Rate constants for the reaction of ground state atomic oxygen with methanol

Journal Article · Tue Sep 15 00:00:00 EDT 1981 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.442379· OSTI ID:6004669

Keil, D G; Tanzawa, T; Skolnik, E G; Klemm, R B; Michael, J V

The reaction of O(/sup 3/P) with methanol has been studied using the complementary discharge flow and flash photolysis techniques. In both cases, resonance fluorescence detection of atomic oxygen was employed. The discharge flow (DF) apparatus was used in a temperature range of 298--998 K while the flash photolysis (FP) apparatus was used in the overlapping range of 329--527 K. The apparent bimolecular rate constants for the O-atom/methanol reaction obtained from DF experiments at low temperatures (T< or =450 K) were independent of both the initial O-atom concentration and the mode of O-atom production. In addition, large excesses of O/sub 2/ were added to the flow to intercept the primary reaction product (CH/sub 2/OH), but had no apparent effect on the measured rate constant. Results from the two methods were in good agreement within this limited temperature range (approx.300--500 K). At temperatures above approx.450 K, the apparent rate constants obtained from DF experiments were increasingly sensitive to the O/sub 2/ concentration, with the rate constants being smaller when determined in the presence of large (O/sub 2/). Since the initial O-atom concentrations were on the order of 10/sup 11/ or less, a simple stoichiometry effect can be ruled out. However, the results of the present kinetic experiments indicated that heterogeneous pyrolysis of CH/sub 3/OH may have occurred in the flow system. This observation is consistent with studies of the adsorption of methanol on silica surfaces. This problem was apparently overcome by adding small amounts of O/sub 2/ and the rate constants obtained in this way were seen to agree well with values extrapolated from the lower temperature DF and FP experiments. The rate data from DF and FP experiments were thus combined to obtain the following Arrhenius expression (298--998 K): k/sub 1/ (T) = (2.70 +- 0.50) x 10/sup -11/ exp(-5030 +- 160/RT cm/sup 3/ molecule/sup -1/ s/sup -1/.

• Research Organization: Brookhaven National Laboratory, Upton, New York 11973
• OSTI ID: 6004669
• Journal Information: J. Chem. Phys.; (United States), Vol. 75:6
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
METHANOL
CHEMICAL REACTION KINETICS
COMBUSTION
OXYGEN
GROUND STATES
ALCOHOLS
CHEMICAL REACTIONS
ELEMENTS
ENERGY LEVELS
HYDROXY COMPOUNDS
KINETICS
NONMETALS
ORGANIC COMPOUNDS
OXIDATION
REACTION KINETICS
THERMOCHEMICAL PROCESSES
400301* - Organic Chemistry- Chemical &amp; Physicochemical Properties- (-1987)