Mesostructured cellular foams modified by niobium or tantalum and functionalized with (3-mercaptopropyl)trimethoxysilane - Raman inspired reduction of synthesis time

摘要

The synthesis of mesostructured cellular foams (MCF) modified by niobium or tantalum source and functionalized with MPTMS (3-mercaptopropyl)trimethoxysilane was monitored in situ by Raman spectroscopy. The results from Raman monitoring prompted us to check for a possibility of shorter time synthesis of mesostructured cellular foams. A series of MCFs materials prepared using different times of gel mixing (5 h and standard 20 h) were synthesized. The samples obtained were characterized by N-2 adsorption/desorption, XRD, TEM, XRF, elemental analysis, UV-Vis, FTIR and amperometric titration. The effects of niobium and tantalum on the rate and efficiency of thiol oxidation as well as on the time of silica formation were explored. The most important outcome of the study is the evidence of the formation of MCFs materials having strong Bronsted acidic centers in a shorter preparation time. SO3H groups form faster than in MP-MCF material in the presence of niobium or tantalum in the synthesis gel. The extension of synthesis time for silica and tantalosilicate samples leads to more efficient oxidation of thiol species. This feature does not depend on the synthesis time of niobiosilicate materials. (C) 2014 Elsevier B.V. All rights reserved.