| NSF Org: |
CBET Division of Chemical, Bioengineering, Environmental, and Transport Systems |
| Recipient: |
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| Initial Amendment Date: | May 25, 2018 |
| Latest Amendment Date: | August 21, 2019 |
| Award Number: | 1804436 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Robert McCabe
CBET Division of Chemical, Bioengineering, Environmental, and Transport Systems ENG Directorate for Engineering |
| Start Date: | September 1, 2018 |
| End Date: | February 28, 2022 (Estimated) |
| Total Intended Award Amount: | $300,000.00 |
| Total Awarded Amount to Date: | $340,682.00 |
| Funds Obligated to Date: |
FY 2019 = $40,682.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
1350 BEARDSHEAR HALL AMES IA US 50011-2103 (515)294-5225 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
617 Bissell Road Ames IA US 50011-1098 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): |
Catalysis, EPSCoR Co-Funding |
| Primary Program Source: |
01001920DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.041 |
ABSTRACT
Biomass, produced from agricultural waste and non-edible plants, offers an abundant, cheap, and renewable source of chemical raw materials that can be upgraded to a wide range of chemical products. The complexity of the biomass-derived raw materials necessitates finely tuned catalysts that can attack specific chemical bonds to form desired products. In this study, catalysts consisting of noble metals dispersed on carbon supports will be tuned to produce specific chemicals, with emphasis on engineering the carbon materials in ways that direct the chemistry towards the targeted chemical products. The science and engineering generated by the study will promote the production of chemicals from renewable feedstocks, thereby decreasing dependence on fossil resources, reducing global carbon footprint, stimulating and diversifying rural economies, and promoting a range of educational opportunities.
Metal-support interactions provide a suitable handle to engineer the catalytic activity of a chosen metal function through both chemical and electronic effects. Such interactions have been generally overlooked in the case of carbon as this material is usually considered to be inert in catalysis. Yet, there is ample evidence in materials science that the electronic properties of carbons can be tailored by varying the nature and concentration of the oxygen moieties that cover their surface. As a result, the work function of conventional carbon scaffolds can be modulated between 4.4 and 5.4 eV, providing an ideal platform for studying and harnessing electronic metal-support interactions without the challenges associated with atom mobility that are common for oxides. The project will decouple the chemical and electronic interactions introduced by oxygen moieties and reveal their true effects on the hydrogenation performance of supported palladium (Pd) and platinum (Pt) nanoparticles. Cinnamaldehyde and furfural will be utilized as probe molecules as they present both carbon-carbon and carbon-oxygen double bonds - two functionalities common in bio-based chemicals. The associated fundamental understanding will yield transformative concepts for manipulating the performance of carbon-supported catalysts, in particular Pd/C and Pt/C, two catalysts with broad applications in the chemical industry. Broader aspects of the project will include several educational and outreach activities highlighted by a student-led community-based program "Be Iowa Smart" that will attract a diverse group of students to science, technology, engineering, and mathematics (STEM) disciplines, and build a competitive and globally engaged workforce in Iowa and the Midwest.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
The rational design of catalysts for the selective hydrogenation of multifunctional chemicals remains a major challenge that affects a wide range of transformations in the pharmaceutical, fragrance, flavors, and biobased chemical industries. Carbon is typically preferred over conventional oxide supports for these hydrogenations as it affords supported metal catalysts with superior selectivity and stability, especially for reactions in water. However, the positive role of the carbon support on the performance of the metal active phase remains poorly understood and descriptors that would guide future catalyst design are desperately needed. This project built on recent advances in carbon research that demonstrated correlations between the defect structure of nanocarbons and their optoelectronic properties. Variations in the support's electronic properties were expected to modulate the electronic structure of decorating metal nanoparticles, hence their catalytic performance.
This project demonstrated that oxygen-containing functional groups that are ubiquitous on carbon surfaces have a doping effect on the electronic properties of the carbon material and shift its work function. Increasing the oxygen concentration from 7 to 33% for reduced graphene oxide, a model carbon support, shifted its work function from 4.5 to 5.1 eV. This shift induced a charge transfer near the metal-carbon interface of Pd/C catalysts and the formation of a charge-depleted Pdδ+ phase. A linear correlation was established between the concentration of oxygen groups at the surface, the support's work function, and the Pdδ+ contribution in Pd3d X-ray photoelectron spectra. These electronic-metal support interactions (EMSI) were found to have a dramatic role on the catalytic activity of Pd/C as the intrinsic rate of Pd atoms near the interface was enhanced 200 fold compared to atoms at the apex of 5 nm particles. Moreover, a 0.6 eV increase in the support's work function translated into a 23 percentage point increase in the selectivity of the Pd active phase, from 73% to 96%, for the hydrogenation of cinnamaldehyde, a model α,β-unsaturated compound. Similar correlations were observed in the case of nitrogen-doped carbon supports.
The linear correlations established thorough this project between carbon surface chemistry, support work function, and catalytic activity of the supported metal phase will enable the rational design of carbon-supported catalysts for a wide range of thermocatalytic and electrocatalytic reactions. In addition to these scientific advances, this project served as a platform to train three graduate students and four undergraduates.
Last Modified: 06/30/2022
Modified by: Jean-Philippe Tessonnier
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