High Pressure Adsorption of CO₂and CH₄on Zr-MOFs

Adsorption equilibrium of CO 2 and CH 4 at three different temperatures was measured on three isoreticular Zr-MOFs: Zr(1,4-BDC) (UiO-66), Zr(4,4′-BPDC) UiO-67, and Zr(2,6-NDC) (DUT-52). Adsorption equilibrium data was measured at 298, 313, and 343 K up to 30 bar for CO 2 and 80 bar for CH 4 . The three adsorbents have increasing surface areas, pore volumes, and pore sizes in the order UiO-66 < DUT-52 < UiO-67. The maximum CO 2 and CH 4 loading and selectivity follow the same trend. The relatively low isosteric heats of adsorption of CO 2 for the three adsorbents indicate potential application at high partial pressures of CO 2 in so-called precombustion schemes. Since equilibrium selectivity was higher for UiO-67, adsorption kinetics of pure gases was also measured in this adsorbent. Diffusion of both molecules is very fast, allowing the use of equilibrium theory for estimation of process performance of this adsorbent.