Adsorption and diffusion of CO2 in CPO-27–Ni beads

Abstract

The present work involves the scale-up and characterization of CPO-27–Ni metal organic framework using a range of experimental techniques aimed at determining equilibrium and kinetic parameters to assess its potential for post-combustion carbon capture. CPO-27–Ni was prepared from its precursors by molecular gastronomy methods in kilogram scale. Adsorption of isotherms of pure CO2 and N2 were obtained for diferent temperatures on these beads, using a volumetric apparatus and the isotherms were ftted to a dual-site Langmuir model. A series of experiments were then carried out in the volumetric apparatus by dosing a known volume of CO2 and the pressure was monitored with time. The difusional time constants were then extracted by ftting the series of curves to an isothermal difusion model. From the time constants, the values of the difusivities were obtained and compared with the values obtained from frst principles correlations, which employed the pore size, and the porosity values from independent mercury porosimetry experiments. The results from the analysis showed that the transport of CO2 in the beads was well described by a combination of Knudsen and viscous difusion mechanisms. Experiments were also carried out using a zero-length column (ZLC) apparatus by preparing a 10% CO2–He and 10% CO2– N2 mixture. The analysis of the ZLC curves showed that the two diferent carrier gases had an efect of the long-time slope, indicating the presence of a macropore-controlled difusion mechanism.