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 CO 2 and N 2 were obtained for different temperatures on these beads, using a volumetric apparatus and the isotherms were fitted to a dual-site Langmuir model. A series of experiments were then carried out in the volumetric apparatus by dosing a known volume of CO 2 and the pressure was monitored with time. The diffusional time constants were then extracted by fitting the series of curves to an isothermal diffusion model. From the time constants, the values of the diffusivities were obtained and compared with the values obtained from first 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 CO 2 in the beads was well described by a combination of Knudsen and viscous diffusion mechanisms. Experiments were also carried out using a zero-length column (ZLC) apparatus by preparing a 10% CO 2 -He and 10% CO 2 -N 2 mixture. The analysis of the ZLC curves showed that the two different carrier gases had an effect of the long-time slope, indicating the presence of a macropore-controlled diffusion mechanism.

Exploring new sources of efficiency in process-driven materials screening for post-combustion carbon capture

“…Similar to the cases of Zeolite 13X 58 and MOF74-Ni, 60 transport of CO 2 and N 2 in other two materials studied here is also controlled by macropore diffusion, which is the most likely scenario for all pelletized microporous materials that have pore openings greater than 4 Å within their crystal structure. 61,62 During optimization, CySim makes sure that all simulations achieve a cyclic steady state (CSS) condition by checking simulations against the specific criteria explained here.…”

“…† Here, we note that the simulated adsorption isotherms of N 2 in MOF74-Ni ( Fig. 5(d)) largely underestimate experimental data reported in the literature 60 which is shown in Fig. S2 of the ESI.…”

“…binder has no thermal effect). For this, following literature values are used for specific heat capacity of each material: Cu-BTC = 1457 J kg À1 K À1 ; 69,70 MOF74-Ni = 1100 J kg À1 K À1 ; ‡ 60 Silicalite-1 = 771 J kg À1 K À1 ; 71 Zeolite 13X = 920 J kg À1 K À1 . 72 (2) For the second scenario, it is assumed that the specific heat capacity of all materials is similar to that of Zeolite 13X (i.e.…”

“…Solid lines represent the second case where C p is assumed to be equal 920 J kg À1 K À1 for all materials. ‡ Specific heat capacity of pelletized MOF74-Ni measured by Krishnamurthy et al 60 using the thermogravimetric differential scanning calorimetry (TGA-DSC) method. We obtained this information through direct communication with the authors, although they have not reported this value in their recent publication.…”

“…61,62 This has been experimentally demonstrated for diffusion of CO 2 in pelletized samples of Zeolite 13X 58 and MOF74-Ni. 60 Here, we start with the overall mass balance for the adsorption column which can be formulated as follows:…”