Gas-phase Boudouard disproportionation reaction between highly vibrationally excited CO molecules

Abstract The gas-phase Boudouard disproportionation reaction between two highly vibrationally excited CO molecules in the ground electronic state has been studied in optically pumped CO. The gas temperature and the CO vibrational level populations in the reaction region, as well as the CO 2 concentration in the reaction products have been measured using FTIR emission and absorption spectroscopy. The results demonstrate that CO 2 formation in the optically pumped reactor is controlled by the high CO vibrational level populations, rather than by CO partial pressure or by flow temperature. The disproportionation reaction rate constant has been determined from the measured CO 2 and CO concentrations using the perfectly stirred reactor (PSR) approximation. The reaction activation energy, 11.6 ± 0.3 eV (close to the CO dissociation energy of 11.09 eV), was evaluated using the statistical transition state theory, by comparing the dependence of the measured CO 2 concentration and of the calculated reaction rate constant on helium partial pressure. The disproportionation reaction rate constant measured at the present conditions is k f  = (9 ± 4) × 10 −18  cm 3 /s. The reaction rate constants obtained from the experimental measurements and from the transition state theory are in good agreement.

[1]  G. F. Homicz,et al.  13C and 18O isotope enrichment by vibrational energy exchange pumping of CO , 1983 .

[2]  Robert L. DeLeon,et al.  Vibrational energy exchange rates in carbon monoxide , 1986 .

[3]  I. Adamovich,et al.  Time-resolved Fourier transform infrared spectroscopy of optically pumped carbon monoxide , 2000 .

[4]  J. P. Appleton,et al.  Shock‐Tube Study of Carbon Monoxide Dissociation Using Vacuum‐Ultraviolet Absorption , 1970 .

[5]  P. Roth,et al.  Atomic resonance absorption spectroscopy measurements on high-temperature CO dissociation kinetics , 1993 .

[6]  J. Rich,et al.  Isotope Separation by Vibration-Vibration Pumping , 1986 .

[7]  Philip L. Walker,et al.  Gas Reactions of Carbon , 1975 .

[8]  I. Adamovich,et al.  Time-resolved measurements of ionization and vibration-to-electronic energy transfer in optically pumped plasmas , 2005 .

[9]  M. Capitelli,et al.  Vibrational Kinetics, Dissociation, and Ionization of Diatomic Molecules Under Nonequilibrium Conditions , 1986 .

[10]  Hansong Cheng,et al.  On the mechanism and energetics of Boudouard reaction at FeO(1 0 0) surface: 2CO→C+CO2 , 1999 .

[11]  Ralph G. Pearson,et al.  Kinetics and Mechanism, Second Edition , 1961 .

[12]  Yong P. Chen,et al.  Control of chemical reaction pathways by femtosecond ponderomotive forces: Time-resolved multiphoton ionization spectroscopic study of OCIO photodissociation , 1997 .

[13]  J. Rich,et al.  4 – Relaxation of Molecules Exchanging Vibrational Energy , 1982 .

[14]  I. Adamovich,et al.  Electron density and recombination rate measurements in CO-seeded optically pumped plasmas , 2001 .

[15]  A. Bloom,et al.  Gas lasers. , 1968, Applied optics.

[16]  R. G. Rehm,et al.  Vibrational Relaxation of Anharmonic Oscillators with Exchange‐Dominated Collisions , 1968 .

[17]  J. Rich,et al.  C2 and CN formation by optical pumping of CO/Ar and Co/N2/Ar mixtures at room temperature , 1979 .

[18]  J. Martin,et al.  Transfer of vibrational energy to electronic excited states and vibration enhanced carbon production in optically excited V−V pumped CO , 1995 .

[19]  R. Hanson.  Shock‐tube study of carbon monoxide dissociation kinetics , 1974 .

[20]  G. Liuti,et al.  Isotopic Enrichment in the Photochemistry of CO with the 2062‐Å Iodine Line , 1966 .

[21]  Auerbach,et al.  Enhanced reactivity of highly vibrationally excited molecules on metal surfaces , 1999, Science.

[22]  I. Adamovich,et al.  Electron-mediated vibration–electronic (V–E) energy transfer in optically pumped plasmas , 2001 .

[23]  I. Adamovich,et al.  Vibrationally stimulated ionization of carbon monoxide in optical pumping experiments , 1993 .