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Article FAU & CUP - J. Phys. Chem. C

Role of Oxygen in Acetic Acid Decomposition on Pt(111)

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J. Phys. Chem. C online published on June 9, 2014 read more on ACS pages

Armin Neitzel1, Yaroslava Lykhach1, Viktor Johánek2, Nataliya Tsud2, Tomáš Skála2, Kevin C. Prince3,4, Vladimír Matolín2, and Jörg Libuda1,5,*

1 Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany, Fax: (+49) 9131-8528867, http://www.chemie.uni-erlangen.de/libuda
2 Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University in Prague, V Holešovičkách 2, 180 00 Prague 8, Czech Republic
3 Sincrotrone Trieste SCpA, Strada Statale 14, km 163.5, 34149 Basovizza-Trieste, Italy
4 IOM, Strada Statale 14, km 163.5, 34149 Basovizza-Trieste, Italy
5 Erlangen Catalysis Resource Center, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany

We have investigated the role of co-adsorbed atomic oxygen during decomposition of acetic acid on Pt(111) by means of temperature programmed desorption (TPD) and synchrotron radiation photoelectron spectroscopy (SRPES). Reaction mechanisms have been established through identification of desorbing products and surface species formed during decomposition of acetic acid, both on Pt(111) and oxygen pre-exposed p(2×2)–O/Pt(111). Acetate and molecularly adsorbed acetic acid are formed on both samples during adsorption of acetic acid at 150 K. On p(2×2)–O/Pt(111), however, surface acetyl is identified as the principal species. The major decomposition channel for acetate and acetic acid involves formation of ketene and acetaldehyde at 222 K and this reaction is not affected by co-adsorbed oxygen. In the following reactions, partial decomposition of acetaldehyde yielded ethylene, ethylidene, ethylidyne, and small amounts of CO and methoxy on both samples. Large amounts of acetyl are formed on p(2×2)–O/Pt(111). Above 222 K, decomposition of acetate on Pt(111) yields acetic acid, hydrogen, methane, and CO. In contrast, the species desorbing from p(2×2)–O/Pt(111) are the products of acetyl decomposition. In particular, the reaction of acetyl with atomic oxygen and surface hydroxyl groups yields methanol and acetic anhydride at 300 and 450 K, and methane and CO2 at 390 K. Decomposition of acetic acid on both Pt(111) and p(2×2)–O/Pt(111) results in surface carbon from decomposition of ethylidyne and partial C–C bond cleavage in acetyl.