Facile synthesis and catalytic activity of nanoporous SBA-1

Abstract

Nanoporous solids find wide spread applications in the field adsorption science, catalysis and host guest chemistry owing to their tunable pore size, unusually high surface area, good thermal stability and chemical inertness etc. Herein we report the facile synthesis of nanoporous SBA-1; a silica based cubic material having three dimensional pore architecture. The samples were prepared at room temperature from a gel containing TEOS, CTAB and HCl. The samples were characterized by XRD, HRTEM, FESEM, nitrogen adsorption–desorption, TG, FTIR and Raman measurements. The reflections observed in XRD studies are typical of ordered SBA-1 structure. HRTEM analysis show uniform and well ordered pore channels possessing long range ordering. FESEM patterns showed perfectly spherical morphology and uniform particles size of 1–1.5 μ. Nitrogen adsorption–desorption studies indicated the surface area of 1138 m² g⁻¹, pore volume of 0.63 cm³ g⁻¹ and average pore size of ~ 23 Å. About 43 % of total weight loss was noticed in TGA referred the highly porous nature of SBA-1. Apart from normal zeolitic vibrations, SBA-1 possesses large number of internal surface hydroxyl groups as revealed by FTIR studies. The typical vibrations of silicate and cetyltrimethylammonium bromide were observed in Raman studies. Catalytic oxidation studies of veratryl alcohol over SBA-1, resulted in formation of two important fine chemicals such as veratryldehyde and/or veratric acid. The product selectivity was tuned by optimizing the reaction conditions. Surface hydroxyl groups in combination with oxidant are presumed to play a key role for the observed activity.