Karbon dioksit ve metanın çeşitli aerojeller üzerine adzorpsiyonunun termodinamiği araştırma

Thermodynamics of carbon dioxide and methane adsorption on various aerogels was investigated to evaluate their potential as adsorbents for carbon dioxide capture and methane storage. Excess CO2 and CH4 adsorption isotherms on aerogels such as silica, resorcinol-formaldehyde, carbon and wheat starch were measured using a volumetric method in the temperature range of 298-328 K and pressures up to 120 bar. Total or absolute adsorption isotherms were calculated from experimentally obtained excess adsorption isotherms using the pore volume of each adsorbent. It was determined that silica aerogel had maximum absolute CO2 uptake of 14 mmol/g at 308 K and 35 bar and resorcinol-formaldehyde aerogel (RFA-17) had maximum absolute CH4 uptake of 22 mmol/g at 298 K and 100 bar. CO2 and CH4 adsorption isotherms for silica aerogel were well represented with the Langmuir model. CO2 isotherms for resorcinol-formaldehyde, carbon and wheat starch aerogel and CH4 isotherms for carbon and resorcinol-formaldehyde aerogels were fitted with the Freundlich model. It was also found that the excess CO2 uptake correlated well with the mesopore surface area of each aerogel at various pressures while micropore surface area significantly influenced CH4 uptake in aerogels. The isosteric heat of adorption for each aerogel was also determined from the variation of pressure with temperature at a constant excess uptake and was found to be dependent on the surface coverage. Among all aerogels, wheat starch aerogel had highest heats of CO2 adsorption and resorcinol-formaldehyde aerogel had highest heats of CH4 adsorption. Adsorption capacities of aerogels determined were comparable with other classes of adsorbents and presents an opportunity for further investigation of aerogels as potential materials for applications in carbon dioxide capture and methane storage.