The second limit of hydrogen + carbon monoxide + oxygen mixtures

✍ Scribed by R. R. Baldwin; D. Jackson; A. Melvin; B. N. Rossiter

• Publisher: John Wiley and Sons
• Year: 1972
• Tongue: English
• Weight: 785 KB
• Volume: 4
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550040305

✦ Synopsis

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 (33) 0 + CO + M = COz + M Theseestimatesofks3=3.9 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 HZ in the reaction (4) H + 0 2 + M = HOp + M Use of a computer treatment to interpret the second limit of CO + HZ + 0 2 mixtures in aged boric-acid-coated vessels at 500°C gives a value of m c o = 0.74 f 0.04 together with an estimate of ks2 (H + CO $. M" = HCO + M")/ka = 0.022 =t 0.003, which leads to k32 = 2.3 X 1 0 8 liter2 mole-2 sec-' (M = H2) at 500°C.