Preparation of highly sulfonated hyper-crosslinked polymers as promising ammonia adsorbents with excellent performance

The capture of ammonia (NH3) from exhaust gases is essential for improving the environmental quality and ecological health. Developing structurally stable adsorbents with excellent performance remains a challenge. In this work, we synthesized three novel sulfonated hyper-crosslinked polymers (sHCPs) with distinct structural characteristics and evaluated their NH3 adsorption performance. Notably, the preferred sHCP-1 demonstrated remarkable stability and an impressive NH3 uptake capacity of 11.54 mmol/g at 30 degrees C and 1.0 bar. Moreover, it can maintain an NH3 adsorption capacity exceeding 10.0 mmol/g after ten regeneration cycles. The adsorption of NH3 on the sHCP-1 conformed to the pseudo second kinetic and Weber-Morris diffusion models. Comprehensive thermodynamic and spectroscopic analyses of NH3 on sHCP-1 were performed to elucidate the adsorption behavior. The adsorption mechanism clarified that the well-developed micro/mesoporous structure provided abundant adsorption sites, where the chemisorption between acidic -SO3H groups and basic NH3 facilitated the formation of NH4+ from NH3. Present work systematically investigated the NH3 adsorption process of sHCPs, offering valuable insights for the development of efficient and reversible NH3 adsorbents.