Rigid/Flexible Organic Structure Directing Agents for Directing the Synthesis of Multipore Zeolites: A Computational Approach

The preferential crystallization of pure silica ITQ-39 and MFI zeolites using SDAEt and SDAPr, respectively, as organic structure directing agents (SDAs) is investigated here by theoretical methods using a periodic DFT-D model. For this purpose, the templating roles of SDAEt and SDAPr have been analyzed following a systematic study of the interaction of these two SDAs with the previously described zeolites through SDA stabilization energies (balance of intermolecular SDA dispersive interactions and SDA strain). From theoretical studies, it has been found that SDAEt located inside ITQ-39 zeolite and SDAPr placed within MFI show the largest stabilizations. These theoretical results agree with previous experimental observations for the preferential crystallization of pure silica ITQ-39 and MFI using SDAEt and SDAPr molecules, respectively.