Elsevier

Surface Science

Volume 406, Issues 1–3, 31 May 1998, Pages 125-137
Surface Science

Adsorption and reaction of carbon dioxide on pure and alkali-metal promoted cold-deposited copper films

https://doi.org/10.1016/S0039-6028(98)00105-8Get rights and content

Abstract

The adsorption and reaction of carbon dioxide on pure and potassium-doped cold-deposited copper films has been investigated at low temperatures and under UHV conditions using surface enhanced Raman spectroscopy (SERS) and X-ray photoemission spectroscopy (XPS). On pure copper films, an activated anionic COδ2 species has been observed in addition to a weakly physisorbed CO2 species. On potassium-doped copper films, monodentate carbonate as well as carbon monoxide has been observed in addition to the two carbon dioxide species. After adsorbing CO2 on preadsorbed hydrogen, weak features at 2841 and 2949 cm−1 indicate the formation of formate. This result is compared to formate on pure copper films, synthesised by adsorbing formic acid on preoxidised copper films and subsequent annealing to 200 K.

Introduction

Even in the early 1980s, the investigation of the chemistry of carbon dioxide was thought of as being of only minor importance, because the molecule was expected to be rather unreactive in the sense that in many cases the reactions had to overcome a rather high activation barrier 1, 2. However, by the introduction of a metal complex (e.g. in the form of a catalyst) this barrier can be reduced, going along with an increase in the reaction rate. However, only after the introduction of the so-called “ICI” process for methanol synthesis [3], and especially after the claim that carbon dioxide was the source of carbon in the reaction had been widely accepted, has the adsorption and activation of CO2 become object of intense research. Reviews of the current understanding of carbon dioxide chemistry have been published recently 4, 5.

Here we present our recent results of the investigation of carbon dioxide adsorption, activation and reaction on rough copper surfaces using surface enhanced Raman spectroscopy and X-ray photoelectron spectroscopy. The results have implications for the industrial methanol synthesis process, where methanol is produced by passing syngas (CO/CO2/H2) over a Cu/ZnO/Al2O3 catalyst. It seems that in this process the CO2 is the main source of carbon 6, 7, that at least the critical steps of the reaction take place on copper sites [8], and that the role of ZnO may be to maintain more of the metallic copper in the form of thin islands [9]. Special regard was directed in our experiments towards the reaction of carbon dioxide or its reaction products with coadsorbed hydrogen atoms to form an adsorbed formate species, because there is much evidence that formate is the pivotal intermediate in methanol synthesis [10].

The article is structured as follows: after an experimental section, the results of the investigations of the adsorption of carbon dioxide on clean and K-promoted copper are presented. The subsequent sections concern the coadsorption of carbon dioxide and atomic hydrogen on K-doped copper, and for comparison a discussion of synthesised formate adsorbed on clean and alkal-metal doped copper surfaces. The literature concerning these topics will be discussed in the relevant sections.

Section snippets

Experimental

The UHV chamber used in the experiments has been described previously [11]. Copper films were prepared in-situ by depositing the metal on to polished copper plates, which were cooled to a temperature TS of typically around 40 K. Depositing metals in this manner creates highly porous films with substantial amounts of atomic-scale defects 12, 13, 14. Doping of the alkali metal was performed using standard dispensers (SAES Getters). The amount of deposited copper as well as of the alkali metal was

CO2 adsorption on clean Cu

In its dependence on the substrate, carbon dioxide shows a rather complex adsorption behaviour. According to the crystallographic orientation and the properties of surface physisorption, chemisorption and even dissocation and reaction can occur.

At sufficiently low temperatures, CO2 is only weakly adsorbed on low-index copper surfaces in its molecular form. For Cu(100), a desorption temperature between 86 and 90 K has been found, depending on the surface coverage [22]. On cold-deposited copper

Summary

Surface enhanced Raman spectra of CO2 and HCOOH adsorbed on clean and alkali-metal doped copper surfaces have been presented. As well as activation, a reaction of the carbon dioxide to give carbonate and carbon monoxide has been observed on a potassium-doped cold-deposited copper surface. The experiments give no indication of possible intermediates in the reaction path. When coadsorbing CO2 and atomic H on such a substrate, the formation of a surface-bound formate species seems to occur when

