Aluminum Anodization in Oxalic Acid: Controlling the Texture of Al2O3/Al Monoliths for Catalytic Aplications

The anodization and postanodization processes of aluminum in order to prepare monoliths for catalytic applications have been studied in this work using oxalic acid as electrolyte. The effect of anodization variables (anodization time, current density, temperature, and electrolyte concentration) and postanodization processes on the surface morphology and textural properties of AAO (anodic aluminum oxide) films is analyzed. The anodization variables affect the two main processes taking part in the Al2O3 layer formation: alumina generation and its dissolution that are controlled by temperature, electrolyte concentration and time. The proper combination of both processes, as a result of the anodization variables choice, produces adherent alumina layers with tailored porosity and surface morphology that show excellent properties to be used as catalyst structured support. Larger pore sizes and the complete absence of sulfur that may poison reduced metal−supported active phases are main differences with the classical, most often used, sulfuric acid anodization process.