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Seifert J, Carey SJ, Schauermann S, Shaikhutdinov S, Freund HJ. Water and Carbon Dioxide Adsorption on CaO(001) Studied via Single Crystal Adsorption Calorimetry. Top Catal 2021. [DOI: 10.1007/s11244-021-01431-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
AbstractA new method to analyze microcalorimetry data was employed to study the adsorption energies and sticking probabilities of D2O and CO2 on CaO(001) at several temperatures. This method deconvolutes the line shapes of the heat detector response into an instrument response function and exponential decay functions, which correspond to the desorption of distinct surface species. This allows for a thorough analysis of the adsorption, dissociation, and desorption processes that occur during our microcalorimetry experiments. Our microcalorimetry results, show that D2O adsorbs initially with an adsorption energy of 85–90 kJ/mol at temperatures ranging from 120 to 300 K, consistent with prior spectroscopic studies that indicate dissociation. This adsorption energy decreases with increasing coverage until either D2O multilayers are formed at low temperatures (120 K) or the surface is saturated (> 150 K). Artificially producing defects on the surface by sputtering prior to dosing D2O sharply increases this adsorption energy, but these defects may be healed after annealing the surface to 1300 K. CO2 adsorbs on CaO(001) with an initial adsorption energy of ~ 125 kJ/mol, and decreases until the saturation coverage is reached, which is a function of surface temperature. The results showed that pre-adsorbed water blocks adsorption sites, lowers the saturation coverage, and lowers the measured adsorption energy of CO2. The calorimetry data further adds to our understanding of D2O and CO2 adsorption on oxide surfaces.
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O'Brien CP, Dostert KH, Hollerer M, Stiehler C, Calaza F, Schauermann S, Shaikhutdinov S, Sterrer M, Freund HJ. Supports and modified nano-particles for designing model catalysts. Faraday Discuss 2016; 188:309-21. [DOI: 10.1039/c5fd00143a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In order to design catalytic materials, we need to understand the essential causes for material properties resulting from its composite nature. In this paper we discuss two, at first sight, diverse aspects: (a) the effect of the oxide–metal interface on metal nanoparticle properties and (b) the consequences of metal particle modification after activation on the selectivity of hydrogenation reactions. However, these two aspects are intimately linked. The metal nanoparticle’s electronic structure changes at the interface as a catalyst is brought to different reaction temperatures due to morphological modifications in the metal and, as we will discuss, these changes in the chemistry lead to changes in the reaction path. As the morphology of the particle varies, facets of different orientations and sizes are exposed, which may lead to a change in the surface chemistry as well. We use two specific reactions to address these issues in some detail. To the best of our knowledge, the present paper reports the first observations of this kind for well-defined model systems. The changes in the electronic structure of Au nanoparticles due to their size and interaction with a supporting oxide are revealed as a function of temperature using CO2 activation as a probe. The presence of spectator species (oxopropyl), formed during an activation step of acrolein hydrogenation, strongly controls the selectivity of the reaction towards hydrogenation of the unsaturated CO bond vs. the CC bond on Pd(111) when compared with oxide-supported Pd nanoparticles.
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Affiliation(s)
| | - K.-H. Dostert
- Fritz Haber Institute of the Max Planck Society
- Department of Chemical Physics
- 14195 Berlin
- Germany
| | - M. Hollerer
- Institute of Physics
- University of Graz
- Austria
| | - C. Stiehler
- Fritz Haber Institute of the Max Planck Society
- Department of Chemical Physics
- 14195 Berlin
- Germany
| | - F. Calaza
- Fritz Haber Institute of the Max Planck Society
- Department of Chemical Physics
- 14195 Berlin
- Germany
| | - S. Schauermann
- Fritz Haber Institute of the Max Planck Society
- Department of Chemical Physics
- 14195 Berlin
- Germany
- Institut für Physikalische Chemie
| | - S. Shaikhutdinov
- Fritz Haber Institute of the Max Planck Society
- Department of Chemical Physics
- 14195 Berlin
- Germany
| | - M. Sterrer
- Institute of Physics
- University of Graz
- Austria
| | - H.-J. Freund
- Fritz Haber Institute of the Max Planck Society
- Department of Chemical Physics
- 14195 Berlin
- Germany
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McInroy AR, Uhl A, Lear T, Klapötke TM, Shaikhutdinov S, Schauermann S, Rupprechter G, Freund HJ, Lennon D. Morphological and chemical influences on alumina-supported palladium catalysts active for the gas phase hydrogenation of crotonaldehyde. J Chem Phys 2011; 134:214704. [DOI: 10.1063/1.3593472] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- A R McInroy
- Department of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
