A Facile Temperature-Controlled “Green” Method to Prepare Multi-kinds of High-Quality Alumina Hydrates via a Ga-In-Sn-Alloyed Aluminum–Water Interface Reaction

The Al sheets alloyed by Ga-In-Sn are generally utilized to react with water for H₂ production, while the valuable byproducts, i.e., alumina hydrates, have not been fully studied. In this work, through controlling the reaction temperature, three types of alumina hydrates, bayerite (40 °C), pseudo-boehmite (PB) (70-120 °C), and boehmite (130-160 °C), were successfully prepared based on a series of interface reactions and structural transformations. These alumina hydrates and their calcined products (alumina) possess high purity with a total impurity element content of <450 ppm, especially an extremely low sodium content (<21 ppm) and iron content (<52 ppm). Significantly, the obtained pseudo-boehmite displays excellent surface properties (specific surface area: 332.7 m² g^-1, pore volume: 0.3 cm³ g^-1, and pore diameter: 3.6 nm), competitive to the current commercial SB powder by Sasol. This work not only deepens the understanding of the byproducts in a Ga-In-Sn-alloyed Al-water reaction but also establishes a facile "green" method oriented to industrial applications, which is promising for the linkage benefits of the hydrogen production industry.