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The free radical oxidation of CH2O in the presence of NO2 and NO

1981; Elsevier BV; Volume: 15; Issue: 2 Linguagem: Inglês

10.1016/0047-2670(81)85005-8

1873-2658

Boyce M. Morrison, Julian Heicklen,

Catalysis and Oxidation Reactions

NO2 was photolyzed at 366 nm and 296 K in the presence of CH2O and O2 and in some runs with added NO or N2. The measured products were CO, CO2 and HCOOH. H2 and N2O were not produced. Both the CO and the CO2 were produced in a linear fashion with irradiation time, but the HCOOH grew after a marked induction period. From the CO2 quantum yields at high [O2]/[NO2] ratios an upper limiting value of 0.16 ± 0.02 was found for k3b/k3 where reactions (3a) and (3b) are This is lower than the value of approximately 0.30 reported for k3b/k3 by Chang and Barker. From the CO and CO2 yields the competition for HCO between O2 and NO2 could be measured. The ratio k9/k7a was found to be 0.21 ± 0.07 and was independent of pressure. The analysis required knowledge of some other rate coefficients. If those rate coefficients are completely in error, k9/k7a could be as high as 0.63. With the literature value of 5.6 × 10−12 cm3 s−1 for k9, the best value for k7a is (2.7 ± 0.9) × 10−11 cm3 s−1 with a lower limiting value of (8.9 ± 3.0) × 10−12 cm3 s−1. Information was also obtained on the reaction of HO2 with CH2O which produces HCOOH. An approximate value of (1.4 – 3.2) × 10−13 cm3 s−1 was found for the rate coefficient for this reaction which is about 14 – 32 times greater than the estimate of Su et al.