Acknowledgements

This research was carried out as part of the project “Catalytic Chemistry of CO2 at Clean and Modified Metal, Oxide and Metal-Oxide Surfaces: a Surface Science Approach”, and was supported by the European Union (Contract No. BRE2.CT93.0448, Project No. 5027) and the Ministerium für Wissenschaft und Forschung des Landes Nordrhein–Westfalen. We have profited from discussions with A. Carley, H.-J. Freund, M.W. Roberts, M. Spencer and their co-workers. Special thanks are due to M. Faubel for

References (103)

  • F Solymosi

    J. Mol. Catal.

    (1991)
  • H.-J Freund et al.

    Surf. Sci. Rep.

    (1996)
  • G.C Chinchen et al.

    Appl. Catal.

    (1987)
  • G.C Chinchen et al.

    Appl. Catal.

    (1986)
  • J Yoshihara et al.

    J. Catal.

    (1996)
  • M.S Spencer

    Surf. Sci.

    (1995)
  • J.H Scofield

    J. Electron Spectrosc. Relat. Phenom.

    (1976)
  • P.B Rasmussen et al.

    Surf. Sci.

    (1992)
  • C.T Campbell et al.

    Surf. Sci.

    (1987)
  • J Krause et al.

    Surf. Sci.

    (1996)
  • S.S Fu et al.

    Surf. Sci.

    (1992)
  • I.A Bönicke et al.

    Surf. Sci.

    (1994)
  • V.M Browne et al.

    Appl. Surf. Sci.

    (1991)
  • W Akemann et al.

    Surf. Sci.

    (1992)
  • W Akemann et al.

    Surf. Sci.

    (1993)
  • H Behner et al.

    Surf. Sci.

    (1986)
  • H Behner et al.

    Surf. Sci.

    (1985)
  • H.-J Freund et al.

    Surf. Sci.

    (1987)
  • M Pirner et al.

    Surf. Sci.

    (1987)
  • G Wedler et al.

    Vacuum

    (1990)
  • J Wambach et al.

    Surf. Sci.

    (1989)
  • S Wohlrab et al.

    Surf. Sci.

    (1989)
  • E.V Thomsen et al.

    Surf. Sci.

    (1994)
  • J Onsgaard et al.

    Surf. Sci.

    (1995)
  • S Hadenfeldt et al.

    Surf. Sci.

    (1996)
  • H.-J Freund et al.

    Surf. Sci.

    (1986)
  • J Onsgaard et al.

    Surf. Sci.

    (1997)
  • J Mascetti et al.

    Surf. Sci.

    (1985)
  • Ü Ertürk et al.

    Surf. Sci.

    (1983)
  • W Eberhardt et al.

    Solid State Commun.

    (1982)
  • F Greuter et al.

    Solid State Commun.

    (1983)
  • G Anger et al.

    Surf. Sci.

    (1989)
  • J.M Campbell et al.

    Surf. Sci.

    (1991)
  • C.L.A Lamont et al.

    Chem. Phys. Lett.

    (1995)
  • K Gundersen et al.

    Surf. Sci.

    (1993)
  • E.M McCash et al.

    Surf. Sci.

    (1989)
  • R.L Toomes et al.

    Surf. Sci.

    (1996)
  • D.A Outka et al.

    Surf. Sci.

    (1985)
  • L.S Caputi et al.

    Surf. Sci.

    (1993)
  • F.M Leibsle et al.

    Surf. Sci.

    (1995)
  • M Bowker et al.

    Surf. Sci.

    (1996)
  • S Haq et al.

    Surf. Sci.

    (1997)
  • T Sueyoshi et al.

    Surf. Sci.

    (1996)
  • Ü Ertürk et al.

    J. Electron Spectrosc. Relat. Phenom.

    (1986)
  • D.P Woodruff et al.

    Surf. Sci.

    (1988)
  • A. Behr, Carbon Dioxide Activation by Metal Complexes, VCH, Weinheim,...
  • A Behr

    Angew. Chem.

    (1988)
  • G.C Chinchen et al.

    Chemtech

    (1990)
  • G.C Chinchen et al.

    J. Chem. Soc., Faraday Trans. I

    (1987)
  • M Pohl et al.

    J. Raman Spectrosc.

    (1996)
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