Preparation of trityl cations in faujasite micropores through supercritical CO2 impregnation

In this paper, we investigated on the preparation of three zeolite encapsulated-trityl cations (trityl, dimethoxytrityl and methoxytrityl) using supercritical CO2 (scCO(2)) as the processing media. Since the studied trityl cations had a size larger than the diameter of the zeolite channels, the fabrication was based on a ship-in-a-bottle procedure using benzene, benzaldehyde, anisole, diphenylcarbinol and benzophenone as building blocks. The different cations were prepared by nucleophilic substitution, using the inner super-cage of the acid zeolite as both a microreactor and a negative counterion for the trityl cation. The obtained impregnated samples were purified by cleaning with a continuous flow of scCO(2). Loaded amounts of ca. 8 wt.% were obtained following the supercritical procedure. The successful formation of the cation was confirmed by using optical spectroscopies, such as UV-vis diffuse reflectance and FTIR spectroscopies. (C) 2010 Elsevier Inc. All rights reserved.