Presented By: Chemical Engineering
ChE SEMINAR: Phillip Christopher, University of California Santa Barbara
"Pixie dusts in heterogeneous catalysis: Using ultra-dilute metal alloys to promote selectivity and stability"
Abstract:
Industrial heterogeneous catalysts ubiquitously contain trace amounts (ppm) of “promoters” species, which can substantially promote activity, selectivity, or stability. Recently, it has been observed that the addition of very small amounts (<1:100 atom %) transition metal atoms (e.g. Pt, Pd, Ni) to coinage metal (Au, Ag and Cu) surfaces can drastically promote selectivity in hydrogenation and dehydrogenation catalysis. The unique catalytic behavior of these ultra-dilute alloys derives from bifunctional reaction pathways where molecular activation at the dispersed promoter sites results in intermediate spillover onto the coinage metal host, enabling distinct reactivities. Here, I will discuss the design of ultra-dilute alloy catalysts with a focus on selective ethylene epoxidation on Ag-based alloys and sintering resistance of Cu-based alloys during accelerated aging. I will highlight how a combination of theory, surface science, in-situ spectroscopy and high surface area catalyst measurements can be used to design and understand the function of dilute promoters. These findings demonstrate that dilute alloy catalysts have potential to improve catalyst performance beyond hydrogenation/dehydrogenation chemistries and that they offer potential for simultaneous promotion of rate/selectivity and stability.
Speaker Bio:
Phillip Christopher earned his B.S. in chemical engineering from University of California, Santa Barbara in 2006 and his M.S and Ph.D. in chemical engineering from University of Michigan in 2011 working with Prof. Suljo Linic. From 2011-2017 he was an Assistant Professor at University of California, Riverside. In 2017 he moved to the University of California, Santa Barbara where he is a Professor and Vice Chair for Undergraduate Affairs in the Chemical Engineering Department and the Mellichamp Chair in Sustainable Manufacturing. He serves as a Senior Editor for ACS Energy Letters. His research interests are in sustainable chemical conversion, heterogeneous catalysis by supported metals, dynamic behavior of catalysts, and photocatalysis by metal nanostructures. He has been given various awards including the Presidential Early Career Award for Scientists and Engineers (PECASE), AIChE CRE Division Young Investigator Award, and Ipatieff Prize from the ACS.
Industrial heterogeneous catalysts ubiquitously contain trace amounts (ppm) of “promoters” species, which can substantially promote activity, selectivity, or stability. Recently, it has been observed that the addition of very small amounts (<1:100 atom %) transition metal atoms (e.g. Pt, Pd, Ni) to coinage metal (Au, Ag and Cu) surfaces can drastically promote selectivity in hydrogenation and dehydrogenation catalysis. The unique catalytic behavior of these ultra-dilute alloys derives from bifunctional reaction pathways where molecular activation at the dispersed promoter sites results in intermediate spillover onto the coinage metal host, enabling distinct reactivities. Here, I will discuss the design of ultra-dilute alloy catalysts with a focus on selective ethylene epoxidation on Ag-based alloys and sintering resistance of Cu-based alloys during accelerated aging. I will highlight how a combination of theory, surface science, in-situ spectroscopy and high surface area catalyst measurements can be used to design and understand the function of dilute promoters. These findings demonstrate that dilute alloy catalysts have potential to improve catalyst performance beyond hydrogenation/dehydrogenation chemistries and that they offer potential for simultaneous promotion of rate/selectivity and stability.
Speaker Bio:
Phillip Christopher earned his B.S. in chemical engineering from University of California, Santa Barbara in 2006 and his M.S and Ph.D. in chemical engineering from University of Michigan in 2011 working with Prof. Suljo Linic. From 2011-2017 he was an Assistant Professor at University of California, Riverside. In 2017 he moved to the University of California, Santa Barbara where he is a Professor and Vice Chair for Undergraduate Affairs in the Chemical Engineering Department and the Mellichamp Chair in Sustainable Manufacturing. He serves as a Senior Editor for ACS Energy Letters. His research interests are in sustainable chemical conversion, heterogeneous catalysis by supported metals, dynamic behavior of catalysts, and photocatalysis by metal nanostructures. He has been given various awards including the Presidential Early Career Award for Scientists and Engineers (PECASE), AIChE CRE Division Young Investigator Award, and Ipatieff Prize from the ACS.
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