Ordered Mesoporous Alumina and Their Composites Based on Evaporation Induced Self-Assembly for Adsorption and Catalysis

Abstract

Ordered mesoporous alumina (OMA) and the related composites with large surface areas, organized mesoporous channels, narrow pore size distributions, and high thermal stability have been explored in considerable fields like adsorption and catalysis. Compared with other synthesis methods, evaporation induced selfassembly (EISA) technology affords a superior potential for the synthesis of both OMA and OMA composites. This review focuses on the synthesis, adsorption, and catalytic performance of OMA and their composites based on one-pot EISA technique over the past decade. The effect of synthesis conditions including templates, alumina precursors, etc. on the morphology of OMA was discussed in the first part. Using the one-pot EISA method, modified metal particles and even single atom species were highly distributed in the ordered mesoporous channels of OMA with strong metal−support interaction, which obviously restricts the aggregation and sintering of active metal sites. In terms of the unique structure properties, moderate acidity, as well as a large amount of active metal sites, the activity and stability of OMA and OMA composites obtained by the EISA method in adsorption and catalysis were discussed, and the related opportunities in synergistic catalysis and single atom catalysis were also highlighted.

Synthesis of Ordered Mesoporous Zr-Al Composite Oxides with Excellent Structural and Textural Properties and Extremely High Stability

“…For samples OMZA-x and OMA, the evidence for the presence of ordered mesostructure is presented by the small-angle XRD patterns. As can be seen in Figure 2 , all samples exhibited two well-resolved diffraction peaks in a 2θ range from 0.5° to 3°, characterizing an ordered mesostructure in the pore arrangement [ 8 , 15 , 35 ]. Taking the sample OMZA-6 for example, a very strong diffraction peak at 0.94° and one weak broad peak around 1.64° are clearly obvious.…”

“…The detailed textural properties of these samples are listed in Table 1 . From Figure 5 a, it can be seen that all samples exhibited typical IV-type isotherms with relatively steep capillary condensation steps, signifying the presence of uniform mesopores [ 8 , 26 ]. It is noteworthy that samples OMZA-x (except for OMZA-2) demonstrated a steeper capillary condensation step than that of sample OMA, corresponding to a much narrower mesoporous size distribution ( Figure 5 b), which is well in accordance with the characterization result from the small-angle XRD analysis ( Figure 2 ).…”

“…Since the first invention of M41s series of silica materials [ 1 , 2 ], ordered mesoporous materials possessing large pore volume and high specific surface area as well as tunable mesoporous structures have attracted extensive attention for the development of high-efficiency catalysts using in the conversion of macromolecules [ 3 ], and numerous non-silicon-based ordered mesoporous materials with excellent structural, textural, and surface properties have been successively synthesized [ 4 , 5 , 6 , 7 ]. Compared to ordered mesoporous silica materials, ordered mesoporous alumina materials as catalysts or catalyst supports exhibit much more broad application prospects in various petrochemical processes, including hydrodesulfurization, cracking, and hydrocracking of petroleum feedstocks [ 8 , 9 , 10 , 11 , 12 ], because of the thoughtful combination of both the chemical properties of alumina and ordered mesoporous characteristics. At present, ordered mesoporous alumina materials are generally synthesized via two main strategies.…”

“…The evaporation induced self-assembly (EISA) method is another soft-template self-assembly approach for the successful preparation of ordered mesoporous materials, especially ordered mesoporous metal oxides [ 7 , 8 , 21 , 22 , 23 ]. Via such a method, a series of ordered mesoporous alumina materials with different mesostructures and tunable mesoporous sizes have also been successfully prepared by adjusting the hydrophilic-hydrophobic properties of surfactants or introducing suitable catalysts into the initial synthesis solution [ 8 , 24 , 25 , 26 ]. During the EISA process, the utilization of volatile non-aqueous solvents (such as anhydrous ethanol and tetrahydrofuran) can effectively slow down the hydrolysis-condensation rate of aluminum precursors, and a self-assembly ordered organic-inorganic composite micelle structure can be induced by gradually increasing the surfactant concentration during the solvent evaporation process.…”

A Robust Mesoporous Al2O3‐Based Nanocomposite Catalyst for Abundant NOx Storage with Rational Design of Pt and Ba Species

“…Alumina (Al 2 O 3 ), mainly in its γ‐phase, is one of the most useful and commercially available catalytic supports for improving the performance of metal catalysts. A large number of studies using ordered mesoporous alumina and their composites have recently been reviewed to give an understanding of their properties such as adsorption and catalysis [23] . According to the contents of this focus review, several gaseous molecules such as CO, CO 2 , and CH 4 were catalytically converted by combining metal catalysts and metal oxide co‐catalysts.…”