One-Pot Synthesis of MeAl2O4 (Me = Ni, Co, or Cu) Supported on γ-Al2O3 with Ultralarge Mesopores: Enhancing Interfacial Defects in γ-Al2O3 To Facilitate the Formation of Spinel Structures at Lower Temperatures

Sintering is an important issue in creating crystalline metal oxides with high porosity and surface area, especially in the case of high-temperature materials such as metal aluminates. Herein we report a rationally designed synthesis of metal aluminates that diminishes the surface area loss due to sintering. MeAl2O4 (Me = Ni, Co or Cu) supported on gamma-Al2O3 with ultralarge mesopores (up to 30 nm) was synthesized through microwave-assisted peptization of boehmite nanoparticles and their self-assembly in the presence of a triblock copolymer (Pluronic P123) and metal nitrates, followed by co-condensation and thermal treatment. The resulting materials showed the surface area up to 330 m(2).g(-1), porosity up to 1.6 cm(3)-g(-1), and very good thermal stability. The observed enhancement in their thermomechanical resistance is associated with the faster formation of the metal aluminate phases. The nanometer scale path diffusion and highly defective interface of gamma-alumina facilitate the counter diffusion of Mex+ and AL(3+) species and further formation of the metal aluminate phase. Additionally, it is shown that the type of transition metal affects the pore size of the nanostructured metal oxide by shifting the decomposition temperature of the triblock copolymer. Overall, the synthesis strategy requires easy steps and readily available precursors and promotes the formation of highly porous nanostructured oxides suitable for several applications such as catalysis and adsorption.