Ordered nanoporous silicates (IITM-56): Synthesis, characterization and applications

Mesoporous molecular sieves are special class of materials with ordered arrays of uniform pores, high surface areas and large pore volumes. These periodic silica/silica-based materials are promising for variety applications including catalysis, adsorption and separation processes. Two most common types involve MCM-41 and SBA-15 has ordered structures consisting of two dimensional hexagonal arrays of uniform mesoporous. SBA-15 has larger pores, thicker walls and higher thermal stability as compared to other mesoporous silicas including MCM-41. However, it is of interest to make materials with a combination of moderate pore size and thicker wall structure. Therefore, in this investigation, an attempt has been made to prepare materials with desired characteristics using oligomeric alkyl poly ethylene oxide (Brij-56) surfactant template. We report here, for the first time, a novel mesoporous silicate material, designated as IITM-56, with a (moderate) pore size of 38.4 Å and a wall thickness of 21 Å. XRD pattern of IITM-56 depicts structure which is typical characteristics of MCM-41/SBA-15. TG studies of IITM-56 show a 49% weight loss in conjunction with exothermic transition (DTA) suggestive of mesoporous nature of the material. This further confirmed by N2 sorption measurements, which indicate type IV isotherm with capillary condensation at 0.3-0.4 (P/Po).