Ammonia oxidation at high pressure and intermediate temperatures

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• 作者：Yu Song^a ; ^b ; Hamid Hashemi^a ; Jakob Munkholt Christensen^a ; Chun Zou^b ; Paul Marshall^c ; Peter Glarborg^a ; ^{pgl@kt.dtu.dk" class="auth_mail" title="E-mail the corresponding author}
• 关键词：NH3 oxidation ; High pressure ; Flow reactor ; H2NO  ; +  ; O2 rate constant ; Kinetic model
• 刊名：Fuel
• 出版年：2016
• 出版时间：1 October 2016
• 年：2016
• 卷：181
• 期：Complete
• 页码：358-365
• 全文大小：1448 K

文摘

Ammonia oxidation experiments were conducted at high pressure (30 bar and 100 bar) under oxidizing and stoichiometric conditions, respectively, and temperatures ranging from 450 to 925 K. The oxidation of ammonia was slow under stoichiometric conditions in the temperature range investigated. Under oxidizing conditions the onset temperature for reaction was 850–875 K at 30 bar, while at 100 bar it was about 800 K, with complete consumption of NH₃ at 875 K. The products of reaction were N₂ and N₂O, while NO and NO₂ concentrations were below the detection limit even under oxidizing conditions. The data were interpreted in terms of a detailed chemical kinetic model. The rate constant for the reaction of the important intermediate H₂NO with O₂ was determined from ab initio calculations to be 2.3 × 10² T^2.994 exp(−9510 K/T) cm³ mol⁻¹ s⁻¹. The agreement between experimental results and model work was satisfactory. The main oxidation path for NH₃ at high pressure under oxidizing conditions is NH₃ $\stackrel{+\text{OH}}{⟶}$ NH₂ $\stackrel{+{\text{HO}}_2\text{,}{\text{NO}}_2}{⟶}$ H₂NO $\stackrel{+{\text{O}}_2}{⟶}$ HNO $\stackrel{+{\text{O}}_2}{⟶}$ NO $\stackrel{+{\text{NH}}_2}{⟶}$ N₂. The modeling predictions are most sensitive to the reactions NH₂ + NO = NNH + OH and NH₂ + HO₂ = H₂NO + OH, which promote the ammonia consumption by forming OH radicals, and to NH₂ + NO = N₂ + H₂O and NH₂ + NO₂ = N₂O + H₂O, which are the main chain-terminating steps.