Oct
14
Perhaps the First Molecular Filter Arrives
October 14, 2011 | 2 Comments
At the University of Minnesota a research team has designed a specialized type of molecular sieve that could make the production of gasoline, plastics and various chemicals more cost effective and energy efficient.
After more than a decade of research, the team devised a means for developing freestanding, ultra-thin zeolite nanosheets that as thin films can speed up the filtration process and require less energy. The team has a provisional patent and hopes to commercialize the technology.
Considered a breakthrough, the research led by chemical engineering and materials science professor Michael Tsapatsis in the university’s College of Science and Engineering, has been published in the most recent issue of the journal Science.
Separating mixed substances can require considerable amounts of energy, with current estimates running about 15 percent of the total energy consumption, with much wasted due to process inefficiencies. When fuel was abundant and inexpensive, separation technology was not a major consideration when designing industrial separation processes such as distillation for purifying gasoline and polymer precursors. But as energy prices rise and policies promote efficiency, the need for more energy-efficient alternatives has expanded.
The leading field for more energy-efficient separations is high-resolution molecular separation with membranes. Membranes perform adsorption and/or sieving of molecules with minute size and shape differences much like a filter. Among the candidates for selective separation membranes, zeolite materials (crystals with molecular-sized pores) show particular promise.
Zeolites have been used as adsorbents and catalysts for several decades. But there have been substantial challenges in organizing zeolitic crystal materials into extended sheets that remain intact. To enable energy-savings technology, scientists needed to develop cost-effective, reliable and scalable deposition methods for building thin film zeolite sheets.
The University of Minnesota team’s innovation is to use 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.
Kumar Varoon, a University of Minnesota chemical engineering and materials science Ph.D. candidate and one of the primary authors of the paper said, “We think this discovery holds great promise in commercial applications. This material has good coverage and is very thin. It could significantly reduce production costs in refineries and save energy.”
Folks in the fuel business have to be cheered up with this news. In petroleum refining heat is a major cost and consumes a sizable share of the incoming energy to function. Any substitution that costs less would put the energy back into the market as well, releasing much more fuel to market In Biofuels an important expense is in separation technology and case for most of the detractors success in complaining about efficiency. A breakthrough to commercial scale would soon flow across the developed word affecting practically every type of fluid handling in production over time.
The University of Minnesota success is a bigger deal than first glance would suggest. Just consider the value in separating the main products of oil without heating to hundreds of degrees or producing alcohols without heating for the distillation. The process effects are considerable too; a filtration step substituted for distillation could make continuous flow more practical than batches. The impacts are not fully known, but projection suggests a far-reaching impact.
It’s a big group at Minnesota, members of the research team include Ph.D. candidates Kumar Varoon and Xueyi Zhang; postdoctoral fellows Bahman Elyassi and Cgun-Yi Sung; former students and Ph.D. graduates Damien Brewer, Sandeep Kumar, J. Alex Lee and Sudeep Maheshwari, graduate student Anudha Mittal; former undergraduate student Melissa Gettel; and faculty members Matteo Cococcioni, Lorraine Francis, Alon McCormick, K. Andre Mkhoyan and Michael Tsapatsis.
The research is backed by the United States Department of Energy (including the Carbon Sequestration Program and the Catalysis Center for Energy Innovation — An Energy Frontier Center), the National Science Foundation and a variety of University of Minnesota partners.
Step one is finally here, thanks to the folks noted above.
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