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