(169e) Synthesis and Characterization of Novel Hierarchically Structured Aluminosilicate Catalysts

Hierarchical materials with pores at two different length scales (meso and macro) integrated in the same particle are of interest in the design of novel structured catalysts. These materials with the combined advantages of high surface area and reduced diffusion resistance have the potential to be highly efficient catalysts. Previously, our group reported the first one-pot synthesis of hierarchically structured meso-macroporous alumina. Beginning from alkoxide precursors, these unique morphologies are obtained in solution by spontaneous self-assembly of metal oxide nanoparticles as mesoporous walls around macroporous channels. This relatively simple synthesis approach does not require the presence of any templating agent. After the discovery of hierarchical alumina, hierarchical materials from other metal oxides such as titania and zirconia were successfully synthesized for comparative studies. The work to be presented here discusses unprecedented synthesis routes to novel hierarchically structured aluminosilicates that were recently developed based on our previous work with individual alkoxides. The synthesized materials were characterized for their structural morphology and textural properties as well as catalytic properties through multiple characterization techniques. The synthetic routes were evaluated both on the basis of the creation of acidity and the quality of multi-scale porous structure, since both are crucial for the catalyst performance. Presented will be results demonstrating the synthesis of hierarchical meso-macroporous aluminosilicate materials having the presence of both Brönsted and Lewis acidity. These materials were catalytically active and were investigated further for their performance in the acid-catalyzed esterification of free fatty acids with methanol to produce methyl esters.