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McKelvey School of Engineering

EECE Seminar - Mark Swihart

Friday, November 19, 2021 | 11:00 AM - 12:00 PM

Uncas A. Whitaker Hall, Whitaker Auditorium, Room 100
6760 Forest Park Pkwy, St. Louis, MO 63105, USA

Mark Swihart,  UB Distinguished Professor and Department Chair, Chemical and Biological Engineering, University at Buffalo (SUNY)

Flame-based Aerosol Synthesis of Metal Nanoparticles and Supported-Metal Nanostructures

Abstract: This talk will introduce a nanomaterial synthesis method that we call the High-Temperature Reducing Jet (HTRJ) process, describe some of the materials generated by this process, and discuss their applications. Flame-based processes are the dominant commercial approach to the production of large-volume nanomaterials such as carbon black, fumed silica, and titania nanoparticles. However, flame-based synthesis of non-noble metal nanoparticles is not usually possible, due to the presence of an oxidizing region in the flame and coupling between flame chemistry and particle formation chemistry. Our HTRJ process overcomes these limitations and also allows synthesis at lower temperature than in conventional flame reactors. In our HTRJ reactor system, the hot combustion products of a fuel-rich hydrogen flame pass through a converging-diverging nozzle to accelerate them to sonic or supersonic velocity. An aqueous precursor solution injected at the throat section of the nozzle is atomized by the high velocity gas stream, providing exceptionally rapid heating and mixing of the hot gas and liquid droplets. For many metals, the droplets evaporate, and the precursor decomposes, initiating nucleation of particles in a reducing environment containing excess H2. After the reaction zone, particles are cooled immediately to prevent further particle growth and coalescence. This approach separates combustion chemistry from particle formation chemistry, allowing use of low-cost aqueous solutions of metal nitrates and other salts as precursors. Metals that can be reduced by hydrogen in the presence of water are generated as metallic nanoparticles. Complete conversion of precursors to particles allows precise composition control of alloys and multi-component mixtures. Metals that cannot be reduced by hydrogen in the presence of water form as oxides in this system, and very often follow a droplet-to-particle route, rather than a gas-to-particle route, producing dense or hollow micro- or nano-spheres. Our recent and current efforts include single-step synthesis of metal alloy particles supported on metal oxides or reduced graphene oxide (RGO), integrated synthesis and surface passivation, production of mesoporous silica and other mesoporous ceramics by droplet-to-particle conversion, and applications of these materials in conductive inks, membranes for hydrogen/CO2 separation, and catalysis.

 

Event Type

Seminar/Colloquia

Schools

McKelvey School of Engineering

Topic

Science & Technology

Department
Energy, Environmental & Chemical Engineering
Event Contact

Jesi Hempstead

Speaker Information

Mark T. Swihart earned a B.S. from Rice University in 1992, and a Ph.D. in 1997 from the University of Minnesota, both in Chemical Engineering, then spent one year as a post-doctoral researcher in Mechanical Engineering at the University of Minnesota. Professor Swihart joined the faculty of the department of Chemical and Biological Engineering at the University at Buffalo (SUNY) in 1998, has been a full professor since 2008, and was named a UB Distinguished Professor in 2014. He currently serves as Department Chair. His research interests include synthesis, processing, and applications of nanoparticles and other nanomaterials. He has co-authored nearly 300 peer-reviewed journal papers, which have been cited nearly 20,000 times. Swihart has received the Kenneth Whitby award from the American Association for Aerosol Research, the Schoellkopf medal from the American Chemical Society, and the J.B. Wagner award from the Electrochemical Society, along with university awards for research, teaching, and mentoring of undergraduate researchers. He is a fellow of the American Association for the Advancement of Science and the American Institute of Chemical Engineers. Swihart currently serves as an editor for Aerosol Science and Technology, and on the Board of Consulting Editors of AIChE Journal. He has served as research advisor to more than eighty current and former graduate students and more than 110 undergraduate researchers at UB.

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