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Flores-Camacho JM, Fischer-Wolfarth JH, Peter M, Campbell CT, Schauermann S, Freund HJ. Adsorption energetics of CO on supported Pd nanoparticles as a function of particle size by single crystal microcalorimetry. Phys Chem Chem Phys 2011; 13:16800-10. [DOI: 10.1039/c1cp21677e] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Schalow T, Brandt B, Starr DE, Laurin M, Shaikhutdinov SK, Schauermann S, Libuda J, Freund HJ. Particle size dependent adsorption and reaction kinetics on reduced and partially oxidized Pd nanoparticles. Phys Chem Chem Phys 2007; 9:1347-61. [PMID: 17347708 DOI: 10.1039/b614546a] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Combining scanning tunneling microscopy (STM), IR reflection absorption spectroscopy (IRAS) and molecular beam (MB) techniques, we have investigated particle size effects on a Pd/Fe(3)O(4) model catalyst. We focus on the particle size dependence of (i) CO adsorption, (ii) oxygen adsorption and (iii) Pd nanoparticle oxidation/reduction. The model system, which is based on Pd nanoparticles supported on an ordered Fe(3)O(4) film on Pt(111), is characterized in detail with respect to particle morphology, nucleation, growth and coalescence behavior of the Pd particles. Morphological changes upon stabilization by thermal treatment in oxygen atmosphere are also considered. The size of the Pd particles can be varied roughly between 1 and 100 nm. The growth and morphology of the Pd particles on the Fe(3)O(4)/Pt(111) film were characterized by STM and IRAS of adsorbed CO as a probe molecule. It was found that very small Pd particles on Fe(3)O(4) show a strongly modified adsorption behavior, characterized by atypically weak CO adsorption and a characteristic CO stretching frequency around 2130 cm(-1). This modification is attributed to a strong interaction with the support. Additionally, the kinetics of CO adsorption was studied by sticking coefficient experiments as a function of particle size. For small particles it is shown that the CO adsorption rate is significantly enhanced by the capture zone effect. The absolute size of the capture zone was quantified on the basis of the STM and sticking coefficient data. Finally, oxygen adsorption was studied by means of MB CO titration experiments. Pure chemisorption of oxygen is observed at 400 K, whereas at 500 K partial oxidation of the particles occurs. The oxidation behavior reveals strong kinetic hindrances to oxidation for larger particles, whereas facile oxidation and reduction are observed for smaller particles. For the latter, estimates point to the formation of oxide layers which, on average, are thicker than the surface oxides on corresponding single crystal surfaces.
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Affiliation(s)
- T Schalow
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany
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Schalow T, Brandt B, Starr DE, Laurin M, Schauermann S, Shaikhutdinov SK, Libuda J, Freund HJ. Oxygen-induced Restructuring of a Pd/Fe3O4 Model Catalyst. Catal Letters 2006. [DOI: 10.1007/s10562-005-0007-5] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Johánek V, Schauermann S, Laurin M, Gopinath CS, Libuda J, Freund HJ. On the Role of Different Adsorption and Reaction Sites on Supported Nanoparticles during a Catalytic Reaction: NO Decomposition on a Pd/Alumina Model Catalyst. J Phys Chem B 2004. [DOI: 10.1021/jp031371f] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- V. Johánek
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Department of Chemical Physics, Faradayweg 4-6, 14195 Berlin, Germany, and National Chemical Laboratory, Catalysis Division, Pune 411 008, India
| | - S. Schauermann
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Department of Chemical Physics, Faradayweg 4-6, 14195 Berlin, Germany, and National Chemical Laboratory, Catalysis Division, Pune 411 008, India
| | - M. Laurin
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Department of Chemical Physics, Faradayweg 4-6, 14195 Berlin, Germany, and National Chemical Laboratory, Catalysis Division, Pune 411 008, India
| | - Chinnakonda S. Gopinath
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Department of Chemical Physics, Faradayweg 4-6, 14195 Berlin, Germany, and National Chemical Laboratory, Catalysis Division, Pune 411 008, India
| | - J. Libuda
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Department of Chemical Physics, Faradayweg 4-6, 14195 Berlin, Germany, and National Chemical Laboratory, Catalysis Division, Pune 411 008, India
| | - H.-J. Freund
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Department of Chemical Physics, Faradayweg 4-6, 14195 Berlin, Germany, and National Chemical Laboratory, Catalysis Division, Pune 411 008, India
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Schauermann S, Hoffmann J, Johánek V, Hartmann J, Libuda J. Adsorption, decomposition and oxidation of methanol on alumina supported palladium particles. Phys Chem Chem Phys 2002. [DOI: 10.1039/b203250n] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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