Reaction Rates of Hydrogen, Ammonia, and Methane with Mixtures of Atomic and Molecular Oxygen

Abstract

The stirred-reactor technique was used to measure the reaction rates of H2, NH3, and CH4 with mixtures of atomic and molecular oxygen (O+O2) at temperatures ranging from 350° to 600°K. A mass spectrometer capable of detecting atomic oxygen and hydrogen was used to analyze the reacting mixture in the stirred reactor. It was discovered that atomic oxygen could be quantitatively monitored by the mass spectrometer at a mass-to-charge ratio of 8. The reaction of H2 with the O+O2 mixture was found to be a chain reaction, with four to six atoms of oxygen consumed for each hydrogen molecule. The rate constant for the disappearance of atomic oxygen was 3×1013 exp(−8300/RT) cc mole−1 sec−1. The products of the reaction were H2O and H. The reactions of NH3 and CH4 with the O+O2 mixture were complex chain reactions, with a minimum of eight atoms of oxygen disappearing for each molecule of NH3 or CH4. Rate constants for atomic-oxygen disappearance were 3×1012 exp (−4800/RT) cc mole−1 sec−1 and 2×1013 exp (−6900/RT) cc mole−1 sec−1,respectively. The products of the former reaction were NO, H2O, and small amounts of H2 and H. The products of the latter reaction were H2O, CO2, and small amounts of CO, H2, and H.