Formation of hierarchical boehmite with different nanostructures in dry-gel conversion process

Abstract

Boehmite nanostructures with different morphologies were prepared through polymorphic transformation of bayerite in the dry-gel conversion process with acetic acid solutions as steam source. The evolution of the crystalline structures and morphologies of nanoparticles tightly relied on the composition of the steam source, where H₂O in the vapor offered the hydrothermal environment for the formation of boehmite crystalline structure and preferred the flake-like morphology while HAc adjusted the particle morphologies from flakes to nano-rods. Notably, the nano-structured particles aggregated together and led to the formation of microsized hierarchical boehmite structures. After dehydration, the boehmite can transform to γ-Al₂O₃ with the hierarchical structures well preserved, resulting in good textural properties.