The formation and properties of large-surface-area intergranular mesoporous Al2O3 particles

Mesoporous γ-Al2O3 with pores formed between nanocrystals was synthesized via the hydrothermal method, varying the ethanolamines (monoethanolamine, diethanolamine, triethanolamine), pH values (6.5, 7.5, 8.5) and the temperature of the thermal treatment. Characterization techniques, including nitrogen physisorption, X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric-differential scanning calorimetry-mass spectrometry (TG-DSC-MS), and transmission electron microscopy (TEM), were employed to study the textural and structural properties of the materials. Thermal treatment at 500 ◦C produced mesoporous γ-Al2O3 with pores formed between nanoparticles. The materials synthesized with triethanolamine exhibited the narrowest pore size distribution and the highest specific surface area, particularly at higher pH values. The thermal treatment temperature significantly influenced the textural properties and crystallinity, with γ-Al2O3 retained up to 900 ◦C and the transformation to non-porous α-Al2O3 occurring at 1300 ◦C. These results demonstrate the critical role of synthesis parameters in understanding and optimizing the pore size and phase stability of mesoporous alumina.