Different functional groups modified porous organic polymers used for low concentration CO2 fixation

One-step synthesis of nitrogen-rich organic polymers for efficient catalysis of CO2 cycloaddition

Nitrogen-rich organic polymer poly(chloride triazole) (PCTs) was synthesized by a one-step method as metal-halogen-free heterogeneous catalyst for the solvent-free CO2 cycloaddition. PCTs had abundant nitrogen sites and hydrogen bond donors, exhibited great activity for the cycloaddition of CO2 and epichlorohydrin, and achieved 99.6% yield of chloropropene carbonate under the conditions of 110 ℃, 6 h, and 0.5 MPa CO2. The activation of epoxides and CO2 by hydrogen bond donor and nitrogen sites was further explained by density functional theory (DFT) calculations. In summary, this study showed that nitrogen-rich organic polymer is a versatile platform for CO2 cycloaddition, and this paper provides a reference for the design of CO2 cycloaddition catalysts.

High-Surface-Area Metalloporphyrin-Based Porous Ionic Polymers by the Direct Condensation Strategy for Enhanced CO2 Capture and Catalytic Conversion into Cyclic Carbonates

Metalloporphyrin-based porous organic polymers (POPs) that behave as advanced biomimetic nanoreactors have drawn continuous attention for heterogeneous CO₂ catalysis in the past decades. Inspired by the double activation model of epoxides, the design and synthesis of metalloporphyrin-based porous ionic polymers (PIPs) are considered as one of the most promising approaches for converting CO₂ to cyclic carbonates under cocatalyst- and solvent-free conditions. To overcome the obstacle of poor reaction activity of ionic monomers or highly irregular stacking architecture, in this paper, we have proposed and demonstrated a modular bottom-up approach for constructing a series of high-surface-area metalloporphyrin-based PIPs in high yields by the direct condensation strategy, thus boosting the close contact of multiple active sites and achieving the enhanced CO₂ capture and catalytic conversion into cyclic carbonates with high turnover frequencies under mild conditions. These recyclable aluminum-porphyrin-based PIPs are featured with high surface areas, prominent CO₂ adsorptive capacities, rigid porphyrin skeletons, and flexible ionic pendants, as well as the matched amounts and spatial positions of metal centers and ionic sites, in which is demonstrated to be one of the quite competitive catalysts. Therefore, this strategy of introducing ionic components into the porphyrin frameworks as flexible side chains rather than main chains and adjusting the reactivity ratios of comonomers by structure-oriented methods, provides feasible guidance for the multifunctionalization of metalloporphyrin-based POPs, thereby increasing the accessibility of multiple active sites and improving their synergistic catalytic behavior.

Adjustable Functionalization of Hyper-Cross-Linked Polymers of Intrinsic Microporosity for Enhanced CO2 Adsorption and Selectivity over N2 and CH4

In this paper, we report the design, synthesis, and characterization of a series of hyper-cross-linked polymers of intrinsic microporosity (PIMs), with high CO₂ uptake and good CO₂/N₂ and CO₂/CH₄ selectivity, which makes them competitive for carbon capture and biogas upgrading. The starting hydrocarbon polymers' backbones were functionalized with groups such as -NO₂, -NH₂, and -HSO₃, with the aim of tuning their adsorption selectivity toward CO₂ over nitrogen and methane. This led to a significant improvement in the performance in the potential separation of these gases. All polymers were characterized via Fourier transform infrared (FTIR) spectroscopy and ¹³C solid-state NMR to confirm their molecular structures and isothermal gas adsorption to assess their porosity, pore size distribution, and selectivity. The insertion of the functional groups resulted in an overall decrease in the porosity of the starting polymers, which was compensated with an improvement in the final CO₂ uptake and selectivity over the chosen gases. The best uptakes were achieved with the sulfonated polymers, which reached up to 298 mg g^-1 (6.77 mmol g^-1), whereas the best CO₂/N₂ selectivities were recorded by the aminated polymers, which reached 26.5. Regarding CH₄, the most interesting selectivities over CO₂ were also obtained with the aminated PIMs, with values up to 8.6. The reason for the improvements was ascribed to a synergetic contribution of porosity, choice of the functional group, and optimal isosteric heat of adsorption of the materials.

Novel porous organic polymers functionalized by metalloporphyrin and phosphonium salts for the efficient synergistic catalysis of CO2 conversion under mild conditions

Metalloporphyrin- and phosphonium-functionalized porous organic polymers (POPs) were fabricated successfully via a post-synthesis modification strategy, which were demonstrated to be efficient heterogeneous catalysts for CO2 conversion.