CBE Seminar: Low-temperature Dry Reforming of Methane over PT Promoted NiCe@SiO2 Multi–Yolk–Shell Nanotube Catalysts; and Engineering a Nicotinamide Mononucleotide Redox Cofactor System for Biocatalysis

Engineering Hall 2430 - Colloquia Room
William Black and Sunkyu Kim

Ph.D. Candidates
Department of Chemical and Biomolecular Engineering
UC Irvine

Low Temperature Dry Reforming of Methane Over PT Promoted NiCe@SiO2 Multi–Yolk–Shell Nanotube Catalysts

Abstract: Dry reforming of methane (DRM) can be used to utilize greenhouse gases of CO2 and CH4, and convert biogas to value-added chemicals. DRM is typically performed at elevated reaction temperatures (> 750 ºC) due to the high energy needed to activate C–H and C–O bonds. This condition not only increases the operating costs but also causes catalyst sintering and carbon formation leading to catalyst deactivation. Therefore, low-temperature (< 600 ºC) DRM is desired and has been researched on noble metal promoted (e.g., Pt, Ir, and Rh) Ni-based catalysts, since they can exhibit high activity and stability against carbon deposition. In this work, Pt promoted NiCe@SiO2 multi–yolk–shell nanotube catalysts have been investigated for low-temperature (500 ºC) DRM. Our previous results confirmed that the NiCe@SiO2 multi–yolk–shell nanotube structure could exhibit a high turnover frequency and high resistance to carbon deposition compared to conventional NiCe/SiO2Imp synthesized by impregnation method in tri-reforming of methane at 750 ºC. These multi–yolk–shell nanotube structures have been further evaluated for DRM reaction at 500 ºC and the effect of Pt promotion is investigated. The PtNiCe@SiO2 shows stable activity, whereas the activity of PtNiCe/SiO2Imp decrease to 48.7% of its initial activity during 20 h of DRM reaction. PtNiCe@SiO2 with 0.25 wt.% of Pt loading has higher resistance to carbon deposition than any other catalysts in this work. It is possible that the Pt–Ni alloy formation and multi–yolk–shell structure could enhance the DRM activity and lead to a lower carbon deposition. In the presentation, I will provide a detailed characterization of the samples using electron microscopy and x-ray spectroscopy, and elucidate the effect of Pt and Ni interaction on catalyst activity.

Bio: Sunkyu Kim joined the Erdem Sasmaz lab in the fall of 2016, and he is now a Ph.D. student in the Department of Chemical and Biomolecular Engineering. His experimental research currently focuses on synthesizing nanomaterials and applying them to the heterogeneous catalytic reactions such as methane reforming and CO2 hydrogenation. 

Engineering a Nicotinamide Mononucleotide Redox Cofactor System for Biocatalysis

Abstract: One major challenge of engineering microoranisms is the ability to specifically control the flow of electrons, carbon and energy throughout the cell. These shared resources are sensitive to disruption, and large amounts of these resources are required for production of these compounds. Black's talk will focus on recent work from the Li Group, which developed an insulated electron delivery system within a cell, much like putting insulation around a wire in electronics. The foundation of this system is a computationally designed enzyme that can selectively reduce the noncanonical redox cofactor (electron donor and acceptor), nicotinamide mononucleotide, NMN+. This system has shown great robustness to support diverse redox chemistries in vitro with a high total turnover number, to channel reducing power in Escherichia coli whole cells specifically from glucose to a pharmaceutical intermediate, and to sustain the high metabolic flux required for the central carbon metabolism to support growth.

Bio: Will Black is a Ph.D. candidate in the Han Li Group in the the Department of Chemical and Biomolecular Engineering.