Zeolites are key catalysts in industry, including in petroleum refining, where they are widely used in fluid catalytic cracking and hydrocracking processes. More than 100 different types of synthetic zeolites have been produced, and synthesis strategies and design frameworks have continuously evolved over the years to improve performance and efficiency even further. Now, scientists from the University of Houston, including Jeffrey Rimer, Abraham E. Dukler Professor of chemical and biomolecular engineering at UH, have published a review article in Nature Synthesis summarizing methods developed over the past decade to prepare state-of-the-art zeolites with nano-sized dimensions and hierarchical structures.
The article emphasizes that smaller is better and that structure is critical. Rimer noted challenges with small pore sizes such as diffusion limitations and the obstruction of small molecules entering pores due to the accumulation of carbonaceous deposits known as coke. In order to overcome such challenges, newer methods must be developed that allow for smaller-sized zeolites with higher surface area, although producing zeolites smaller than 100 nm is a challenge in itself, Rimer said. The advanced methods described in the article aim to help accomplish these goals, including through the use of novel design principles like finned zeolites, which were invented at Rimer’s lab. The procedure for producing finned zeolites makes it easier to synthesize zeolite crystals with sizes less than 100 nm and enhanced mass-transport properties with the growth of fin-like protrusions on seed crystals.
The review also covers the emerging role of data analytics and machine learning in aiding zeolite design, and provides future perspectives in this growing area of research. Infusing computational and big data analyses in zeolite production can move the process away from trial-and-error methodologies, ultimately accelerating both the design and synthesis processes, and the reactions of zeolites themselves. This improved efficiency has many socio-economic advantages in a range of applications.
“Improved zeolite design includes the development of improved catalysts for energy applications (including advancements in alternative energy), new technologies for regulating emissions that impact the environment and separations to improve industrial processes with impact on petroleum refining, production of chemicals and water purification,” said Rimer.