Mechanism of the chain process forming H2 in the photooxidation of formaldehyde

A mechanism for the formation in a chain of H2, CO, and HCOOH in the photooxidation of formaldehyde is proposed. This mechanism is initiated by the addition of HO2 to formaldehyde. Hydrogen atoms are produced by the thermal dissociation of the HOCH2O radical: HOCH2O → H + HCOOH; ΔH = + 3.2 kcal/mol [5]. Photolysis of CH2OO2NO mixtures and product analysis were carried out in conjunction with kinetic simulation yielding an estimate for the activation energy of the dissociation reaction : E5 = 14.9 ± 1.0 kcal/mol. Previous observations of this chain process are considered in view of this mechanism.