Template-free method for the synthesis of high-pore-volume γ-Al₂O₃ nanofibers in a membrane dispersion microreactor

Abstract

Mesoporous γ-Al2O3 nanofibers with high pore volume and uniform pore size distributions were successfully synthesized via a template-free method in a membrane dispersion microreactor followed by calcination. The effects of crystal temperature, pH values, continuous phase concentration and washing solvent on the γ-Al2O3 nanofibers were carefully studied. The results showed that the as-obtained γ-Al2O3 nanofibers showed a length of 40–60 nm and a width of 3.2–3.4 nm, which were attributed to the high microscopic mixing rate in the membrane dispersion microreactor. Moreover, the precursors of γ-Al2O3 nanofibers treated with deionized water and mixed deionized water/alcohol solution had high pore volumes, reaching to 1.60 ml g−1 and 2.00 ml g−1, respectively. Furthermore, the adsorption performance of γ-Al2O3 nanofibers with high pore volumes was also investigated. These fibers showed an excellent adsorption capacity of 1323.68 mg g−1 for the removal of Congo red from aqueous solution, thereby indicating their potential for applications in adsorption and other related areas.

Advances in Microfluidic Synthesis of Solid Catalysts

“…Benefiting from the high microscopic mixing rate of the membrane dispersion microreactor, the mesoporous γ-Al 2 O 3 nanofibers were synthesized by a simple, template-free and singlephase microfluidic method using NaAlO 2 and Al(NO 3 ) 3 •9H 2 O as raw materials. And the obtained γ-Al 2 O 3 nanofibers showed considerable pore volumes and uniform pore size distributions compared with those prepared by traditional batch stirring methods [129]. The morphology-controlled synthesis of ZnO nanostructures (spindles, sheets and spheres) was reported via the precipitation of Zn(NO 3 ) 2 and NaOH by a facile surfactant-free method in microreactors (under single-phase flow) [130].…”

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

“…Coprecipitation is usually implemented in a stirred tank, but the pore properties of the γ-Al 2 O 3 product obtained via this method are not satisfactory. To overcome the long mass-transfer distance and unsatisfactory mixing performance of stirred tanks, the use of a membrane dispersion microreactor has been investigated. , Wan et al synthesized γ-Al 2 O 3 with a pore volume of 1.52 cm 3 /g and a specific surface area 403.8 m 2 /g under the NaAlO 2 concentration of 1.25 mol/L and the Al 2 (SO 4 ) 3 concentration of 0.25 mol/L. The core structure of a microreactor comprises a stainless steel microfiltration membrane which allows the fluid to be dispersed into tiny droplets with an extremely large interfacial area and short mass-transfer distance in the continuous microchannel, resulting in a substantially improved mass-transfer rate.…”

Micro-Octahedron Cu2O-Based Photocatalysis-Fenton for Organic Pollutant Degradation: Proposed Coupling Mechanism in a Membrane Reactor

“…A controlled synthesis of nanoscaled metal oxides by tuning the crystallography architecture is aimed for target properties and functions. It has been reported that steel-stainless membrane microreactors were successfully applied to produce dispersed nanosilica, size-controllable CeO 2 nanoparticles, and high-pore-volume γ-Al 2 O 3 nanofibers . The shaped Cu 2 O microcrystals were selectively prepared with the membrane dispersion one-step method based on our previous work …”

“…It has been reported that steel-stainless membrane microreactors were successfully applied to produce dispersed nanosilica, 8 size-controllable CeO 2 nanoparticles, 9 and high-pore-volume γ-Al 2 O 3 nanofibers. 10 The shaped Cu 2 O microcrystals were selectively prepared with the membrane dispersion one-step method based on our previous work. 11 Cu 2 O-based photocatalysis and Fenton oxidation could be combined for efficient degradation of organic pollutants driven by both photoenergy and chemical potential.…”