Sulfonated and ordered mesoporous polymers for reversible adsorption of ammonia: Elucidation of sequential pore-space diffusion

NH3 adsorption and separation are pivotal for its safety and efficient utilization, but most solid adsorbents show either low capacity or unsatisfied separation performance. Herein, we report sulfonated and ordered mesoporous polymers (SOMPs) synthesized from solvent-free manual-grinding of resorcinol and 1,4-phthalaldehyde with copolymer template, curing at 140 ∼ 220 °C, simultaneous sulfonation and template removal by treating with H2SO4. The prepared SOMPs possess ordered mesopores with abundant microporosity, large surface areas (∼697 m2/g), and extremely-high –SO3H densities (∼4.48 mmol/g). Their NH3 adsorption capacities are as high as 15.09 mmol/g (25 °C, 1.0 bar), exhibiting NH3 breakthrough time and saturated capacity up to 138 min/g and 6.16 mmol/g, respectively (5.0v%NH3/23.75v%N2/71.25v%H2). Versatile characterizations together with molecular dynamics simulations demonstrate the superior NH3 adsorption performance originates from strong affinity of –SO3H group with NH3 in sequential pore-space of SOMPs, which not only enhances the molecular recognition ability, but also effectively promotes NH3 fast diffusion inside SOMPs.