A reactivity index study to choose the best template for a particular zeolite synthesis

The activity of different representative templating molecules along with ze olite framework is investigated using a range of reactivity indexes using d ensity functional theory (DFT), From the values of local softness and the c harge on the hydrogen atom of the bridging hydroxyl, resulting from the pre sence of aluminum in the framework, it is observed that the acidities of th e aluminum containing zeolite type model systems are dependent on several c haracteristics which are of importance within the framework of hard and sof t acids and bases (HSAB) principle. We investigated the local softness of t he interacting templates to compare their affinity with the zeolite framewo rk cluster models. The cluster models are chosen to mimic the secondary bui lding units of zeolite crystals for both silicalite and silica aluminates. The conformational flexibility was brought out as common features of those representative organic templates. The influence of the nature of the functi onal group and alkyl group on the electronic interaction is studied systema tically. An a priori rule is formulated to choose the best template for a p articular zeolite (e.g., ZSM-5) synthesis. The role of water during nucleat ion process is monitored in terms of solvation energy to rationalize the fu ndamental mechanism of crystal growth.