Further Shock-Tube Studies by Infrared Emission of the Decomposition of Ammonia

Jacobs, T. A.

doi:10.1021/j100797a030

Cited by 23 publications

(9 citation statements)

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Section: Thermal Decomposition Of Ammoniamentioning

confidence: 74%

“…A similar expression has been given by Jacobs (1963) but with an activation energy of 77.7 kcal/mole and a pre-exponential factor of 2 . 5~1 0 '~ Vmole-s. Jacobs (1963) determined, based on shock tube experiments, that the reaction order with respect to ammonia was 3/2, while the order with respect to argon was 1/2. Regardless of which (if either) expression is correct, the extent of ammonia decomposition expected at tank temperatures by homogeneous unimolecular decomposition is infinitesimally small and may be neglected.…”

Section: Thermal Decomposition Of Ammoniamentioning

confidence: 74%

See 1 more Smart Citation

Thermal and combined thermal and radiolytic reactions involving nitrous oxide, hydrogen, and nitrogen in the gas phase; comparison of gas generation rates in supernate and solid fractions of Tank 241-SY-101 simulated waste

Bryan¹,

Pederson²

1995

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DISCLAIMERPortions of this document may be illegible in electronic image products. lrnages are produced from the best available original document. Executive Summary. This report summarizes progress made in evaluating mechanisms by which flammable gases are generated in Hanford double-shell tank wastes, based on the results of laboratory tests using simulated waste mixtures. Work described in this report was conducted at Pacific Northwest Laboratory (PNL)Ca) for the Flammable Gas Safety Project, the purpose of which is to develop information needed to support Westinghouse Hanford Company (WHC) in their efforts to ensure the safe interim storage of wastes at the Hanford Site. This work is related to gas generation studies being performed at Georgia Institute of Technology (GIT), under subcontract to PNL, using simulated wastes, and to studies being performed at WHC using actual wastes.Described in this report are 1) the results of tests to evaluate the rates of thermal and combined thermal and radiolytic reactions involving flammable gases, and 2) the results of experiments intended to compare gas generation rates in a homogeneous liquid with those in a heterogeneous slurry. Flammable gases generated by the radiolysis of water and by the the&al and radiolytic decomposition of organic waste constituents may themselves participate in further reactions. Examples include the decomposition of nitrous oxide to yield nitrogen and oxygen, the reaction of nitrous oxide and hydrogen to produce nitrogen and water, and the reaction of nitrogen and hydrogen to produce ammonia. The composition of the gases trapped in bubbles in the wastes therefore may change continuously as a function of the time that the gas bubbles are retained. It has often been assumed, although not demonstrated, that the rates of flammable gas generation in the convecting liquid layer and nonconvecting settled solids layer in W o r d double-shell waste tanks are approximately equal. Factors that could lead to different gas generation rates in the two layers include different water content, different concentrations of organic waste components, and catalysis by solid phases. Gas Reactions under T h e m l and Combined T h e m 1 and Radiolytic Conditions:The decomposition of nitrous oxide, reactions between nitrous oxide, and reactions between nitrogen and hydrogen under thermal and combined thermal and radiolytic conditions were investigated in the temperature range of 60 to 150°C. Radiation doses ranged from 0 to more than 100 Mrad (60Co), while reaction times extended to 500 hours. Reactions were performed in stainless steel vessels that allowed continuous monitoring of gas pressures. Gas compositions were evaluated using mass spectrometry and infrared spectrometry. Simulated waste mixtures were excluded from these tests.The primary radiolytic/thermal products of nitrous oxide decomposition were nitrogen, oxygen, and nitrogen dioxide. Under thermal-only conditions, the extent of nitrous oxide decomposition was too small to be observable. Under combined the...

