Thermal Chemistry of Trimethyl Acetic Acid on TiO₂(110)

Journal Article · Thu Mar 18 04:00:00 EST 2004 · Journal of Physical Chemistry B, 108(11):3592-3602

DOI:https://doi.org/10.1021/jp036713w· OSTI ID:15007495

White, J M; Szanyi, Janos; Henderson, Michael A

Based on temperature programmed desorption and isothermal reaction mass spectrometry, the thermal surface chemistry of trimethyl acetic acid, (CH)CCOOH, dosed onto a well characterized single crystal TiO(110) surface is described. Deprotonation occurs at or below 300 K to form trimethyl acetate, (CH)CCOO-, and hydroxide, OH-. (CH)CCOO- is bound to exposed Ti cations and OH- involves a bridging oxygen atom of the substrate. Based on temperature programmed desorption and isothermal reaction mass spectrometry, the desorbing products include (CH)CCOOH, isobutene (i-CH), carbon monoxide and water accompanied by smaller amounts of other products including methyl isopropenyl ketone (CH=C(CH)C(=O)CH), isobutane (i-C4H10), and di-t-butyl ketone, (CH)CC(=O)C(CH). Much of the (CH)CCOO- is relatively stable and decomposes to release mainly carbon monoxide and isobutene above 550 K with a maximum rate at 660 K. Thermal desorption to 750 K leaves a carbon-free surface that is indistinguishable from the initially clean surface. During dosing at 550 K, a steady-state reaction condition is realized with about half the adsorption sites being occupied at any instant.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 15007495
• Report Number(s): PNNL-SA-40464; 3460; KC0302010
• Journal Information: Journal of Physical Chemistry B, 108(11):3592-3602, Journal Name: Journal of Physical Chemistry B, 108(11):3592-3602
• Country of Publication: United States
• Language: English

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