Flow-Tube Investigations of Hypergolic Reactions of a Dicyanamide Ionic Liquid Via Tunable Vacuum Ultraviolet Aerosol Mass Spectrometry

Abstract

Hydroxylammonium nitrate (HAN) is a promising candidate to replace highly toxic hydrazine in monopropellant thruster space applications. The reactivity of HAN aerosols on heated copper and iridium targets was investigated using tunable vacuum ultraviolet photoionization time-of-flight aerosol mass spectrometry. The reaction products were identified by their mass-to-charge ratios and their ionization energies. Products include NH 3 , H 2 O, NO, hydroxylamine (HA), HNO 3 , and a small amount of NO 2 at high temperature. No N 2 O was detected under these experimental conditions, despite the fact that N 2 O is one of the expected products according to the generally accepted thermal decomposition mechanism of HAN. Upon introduction of iridium catalyst, a significant enhancement of the NO/HA ratio was observed. This observation indicates that the formation of NO via decomposition of HA is an important pathway in the catalytic decomposition of HAN.

Catalytic Decomposition of Hydroxylammonium Nitrate Ionic Liquid: Enhancement of NO Formation

“…Details about the experimental setup can be found elsewhere. 21,22 By tunable vacuum ultraviolet photoionization time-of-flight mass spectrometry, HAN decomposition product masses were detected with mass-to-charge ratios (m/z) of 17, 18, 30, 32, 33, 44, 46 and 63, seen in Figure 1. The primary thermal decomposition products (formation of HNO 3 at m/z 63 and H 2 NOH at m/z 33 represented by reaction 1) can be seen in Figure 1.…”

Controlled Chemistry via Contactless Manipulation and Merging of Droplets in an Acoustic Levitator

“…The most commonly employed hypergolic propellant is composed of a dinitrogen tetroxide (N 2 O 4 ) oxidizer and hydrazine (N 2 H 4 ) fuel. , Hydrazine has critical shortcomings, however, including toxicity, an inherently high vapor pressure, and corrosiveness . Several ionic liquids (ILs) have been found to be hypergolic with common oxidizers, − for example, 1-butyl-3-methylimidazolium dicyanamide ([BMIM]­[DCA]) (Figure S1) and white-fuming nitric acid (WFNA) . Owing to suitable physical properties of ionic liquids such as the melting point, energy density, and viscosity and the potential to tune these properties by selecting different anion and cation combinations, there has been intensive research to develop ionic-liquid-based hypergolic fuels that avoid the disadvantages of hydrazine-based propellants. − The two-droplet merging technique coupled with the complementary spectroscopic probes interfaced to the levitator apparatus is an ideal set up to perform such hypergolic ignition studies and explore the underlying chemistry.…”

“…The Q -branch wavenumbers and vibrational mode assignments for bands a*–d* of the nitric acid droplet before the merging are presented in Table S1 . The vibrational modes for bands a–n of the gaseous products are assigned in Table S2 to carbon dioxide (CO 2 ) [ν 3 (σ u + ) asymmetric stretching mode, 2349 cm –1 ; ν 2 (π u ) bending mode, 668 cm –1 ] and nitrous oxide (N 2 O) [ν 3 (σ + ) N–N stretching, 2223 cm –1 ; ν 1 (σ + ) N–O stretching mode, 1285 cm –1 ] in accordance with the following reaction mechanism between the [DCA] − (or [N­(CN) 2 ] − ) anion and nitric acid: …”

Catalytic decomposition of hydroxylamine nitrate and hydrazine nitrate using Ru/ZSM-5 catalyst under mild reaction conditions

“…Among various metal catalysts proposed for hydrazine decomposition, noble metals, such as Ru and Pt, exhibited good catalytic activity and stability in acid solutions. 14,15 However, only several examples have been reported focusing on the kinetics and mechanism of catalytic decomposition of hydrazine, [16][17][18][19][20] which proves that heterogeneous catalysis (reaction (3)) is a promising method for the decomposition of hydrazine and heterogeneous catalytic decomposition of hydroxylamine nitrate has not been reported in HNO 3 system. This method is simple and available, which offers several advantages: (i) reduced solid radioactive waste, (ii) ease of operation, (iii) simple device structure, (iv) small reactor volume.…”