Innovative construction of macroporous–mesoporous structured spherical alumina and its hydrothermal stability

Abstract

The pore structure of spherical alumina supports is closely related to the dispersion of catalytically active components and the diffusion of reactants. Maintaining excellent pore structure under strict reaction conditions is of utmost importance. In this work, spherical γ-Al2O3 support with a bimodal pore structure, composed of macropores and mesopores, was successfully synthesized using dodecane as the pore-forming agent through the oil–ammonia column-shaping method. The morphology and internal pore structure of the alumina were found to be influenced by the amount of surfactant added and ultrasound treatment conditions. Notably, when concentration of surfactant was 4‰ and ultrasound voltage of 20 V was applied, the resulting γ-Al2O3-4‰-20 displayed a highly concentrated distribution of macropores with an average pore size of 100 nm, resulting in an impressive porosity of 69.21%. In contrast, the untreated sample of γ-Al2O3-0-0 only exhibited a mesoporous distribution with a porosity of 54.03%. Moreover, after being subjected to a hydrothermal treatment in a high temperature (600 °C) and high humidity (water vapor) environment for 120 h, the γ-Al2O3-4‰-20 sample maintained a high BET specific surface area of 170.9 m2 g−1 and mercury intrusion porosimetry specific surface area of 263.3 m2 g−1.