Phase transformation optimization from boehmite to γ-Al2O3 and duplex microstructure: γ-/δ-Al2O3 to enhance the catalytic applications of 3D-printed scaffolds

Direct Ink Writing (DIW) was used to fabricate ceramic scaffolds with tailored geometries and porosity for catalytic applications. The thermal conversion of boehmite (AlOOH) to γ -alumina ( γ -Al₂O₃) was studied to optimize sintering for a γ -/ δ -Al₂O₃ duplex microstructure. Ceramic inks (20–35 wt.% solids) with Pluronic F-127® were 3D-printed and treated at 450-600 °C. Complete AlOOH-to- γ -Al₂O₃ transformation occurred at 450 ºC with structural integrity. Scaffolds showed 10-12% shrinkage, porosity, and mechanical properties comparable to Cold Isostatic Pressing. In ethanol dehydration, γ -/ δ -Al₂O₃ scaffolds sintered at 600 ºC achieved ~95% ethanol conversion and higher ethylene yield versus ~10% for γ -Al₂O₃-only scaffolds at 450 ºC. • Optimized γ -/ δ -Al₂O₃ phases enhance ethanol dehydration efficiency. • 3D-printed scaffolds via DIW enable controlled porosity and geometry. • Duplex γ -/ δ -Al₂O₃ shows higher ethanol conversion at lower temperatures. • Tailored sintering yields superior catalytic activity without post-treatment. • Phase engineering and DIW improve catalyst performance and sustainability.