Study on the Synthesis of High-Purity γ-Phase Mesoporous Alumina with Excellent CO₂ Adsorption Performance via a Simple Method Using Industrial Aluminum Oxide as Raw Material

To mitigate the global greenhouse effect and the waste of carbon dioxide, a chemical raw material, high-purity γ-phase mesoporous alumina (MA) with excellent CO2 adsorption performance was synthesized by the direct aging method and ammonium salt substitution method. With this process, not only can energy consumption and time be shortened to a large extent but the final waste can also be recycled to the mother liquor by adding calcium hydroxide. Reaction conditions, i.e., pH value, calcination temperature, and desodium agent, were investigated in detail with the aid of X-ray fluorescence spectrum (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) and Barret-Joyner-Hallender (BJH) methods, nonlocal density functional theory (NLDFT), transmission electron microscopy (TEM), temperature-programmed desorption of CO2 (CO2-TPD), and presented CO2 adsorption measurement. The results of this study are summarized as follows: the impurity content of the MA synthesized under optimal conditions is less than 0.01%, and its total removal rate of impurities is 99.299%. It was found that the MA adsorbent has a large specific surface area of 377.8 m2/g, pore volume of 0.55 cm3/g, and its average pore diameter is 3.1 nm. Under the condition of a gas flow rate of 20 cm3/min, its CO2 adsorption capacity is 1.58 mmol/g, and after 8 times of cyclic adsorption, the amount of CO2 adsorption remained basically unchanged, both of which indicate that the material has excellent adsorption properties and can be widely used for the adsorption of carbon dioxide