Liquid, solvated amine based carbon capture is the core of all commercial or planned CO2 capture operations. Despite the intense research, few have looked systematically into the nature of amine molecules and their CO2 interaction. Here, we report a systematic introduction of linear ethylene amines on the walls of highly porous Davankov type network structures through simple bromination intermediates. Surprisingly, isosteric heats of CO2 adsorption show a clear linear trend with the increase in the length of the tethered amine pendant groups, leading to a concerted cooperative binding with additional H-bonding contributions from the unassociated secondary amines. CO2 uptake capacities multiply with the nitrogen content, up to an unprecedented four to eight times of the starting porous network under flue gas conditions. The reported procedure can be generalized to all porous media with the robust hydrocarbon framework in order to convert them into effective CO2 capture adsorbents.

Seawater contains uranium in surprisingly high quantities that can supply vast energy, if recovered economically. Attempts to design effective sorbents led to the identification of organic functional groups such as amidoximes. Here we report a porous polymer, a polymer of intrinsic microporosity (PIM) with permanent pores that feature amidoxime pendant groups, which is capable of removing more than 90% uranyl [U(VI)] from seawater collected from the Ulleung basin of the East Sea of the Republic of Korea. From this uptake, over 75% was collected in less than six hours, leading to highly feasible field applications. When the seawater was acidified by bubbling CO2 (pH = 5.4), the uptake increased dramatically. Regeneration studies showed full recovery of sorbents and no loss in capture capacity. Our results indicate that successful uranium recovery can be realized by scalable applications of porous polymeric networks and when low cost CO2 is co-administered, uptake can be significantly enhanced.

Solid sorbents for chemisorptive carbon dioxide uptake in post-combustion scenarios require strong binding groups like amines. Post-synthetic impregnation of reactive amines requires large pore volumes. Covalent organic polymers (COPs) are microporous (or narrow mesoporosity) network polymers with physisorptive behavior. Herein as the first of such attempt in porous organic polymers, we modified COP-1, which is an inexpensive, scalable porous polymer for effective amine loading. By expanding the pore of COP-1 through hard templation by silica, the surface area and pore volume are increased by 2.3 and 2.9 times, respectively. It was shown that the increase of pore volume was mostly from pores larger than 5 nm and it correlates well with the silica particle size (12 nm) and the inter-particle pore sizes of silica (31 nm). As a result, amine impregnated Si-COP-1 adsorbs CO2 with the increase of 2.44 at 273 K and 4.06 times at 298 K (at flue gas relevant partial pressure of 0.15 bar) over the parent COP-1. Our results show the possibility of tuning porosity for developing industrially feasible CO2 capturing sorbents.

Designed catalyst poisons can be deliberately added in various reactions for tuning chemoselectivity. In general, the poisons are “transient” selectivity modifiers that are readily leached out during reactions and thus should be continuously fed to maintain the selectivity. In this work, we supported Pd catalysts on a thermochemically stable cross-linked polymer containing diphenyl sulfide linkages, which can simultaneously act as a catalyst support and a “permanent” selectivity modifier. The entire surfaces of the Pd clusters were ligated (or poisoned) by sulfide groups of the polymer support. The sulfide groups capping the Pd surface behaved like a “molecular gate” that enabled exceptionally discriminative adsorption of alkynes over alkenes. H2/D2 isotope exchange revealed that the capped Pd surface alone is inactive for H2 (or D2) dissociation, but in the presence of coflowing acetylene (alkyne), it becomes active for H2 dissociation as well as acetylene hydrogenation. The results indicated that acetylene adsorbs on the Pd surface and enables cooperative adsorption of H2. In contrast, ethylene (alkene) did not facilitate H2–D2 exchange, and hydrogenation of ethylene was not observed. The results indicated that alkynes can induce decapping of the sulfide groups from the Pd surface, while alkenes with weaker adsorption strength cannot. The discriminative adsorption of alkynes over alkenes led to highly chemoselective hydrogenation of various alkynes to alkenes with minimal overhydrogenation and the conversion of side functional groups. The catalytic functions can be retained over a long reaction period due to the high thermochemical stability of the polymer.

Porous polybenzimidazole polymers have been under investigation for high and low pressure CO2 adsorption due to the well-built stability under high pressure and at various temperatures. Pressure swing and temperature swing processes like integrated gasification combined cycle require materials which can operate efficiently at high pressure and high temperature and can remove CO2. In this manuscript we report synthesis, characterization and evaluation of two polybenzimidazole materials (PBI-1 and PBI-2), which were prepared with two different solvents and different cross-linking agents by condensation techniques. Low and high pressure CO2 sorption characteristic of both the materials were evaluated at 273 and 298 K. Thermal gravimetric analysis showed high temperature stability up to 500 °C for the studied materials. PBI-1 has shown very good performance by adsorbing 3 times more (1.8025 mmolg−1 of CO2) than PBI-2 at 0 °C and at low pressures. Despite low surface area results obtained via BET techniques, at 50 bars PBI-1 adsorbed up to 6.08 mmolg−1 of CO2. Studied materials have shown flexible behavior under applied pressure that leads to so-called “gate-opening” adsorption behavior and it makes these materials promising adsorbents of CO2 at high pressures and it is discussed in the manuscript in detail.