Copper(I)-Catalyzed Synthesis of Nanoporous Azo-Linked Polymers: Impact of Textural Properties on Gas Storage and Selective Carbon Dioxide Capture

A new facile method for synthesis of porous azo-linked polymers (ALPs) is reported. The synthesis of ALPs was accomplished by homocoupling of aniline-like building units in the presence of copper­(I) bromide and pyridine. The resulting ALPs exhibit high surface areas (SA_BET = 862–1235 m² g^–1), high physiochemical stability, and considerable gas storage capacity especially at high-pressure settings. Under low pressure conditions, ALPs have remarkable CO₂ uptake (up to 5.37 mmol g^–1 at 273 K and 1 bar), as well as moderate CO₂/N₂ (29–43) and CO₂/CH₄ (6–8) selectivity. Low pressure gas uptake experiments were used to calculate the binding affinities of small gas molecules and revealed that ALPs have high heats of adsorption for hydrogen (7.5–8 kJ mol^–1), methane (18–21 kJ mol^–1), and carbon dioxide (28–30 kJ mol^–1). Under high pressure conditions, the best performing polymer, ALP-1, stores significant amounts of H₂ (24 g L^–1, 77 K/70 bar), CH₄ (67 g L^–1, 298 K/70 bar), and CO₂ (304 g L^–1, 298 K/40 bar)