Mesopore Connectivity Improving Aerosol-Assisted Synthesis of Mesoporous Alumina Powders with High Surface Area.

Abstract

Considering the closed packing of supramolecular mediated cage-type (spherical) mesopores inside spherical particles that are typically obtained by the aerosol-assisted process, uniform mesopores cannot be packed so periodically and then the mesopores are less connected and/or occasionally isolated, leading to the formation of low-surface-area mesoporous particles. In this study, we proposed the controlled swelling of such cage-type mesopores for improving their connectivity. Actually, we succeeded in preparing high-surface-area mesoporous alumina powders using poly(oxyethylene)- block-poly(oxypropylene)- block-poly(oxyethylene) (EO nPO mEO n) type triblock copolymers such as Pluronic P123. The surface area of the mesoporous alumina powders was originally low (278 m2 g-1 without organic additives), which can be drastically increased up to ca. 540 m2 g-1 through the controlled welling with suitable addition of 1,3,5-trimethylbenzene and 1,3,5-triisopropylbenzene. The insight is promising for further development of the aerosol-assisted approach for recovering high-quality mesoporous powders and helpful for rational catalyst design by utilizing mesoporous alumina powders with extremely high surface area.