Title: Synergy between Ceria Oxygen Vacancies and Cu Nanoparticles Facilitates the Catalytic Conversion of CO₂ to CO under Mild Conditions

Abstract

The performance of supported metal catalysts can depend on many factors, including metal particle size and dispersion and metal–support interactions, and differentiation of these effects is challenging because of their interwoven relationship. Copper/ceria catalysts are well-known redox catalysts studied in the conversion of CO and CO₂ via oxidation and/or reduction pathways. The redox behaviors of each species, Cu-CuO and CeO_x-CeO₂, are often suggested to be interlinked, allowing ceria-supported copper domains to outperform copper species on other, nonredox active supports. In this work, the catalytic activity of nanosized Cu supported on either cerium oxide or mesoporous silica is explored using samples where the Cu weight loading, particle size, and dispersion of Cu are held constant to highlight the impact of the two supports on catalytic performance without additional influencing factors. The Cu/CeO₂ catalysts are synthesized via a space-confined method to limit the growth of CeO₂ particles and to achieve a high dispersion of Cu. Through in situ XRD and XAS, it is shown that the presence of Cu nanoparticles on the CeO₂ support lowers the reduction temperature of CeO₂, allowing formation of oxygen vacancies at low temperatures <300 °C. The Cu/CeO_x catalyst demonstrates 100% CO selectivity in the low temperature (300more » °C) and ambient pressure conversion of CO₂ to CO, even when approaching equilibrium conversion. Moreover, this catalyst is approximately 4 times more active than the corresponding Cu/SiO₂ catalyst with otherwise similar structural attributes. The potential reaction pathways are probed by in situ FTIR and in situ XAS at various temperatures, identifying Cu⁺-CO species and oxygen vacancies forming under some conditions. The collected experimental evidence also suggests a reaction sequence for CO₂ hydrogenation over Cu/CeO_x catalysts, consistent with DFT reports in the literature.« less

Authors:

Yang, Sheng-Chiang ^[1]; Pang, Simon H.  ^[2];

• Search DOE PAGES for author "Pang, Simon H."
• Search DOE PAGES for ORCID "0000-0003-2913-1648"

Sulmonetti, Taylor P. ^[2]; Su, Wei-Nien  ^[2];

• Search DOE PAGES for author "Su, Wei-Nien"
• Search DOE PAGES for ORCID "0000-0003-1494-2675"

Lee, Jyh-Fu ^[3]; Hwang, Bing-Joe  ^[1];

• Search DOE PAGES for author "Hwang, Bing-Joe"
• Search DOE PAGES for ORCID "0000-0002-3873-2149"

Jones, Christopher W.  ^[2]

• Search DOE PAGES for author "Jones, Christopher W."
• Search DOE PAGES for ORCID "0000-0003-3255-5791"

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+ Show Author Affiliations

1. Georgia Inst. of Technology, Atlanta, GA (United States); National Taiwan Univ., Taipei (Taiwan)
2. Georgia Inst. of Technology, Atlanta, GA (United States)
3. National Synchrotron Radiation Research Center, Hsinchu (Taiwan)

Publication Date:

Tue Nov 13 00:00:00 EST 2018

Research Org.:

Energy Frontier Research Centers (EFRC) (United States). Center for Understanding and Control of Acid Gas-induced Evolution of Materials for Energy (UNCAGE-ME); Georgia Institute of Technology, Atlanta, GA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1566567

Grant/Contract Number:  

SC0012577

Resource Type:

Accepted Manuscript

Journal Name:

ACS Catalysis

Additional Journal Information:

Journal Volume: 8; Journal Issue: 12; Journal ID: ISSN 2155-5435

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; catalysis (heterogeneous); defects; membrane; carbon capture; materials and chemistry by design; synthesis (novel materials); synthesis (self-assembly); synthesis (scalable processing)