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Steady‐state rate of decomposition of formaldehyde on Ru(001)

Sun, Y.-K. and Chan, C.-Y. and Weinberg, W. H. (1989) Steady‐state rate of decomposition of formaldehyde on Ru(001). Journal of Vacuum Science and Technology A, 7 (3). pp. 1983-1985. ISSN 0734-2101. doi:10.1116/1.575997.

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The steady‐state, absolute rate of decomposition of formaldehyde on the Ru(001) surface has been measured as a function of surface temperature from 310 to 750 K and for reactant pressures between 9.7×10^(−8) and 1.6×10^(−6) Torr. The only observed reaction products were carbon monoxide and hydrogen. Postreaction Auger spectroscopic analysis revealed a clean surface. Two distinct kinetic regimes are observed. At relatively low surface temperatures (and/or high formaldehyde pressures), the rate is zero order in formaldehyde pressure with an apparent activation energy of 23±0.5 kcal/mol and an apparent preexponential factor of 4×10^(11) s^(−1). The rate becomes flux limited and first order in formaldehyde pressure with an apparent activation energy of zero at relatively high surface temperatures (and/or low formaldehyde pressures). Perdeutero‐formaldehyde decomposes on Ru(00l) with the same kinetic parameters as HCHO. The lack of a kinetic isotope effect indicates that C–H bond cleavage is not the rate‐limiting step under these experimental conditions. In the low‐temperature regime, the surface is saturated with CO, and the rate is CO desorption limited. Dissociative chemisorption of formaldehyde is irreversible since no isotopic exchange products were observed by reacting a mixture of HCHO and D2 with a molar ratio of 1:4 at a total pressure of 1×10^(−6) Torr.

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Additional Information:© 1989 American Vacuum Society. Received 3 October 1988; accepted 5 December 1988. This work was supported by The National Science Foundation under Grant No. DMR-8500789.
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Subject Keywords:Formaldehyde; decomposition; steady-state conditions; medium temperature; high temperature; high vacuum; ruthenium; surface properties; surface reactions; coatings; carbon monoxide; hydrogen; chemical reaction yield; chemical reaction kinetics; mass spectroscopy; auger electron spectroscopy; electron diffraction; photoelectron spectroscopy; x radiation
Issue or Number:3
Classification Code:PACS: 82.30.Lp
Record Number:CaltechAUTHORS:20120517-134236753
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Official Citation:Steady-state rate of decomposition of formaldehyde on Ru(001) Y.-K. Sun, C.-Y. Chan, and W. H. Weinberg, J. Vac. Sci. Technol. A 7, 1983 (1989), DOI:10.1116/1.575997
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:31531
Deposited On:18 May 2012 15:03
Last Modified:09 Nov 2021 19:55

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