Experimental and numerical study of CO₂ adsorption on Ni/DOBDC metal-organic framework

Metal-organic frameworks show promising applications for carbon capture and storage. In this research, CO₂ adsorption on a Ni/DOBDC metal-organic framework was experimentally studied at a pressure range of 0 kPa-100 kPa and a temperature range of 25°C-115°C. The adsorption of CO₂ and selectivity for CO₂/CH₄ were also numerically examined through the grand canonical Monte Carlo method. The adsorbed amount increased significantly at the initial stage and then rose in a steady manner with increased pressure. In contrast, the isosteric heat of adsorption gradually decreased. As the temperature increased, the adsorbed amount decreased linearly, but the isosteric heat of adsorption remained nearly unchanged. The sites and density profiles of the adsorbate provided insight into the formed Ni²⁺⋯O=C=O at the molecular level. The selectivity for CO₂/CH₄ was sensitive to pressure and temperature. The electronic contribution could reach 62.0%-68.3% in the 0 kPa-100 kPa pressure range and 40.7%-68.3% in the 25°C-115°C temperature range.