(147c) Molecular Models to Predict the Influence of Templating Molecules on the Structure and Organization of Zeolites

Extensive research has been conducted to uncover the relationship between zeolite structure and its catalytic performance. Nevertheless, the synthesis of zeolite in the assistant of templating molecules is a complex process that is not well understood yet and the current ability to synthesize zeolite with desired structure is still restricted. With the advancements in theoretical simulation and computation resources, we now process the potential to accelerate the discovery through investigations at the molecular scale. My research interests lie in exploring the potential of molecular models to understand and predict various synthesis conditions that control the structure and composition of zeolites.

To address the challenge, I have pursued three goals. First, I have improved the predictivity of molecular models to indicate zeolite crystallization tendencies between CHA and AEI zeolites. The guest-host interaction energy (GHIE) between full siliceous zeolite and charge-neutral templates has been utilized to predict the propensity of the templating molecules in facilitating the crystallization of specific zeolite topologies, but there is a clear need to enhance the efficiency and accuracy of the model. By analyzing both the energetics and configurations of the template in the void of zeolite with different potential models and sampling techniques, we introduced a secondary shape descriptor of the template molecule that is able to correctly predict crystallization tendencies between CHA and AEI zeolite.

Second, I investigated the impact of templates on the distribution of heteroatoms (specifically aluminum) within the zeolite framework. Given the evidence from previous work that template molecules can electrostatically direct the incorporation of Al, we expanded the model by isomorphically substituting Al into the model and introduce charges. Through thoroughly exploring the configurational space of CHA with different Al configurations and template molecule configurations, we compared the energetics of all Al configurations and successfully explained the observed Al siting preferences in experiment. As a result, I have been able to provide guidance on utilizing novel templates that result in diverse zeolite crystallization patterns.

Third, I constructed simulation strategies to explore the impact of templates on the composition of zeolite. With the Al-decorated zeolite model, we further incorporated defects into the system. By comparing the relative formation energy of different compositions, we provide a rationale for the observed ability of CHA to access a wide composition range when synthesized with a specific template molecule.

In conclusion, I used novel techniques to develop computational models and provide insights into relationships between template molecules and their influence on crystallization patterns of zeolite. My work will serve as a valuable guide for the industry, enabling the synthesis of zeolites with enhanced catalytic performance at reduced costs.

Biosketch

I am a Ph.D. candidate in chemical engineering at the University of Notre Dame, under the guidance of Professor William Schneider. With a strong background in molecular simulation, I possess four years of experience in this field, coupled with expertise in microporous material synthesis and catalysis. Furthermore, I have gained experience in machine learning techniques applied in the chemistry field. Through collaboration with research groups and industry partners, I have effectively tackled industrial challenges by guiding experiments and providing atomic insights with simulations. As I look ahead, I am actively seeking full-time employment opportunities commencing in the summer of 2024.