The project addresses improved designs of crystalline zeolite materials used in applications ranging from catalysis and energy storage to electronics design. The nanometer sized pores of the zeolite materials are ideally suited for a wide range of separations and selective catalytic conversions in the chemical and petroleum industries. A promising strategy for improving the properties of zeolites is to tune crystal shape and size using targeted synthetic approaches. The overall goal of this project is to develop computer simulation methods for rapidly identifying small-molecule compounds known as growth modifiers that can be used to control zeolite crystal shape and size. This will accelerate the development of new catalysts, adsorbents, and separations materials for converting inexpensive and abundant sources of natural gas into fuels and high-valued compounds while simultaneously lowering toxic emissions.
A technique that is broadly utilized in both natural and synthetic crystallization to control crystal habit and morphology is the use of modifiers, which are molecular (or macromolecular) additives that possess an affinity for selectively adsorbing on specific crystal faces and altering the anisotropic rate(s) of growth. The most critical challenge in this field of research, irrespective of the material and application, is the incomplete understanding of the molecular-level interactions and thermodynamic driving forces that govern the adsorption and binding specificity of modifiers to different crystal surfaces. The focus of this project is to integrate zeolite synthesis, characterization, and modeling to develop an experimentally-validated computational platform for characterizing growth modifier effects on crystallization based on equilibrium adsorption properties. This will be achieved by addressing three specific aims: (1) develop, validate, and iteratively refine density functional theory and molecular simulation models for predicting modifier adsorption using experimental benchmark data; (2) assess model predictability and transferability to other modifier-zeolite systems; and (3) elucidate structure-property relationships as a means of establishing guidelines for modifier selection. This computational platform will improve our understanding of the mechanisms governing modifier efficacy and specificity, thereby providing a foundation for identifying effective modifiers and potentially accelerating their discovery by two orders of magnitude. The fundamental knowledge gained from this project will serve as a translational guide for the rational design of growth modifiers, fostering the development of improved strategies for controlling crystallization processes relevant to applications ranging from catalysis to separations and adsorption. The project will also provide educational and outreach components to K-12 students and undergraduates, including opportunities for Houston-area high school students to build molecular zeolite models.
