PYROLYSIS AND OXIDATION OF FORMALDEHYDE IN SHOCK WAVES.
HARVARD UNIV CAMBRIDGE MA GIBBS CHEMICAL LAB
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The pyrolysis and oxidation of formaldehyde have been studied in shock waves by mass spectrometry and by ionization measurements over the temperature range 1400 to 2100 K. The pyrolysis shows first order rate dependance with respect to both formaldehyde and inert gas after a temperature dependent induction period. Experiments with formaldehyde-d2 show that the pyrolysis proceeds by a radical chain mechanism. The formation of the radical H3CO has been detected. The observed activation energy is 28 2.5 kcalmole various mechanisms are suggested to explain this result. The initial stage of the oxidation consists mainly of an oxygen induced decomposition of formaldehyde into CO and H2, followed by branching chain oxidation of the H2 so produced as well as remaining formaldehyde and partial oxidation of the CO. Chemi-ionization is observed in the oxidation reaction, the species H3O and H3CO being the only ions detected. The total yield of ions is virtually independent of temperature. The mechanism of the oxidation reaction and of ion formation is discussed. Author