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.

Zhonglin Li,Jialong Shen,Kun Luo,Zizheng Qu,Chengzhi Wu,Ding Wang,Junxue Chen,Yibing Li,Zhengbing Meng

doi:10.3390/ma14195465

Abstract

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.

Highlights

The present study focuses on synthesizing mesoporous alumina (MA) via novel and practical processes with lower-cost primary materials; the final waste can be recycled to the mother liquor by adding calcium hydroxide
According to the IUPAC (International Union of Pure and Applied Chemistry) classification [50], the nitrogen adsorption–desorption isotherms of powder materials prepared in pH solutions are IV isotherms, indicating all materials are MA
When the P/Po value is small, the amount of N2 adsorption is gradually increased with the increase in partial pressure and the presence of single-molecule adsorption of N2 on the pore surface; with the increase in P/Po, the capillary condensation phenomenon of N2 occurs in the pores

Summary

Introduction

The γ-phase mesoporous alumina (MA) is usually presented as a material with a large specific surface area and excellent chemical activity [10,11,12,13,14]. It has been used extensively in adsorbents, filters, catalysts, and catalyst support. Γ-Al2 O3 with larger specific surface area and higher pore volume is favorable to attract reactants flowing into catalytic and adsorb basic sites It facilitates the formation of active sites per unit area and is beneficial to the catalytic activity and the adsorption property [15,16,17,18,19,20]. Gunathilake et al [40]

Methods

Results

Conclusion