In situ observation of the exchange reaction of formate with molecular formic acid on Ni(110)

Akira Yamakata, Jun Kubota, Junko N. Kondo, Chiaki Hirose, Kazunari Domen, Fumitaka Wakabayashi, Kenzi Tamaru

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

The exchange reaction of adsorbed formate on Ni(110) with formic acid in gas phase was studied by the time-resolved infrared reflection absorption spectroscopy (TR-IRAS). It was found that the pre-adsorbed deuterated formate (DCOO(a)) was changed to HCOO(a) in the presence of HCOOD(g) at the temperature region from 240 to 300 K. In such a temperature region, the formate was stable on the surface in vacuum and the decomposition of formate was not observed. It was suggested that the pre-adsorbed DCOO(a) was desorbed as DCOOD accepting deuterium atom from HCOOD. The activation energy of the exchange reaction was estimated to be 23 ± 2 kJ mol-1. The reaction order with respect to formic acid pressure was 0.3 ± 0.1, while that as to the coverage of DCOO(a), was unity. Taking into account all the experimental results, the exchange of pre-adsorbed formate with post-exposed formic acid is suggested to proceed via forming a hydrogen-bonded intermediate complex on the formate's site, because all the sites were already occupied by formate. The small activation energy of the exchange reaction is discussed on the basis of 'adsorption-assisted desorption'. We propose that when desorption and adsorption are coupled, the activation energy of the exchange reaction should be described as a sum of the potential energy profiles of a desorbing and an adsorbing molecule.

Original languageEnglish
Pages (from-to)73-82
Number of pages10
JournalJournal of Molecular Catalysis A: Chemical
Volume141
Issue number1-3
DOIs
Publication statusPublished - May 6 1999
Externally publishedYes

Keywords

  • Adsorption-assisted desorption
  • Exchange reaction
  • Formate
  • Ni(110)

ASJC Scopus subject areas

  • Catalysis
  • Process Chemistry and Technology
  • Physical and Theoretical Chemistry

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