Magnesia-Incorporated Mesoporous Alumina with Crystalline Frameworks: A Solid Strong Base Derived from Direct Synthesis

Abstract

By use of a surfactant templating method, the direct synthesis of magnesia-incorporated mesoporous alumina (mMgAl-γ) was realized via self-assembly of inexpensive inorganic salts. The structural and basic properties of the obtained materials were well characterized by various approaches. The results show that mMgAl-γ samples possess strong basicity with excellent water-resistant ability, well-defined mesoporous structure, and γ-Al2O3 crystalline frameworks. In comparison with wet impregnation that leads to structural damage, the direct synthesis strategy allows the mesoporous alumina to maintain good mesostructure. For example, the Brunauer−Emmett−Teller surface area of sample mMgAl(0.1)-γ can reach 328 m2·g−1, which is obviously higher than that of the sample prepared by a conventional impregnation method (239 m2·g−1). Further investigations evidence that the fabrication of suitable preassembled mesoporous precursors is crucial for the efficiency of the present direct synthesis strategy. In the process of calcination, the strongly basic species MgO was produced simultaneously and in situ coated on newly formed mesoporous γ-Al2O3 from preassembled precursors. Besides mMgAl-γ, mesoporous γ-Al2O3 materials functionalized with iron, chromium, and lead oxides were also successfully prepared, which demonstrates the generality of the strategy.

Design and fabrication of mesoporous heterogeneous basic catalysts

“…262 The obtained materials showed a mesoporous structure with no long-range order in the pore arrangement. 262 The obtained materials showed a mesoporous structure with no long-range order in the pore arrangement.…”

“…262 The results indicated that the strategy of direct synthesis allowed the mesoporous g-Al 2 O 3 to maintain its structure, while wet impregnation led to considerable structural damage. 262 The results indicated that the strategy of direct synthesis allowed the mesoporous g-Al 2 O 3 to maintain its structure, while wet impregnation led to considerable structural damage.…”

“…Both alkali metal oxides 260 and alkaline earth metal oxides [261][262][263] have been introduced to mesoporous Al 2 O 3 . Basic oxide modification.…”

One-pot synthesis of mesoporous Cu–γ-Al2O3 as bifunctional catalyst for direct dimethyl ether synthesis

“…[20][21][22]. Compared to the conventional wet impregnation method, the mesoporous alumina supported metals by one-pot method were reported to have high-quality mesostructures that exhibit strong metal-support interactions and a homogeneous distribution of active sites [23]. A bifunctional catalyst for one-step DME synthesis can be obtained by loading copper on the surface of c-Al 2 O 3 using the conventional impregnation method or the co-precipitation and deposition method reported by Baek et al [24].…”

Effect of reduction–oxidation treatment on structure and catalytic properties of ordered mesoporous Cu–Mg–Al composite oxides

“…Later, this method was further extended to synthesize mesoporous alumina-supported metal oxides (NiO, Cr 2 O 3 , CeO 2 , etc.) [20][21][22][23], and the high-quality mesoporous structure with strong metalsupport interactions and homogeneous distribution of active component was observed [24,25].…”