Ammonium Aluminum Carbonate Hydroxide (AACH) as a Precursor of AlF₃‐Al₂O₃ Supports in Hydrogenation Catalysts – Synthesis, Characterization, and Application

Abstract The application of an innovative synthesis method for binary oxo‐fluoride supports (AlF₃–Al₂O₃), iridium catalysts with high hydrogenation activity were obtained. The use of these supports was found to enhance the reducibility and dispersion of the iridium phase, while the presence of acid sites of varying strengths contributed to higher catalytic activity in the toluene hydrogenation reaction. The innovation of the applied synthesis method lies in the use of ammonium aluminum carbonate hydroxide (AACH) as the aluminum source and hydrogen fluoride as the fluorine source. Proper selection of the AACH and HF ratios enables the synthesis of binary materials with controlled Al₂O₃ and AlF₃ content, as well as tailored textural, structural, and acidic properties. The effect of calcination temperature on crystallinity, the type of crystal phases formed, and the resulting porous structure of the binary supports was investigated. It was found that the AlF₃–Al₂O₃ support, after calcination at 500 °C, exhibits a mesoporous structure with a surface area of 102 m 2 /g and the presence of the AlF 1.96 (OH) 1.04 phase, which proved to be the most effective support for the iridium active phase. The influence of specific surface area, support acidity, and iridium dispersion on catalytic activity was evaluated.