Fast, Large-Scale, and Stable Preparation of η-Al₂O₃ Microspheres by Fully Utilizing N,N-Dimethylformamide at Room Temperature

Abstract

A fast, large-scale, and stable preparation method was successfully developed to obtain η-Al2O3 microspheres with particle sizes of 3–10 μm from cheap and widely sourced NaAlO2 solution using N,N-dimethylformamide (DMF) as a morphological modifier and a precipitant simultaneously at room temperature. The yield of alumina increases from 33.3 to 77.3% by increasing the dose of DMF from 100 to 400 mL. The utilization efficiency of DMF significantly increased by adding fresh NaAlO2 into the reused filtrate after separating the bayerite precipitate (precursor of η-Al2O3). Importantly, the η-Al2O3 microspheres obtained from the filtrate-reuse experiments show the stable phase structures, morphologies, and pore structure properties. Furthermore, the typical η-Al2O3 microspheres supported Pd catalyst presents a higher catalytic activity of 10.6 g/L for the hydrogenation of anthraquinone than that of the commercial γ-Al2O3-supported Pd catalyst (8.5 g/L), suggesting that the as-prepared η-Al2O3 microspheres have good application prospects for catalytic hydrogenation and related fields.

Red-Emitting Cr3+ on α-Al2O3:Cr Spheres Obtained in Seconds Using Laser Processing

“…The main fabrication approaches typically involve the melting of glass materials or the sol-gel process [26]. Other methods to produce crystalline spheres of different sizes (from nano to some millimeters) have been reported and include laser ablation [25,[28][29][30], spray pyrolysis [31,32], microfluidic synthesis strategies [33], hydrolysis-precipitation methods [34], hydrothermal [35], and even other laser sintering approaches [36].…”

One‐step synthesis of flower‐like η‐Al 2 O 3 via supercritical hydrothermal method

“…Between various phases of alumina, γ and η‐Al 2 O 3 , with similar structures, have been widely employed as catalysts or catalyst support in the Fischer–Tropsch process, hydrocracking and so on [31–33]. Compared with γ‐Al 2 O 3 , η‐Al 2 O 3 has higher activity due to its lower surface energy and higher specific surface area, which is proper for catalytic applications [34, 35].…”

“…They produced η‐Al 2 O 3 by calcination of basic aluminium sulfate at 900°C. In another research, η‐Al 2 O 3 was produced by calcination bayerite (γ‐Al(OH) 3 ), which had been formed from the hydrolysis of NaAlO 2 solution [34]. Seo et al prepared η‐Al 2 O 3 using a two‐step approach, i.e.…”