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Figure 10 (a) shows the experimental (points) and fitted (lines) CO2 breakthrough curves of sample C5*1h20min at different flow rates. The model fit the experimental data of sample C5*1h20min quite well with = 0.05 for a coefficient of mass transfer k of 5.2 s-1, see Table 2. The corresponding effective diffusivity was estimated to 4 · 10-12 m2/s using equation 9. Literature data on the diffusivity of CO2 in NaX is scarce and scatters significantly. Plant et al. [58] reported a diffusivity of 6·10-10 m2/s, whereas data presented by Böhm et al. [59] and Bulow [45] indicated that the diffusion of CO2 in NaX showed a complex behaviour which was assigned to two superimposed steps with different rates. No attempts where made to deconvolute the different steps, however the data presented by Bulow indicated that the overall diffusivity was significantly lower than 3·10-11 m2/s which is in agreement with the diffusivity obtained in this work. Figure 10 (b) shows the experimental and fitted CO2 breakthrough curves for sample G9. Again, the model fit the experimental data of sample G9 quite well with = 0.03 for a coefficient of mass transfer k of 0.072 s-1. This fitted mass transfer coefficient is 72 times smaller than the one for sample C5*1h20min. This low mass transfer coefficient is likely an effect of the large diffusion length in the sediments on top of the film, which constitute the main fraction of this adsorbent as discussed above and dominates the adsorption behavior of this sample. As pointed out above, the radii of the sediments is ranging from ca. 0.5 to 10 m. However, under the assumption that the sediments on sample G9 are spherical particles with an average radius of 5 m, the diffusivity can be estimated from Eq. (10). The diffusivity of sample G9 is thus about 1 · 10-13 m2/s and is thus about one order of magnitude lower than sample C5*1h20min (4 · 10-12 m2/s), see Table 2. This lower diffusivity in sample G9 may be a result of better intergrown crystals in the sediments of sample G9 compared to the crystals in the film of sample C5*1h20min as discussed above. Even under the assumption that the sediments on sample G9 are spherical particles with an average radius of 10 m (the 80PDF Image | Structured Zeolite Adsorbents for PSA Applications
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CO2 Organic Rankine Cycle Experimenter Platform The supercritical CO2 phase change system is both a heat pump and organic rankine cycle which can be used for those purposes and as a supercritical extractor for advanced subcritical and supercritical extraction technology. Uses include producing nanoparticles, precious metal CO2 extraction, lithium battery recycling, and other applications... More Info
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