Journal Articles (before-1995)

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    Oxidation of Formaldehyde in KCl-coated Vessels
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (07), 1974) Baldwin, Roy R.; Fuller, Alan R.; Longthorn, David; Walker, Raymond W.
    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 A'i, k7jk^ and ka. HCHO + O2->HO2 + HCO HO2 + HO2->H2O2 + O2 surface HO2---->4H2O + JO2 surface H2o2—>H2O + 4O2. (1) (4) (7) (8) Comparison of the experimental values for k7/kf and ka with those calculated from diffusion theory indicates that the destruction of HO2 at the surface is fully diffusion controlled, whereas the destruc tion 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 ki have been obtained, the values being 7.65 x 10~’, 2.08 x 10-1, 8.50 x IO-2 and 2.20x 1CF2 dm3 moF* s_1 at 542.5, 500, 471 and 440.5°C, respectively. These values give the Arrhenius parameters At = 2.04x 1010 dm3 moF1 s~l, £\ = 38.9 ± 1.5 kcal moF1. The absence of any diameter effect on the value of k, confirms that the parameters refer to the homogeneous pro cess.
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    Low Temperature Gas-phase Oxidation of Aldehydes: Part 2.—Retardation by Formaldehyde above 120°C
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (1-6), 1974) Dixon, David J.; Skirrow, Geoffrey; Tipper, Charles F. H.
    The effect of added formaldehyde on the oxidation of acetaldehyde and propionaldehyde between 119 and 188°C has been studied using a static system. Formaldehyde retards the oxidation, and at 188°C the rate after 25 % consumption of CH3CHO(ρ0.25) is linearly related to the reciprocal of the initial concentration of CH2O(Fi). However, at 119°C ρ0.25 decreases to a minimum and then increases as Fi is increased. The change in formaldehyde concentration during retarded oxidations showed that CH3CHO and CH2O are both removed mainly by reaction with peracetyl radicals, CH3CO3+ CH3CHO→CH3CO3H + CH3CO (3), CH3CO3+ HCHO→CH3CO3H + HCO (7)k7/k3 being about 2.4 at 119 and 188°C. Only about one in seven of the formyl radicals give carbon monoxide at 119°C. The kinetic and analytical data are explained on the basis of the mechanism given in Part 1 with the addition of reaction (7). It is suggested that some performic acid is formed at 119°C and causes extra branching by reaction with acetaldehyde.
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    Addition of Formaldehyde to Slowly Reacting Hydrogen + Oxygen Mixtures
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (7), 1972) Baldwin, R R; Fuller, A R; Walker, R W
    The effect of HCHO in reducing the induction periods of H2+ O2+ N2 mixtures at 500°C has been examined for a range of mixture composition, using HCHO concentrations in the range 0.05–1.0 %. Computer treatment shows that the marked reduction can only be accounted for by the reaction HO2+ HCHO = H2O2+ HCO(24). A detailed computer analysis of the results for a range of mixtures gives the ratio k24/k½10= 23 (mol l.–1 s)–½. Taking k10(HO2+ HO2= H2O2+ O2)= 1.8 × 109 gives k24= 9.6 × 105 l.mol–1 s–1. With A24= 109, this corresponds to E24= 10.7 kcal mol–1.