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

摘要

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.NH4HCO3and AI2(SO4)3.18H2Owere reacted under vigorous mixing to give an ammonium aluminum carbonate hydroxide (AACH)precursor.γ-Alumina was obtained by calcination of AACH at 550℃ for 6h.The effects of NH4HCO3concentration,pH during aging,and reaction temperature were investigated.The mechanism of bimodal pore formation was clarified.The results showed that large pores (10-100nm) were mainly formed in the reactor and during aging,and small pores (0-10nm)were mainly formed during calcination.When the concentration of NH4HCO3was 1.5mol/L,the aging pH was 9.2,and the reaction temperature was 80℃,γ-alumina with a specific surface area of 504.7m^2/g and pore volume of 1.76mL/g was obtained.The average size of the large pores was about 30nm,and the average size of the small pores was about 4nm.