Synthesis and optimization of 3D porous polymers for efficient CO2 capture and H2 storage

Abstract

In this study, a new porous organic polymer (KFUPM-CO₂) with intrinsic nitrogen atoms as active sites for CO₂ capture was optimized and synthesized via Friedel-Crafts alkylation of triptycene and 2,2-bipyridine. The porous polymer shows a high surface area of 1100 m²/g with a tuned microporosity of less than 1.2 nm, confirmed by NLDFT. KFUPM-CO₂ showed a remarkable CO₂ sorption capacity of 5.6 mmol/g at 273 K, 3.2 mmol/g at 298 K, and a pressure of 760 mmHg KFUPM-CO₂ showed a high enthalpy of adsorption of 43.7 kJ/mol for CO₂ with IAST selectivity of CO₂/N₂ of 127 at 273 K and 97 at 298 K on simulated flue gas composition. Additionally, KFUPM-CO₂ exhibited an H₂ storage capacity of 1.5 wt. % at 77 K and 860 mmHg Grand Canonical Monte Carlo (GCMC) simulations further revealed that KFUPM-CO₂ was mainly stabilized by π-π intra-molecular interactions, and exhibited strong van der Waals attractions to CO₂ molecules via the pyridyl nitrogen atoms, resulting in the rapid uptake. The combined advantages of binding 2,2-bipyridine with triptycene provided a robust porous polymer with abundant nitrogen sites, permanent porosity, and thermal stability, rendering KFUPM-CO₂ an excellent candidate for CO₂ capture and H₂ storage technologies.