Deep Removal of COS and Hg⁰ by Carbon Aerogel in Natural Gas: Good Antipoisoning Properties as well as Synergy Effect at Low Temperatures on 0.9PPD-Cu/CA Adsorbent

A collaborative COS conversion of Hg⁰ in natural gas on the nitrogen-doped and copper oxide-supported carbon aerogel (0.9PPD-Cu/CA), which is synthesized by the <i>p</i>-phenylenediamine sources and carbon source of sodium alginate, was proposed to overcome the easy deactivation of the catalyst, high reaction temperature, and limited lifespan. At 40 °C, the 0.9PPD-Cu/CA presented a 100% COS conversion efficiency in the presence of H₂O; meanwhile, the N doping realized the enhancement of basic density, leading to an improved COS conversion, and the intermediates H₂S in the reaction were wholly adsorbed, implying that 0.9PPD-Cu/CA was a bifunctional carbon material. Furthermore, the Hg⁰ addition achieved a synergistic performance as well as higher COS yield and a significant lifetime period, in which the sulfur immediate could have a high reactive activity for Hg⁰ and the sulfate proportion would be alleviated as well. Subsequently, the catalyst poisoning would be alleviated after the protection of the collaborative process by strengthening the electron transfer, consuming the sulfur-based products, and accelerating the cleavage of the H-S bond. Finally, the synergetic mechanism on COS and Hg⁰ on 0.9PPD-Cu/CA was concluded according to the experimental results and sample analysis. Additionally, the effects of space velocity and the regeneration performance were explored.