Hard-templated macroporous alumina with thick mesoporous walls: The key factors of pore formation

Abstract

This paper focuses on the key factors contributing to pore formation in hard-templated macroporous alumina. Special attention is paid to the formation of a connected pore structure. Two series of samples were prepared, each with different content of the polymeric template. The pore structure of alumina was designed using polystyrene and acrylic copolymers as hard templates. Alumina differed in crystallite morphology (round-like and rod-like) and pore structure (bottleneck-like and slit-like). The templates differed in particle size (100 and 250 nm) and physical state (powder and suspension). All the samples were characterized by N2 adsorption, Hg porosimetry, XRD, and SEM. The data obtained indicate that a hard template made of polymeric particles has the following functions: fixing the pore size and shape, sintering small pores of the material, and creating additional channels to connect macropores. Regardless of the type of polymeric template and Al2O3 precursor, a connected pore system can be formed by adding more than 20 wt% of the template.