26 research outputs found
The Energetics of SurfactantâTemplating of Zeolites
Mesoporosity can be conveniently introduced into zeolites by treating them in basic surfactant solutions. The apparent activation energy involved in the formation of mesopores in USY by surfactantâtemplating was determined using a combination of inâ
situ synchrotron Xâray diffraction and exâ
situ gas adsorption. Additionally, techniques such as pH measurement and thermogravimetry/differential thermal analysis were employed to determine OHâ evolution and cetyltrimethylammonium ion (CTA+) uptake during the development of mesoporosity, thereby providing information about the different steps involved. The combination of both inâ
situ and exâ
situ techniques has allowed determination of the apparent activation energies of the different processes involved in the mesostructuring of USY zeolites for the first time. Apparent activation energies are of the same order of magnitude (30â65â
kJâmolâ1) as those involved in the crystallization of zeolites. Hence, important mechanistic insight into the surfactantâtemplating method was obtained.This work was supported by the Spanish MINECO (PCIN-2013-164) and the EC through the ERA-NET CAPITA(AEI/FEDER, project WAVES, EP7-NMP-266543) and the ALBA Synchrotron (refs. 2016021622 and 2016021729). E.S. thanks the Spanish MINECO and AEI/FEDER, UE (CTQ2015-74494-JIN). E.S. and N.L. acknowledge the University of Alicante support (UATALENTO16-03 and UATALENTO17-05, respectively)