Rate constants for abstraction of hydrogen from ethylene by methyl and ethyl radicals over the temperature range 650–770 K

✍ Scribed by H-X Zhang; M. H. Back

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 630 KB
• Volume: 22
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550220103

✦ Synopsis

Measurements rate constants for abstraction of hydrogen from ethylene by methyl and ethyl radicals relative to the corresponding rate constants for abstraction from hydrogen, over the temperature range 650-770 K, are reported. The method is based on the effect of the addition of small quantities of hydrogen on the rates of formation of methane and ethane in the thermal chain reactions of ethylene. On the assumption that methane and ethane are formed by the following reactions:

(1)

(2)

C2H, + Hz -+ CzH, + H

CZH, + C2H4 ------* CZH, + C2H3 measurements of the relative rates of formation of methane and ethane in the presence and absence of hydrogen gave the following ratios of rate constants: (R = 8.314 Joule mol-' K-') log(k,/k,) = 1.3 t 0.15 + 4000 C 2000/2.3RT log(kJk4) = 1.6 C 0.15 -0 2 2000/2.3RT With values from the literature for k, and k3 the following values were obtained for k2 and k,: log kz(L mol-' SKI) = 8.7 2 0.2 -63000 2 3000/2.3RT log k,(L mol-'s-') = 8.2 2 0.