Synthesis, characterization and catalytic applications of mesoporous γ-alumina from boehmite sol

Abstract

In this study, boehmite sols were used as aluminum precursors for preparing mesoporous alumina (MA) having crystalline framework walls in the presence of non-ionic surfactants as structure directing agents. Nitrogen physisorption showed that aluminas prepared in this way displayed very rich porosities with large mesopores, and both the pore volumes and the pore sizes increased with the surfactant concentration. The improved textural parameters in the samples should be attributed to the three-dimensional interconnected scaffold-like channels, which were formed by randomly ordered stacking and condensing of rigid boehmite nanoparticles with the aid of the surfactant. TEM observations revealed that the precursor morphology had an important effect on the textural properties of the mesoporous alumina. The sample with a corrugated platelet-like morphology exhibited a large surface area of 463 m 2/g, which was reduced to 81 m 2/g after calcination at 1200 °C, indicating a strong resistance to sintering. This material, with its improved textural properties, crystalline framework walls and high thermal stability, not only could increase the dispersion of the active catalytic species, but also could enhance the diffusion efficiency and mass transfer of reactant molecules when employed as catalyst supports. As examples, our MA samples demonstrated a remarkable enhancement in the catalytic performances for both reactions of SO 2 catalytic reduction by CO and catalytic combustion of methane.