Oxidation of formaldehyde in KCl-coated vessels
- 1 January 1974
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases
- Vol. 70, 1257-1268
- https://doi.org/10.1039/f19747001257
Abstract
In the temperature range 440–540°C, the oxidation of HCHO in KCl-coated vessels is reproducible and of short chain length for HCHO concentrations in the range 0.05–4 Torr. Interpretation of the [CO] against time profile permits evaluation of the unknown parameters k1, k7/k1/2 4 and k8. HCHO + O2→ HO2+ HCO (1), HO2+ HO2→ H2O2+ O2(4), HO2 [graphic ommitted] ½ H2O + O2(7), H2O2 [graphic ommitted] H2O +½ O2. (8). Comparison of the experimental values for k7/k1/2 4 and k8 with those calculated from diffusion theory indicates that the destruction of HO2 at the surface is fully diffusion controlled, whereas the destruction of H2O2, though moderately efficient, is not fully diffusion controlled. From measurements at HCHO concentrations below 0.5 Torr, where the chain length is close to unity, effectively direct measurements of k1 have been obtained, the values being 7.65 × 10–1, 2.08 × 10–1, 8.50 × 10–2 and 2.20 × 10–2 dm3 mol–1 s–1 at 542.5, 500, 471 and 440.5°C, respectively. These values give the Arrhenius parameters A1= 2.04 × 1010 dm3 mol–1 s–1, E1= 38.9 ± 1.5 kcal mol–1. The absence of any diameter effect on the value of k1 confirms that the parameters refer to the homogeneous process.Keywords
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