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Section: Thermal Decomposition Of Ammoniamentioning

confidence: 74%

Section: Thermal Decomposition Of Ammoniamentioning

confidence: 74%

Thermal and combined thermal and radiolytic reactions involving nitrous oxide, hydrogen, and nitrogen in the gas phase; comparison of gas generation rates in supernate and solid fractions of Tank 241-SY-101 simulated waste

Bryan¹,

Pederson²

1995

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show abstract

Section: Thermal Decomposition Of Ammoniamentioning

confidence: 74%

“…A similar expression has been given by Jacobs (1963) but with an activation energy of 77.7 kcal/mole and a pre-exponential factor of 2 . 5~1 0 '~ I/mole-s. Jacobs (1963) determined, based on shock tube experiments, that the reaction order with respect to ammonia was 3/2, while the order with respect to argon was 1/2. Regardless of which (if either) expression is correct, the extent of ammonia decomposition expected at tank temperatures by homogeneous unimolecular decomposition is infinitesimally small and can be neglected.…”

Section: Thermal Decomposition Of Ammoniamentioning

confidence: 74%

Thermal and combined thermal and radiolytic reactions involving nitrous oxide, hydrogen, nitrogen, and ammonia in contact with tank 241-SY-101 simulated waste

Bryan¹,

Pederson²

1996

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Tank 241-SY-101 simulated waste. Flammable gases generated by the radiolysis of water and by the thermal and radiolytic decomposition of organic waste constituents may themselves participate in further reactions. Examples include the decomposition of nitrous oxide to yield nitrogen and oxygen, the reaction of nitrous oxide and hydrogen to produce nitrogen and water, and the reaction of nitrogen and hydrogen to produce ammonia. The composition of the gases trapped in bubbles in the wastes might therefore change continuously as a function of the time that the gas bubbles are retained.The decomposition of nitrous oxide, reactions between nitrous oxide and hydrogen, reactions between nitrogen and hydrogen, and decomposition reactions of ammonia in contact with Tank 241-SY-101 simulated waste under thermal and combined thermal and radiolytic conditions were investigated in the temperature range of 60 to 150°C. Radiation doses ranged from 0 to more than 10 Mrad ( @ ' C O ) , while reaction times extended to 70 hours. Reactions were performed in stainless steel vessels that allowed continuous monitoring of gas pressures. Gas compositions were evaluated using mass spectrometry and infrared spectrometry.The primary radiolytic and thermal products of nitrous oxide decomposition were nitrogen, oxygen, and nitrogen dioxide. Under thermal-only conditions, the extent of nitrous oxide decomposition was less than that for the companion experiment under combined thermal and radiolytic conditions. However, the thermal decomposition in the presence of simulated waste was significant compared with that observed in earlier tests in the absence of simulated waste (Bryan and Pederson 1995). G-values measured for the decomposition of nitrous oxide in the presence of simulated waste showed a significant temperature dependence, consistent with a surface reaction with nitrous oxide contributing to the decomposition reaction. G(N20) ranged in value from -7 to -17 in the systems containing wet and dried simulated waste.In contrast, G(N20) for the gas phase decomposition of nitrous oxide was determined to be constant at -12 molecules/100 eV, in good agreement with literature values. No temperature dependence of G(-N20) was apparent from 60 to 150°C. Nitrogen dioxide yields decreased with increasing temperature, while nitrogen yields increased with increasing temperature. Assuming a gamma dose rate of lo00 R/h in the actual wastes, and assuming that nitrous oxide composes 530% of the gases trapped in the nonconvecting layer, it is estimated that = 1 % of the retained nitrous oxide could be consumed by these gas-phase radiolytic reactions per year. However, the thermal decomposition of nitrous oxide contributes significantly to the total decomposition of nitrous oxide when in contact with simulated waste. iii Catalysis of nitrous oxide decomposition by solid phases is a significant possibility. At least some of the gases will be retained as bubbles attached to solid particles, in response to surface tension forces. Thus the gases will be in in...

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“…On the other hand, at lower temperatures, since it takes a long time until the steady state of the concentration of H atoms is realized, the influence of impurity in He as the driver gas contaminates the measurements of H atoms. By omitting these unreliable data, one obtains WSs/W as (4) with a 68.7% confidence limit.…”

Section: Determination Of Klimentioning

confidence: 99%