Mixture adsorption on zeolites applying the temperature-dependency approach

Postcombustion CO2 Capture from Wet Flue Gas by Temperature Swing Adsorption

“…An isotherm model capturing the features of pure component water vapor adsorption as described above is the Guggenheim–Anderson–de Boer (GAB) model: where H w describes the affinity toward the empty adsorption sites (presumably the cations on the zeolite), whereas k accounts for the formation of the water clusters. Moreover, the fact that the data collapse onto a single curve when shown against relative humidity suggests that, on average, the temperature dependence can be accounted for through the vapor pressure of water, consistent with literature data. , Indeed, this three-parameter isotherm is able to describe the adsorption data satisfactorily at the three temperature levels investigated, as shown in Figure b; the values obtained by performing the maximum likelihood estimation with the pure component data at 25, 45, and 65 °C are n w ∞ = 15.42 mol/kg, H w = 96.80, and k = 0.13. As the hysteresis loop is narrow, we do not account for it in the isotherm model, contrary to the case of activated carbon …”

“…This approach has been recommended by Leppäjärvi et al, and its main advantage is that a wide range of temperatures can be described, as required for the TSA process. Indeed, such behavior has been reported , to apply to various zeolites up to temperatures exceeding 100 °C. Similar to the mass transfer coefficient of water vapor on zeolite 13X, literature values of the heat of adsorption for the same system vary, namely, from 43 kJ/mol to beyond 60 kJ/mol. , Krishnamurthy et al, who investigated a vacuum swing adsorption process for a similar feed stream as considered here, used a value between 45 and 55 kJ/mol.…”

An Experimental and Modeling Study of the Adsorption Equilibrium and Dynamics of Water Vapor on Activated Carbon

“…It is assumed that the temperature dependence of the isotherm can be described through the variation of the vapor pressure with temperature, thus implying that the heat of adsorption equals the heat of condensation. ,, This allows one to write the adsorption model in terms of the RH only, and not explicitly as a function of temperature.…”

Modeling water vapor adsorption/desorption cycles

“…This is consistent with the assumption that the heat of adsorption equals the heat of condensation. In fact, such behavior in the case of water adsorption has been reported in the literature (Leppäjärvi et al 2012(Leppäjärvi et al , 2013. Moreover, it is assumed that the hysteresis loop is independent of temperature in the range considered in this study.…”