A University of Minnesota team has made major progress in the quest to design a specialized type of molecular sieve that could make the production of gasoline, plastics, and various chemicals more cost-effective and energy-efficient. The research was led by chemical engineering and materials science professor Michael Tsapatsis.
After over a decade of research, the team devised a means for developing free-standing, ultra-thin zeolite nanosheets that as thin-films can speed up the filtration process and require less energy. The researchers have a provisional patent and hope to commercialize the technology.
Separating mixed substances can demand considerable amounts of energy — currently estimated to be approximately 15 percent of the total energy consumption — part of which is wasted due to process inefficiencies. One promising option for more energy-efficient separations is high-resolution molecular separation with membranes. They are based on preferential adsorption and/or sieving of molecules with minute size and shape differences. Among the candidates for selective separation membranes, zeolite materials (crystals with molecular-sized pores) show particular promise.
While zeolites have been used as adsorbents and catalysts for several decades, there have been substantial challenges in processing zeolitic materials into extended sheets that remain intact. To enable energy-savings technology, scientists needed to develop cost-effective, reliable, and scalable deposition methods for thin-film zeolite formation.
The team used sound waves in a specialized centrifuge process to develop “carpets” of flaky crystal-type nanosheets that are not only flat, but have just the right amount of thickness. The resulting product can be used to separate molecules as a sieve or as a membrane barrier in both research and industrial applications.
“We think this discovery holds great promise in commercial applications,” said Kumar Varoon, a University of Minnesota chemical engineering and materials science Ph.D. candidate. “This material has good coverage and is very thin. It could significantly reduce production costs in refineries and save energy.”