Collaborative Research: Controlling the Catalytic Properties of SSZ-39 Through Rational Synthesis: An Integrated Computational and Experimental Approach

Washington State University, Pullman WA

Investigators

Abstract

The project focuses on advances in synthesis techniques for zeolites – catalytic and molecular sieve materials used widely in the petroleum and chemical industries, and in environmental pollution control. Specifically, the research focuses on understanding the process by which compounds known as organic structure directing agents (OSDAs) promote the growth of zeolite crystals that display specific physical and catalytic properties. The investigators will integrate experiment and theory toward this goal, where cutting-edge simulation tools will be coupled with experimental measurements and advanced characterization techniques. While the targeted zeolites are those used in diesel engine emissions control, the knowledge generated in the work will be broad-sweeping in scope. As such, the findings will have implications for renewable energy, improved technologies for advanced material production, and new approaches to generating intermediates/products in the pharmaceutical industry. The project incorporates educational and workforce training opportunities for graduate and undergraduate students, including cross-training of graduate students between the research groups. Outreach activities will include interactive modules for K-12 outreach, a distance learning course related to emerging energy technologies, and new lab safety training modules for students. All of those can be widely disseminated, adding to options for remote learning that will become more essential as the nation weathers the impacts of the COVID-19 pandemic. The push for new energy sources has required an expansion in our understanding of fundamental chemistry. This is particularly true with respect to catalysis, with metal exchanged zeolites being actively utilized within industry. A significant roadblock to the further implementation of new zeolite catalysts is the general inability to control local structure such as active site spatial arrangement, a grand challenge problem in zeolite science. Recent work by one of the investigators’ research groups indicates that it is potentially possible to control the aluminum arrangement within the framework of a small pore zeolite (known as SSZ-39) by simply varying the relative amount of the cis and trans isomer of the organic structure directing agent used in synthesis. The research objective of the project is thus to guide the rational synthesis of zeolites with controlled active site arrangement by understanding the nucleation and growth of SSZ-39 from a faujasite zeolite. The central hypothesis of the project is that the nucleation and growth of SSZ-39, in an interconversion process from faujasite, is controlled by the dissolution of the faujasite, with the SSZ-39 forming at the faujasite/aqueous interface via heterogeneous nucleation off the dissolving faujasite crystal. Research efforts will focus on ways to control the aluminum arrangement in a system where all synthesis parameters (save the isomer ratio) are held fixed. However, the understanding—and potential for efficient design—of active site control in zeolites requires both experimental and computational methodologies, as zeolite synthesis is complex and cannot be adequately described without advances in the marriage of experimental and computational research activities. The project thus addresses a critical need to develop comprehensive, multi-scale models and to advance the understanding and value of predictive tools within the STEM pipeline. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.