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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Thermal Decomposition of Gaseous Ammonium Nitrate at Low Pressure: Kinetic Modeling of Product Formation and Heterogeneous Decomposition of Nitric Acid
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Thermal Decomposition of Gaseous Ammonium Nitrate at Low Pressure: Kinetic Modeling of Product Formation and Heterogeneous Decomposition of Nitric Acid

机译：气态硝酸铵在低压下的热分解：产物形成和硝酸非均相分解的动力学模型

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The thermal decomposition of ammonium nitrate, NH4NO3 (AN), in the gas phase has been studied at 423-56 K by pyrolysis/mass spectrometry under low-pressure conditions using a Saalfeld reactor coated with boric acid. The sublimation of NH4NO3 at 423 K was proposed to produce equal amounts of NH3 and HNO3, followed by the decomposition reaction of HNO3, HNO3 + M f OH + NO2 + M (where M ) third-body and reactor surface). The absolute yields of N2, N2O, H2O, and NH3, which can be unambiguously measured and quantitatively calibrated under a constant pressure at 5-6.2 torr He are kinetically modeled using the detailed [H,N,O]-mechanism established earlier for the simulation of NH3-NO2 (Park, J.; Lin, M. C. Technologies and Combustion for a Clean Environment. Proc. 4th Int. Conf. 1997, 34-1, 1-5) and ADN decomposition reactions (Park, J.; Chakraborty, D.; Lin, M. C. Proc. Combust. Inst. 1998, 27, 2351-2357). Since the homogeneous decomposition reaction of HNO3 itself was found to be too slow to account for the consumption of reactants and the formation of products, we also introduced the heterogeneous decomposition of HNO3 in our kinetic modeling. The heterogeneous decomposition rate of HNO3, HNO3 + (B2O3/SiO2) f OH + NO2 + (B2O3/SiO2), was determined by varying its rate to match the modeled result to the measured concentrations of NH3 and H2O; the rate could be represented by k2b ) 7.91 × 107 exp(-12 600/T) s-1, which appears to be consistent with those reported by Johnston and co-workers (Johnston, H. S.; Foering, L.; Tao, Y.-S.; Messerly, G. H. J. Am. Chem. Soc. 1951, 73, 2319-2321) for HNO3 decomposition on glass reactors at higher temperatures. Notably, the concentration profiles of all species measured could be satisfactorily predicted by the existing [H,N,O]-mechanism with the heterogeneous initiation process.
机译：硝酸铵NH4NO3（AN）在气相中的热分解已经通过在低压条件下使用涂有硼酸的Saalfeld反应器在低压条件下通过热解/质谱法在423-56 K下进行了研究。有人提出在423 K处升华NH4NO3以产生等量的NH3和HNO3，然后进行HNO3，HNO3 + M f OH + NO2 + M（其中M）的第三体和反应器表面的分解反应。 N5，N2O，H2O和NH3的绝对产率可以在5-6.2 torr He的恒定压力下进行明确测量和定量校准。使用较早建立的详细[H，N，O]机理进行动力学建模。 NH3-NO2（Park，J .; Lin，MC Technologies and Combustion for a Clean Environment。Proc。4th Int。Conf。1997，34-1，1-5）和ADN分解反应（Park，J .; Chakraborty）的模拟，D .; Lin，MC Proc。Combust。Inst。1998，27，2351-2357）。由于发现HNO3本身的均相分解反应太慢，无法说明反应物的消耗和产物的形成，因此我们在动力学模型中还引入了HNO3的异质分解。通过改变其速率使模拟结果与所测的NH3和H2O浓度相匹配，确定HNO3，HNO3 +（B2O3 / SiO2）f OH + NO2 +（B2O3 / SiO2）的异质分解速率。该速率可以表示为k2b）7.91×107 exp（-12 600 / T）s-1，这似乎与Johnston及其同事所报道的一致（Johnston，HS; Foering，L。; Tao，Y -S。; Messerly，GHJ Am.Chem.Soc.1951，73，2319-2321），用于在较高温度下在玻璃反应器上分解HNO 3。值得注意的是，通过现有的[H，N，O]机制和异质引发过程可以令人满意地预测所有被测物种的浓度分布。

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