Triptycene based microporous hypercrosslinked polymer with amino functionality for selective CO2 capture

Abstract

The increasing CO₂ concentration in the atmosphere contributes significantly to global warming, necessitating effective capture techniques. Though amine-based solvents are commonly used, they have drawbacks like high energy consumption and corrosion. Physical adsorption using microporous sorbents with polar groups emerges as a promising alternative, offering high efficiency and selectivity for CO₂ capture. This work presents the design of a new microporous hypercrosslinked polymer with amino groups derived from the 3D molecular building block triptycene (TBMP-NH₂), for CO₂ capture applications. The triptycene unit in the polymer backbone provides high surface area, thermal stability, and microporosity. TBMP-NH₂ demonstrates excellent thermal stability (T_d > 350°C), considerable microporosity, and a high BET-specific surface area of 866 m²/g, making it a promising microporous adsorbent. It exhibits a high CO₂ adsorption capacity of 1.86 mmol/g at 273 K and 1.23 mmol/g at 298 K, with a Q_st value of 33.95 kJ/mol, indicating a physisorption mechanism where the micropore volume (V_mic = 0.359 cm³/g) plays a crucial role. TBMP-NH₂ displays good CO₂/N₂ and CO₂/CH₄ selectivity, outperforming several reported porous polymers. Owing to its high physiochemical and thermal properties, and efficient and selective CO₂ capture ability, TBMP-NH₂ can be considered a promising material for CO₂ capture and environmental remediation application.