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

Abstract

A coprecipitation method was developed for the synthesis of fibrous γ-alumina using serial membrane dispersion microreactors with a circulating continuous phase and high concentrations of NaAlO2 and Al2(SO4)3 as reactants. Owing to the ultra-high mixing intensity and reduction of supersaturation due to the large circular phase ratio, a large pore volume and specific surface area and an extremely narrow pore diameter distribution were realized using the high-concentration and high-viscosity precipitation system. The influence of the phase ratio, dispersion order of reactants, Al2(SO4)3 residence time, and the precipitation reaction pH and time were investigated, and the nanofiber formation mechanism was explored employing theoretical calculations. By controlling the Al2(SO4)3 residence time of 3 s, phase ratio of 16, and pH of 8.0, γ-Al2O3 nanofibers with a pore volume of 1.36 cm3/g, a specific surface area of 376 m2/g, and a length/diameter ratio in the range of 30–54 were obtained without any organic reagents. This study provides an economical and readily scalable method for the synthesis of fibrous γ-Al2O3 with excellent pore properties and a large specific surface area, which can potentially be applied as an excellent catalyst support for diesel and bio-oil hydrogenation.

Introducing the I&ECR Virtual Collection of Industrial and Industrially Relevant Research (2022–2023)

“…Engineering chemistry related to Materials and Interfaces is another strong topic area for I&ECR . Here, studies in the collection include a novel methodology of improving polyphenyl sulfide (PPS)-based membranes selected as ACS Editors’ Choice in June 2023, an improvement of lubricant oil properties using carbon nanomaterials, synthetic strategies to prepare γ-alumina by coprecipitation (a cover article in January 2023) and FeNi particles by spray pyrolysis, , the impact of pressure and temperature on sorption of gases by fluoroelastomers, methodologies to improve polymer/clay composite design, novel carbonaceous materials for Li batteries, and a study of rigid polyurethane foam Ostwald ripening from a third member of the 2022 Class of Influential Researchers …”

“…23 Engineering chemistry related to Materials and Interfaces is another strong topic area for I&ECR. Here, studies in the collection include a novel methodology of improving polyphenyl sulfide (PPS)-based membranes selected as ACS Editors' Choice in June 2023, 24 an improvement of lubricant oil properties using carbon nanomaterials, 25 synthetic strategies to prepare γ-alumina by coprecipitation (a cover article in January 2023) and FeNi particles by spray pyrolysis, 26,27 the impact of pressure and temperature on sorption of gases by fluoroelastomers, 28 methodologies to improve polymer/clay composite design, 29 novel carbonaceous materials for Li batteries, 30 ripening from a third member of the 2022 Class of Influential Researchers. 31 Although most studies in Process Systems Engineering come from academic groups, the topic area is very important to industrial researchers, with papers in the collection an August 2023 cover article on the impact of H 2 /N 2 ratio for NH 3 synthesis, 32 a methodology for multipurpose batch plant scheduling, 33 an image-based control method for an agrochemical crystallization process, 34 and a process for preparing propanol from methane.…”