Effects of Sulfur Doping and Humidity on CO2 Capture by Graphite Split Pore: A Theoretical Study
2017
Li, Xiaofang | Xue, Qingzhong | Chang, Xiao | Zhu, Lei | Ling, Cuicui | Zheng, Haixia
By use of grand canonical Monte Carlo calculations, we study the effects of sulfur doping and humidity on the performance of graphite split pore as an adsorbent for CO₂ capture. It is demonstrated that S doping can greatly enhance pure CO₂ uptake by graphite split pore. For example, S-graphite split pore with 33.12% sulfur shows a 39.85% rise in pure CO₂ uptake (51.001 mmol/mol) compared with pristine graphite split pore at 300 K and 1 bar. More importantly, it is found that S-graphite split pore can still maintain much higher CO₂ uptake than that by pristine graphite split pore in the presence of water. Especially, uptake by 33.12% sulfur-doped S-graphite split pore is 51.963 mmol of CO₂/mol in the presence of water, which is 44.34% higher than that by pristine graphite split pore at 300 K and 1 bar. In addition, CO₂/N₂ selectivity of S-graphite split pore increases with increasing S content, resulting from stronger interactions between CO₂ and S-graphite split pore. Moreover, by use of density functional theory calculations, we demonstrate that S doping can enhance adsorption energy between CO₂ molecules and S-graphene surface at different humidities and furthermore enhance CO₂ uptake by S-graphite split pore. Our results indicate that S-graphite split pore is a promising adsorbent material for humid CO₂ capture.
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