Associate Professor Wei Fan of the Chemical Engineering Department has collaborated with UMass Chemistry Professor Scott Auerbach and others to boost our understanding of zeolite catalyst structure and vibrations in an effort that can lead to new materials for clean energy and carbon capture, among many other applications. Their cutting-edge research appeared as the cover story in a recent issue of the Journal of the American Chemical Society (JACS).
The JACS paper describes how the researchers used systematic zeolite syntheses and a technique called Raman spectroscopy, in addition to quantum mechanical modeling, to discover new nano-scale building blocks they call “tricyclic bridges” (or collections of three zeolite rings connected together) to help explain the porous structures of zeolites and their dynamical behaviors.
The co-authors also include first author Tongkun Wang and Song Luo at UMass Amherst, along with others at Worcester Polytechnic Institute.
As Fan and Auerbach explain in the News Office story, zeolite crystals, employed for refining petroleum to gasoline and biomass into biofuels among other applications, are the most commonly used catalysts by weight on the planet, and discovering mechanisms for how zeolites form has been of intense interest to the chemical industry and others.
The researchers say they hope their advance on a new way to understand zeolite structure and vibrations leads to new, tailor-made zeolites for use in sophisticated new applications.
Fan explains that, until now, experimental studies on the synthesis of zeolites with new structures and compositions have been based on trial-and-error methods, and he says the process has posed a “tantalizing challenge.”
The contribution of this research, based on tricyclic bridges, is a groundbreaking tool for understanding crystallization pathways, opening the door to designing materials for advanced applications in catalysis and separations, as the researchers say.
In addition, the researchers point out in the News Office article that “it is often assumed with little evidence that Raman bands can be assigned to individual zeolite rings.”
Auerbach, Fan, and their collaborators tested this assumption and found that understanding Raman spectra with individual rings is too simplistic, and that tricyclic bridges play a critical role in zeolite vibrations. Using this research, they discovered a precise relationship between zeolite bond angle and Raman frequency that can be used to pinpoint structures that form during zeolite crystallization.
According to the News Office, in their future work Auerbach, Fan, and their team plan to measure and model Raman spectra during the zeolite crystallization process to determine which tricyclic bridges are present and will become inherited by the resulting zeolites.
Fan is the principal investigator in the Fan Porous Materials Research Group, which focuses on the rational synthesis of nanoporous materials for biorefinery and drug delivery. Fan says that in his research the pore structure and size, surface properties, and active sites are tailored based on the comprehensive understanding of their crystallization mechanism.
Auerbach heads the CRUNCH Lab, which he says, “lives at the fertile intersection of computational science, nanotechnology, and clean energy — three of the most interesting and important areas of current science and engineering.” Auerbach says that the CRUNCH stands for “Chemistry Research Using Nice Computer Hardware” and focuses on building bridges between the predictive power of computational chemistry and important problems in chemical engineering. (February 2020)