Systematic Postsynthetic Modification of Nanoporous Organic Frameworks for Enhanced CO₂ Capture from Flue Gas and Landfill Gas

Abstract

Controlled postsynthetic nitration of NPOF-1, a nanoporous organic framework constructed by nickel(0)-catalyzed Yamamoto coupling of 1,3,5-tris­(4-bromophenyl)­benzene, has been performed and is proven to be a promising route to introduce nitro groups and to convert mesopores to micropores without compromising surface area. Reduction of the nitro groups yields aniline-like amine-functionalized NPOF-1-NH2 that has a micropore volume of 0.48 cm3 g–1, which corresponds to 71% of the total pore volume and a Brunauer–​Emmett–​Teller surface area of 1535 m2 g–1. Adequate basicity of the amine functionalities leads to modest isosteric heats of adsorption for CO2, which allow for high regenerability. The unique combination of high surface area, microporous structure, and amine-functionalized pore walls enables NPOF-1-NH2 to have remarkable CO2 working capacity values for removal from landfill gas and flue gas. The performance of NPOF-1-NH2 in CO2 removal ranks among the best by porous organic materials.

Phosphonates Meet Metal−Organic Frameworks: Towards CO2 Adsorption

“…On the other hand, at 298 K CO 2 , CH 4 and N 2 uptakes have been determined to be 0.86, 0.20 and 0.05 mmol/g, respectively (Figure a). A high CO 2 uptake in combination to low N 2 and CH 4 uptake prompted us to calculate the selectivity towards CO 2 using the ideal adsorbed solution theory (IAST) which is an effective tool in studying gas adsorption selectivity in various classes of porous materials ,. At the CO 2 partial pressure of 0.05 bar, which represents a typical flue gas composition, we extrapolated a selectivity of 60 for CO 2 over N 2 (Figure b), and we observe a decrease in selectivity as the CO 2 partial pressure increases, likely a consequence of saturation at lower pressure of the most selective sites.…”

Robust C–C bonded porous networks with chemically designed functionalities for improved CO2 capture from flue gas

“…Furthermore, the chemical reactions involved in the formation of these structures do not allow obtaining free nitrile or amine functionalities. The most used strategy to install available functional groups on porous materials is through post-modification, which often requires several steps and harsh conditions, and yields low porosity [12–13]. …”

“…The chemisorptive behavior and stronger binding affinity is reflected in the higher Q st value of 49.9 kJ mol −1 . The moderate binding energy is optimal for CO 2 capture, as too strong binding requires high regeneration energy and raises the overall cost of the carbon capture operations [12,25]. …”

Holey Graphitic Carbon Derived from Covalent Organic Polymers Impregnated with Nonprecious Metals for CO2 Capture from Natural Gas

“…In addition to selectivity, we further assess the applicability of these three COP graphene in CO 2 separation processes using other four adsorbent evaluation criteria, i.e., CO 2 uptake under adsorption conditions, working CO 2 capacity, regenerability, and sorbent selection parameter. For comparison, representative MOFs, COPs, zeolites, and microporous carbons are also enclosed and evaluated through a vaccum swing adsorption (VSA) process, adsorption pressure to 1 bar and desorption pressure to 0.1 bar. As shown in Table 2 , MOFs, COPs, zeolites, and microporous carbons show higher N ads 1 and Δ N 1 values due to larger surface area and volume than those of COP graphene.…”