A novel method for production of nitrogen fertilizer with low energy consumption by efficiently adsorbing and separating waste ammonia

Recovering waste NH₃ to be used as a source of nitrogen fertilizer or liquid fuel has recently attracted much attention. Current methods mainly utilize activated carbon or metal-organic frameworks to capture NH₃, but are limited due to low NH₃ adsorption capacity and high cost, respectively. In this study, novel porous materials that are low cost and easy to synthesize were prepared as NH₃ adsorbents by precipitation polymerization with acid optimization. The results showed that adsorption sites (‒COOH, –OH, and lactone) which form chemical adsorption or hydrogen bonds with NH₃ were successfully regulated by response surface methods. Correspondingly, the dynamic NH₃ adsorption capacity increased from 5.45 mg g⁻¹ to 129 mg g⁻¹, which is higher than most known activated carbon and metal-organic frameworks. Separation performance tests showed that NH₃ could also be separated from CO₂ and CH₄. The findings in this study will advance the industrialization of NH₃ polymer adsorbents and provide technical support for the recycling of waste NH₃.