CO₂ Mixture Adsorption at Single-Walled Carbon Nanotube: Effects from Different Gases and Stoichiometric Ratios

摘要

Using adsorption locator for the most stable adsorption site searches, the authors investigated adsorption of mixture of gases with different carbon dioxide mole ratio at a single-walled carbon nanotube (SWCNT). A total of six mixtures were investigated, two mixtures consist of hydrogen,nitrogen and carbon dioxide with compositions 3:1:1 and 3:1:2. Whereas the remaining four mixtures consist of ammonia and carbon dioxide with compositions 5:1, 4:1, 3:1 and 3:2. Results demonstrated that gas interactions with carbon nanotubes increased as the mole ratio of carbon dioxide increasedin H_(2), N_(2) and CO_(2) mixture, conversely decreased for NH_(3) and CO_(2) mixture. After increasing CO_(2) mole fraction from 1/5 to 1/3 for hydrogen, nitrogen and carbon dioxide mixture, adsorption energy and rate on carbon nanotube atomsincreased by 45 and 33%, respectively, due to a 59% increase in Van der Waal interactions. The preferred molar ratio of H_(2), N_(2) and CO_(2) mixture for adsorption is 3:1:2. The maximum adsorption energy and rate for NH_(3) and CO_(2) mixture is obtainedusing the 5:1 sample. Adsorption energy for the NH_(3) and CO_(2) mixtures increased by 18% when the ratio changed from 3:1 to 3:2 while the adsorption rate decreased considerably.