The Heterogeneous Reaction of NO2 with NH4Cl: A Molecular Diffusion Tube Study
The Heterogeneous Reaction of NO2 with NH4Cl: A Molecular Diffusion Tube Study
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DOI：
10.1007/s10874-005-5898-4
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发表时间：
2005-02
影响因子：
2
通讯作者：
N. Takenaka;M. Rossi
中科院分区：
文献类型：
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作者：
N. Takenaka;M. Rossi
在295-335K的分子扩散管实验中研究了二氧化氮与氯化铵的非均相相互作用，并用蒙特卡罗轨迹计算对其进行了解释。NO2在NH4Cl295K时的表面停留时间(τSURF)等于15μS，在323K时随温度升高而增大(τSURF=45μS)，超过323K后可能减小。NO2在NH4Cl2上的吸收速率在[NO2]中遵循一级速率规律，295K时的吸收系数γ=7×10−5，在323K时随温度升高而增加(γ=2.1×10−4)，当温度超过323K时，NO2的吸收速率可能降低。结果表明，NO_2与NH_4Cl反应为反向歧化反应，其中两个摩尔的NO_2生成中间体亚硝酸铵和硝基氯NO_2Cl。NH4NO2的分解有两条途径，一条是分解成亚硝酸、HONO和NH3，另一条是分解成氮和水。在298K时，HONO+NH_3与N_2+H_2O的支化比约为20，且随温度升高而增大。
The heterogeneous interaction of nitrogen dioxide with ammonium chloride was investigated in a molecular diffusion tube experiment at 295–335 K and interpreted using Monte Carlo trajectory calculations. The surface residence time (τsurf) of NO2on NH4Cl is equal to 15 μs at 295 K, increases with temperature up to 323 K (τsurf= 45 μs) and probably decreases beyond 323 K. The same experiment also yields uptake coefficients, γ, which are derived from the absolute number of surviving molecules effusing out of the diffusion tube. The rate of uptake of NO2on NH4Cl followed a rate law first order in [NO2] and the uptake coefficient γ is equal to 7 × 10−5at 295 K, increases with temperature up to 323 K (γ = 2.1 × 10−4) and probably decreases beyond 323 K. Nitrous acid, water and nitrogen were detected as products. From these products, it is concluded that the reaction of NO2with NH4Cl is a reverse disproportionation reaction where two moles of NO2result in ammonium nitrite, NH4NO2, as an intermediate, and nitryl chloride, NO2Cl. NH4NO2decomposes in two pathways, one to nitrous acid, HONO and NH3, the other to nitrogen and water. The branching ratio for the production of HONO + NH3to that of N2+ H2O is approximately 20 at 298 K and increases with increasing temperature.