Microporous Hyper-Cross-Linked Aromatic Polymers Designed for Methane and Carbon Dioxide Adsorption

Abstract

A Friedel−Crafts reaction was used to obtain covalent aromatic networks with high surface area and microporosity suited for CO2 and CH4 adsorption, even at low pressures. Starting from tetraphenylmethane and formaldehyde dimethyl acetal in different concentrations, the reaction yields porous polymers which were characterized with a wealth of experimental and computational methods. Thermogravimetry, infrared spectroscopy, and solid-state NMR were used to study the material structure. The pore distributions were measured by applying nonlocal density functional theory analysis to the adsorption isotherms of N2 at 77 K and Ar at 87 K (the latter being more suited for pore widths less than 10 Å). Carbon dioxide and methane were adsorbed at 273 and 298 K to evaluate the performance of these systems in gas capture, separation, and storage. A theoretical model of the porous network was defined to describe the ordered fraction of the material, with particular attention to ultramicropores. Ar, CO2, and CH4 adsorption in this model material was simulated by Monte Carlo techniques with a purposely optimized force field

Triptycene based 1,2,3-triazole linked network polymers (TNPs): small gas storage and selective CO2 capture

“…The SA BET obtained for TNP1, TNP2, TNP3 and TNP4 are 1090 m 2 g -1 , 460 m 2 g -1 , 745 m 2 g -1 and 1348 m 2 g -1 respectively. Irrespective of the nature of ethnyl monomer used in conjugation with 2,6,14-triazidotriptycene, the resulting TNPs are significantly porous and their corresponding surface areas (SA BET ) are comparable or better than a wide variety of microporous polymers reported in literature such as mPAF (948-1314 m 2 g -1 ), 27 Benzimidazole-Linked Polymers (BILPs, 599-1306 m 2 g -1 ), 25,65,66 imine-linked PPFs ( 419-1740 m 2 g -1 ), 24 Nitrogen-Doped Microporous Carbons (263-744 m 2 g -1 ), 29 Imine-Linked POFs (466-1521 m 2 g -1 ), 31 nanoporous azo-linked polymers (ALPs, 862-1235 m 2 g -1 ), 32 "click-based'' POPs (1090-1440 m 2 g -1 ) 33 and triptycene-based microporous polymers such as benzimidazole network (600 m 2 g -1 ), 56 porous polymer derived from Tröger's Base (TB-MOP, 694 m 2 g -1 ), 58 and microporous polyimides (STPIs, 4-541 m 2 g -1 ). Polymers TNP1 and TNP4 synthesized from triethynyl comonomer exhibit higher surface area relative to the other two polymers (TNP2 and TNP3) where diethynyl comonomer has been utilized for polymerization.…”

An atomistic model of a disordered nanoporous solid: Interplay between Monte Carlo simulations and gas adsorption experiments

“…6 and characterized by adsorbing N 2 at 77 K and CO 2 at 273 K; the density of the sample, measured as described above, is 0.53 g/cm 3 ; the adsorption isotherms and the corresponding PSD and CPV are illustrated in Figure 1. The CO 2 adsorption is particularly useful for very narrow pores (then the experiment is limited to lower pressures): it clearly indicates the presence of ultramicropores around 5.1 Å, which are confirmed also by N 2 adsorption, though for this gas such small pores are close to the detection limit.…”

“…64 Notably, the heats of adsorption in mPAF-IV model for both gases compare well with Q st measured for a similar material in ref. 6 (where it is referred to as mPAF-1/16): the experimental values were in the ranges 24-26 kJ/mol for CO 2 and 18-19 kJ/mol for CH 4 .…”

“…[1][2][3][4][5] In this paper we apply different computational techniques, along with experimental measures, to obtain a reliable atomistic structure for a recently synthesized hypercrosslinked polymer, with a peculiar porous structure and very interesting adsorption capacities for methane and carbon dioxide. 6 Nanoporous materials are of great interest for applications in gas storage, 7-9 molecular separation, [10][11][12] heterogeneous catalysis, [13][14][15] and the properties of such materials are critically affected by their porous structure, whose main parameters are the specific surface area, the micro-and mesoporous volumes and the pore size distribution. Remind that, according to the IUPAC rules, nanopores are classified as ultramicropores (with pore diameter below 0.7 nm), micropores (pore diameter between 0.7 and 2 nm) 65 and mesopores (between 2 and 50 nm).…”

“…In particular, the PAF material formed with biphenyl chains (called PAF-1 or PAF-302 in the literature, and synthesized from tetrabromophenylmethane through Yamamoto homo-coupling reaction) has also been exploited for gas adsorption, with excellent uptakes of methane [31][32][33] and CO 2 . [34][35][36] The hypercrosslinked aromatic polymer studied in this paper is obtained by Friedel-Crafts condensation of tetraphenylethene (TPM) and formaldehyde dimethyl acetal (FDA), 6,37 and is referred to as mPAF (i.e. microPorous Aromatic Framework, in analogy to the PAF family mentioned above).…”