Hydrogen-oxygen flame doped with trimethyl phosphate, its structure and trimethyl phosphate destruction chemistry

Abstract

Molecular beam mass spectrometry was used to study the structure of a premixed H 2 -O 2 -Ar(0.26-0.13-0.61) flame without additives, and with additive (0.2–0.4%) of trimethyl phosphate (TMP) stabilized on a flat-flame burner at 47–80 torr. The behavior of TMP in the flame and the influence of the additve on the flame structure have been studied. Mass spectra of samples taken from the flames and intensity profiles of peaks 1 (H), 16 (O), 17 (OH), 18 (H 2 O), 28 (CO), 32 (O 2 ), 40 (Ar), 44 (CO 2 ), 47 (PO), 63 (PO 2 ), and 64 (HPO 2 ). AMU, and of peaks 80, 95, 96, 98, 110, 111, 112, 126 and 140 (TMP) AMU have been measured as a function of the distance from the burner surface to the sampling probe, using a quadrupole mass spectrometer and electron impact ionization at 12.9–21 eV with a spread of electron energy±0.25 eV. Intensity profiles of masses 95, 96, 126, 111, and 112 pass through a maxima, and those of masses 80, 109, and 110 pass through two maxima. Such behavior of intensity profiles shows that the species responsible for these masses are intermediates or fragmentary ions of intermediates. Dimethyl phosphate, dimethyl phosphite, monomethyl phosphate, and monomethyl phosphite were proposed to be the intermediates. The profile of the temperature in the flame has been determined by using a Pt-PtRh (10%) thermocouple covered by Ceramabond 569. The promotion of the H 2 O 2 Ar flame by the TMP additive has been observed. The possible chemical mechanism of TMP destruction is presented.