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

Abstract

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 m 2 g –1 ), high physiochemical stability, and considerable gas storage capacity especially at high-pressure settings. Under low pressure conditions, ALPs have remarkable CO 2 uptake (up to 5.37 mmol g –1 at 273 K and 1 bar), as well as moderate CO 2 /N 2 (29–43) and CO 2 /CH 4 (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 H 2 (24 g L –1, 77 K/70 bar), CH 4 (67 g L –1, 298 K/70 bar), and CO 2 (304 g L –1, 298 K/40 bar).