The second limit of hydrogen + carbon monoxide + oxygen mixtures

Abstract

Previous studies by Buckler and Norrish of the second limit of CO and 0 2 mixtures containing small amounts (0.25-10%) of Hz have been used to obtain the velocity constant of the reaction.9 X lo8 and 3.5 X I081iter2mole-zsec-1(M =H2) at500"and 560°C.respectively, have been combined with other estimates over the range 300°-35000K to give ka3 = 3.0 x lOsexp (-3000/RT) for M = Ar; the considerable scatter in the available points does not encourage any great confidence in this expression and may be attributed at least partly to the different molecules used as M by different workers. For KC1-coated and CsC1-coated vessels at 540°C, studies of the second limit of Hz + 0 2 mixtures, to which CO has been added, have indicated that with both the surfaces, the effect of C O on the limit is masked by changes in the surface nature. In the case of CsCl, the results have enabled a lower limit of about 0.6 to be obtained for the efficiency of CO relative to

Autoignition of H2/CO at elevated pressures in a rapid compression machine

“…Lloyd [34] suggested that since it was assumed that all the participating reactions had been considered, other reactions aiding the decomposition or the underestimation of surface decomposition effects could affect k 28 . Baldwin et al [37] quoted an unpublished work for a value of k 28 /(k 18 + k 19 ) 1/2 which was obtained at 773 K and was a factor of 24 less than the previous measurement of Baldwin et al [35] at the same temperature. Lloyd [34] reported the values of k 28 obtained by using the recommended expression for (k 18 + k 19 ) along with the measurements of Baldwin et al [35][36][37].…”

“…Baldwin et al [37] quoted an unpublished work for a value of k 28 /(k 18 + k 19 ) 1/2 which was obtained at 773 K and was a factor of 24 less than the previous measurement of Baldwin et al [35] at the same temperature. Lloyd [34] reported the values of k 28 obtained by using the recommended expression for (k 18 + k 19 ) along with the measurements of Baldwin et al [35][36][37]. However, when the recently recommended value of Hippler et al [38] for (k 18 + k 19 ) is used, the values of k 28 are a factor of 3 less than those calculated by Lloyd [34].…”

“…k 28 for the measurements of Baldwin et al [35][36][37] is calculated by using (k 18 + k 19 ) from Hippler et al [38]. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]…”

Transient oxygen atom yields in H2?O2 ignition and the rate coefficient for O + H2 ? OH + H

“…For conditions corresponding to those of the middle graphs in Figure 5, independent variations of a factor of 3 in k, and k,, Like reaction ( e ) , this reconibination reaction has the largest potential effect at our lowest experimental temperatures, where k b is smallest. Baldwin and co-workers [20] have correlated determinations of k , at 773 and 833°K with directly measured values of k, near room temperature by the conventional Arrhenius expression k , = 3 X lOI4 exp(-12.6 ( k J ) / R T ) cm6/mole*.s for M = Ar, by which the rate coefficient of reaction (p) increases with increasing temperature. The measured rate of COZ dissociation [7], however, implies that above 2550"K, k, decreases with increasing temperature.…”

Chemical Kinetics in Support of Syngas Turbine Combustion

“…3 and 4 were not adopted in this study even though the reported rate measurements [3, 4] appear to have smaller estimated uncertainties than the previous measurements [57, 58]. Instead, we again applied a weighted least squares fitting to all experimental data available in the literature for k 24 [3,22, 57,[60][61][62][63][64][65][66][67][68][69][70][71][72][73], to yield a new rate correlation, [57] within 30%, and is about 2~3 times higher than the correlation recommended by Friedrichs 33 et al [3]. Over 500-1300 K where the rate coefficient of (R24) was measured by Friedrichs et al…”