Gas-Liquid Interfacial Deposition Synthesis of Alumina with Large Mesopores

The porous structure of alumina is influenced by various factors during the synthesis process.In this study,we proposed a gas-liquid interfacial deposition method,different from conventional liquid-phase reactions,which effectively slows down the precipitation rate,facilitating the investigation of the pore structure and morphology changes of alumina during the synthesis process.Ammonia (NH3);carbon dioxide (CO_(2)) generated by the decomposition of inorganic ammonium salts constitute the gas phase,while the aqueous solution of the inorganic aluminum salt serves as the liquid phase.The gas diffuses,contacts,dissolves and reacts with the inorganic aluminum salt solution,constructing a platform for gas-liquid interfacial deposition at the gas-liquid interface.We precisely regulated the critical factors that affected the precipitation rate during the reaction process,such as gas-liquid reaction methods,precipitant types,aluminum salt types,and reaction temperatures,leading to systematic changes in the pore structures of the obtained alumina.After considering the influence of precipitation rate,pH value,and anion types,we found that the fundamental factor affecting pore structure lies in the water content of the precursors.By controlling the phase and crystallinity of the precursors,alumina with a large mesopore size distribution concentrated at 25.3 nm can be obtained.