Adsorption reversibility using amine-grafted zeolite 13X

https://doi.org/10.1016/j.apsusc.2014.06.164

“CO₂ adsorption and desorption isotherms were measured for the amino-loaded zeolite (ZX10) at two temperatures, 298 and 348 K, which are shown in Fig. 8(a) and (b), respectively.”

“Fig. 8. Adsorption and desorption isotherms of CO₂ at 298 (a) and 348 K (b) for ZX10.”

“The adsorption and desorption CO₂ isotherms at 298 K do not follow the same path and such behavior cannot be attributed to physisorption equilibrium hysteresis under the studied P and T conditions. Such behavior may be due to an irreversible reaction between CO₂ and amine sites present in the adsorbent. On the other hand, the apparent irreversibility observed in Fig. 8a may also be attributed to diffusion limitations imposed by the pore blocking with MEA. This is consistent with the adsorption/desorption isotherms at 348 K, a higher temperature which will eventually enhance intraparticle mass transfer. In fact, both adsorption and desorption isotherms overlap at this temperature. The diffusion resistance and intraparticle mass transfer of CO₂ through filled pores may prevent the achievement of a strict equilibrium in the adsorption branch [25], particularly at the lower temperature (Fig. 8a). At this stage, however, none of these two hypotheses may be ruled out. It is likely that both mechanisms (chemisorption and hindered diffusion) occur.”