Mechanochemical Nonhydrolytic Sol-Gel-Strategy for the Production of Mesoporous Multimetallic Oxides

Mesoporous metal oxides with wide pore size, high surface area, and uniform porous structures have demonstrated excellent advantages in various fields. However, the state-of-art synthesis approaches are dominated by wet chemistry, accompanied by use of excessive solvent, and the requirement of time-consuming drying process. Herein, we report a mechanochemical solid-state route to synthesize mesoporous Al₂O₃ (meso-Al₂O₃) via aluminum isopropoxide-copolymers assembly. The obtained meso-Al₂O₃ shows a record high surface area (∼644 m² g^-1) and narrow pore size distribution (centered at ∼5 nm). Moreover, a mechanochemical nonhydrolytic sol-gel strategy is introduced to fabricate mesoporous metal (Cu, Co, Mn, Fe, Mg, Ni)-aluminum binary oxide by using anhydrous metal chlorides and aluminum isopropoxide interplay. More importantly, four or five metals-aluminum oxide complexes with abundant mesopores and single cubic crystalline phase known as high-entropy ceramics are produced. To the best of our knowledge, mesoporous high-entropy metal oxides have not been prepared before, because the high crystallization temperature would make mesopores collapse. Additionally, this high-entropy property endows (CuNiFeCoMg)O_x-Al₂O₃ with superior SO₂-resisting performance (1000 ppm of SO₂ in N₂ at 280 °C) in the catalytic oxidation of CO compared to single CuO-Al₂O₃