Samiksha Poudyal

Merck & Co., Inc., Rahway, NJ, USA (United States)

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Siris Laursen

University of Tennessee at Knoxville

Xiaoyan Ji

Luleå University of Technology

Jeffrey T. Miller

Purdue University West Lafayette

Brittany M. Armstrong

Merck & Co., Inc., Rahway, NJ, USA (United States)

Morghan Parker

University of Tennessee at Knoxville

John Reardon

University of New Mexico

Barbara Kutchko

National Energy Technology Laboratory

Alan House

William C. Hecker

Brigham Young University

Kari M. Cook

Bridge University

Cooperative Institutions

Merck & Co., Inc., Rahway, NJ, USA (United States)

National Energy Technology Laboratory

United States Department of Energy

University of Pittsburgh

Brigham Young University

United States Military Academy

Nanjing University

Nanjing Tech University

University of Tennessee at Knoxville

University of New Mexico

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Control of Selectivity through a New Hydrogen-Transfer Mechanism in Photocatalytic Reduction Reactions: Electronically Relaxed Neutral H and the Role of Electron–Phonon Coupling

The Journal of Physical Chemistry Letters (2019)

Samiksha Poudyal Morghan Parker Siris Laursen

Controlling the fate of hydrogen in photocatalytic synthesis reactions has been an ongoing challenge in CO2 reduction by H2O and nitrogen fixation efforts. Our studies have identified catalysts (SiC) that exhibit dramatically improved selectivity toward hydrogenation and a photocatalytically active ground-state neutral H that is transferred via vibrational excitation through electronic-vibrational coupling with excited states. This new species and mechanism have been directly connected to the fate of H by comparing GaN and SiC and purposefully manipulated over a single catalyst (SiC) to illustrate generality. Studies included surface reaction modeling using density functional theory (DFT), experimental performance, 1H NMR spectroscopy, and deuterium kinetic isotope effect. The discovery of this mechanism may have considerable impact on the direction of photocatalytic synthesis, the understanding of the coupling of thermal and photoelectrochemical reaction steps, and electronic-vibrational spectrum coupling in energy sequestration.

Kinetic isotope effect

Isotopic labeling

10.1021/acs.jpclett.9b01614

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Photocatalytic CO₂ reduction by H₂O: insights from modeling electronically relaxed mechanisms

Catalysis Science & Technology (2019)

Samiksha Poudyal Siris Laursen

Understanding of the ground-state surface reaction mechanism for photocatalytic CO₂reduction and new connections between catalyst surface reactivity and experimentally observed activity and selectivity are presented to facilitate the development of catalysts that exhibit improved activity, controlled product distributions, and enhanced quantum yield.

Reactivity

Quantum yield

10.1039/c8cy02046a

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Citations (24)

Manufacturing Process Development for Belzutifan, Part 4: Nitrogen Flow Criticality for Transfer Hydrogenation Control

Organic Process Research & Development (2021)

Nastaran Salehi Marzijarani Adam J. Fine Stephen M. Dalby Rekha Gangam Samiksha Poudyal

A scalable and efficient synthesis of hydroxyindanone 3, a key intermediate for belzutifan (MK-6482), is described. Mechanistic studies revealed the sensitivity of the reduction reaction toward the CO2 byproduct. Special effort was required to design a scale-insensitive process for the removal of CO2 with active nitrogen headspace sweeping, supported by process modeling and verification with process analytical technology data. Automated sampling facilitated data-rich experimentation via kinetic profiling, culminating in enhanced understanding and further robustness-based optimization for the reduction reaction. Herein we report the development of a one-pot through-process with direct isolation of 3 in high yield (>90%) and purity (>99 LCAP, >99 ee) at commercial scales. The newly developed process ensures process robustness and improves cycle times and process mass intensity.

Robustness

Process development

Flow chemistry

10.1021/acs.oprd.1c00231

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Citations (21)

Mechanistic Insights into Elevated Temperature Photocatalytic Processes via Combined Experimental and Theoretical Approach

Samiksha Poudyal

Source

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Citations (0)

List of Contributors

Elsevier eBooks (2015)

Kathryn A. Berchtold Tracy L. Bucholz Jeffrey T. Culp David A. Dzombak Alan House

10.1016/b978-0-444-63259-3.01002-8

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Reducibility of alumina-supported cobalt Fischer–Tropsch catalysts: Effects of noble metal type, distribution, retention, chemical state, bonding, and influence on cobalt crystallite size

Applied Catalysis A General (2012)

Kari M. Cook Samiksha Poudyal Jeffrey T. Miller Calvin H. Bartholomew William C. Hecker

Fischer–Tropsch process

Noble metal

10.1016/j.apcata.2012.09.032

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Citations (84)

Insights into Elevated-Temperature Photocatalytic Reduction of CO₂ by H₂O

The Journal of Physical Chemistry C (2018)

Samiksha Poudyal Siris Laursen

Photocatalytic reduction of CO2 for the production of synthesis gas, hydrocarbons, alcohols, or aldehydes from only CO2, H2O, and solar radiation may be a promising route to recycle CO2 waste at the source of its production, reduce atmospheric CO2 through direct removal from Earth's atmosphere, and/or produce CH4 rocket fuel on Mars. In this study, we present the first studies of high-temperature (350 °C) photocatalytic reduction of CO2 in the gas phase over a suite of semiconductors with a range of surface chemical reactivity and bulk electronic properties, namely, SiC, Si, Pt/TiO2, and GaN. The results indicate that catalysts that exhibit high Debye temperatures and elevated surface reactivity may enable the production of new reaction intermediates that facilitate C–O cleavage and full CO2 reduction to CH4. Elevated photocatalyst surface reactivity also correlated with dramatically improved selectivity between hydrogenation (CH4 production) and H2 evolution, for example, 1:8, 1:71, 1:400, and 1:1000+ for SiC, Si, Pt/TiO2, and GaN, respectively. Tests at low (250 °C) and high (350 °C) temperatures over top-performing catalysts, SiC and Si, show that both C–O cleavage and H2O dissociation may be thermally promoted, leading to enhanced CH4, CO, and H2 production, further indicating surface-chemical and thermal-input contributions.

10.1021/acs.jpcc.7b12662

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Citations (34)

Photo- and Electro-Catalysis

Elsevier eBooks (2015)

Siris Laursen Samiksha Poudyal

Overpotential

Clean energy

Energy transformation

10.1016/b978-0-444-63259-3.00008-2

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Citations (10)