FTIR spectroscopy and solid state 13 C NMR spectroscopy. Carbamic acid formed 15 during the chemisorption of CO 2 , as the CO 2 reacted with the amine groups. Due to the formation of carbamic acid, the isosetric heat of adsorption was high, with values up to 80 kJ/mol at a low coverage of CO 2 . It appears that amine-modified porous polymers could be relevant to the removal of CO 2 from gas streams with low concentrations.

Imine-Linked Polymer Based Nitrogen-Doped Porous Activated Carbon for Efficient and Selective CO2 Capture

“…Noteworthy, for the NACs, the uptake of CO 2 at a pressure of 0.2 bar is relatively high (2.7, 2.5 and 2.0 mmol g −1 at 273 K for NAC-800, NAC-700 and NAC-600 respectively). NAC-800 surpasses most porous carbons and is comparable with some high performing sorbents under the same or similar conditions (0.2 bar), such as NMC-800 (2.5 mmol g −1 )29, PP1-2 (1.5 mmol g −1 )26, AC (1.5 mmol g −1 )30 and CS3-A6 (2.6 mmol g −1 )31. It competes with the porous carbon materials and was comparable with some top performing CO 2 adsorption such as NMC-800 (2.5 mmol g −1 )29, NPC-650 (2.4 mmol g −1 )18, MR-1-500 (2.2 mmol g −1 )30.…”

“…synthesized hierarchical macroporous N-doped carbons (MCN) with ordered three-dimensional periodic structures25. However, CO 2 is expected to interact robustly with high polar imines functionalities in the polymer26. Gas adsorption and desorption of porous materials depend not only on the high specific surface area, micropore volume or pore size but also on the chemical composition and structural features of the materials27.…”

Tuning the adsorption and fluorescence properties of aminal‐linked porous organic polymers through N‐heterocyclic group decoration

“…[15][16][17][18] It has been revealed that the properties of polymer depend mainly on the polymer architecture as well as the intrinsic properties of synthons. For example, the polymers comprising of larger conjugated system is of benefit to the adsorption of H 2 19,20 as well as the fluorescent detection of Nitro-benzene derivatives, while the polymers with large N content usually exhibits promoted adsorption affinity toward CO 2 .…”

Ultramicroporous CO2 adsorbents with tunable mesopores based on polyimines synthesized under off-stoichiometric conditions

“…By aldehyde excess, we have recently shown that the aldehyde end groups of the PPs could further be modified by tetramines and form amine-rich chemisorbents for CO 2 [16]. Other effects deviating from a stoichiometric balance were shown by Schmidt et al The monomer-ratio used affected the polymer networks, surface areas and porosities of the polymers [41].…”

“…For such applications, micropores as well as mesopores are advantageous. We recently studied micro-mesoporous polyimines as substrates for cooperative organopalladium catalysis [15] and as substrates for tethering tetramines when developing CO 2 chemisorbents [16]. In this study, we detail how the micro-and mesoporosity can be controlled in such polyimines and how that effects the physisorption of CO 2 .…”