Synthesis of covalent triazine-based frameworks with high CO₂ adsorption and selectivity

Abstract

Four covalent triazine-based frameworks (PCTF-1 to PCTF-4) with triphenylamine as core were synthesized by a consolidated ionothermal reaction between aromatic nitriles under the catalysis of ZnCl2. The Brunauer-Emmett-Teller (BET) specific surface area values of PCTF-1 (853 m 2 g -1 ), PCTF-2 (811 m 2 g -1 ) and PCTF-3 (391 m 2 g -1 ) are against with the increasing length of branched arm, indicating using monomers with longer branches are able to pack more efficiently, resulting in higher density materials with a lower surface area. PCTF-4, compared with PCTF-2, just changed the middle benzene of the branches 10 to benzothiadiazole, however, N2 adsorption isotherms showed its BET specific surface area value (1404 m 2 g -1 ) is the highest among the PCTFs, almost two times than that of PCTF-2. The nitrogen-rich characteristics of C3N3 triazine rings feature the frameworks strong affinity for CO2 and thereby high CO2 adsorption capacity. Especially for PCTF-4 with the benzothiadiazole, it exhibited the highest CO2 uptake (20.5 wt%) at 273 K and 1 bar, this value is one of the highest reported for covalent triazinebased frameworks. The results demonstrate that the introduction of strong polar groups (benzothiadiazole) into a polymer 15 skeleton is an efficient strategy to produce CO2-philic microporous organic polymers with enhanced binding affinity with CO2 molecules. In addition, such PCTFs with high physical-chemical stability and comparable BET surface areas exhibited good ideal CO2/N2 selectivities (14-56) and CO2/CH4 selectivities (11-20) at 273 K, showing these materials are potential candidates for gas storage and separation. However, in the presence of water vapor, the CO2 uptake of all polymers decreased probably due to the formation hydrogen bonding with water, suggesting materials that perform well in dry conditions may deteriorate under 20 practical conditions. a Calculated BET surface area over the pressure range 0.01-0.1 P/P0. b Micropore volume calculated from the N2 adsorption isotherm at P/P0 =0.1 bar. c Total pore volume at P/P0 =0.99 bar. d Dominant pore size calculated by nonlocal density functional theory (NL-DFT).

Carbonization of covalent triazine-based frameworks via ionic liquid induction

“…Porous organic polymers (POPs), an inorganic node free version of porous materials (including crystalline covalent organic frameworks (COFs), 6 and amorphous porous aromatic frameworks (PAFs), 7 polymers of intrinsic microporosity (PIMs), 8 porous polymer networks (PPNs), 9 covalent triazinebased frameworks (CTFs) [10][11][12][13][14][15][16][17][18][19] ) are attracting more and more attention because of their great potential for practical applications, for example, gas storage, separation, catalysis, and electronic device. 20 Among these materials, CTFs can be obtained by using a cheap catalyst such as ZnCl 2 and possess high chemical and thermal stability.…”

Thiophene-based conjugated microporous polymers: preparation, porosity, exceptional carbon dioxide absorption and selectivity

“…We can find that all the samples showed significant uptake even though their surface areas were moderate. 24 The "humidified" samples were then measured again at 1.0 bar and different temperatures (298 K and 273 K) (ESI, Fig. 23 When the temperature was elevated to 273 K, polymer SCMP-COOH@1 shows the highest CO 2 capture capacity of 94 mg g −1 .…”

Rapid Polymerization of Aromatic Vinyl Monomers to Porous Organic Polymers via Acid Catalysis at Mild Condition

“…However, the PTVP‐1 exhibit higher H 2 uptake than the PTVPP due to the higher BET surface area (Figure b). These performances can also be comparable to other materials, such as PCTFs, Azo‐COPs, MOPs, or MOFs and etc. The summary and more detailed comparison of the gas adsorption results are shown in Figure S6 and Table S3, Supporting Information.…”