Decomposition of CH3NH2${\rm CH}_3{\rm NH}_2$: Implications for CHx/NHy${\rm CH}_{\rm {\it x}}/{\rm NH}_{\rm {\it y}}$ radical–radical reactions.

Experiments on methylamine (CH3NH2${\rm CH}_3{\rm NH}_2$) decomposition in shock tubes, flow reactors, and batch reactors have been re‐examined to improve the understanding of hydrocarbon/amine interactions and constrain rate constants for CHx${\rm CH}_{ x}$ + NHy${\rm NH}_{ y}$ reactions. In high‐temperature shock tube experiments, the rapid thermal dissociation of CH3NH2${\rm CH}_3{\rm NH}_2$ provides a fairly clean source of CH3${\rm CH}_3$ and NH2${\rm NH}_2$ radicals, allowing an assessment of reactions of CH3${\rm CH}_3$ with NH2${\rm NH}_2$ and NH. At the lower temperatures in batch and flow reactors, CH3NH2${\rm CH}_3{\rm NH}_2$ is mostly consumed by reaction with H to form CH2NH2${\rm CH}_2{\rm NH}_2$ + H2${\rm H}_2$; these results are useful in determining the fate of the CH2NH2${\rm CH}_2{\rm NH}_2$ radical. Interpretation of these data, along with flow reactor data for the CH3NH2${\rm CH}_3{\rm NH}_2$/H system at lower temperature, indicates that at temperatures up to about 1400 K at atmospheric pressure and above 2000 K at 100 atm, the CH3${\rm CH}_3$ + NH2${\rm NH}_2$ reaction forms mainly methylamine. At sufficiently high temperature, H‐abstraction to form CH4${\rm CH}_4$ + NH and addition–elimination to form CH2NH2${\rm CH}_2{\rm NH}_2$ + H become competitive. The CH3${\rm CH}_3$ + NH reaction, with a rate constant close to collision frequency, forms CH2NH${\rm CH}_2{\rm NH}$ + H, also leading into the hydrocarbon amine pool. Thus, methylamine can be expected to be an important intermediate in co‐combustion of natural gas and ammonia, and more work on the chemistry of CH3NH2${\rm CH}_3{\rm NH}_2$ is desirable. [ABSTRACT FROM AUTHOR]