Preparation and growth mechanism of the flower-like whiskers of γ-, θ-, and α-Al2O3 phases by homogeneous precipitation/calcination method

Sintering and characterization of in situ formed porous cordierite ceramics with nano boehmite additions

“…The obtained cordierite phase is unspecified in shape. Only van Der Waals forces exist between molecules when the water in boehmite is removed, and the original bent whiskers transform into needle‐like morphology, forming the γ‐Al 2 O 3 phase 41 . However, alumina particles with a greater specific area favored the dissolution of Al 3+ ions in the siliceous glass phase, contributing to the nucleation and growth of mullite needles 42 …”

“…Only van Der Waals forces exist between molecules when the water in boehmite is removed, and the original bent whiskers transform into needle-like morphology, forming the γ-Al 2 O 3 phase. 41 However, alumina particles with a greater specific area favored the dissolution of Al 3+ ions in the siliceous glass phase, contributing to the nucleation and growth of mullite needles. 42 In addition, the results showed that increasing the nano boehmite additions increased the crystallinity of the in situ formed phases, as shown in Figure 7D,H with 10 µm magnification for microstructure of samples A15 and C33, respectively.…”

Advances in morphology-controlled alumina and its supported Pd catalysts: synthesis and applications

“…Characterization results revealed that, under closed reactor conditions, the presence of CO 2 from urea hydrolysis increased the system's pressure and inhibited further hydrolysis of urea, leading to a slow increase in OH- concentration in the solution, which promoted the growth of boehmite crystal nuclei into whiskers. 70 The optimal synthesis conditions for obtaining boehmite flower-like whiskers were a temperature of 160 °C and a processing time of 8 hours.…”

Coprecipitation Synthesis of Large-Pore-Volume γ-Alumina Nanofibers by Two Serial Membrane Dispersion Microreactors with a Circulating Continuous Phase

“…Owing to its favorable porosity and thermal and chemical stability, γ-Al 2 O 3 is an essential functional material that has long been used as the catalyst support. − γ-Al 2 O 3 powder stacked by nanofibers with a large length/diameter ratio irregularly has a large pore volume, a pore diameter, and a specific surface area. , These properties are beneficial for the diffusion of hydrocarbon macromolecules and provide sufficient adhesion sites for active metal catalysts, making γ-Al 2 O 3 a favorable catalyst carrier for diesel and bio-oil hydrogenation. − At present, γ-Al 2 O 3 is commonly synthesized in industry from the pseudo-boehmite (PB) precursor. The precursor is fabricated via the precipitation method, − and then, γ-Al 2 O 3 is obtained by drying and calcination . Among the numerous precipitation methods, coprecipitation utilizes the neutralization reaction between NaAlO 2 and acidic aluminum aqueous solutions as follows:…”