Synthesis and characterizations of Al2O3 using Calliandra calothyrsus leaf extract and its potential application for increasing fuel oxidation stability number

Calliandra calothyrsus leaf extract (CLE) successfully produced amorphous and gamma Al₂O₃ by a simple one-pot method. The secondary metabolites of alkaloids and saponins acted as weak base suppliers and capping agents. The various calcination temperatures resulted in different structures and surface morphologies. The flower-like form of gamma Al₂O₃ was observed at high temperatures of 700 °C, and 800 °C. As a result, the rod-flake structure of amorphous Al₂O₃ was obtained at 600 °C according to structural and morphological analysis. Al₂O₃ with a blended fuel containing Research Octane Number (RON) 95 and 10 % ethanol, as a gasoline model, was employed to analyze the oxidation stability number. Interestingly, Al₂O₃ calcined at 600 °C has the highest oxidation stability due to the rod shape of amorphous alumina and a higher average pore size confirmed by XRD, SEM and N₂ adsorption-desorption analyses. This work demonstrates the preparation of Al₂O₃ with different phases using plant extract by a simple one-pot green method and its promising application as a fuel additive for increasing oxidation stability numbers.