Partic. vol. 41 pp. 1-10 (December 2018)
doi: 10.1016/j.partic.2018.04.001

Controllable preparation of γ-alumina nanoparticles with bimodal pore size distribution in membrane dispersion microreactor

Lufan Yang, Mingzhao Guo, Fan Zhang, Yu Jing, Yujun Wang^*, Guangsheng Luo

wangyujun@mail.tsinghua.edu.cn

Abstract

In this paper, we present a new method for preparing γ-alumina nanoparticles with a bimodal pore size distribution by using an efficiently mixing membrane dispersion microreactor. NH₄HCO₃ and Al₂(SO₄)₃∙18H₂O were reacted under vigorous mixing to give an ammonium aluminum carbonate hydroxide (AACH) precursor. γ-Alumina was obtained by calcination of AACH at 550 °C for 6 h. The effects of NH₄HCO₃ concentration, pH during aging, and reaction temperature were investigated. The mechanism of bimodal pore formation was clarified. The results showed that large pores (10–100 nm) were mainly formed in the reactor and during aging, and small pores (0–10 nm) were mainly formed during calcination. When the concentration of NH₄HCO₃ was 1.5 mol/L, the aging pH was 9.2, and the reaction temperature was 80 °C, γ-alumina with a specific surface area of 504.7 m²/g and pore volume of 1.76 mL/g was obtained. The average size of the large pores was about 30 nm, and the average size of the small pores was about 4 nm.

Graphical abstract

Keywords

γ-Al₂O₃; Bimodal pore size distribution; Ammonium aluminum carbonate hydroxide; Membrane dispersion microreactor; Precipitation; Ammonium bicarbonate