Self-heating and spontaneous ignition in the oxidation of gaseous hydrazine

摘要: The spontaneous ignition of gaseous mixtures oxygen and hydrazine has been investigated in a 1 l. spherical vessel over the temperature range 690–770 K. Emphasis is placed on direct detection pre-explosive self-heating reacting gas. Very fine thermocouples (made from 0.025 mm Pt Pt-Rh wires) are used to follow changes, map temperature-position profiles during oxidation: N2H4+ O2→ N2+ 2H2O, ΔH=–138 kcal mol–1.Unusually among gas-phase oxidations, this clearly thermal character. Strong always observed. In accordance with conductive theory heat losses, temperatures not uniform throughout reactant but depend distance centre, being greatest at centre least walls. (approximately) parabolic form absence any significant temperature-step walls confirm convection pressures concerned.A critical rise exists above which stable reaction impossible inevitable. Thermal predicts value 1.61 RT2a/E, i.e., about 70 K, under circumstances where consumption can be ignored, 116 K when it taken into account: observed here 120 K.The + system more difficult handle than some systems previously catalysis thermocouple harder eliminate. These effects, consequences employing finite capacity, also discussed.