Sodium carbonate (Na2CO3) is identified as a hydrolysis reagent for decomposing HMX and
HMX-based explosives to water-soluble, nonenergetic products. The reaction kinetics of Na2CO3
hydrolysis are examined, and a reaction rate model is developed. Greater than 99% of the
explosive at an initial concentration of 10 wt % PBX 9404 was destroyed in less than 5 min at
150 °C. The primary products from Na2CO3 hydrolysis were nitrite (NO2), formate (HCOO-),
nitrate (NO3
-), and acetate (CH3COO-) ions, hexamethylenetetramine, (hexamine: C6H12N4),
nitrogen gas (N2), nitrous oxide (N2O), and ammonia (NH3). The rate of hydrolysis was
characterized for HMX powder and PBX 9404 molding powder from 110 to 150 °C. The rate
was found to be dependent on both the chemical kinetics and the mass transfer resistance. Since
the HMX particles are nonporous and external mass transfer dominates, gas−liquid film theory
for fast chemical kinetics was used to model the reaction rate.
The degradation of HMX-based high explosives (HMX, PBX 9404, and PBX 9501) with sodium
hydroxide solutions is described. To obtain practicable reaction rates, the reaction was carried
out in a pressurized reactor at temperatures up to about 155 °C. Above about 70 °C, mass transfer
rates significantly affect the observed reaction rate. Therefore, a solid−liquid mass transfer model,
based on gas−liquid film theory, was developed to describe the reaction rate. This model
successfully predicted the experimentally observed degradation of explosives. Similar work with
sodium carbonate solutions was reported previously. Faster reaction rates were observed with
sodium hydroxide, a stronger base. Sodium hydroxide is preferred when the explosive contains
a base-resistant binder, such as the binder used in PBX 9501, or when large, pressed pieces of
explosives are used. Sodium carbonate hydrolysis and sodium hydroxide hydrolysis yielded the
same degradation products.
Los Alamos Natlonal Laboratounder contrad W-7405-ENG-3z~By acceptance of thls artlcle, the publisher recognizes that the U.S. Government retains a nonexclushre roy publish or rqroduca the published form of thls contnbutlon, or to allow others to do so. for U.S. Government p u y e s .
AbstractLos Alamos National Laboratory has demonstrated that many energetic materials can be rendered non-energetic via reaction with sodium hydroxide or ammonia. This process is known as base hydrolysis. A pilot scale reactor has been developed to process up to 20 kg of plastic bonded explosive in a single batch operation. In this report, we discuss the design and operation of the pilot scale reactor for the processing of PBX 9404, a standard Department of Energy plastic bonded explosive containing HMX and nitrocellulose. Products from base hydrolysis, although non-energetic, still require additional processing before release to the environment. Decomposition products, destruction efficiencies, and rates of reaction for base hydrolysis will be presented. Hydrothermal processing, previously known as supercritical water oxidation, has been proposed for converting organic products from hydrolysis to carbon dioxide, nitrogen, and nitrous oxide. Base hydrolysis in combination with hydrothermal processing may yield a viable alternative to open burning/open detonation for destruction of many energetic materials.
Alkaline hydrolysis is used to convert high explosives to nonenergetic, aqueous compounds. Base hydrolysis of high explosives is exothermic (∆H RXN ) 2.3 kJ/g), and thermal runaway of the reaction is a possibility at elevated temperatures (>120 °C) where the rate of reaction is large. Thermal runaway could result in an accidental detonation of the energetic material being treated, so safe operating parameters for base hydrolysis need to be determined. To measure the safe operating temperature, base hydrolysis was performed at temperatures ramped from 20 to 300 °C. The results show that PBX 9501 molding powder detonates at a 185 °C bulk temperature in 1.5 M NaOH with a 4.5 °C/min linear temperature ramp and no agitation. The reaction of pressed PBX 9501 with 0.75, 1.5, and 3.0 M NaOH and water and both pressed and nonpressed PBX 9404 with 0.75, 1.5 M, and 3.0 M NaOH and water did not produce a detonation with a 4.5 °C/min linear temperature ramp. A previously developed reaction rate model was used to show that thermal runaway should occur when the base hydrolysis reaction rate reached a maximum at a bulk temperature between 185 and 225 °C.
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