Gas Chromatographic Determination of Nitrogenous Species in Combustion products

Abstract

A simple and reliable gas chromatographic technique has been developed for the measurement of the concentrations of the nitrogenous species N₂, NO, NH₃, N₂O and HCN in combustion products. Separations of the above species, along with H₂, CH₄, CO, CO₂, and H₂O were accomplished on a two column combination of Porapak T and molecular sieve 5A. The choice of the columns was based on an exhaustive literature survey, as well as tests on possible packing combinations. The separations were carried out at three constant temperature conditions of 28, 50 and 150°C. Lower detection limits of approximately 100 ppm were achieved for all of the species (200 ppm for Nha). Probe sampling in a flat flame burner supplied typical combustion product gas mixtures with various levels of the species of interest. Reliability of the nitric oxide concentration measurements was demonstrated by NO yields comparable to previous investigators in addition to nitrogen balances on lean NH₃/CH₄/O₂/Ar flames. Nitrogen dioxide was not detected in the combustion products; however, the results were not conclusive due to the breakdown of NO₂ in the column.