1 research outputs found
Mid-temperature CO<sub>2</sub> Adsorption over Different Alkaline Sorbents Dispersed over Mesoporous Al<sub>2</sub>O<sub>3</sub>
CO2 adsorbents
comprising various alkaline sorption
active phases supported on mesoporous Al2O3 were
prepared. The materials were tested regarding their CO2 adsorption behavior in the mid-temperature range, i.e., around 300
°C, as well as characterized via XRD, N2 physisorption,
CO2-TPD and TEM. It was found that the Na2O
sorption active phase supported on Al2O3 (originated
following NaNO3 impregnation) led to the highest CO2 adsorption capacity due to the presence of CO2-philic interfacial Al–O––Na+ sites, and the optimum active phase load was shown to be
12 wt % (0.22 Na/Al molar ratio). Additional adsorbents were prepared
by dispersing Na2O over different metal oxide supports
(ZrO2, TiO2, CeO2 and SiO2), showing an inferior performance than that of Na2O/Al2O3. The kinetics and thermodynamics of CO2 adsorption were also investigated at various temperatures, showing
that CO2 adsorption over the best-performing Na2O/Al2O3 material is exothermic and follows
the Avrami model, while tests under varying CO2 partial
pressures revealed that the Langmuir isotherm best fits the adsorption
data. Lastly, Na2O/Al2O3 was tested
under multiple CO2 adsorption–desorption cycles
at 300 and 500 °C, respectively. The material was found to maintain
its CO2 adsorption capacity with no detrimental effects
on its nanostructure, porosity and surface basic sites, thereby rendering
it suitable as a reversible CO2 chemisorbent or as a support
for the preparation of dual-function materials