Computer simulation of zeolite synthesis

An interest does exist in synthesising new zeotype structures on the ground of -among others- potentially important industrial applications. Whether this topic has been traditionally regarded as a series of cooking recipes, the recent panorama is quite much changed and a general understanding is growing steadily. Even more recent is the rational use of computational tools in this respect and our approach comes from the atomistic forcefield approach that we have been using successfully to so many other research topics related to zeolites. The role of templates and structure directing agents is being developed and the energy interaction with the zeolite framework is being revised and their different contributions studied separately to see, for example, how van der Waals and electrostatic factors influence the final synthesised material. Our first study on this topic has been the templating role of the trispirrolidinium cation in the synthesis of Al-ZSM-18 zeolite. Our results have validated the technique used and also the template location has been optimised: two positions for the cation were found and the minimum in energy was shown to be the experimentally observed by XRD. Secondly, the important result of predicting the Al distribution in this material was found and its preferential location in the 3-T rings was an important result from the calculations, which was justified in terms of the electrostatic interactions of the cation with the negative charged brought in the zeolite framework by the incorporation of Al atoms.

ZSM-18 with the trispyrrolidinium cation in its minimum energy conformation as found by the calculations and in agreement with the XRD results.