TY - JOUR
T1 - Updated yields of nitrogenated species in flames of ammonia/benzene via introducing an aniline sub-mechanism
AU - Altarawneh, Ibrahem S.
AU - Altarawneh, Mohammednoor
AU - Rawadieh, Saleh E.
AU - Almatarneh, Mansour H.
AU - Shiroudi, Abolfazl
AU - El-Nahas, Ahmed M.
N1 - Funding Information:
This study has been supported by and a start-up grant from the College of Engineering at the United Arab Emirates University, UAEU (grant number: 31N421). Computations were carried out at the high-performance cluster (HPC) of the UAEU.
Publisher Copyright:
© 2021 The Combustion Institute
PY - 2021/6
Y1 - 2021/6
N2 - Ammonia and cyclic aromatic compounds are principal products from combustion of various fractions of biomass. Yet, kinetic mechanistic models on formation of NOx from biomass de-couple the oxidation mechanism of ammonia from that of aromatic molecules. Literature kinetic models do not consider a plausible formation of aniline as the initial product from the interaction of amine radicals and benzene molecules (as the simplest aromatic molecule). Such reaction acts a sink for NH2 radicals, and thus may alter the yields of NOx and HCN. To fill in this gap, this study reports production pathways of aniline from NH2 + benzene reactions, maps out unimolecular decomposition pathways of aniline and its derived anilino radical into, and explores the effect of the title reaction on the yields of small nitrogenated species from co-combustion of ammonia and benzene. We find that anilino radical to preferentially decompose into iso-HNC and a cyclopentadienyl radical. The resonance-stabilized structure of the anilino radical enables it to undergo bimolecular reaction with the aniline molecule to generate N-analogous compounds of dioxins, namely diphenylamine, carbazole, and phenazine. Detail kinetic modeling discloses that decomposition of aniline initiates at 1100 K with ammonia and HCN signify the most abundant N-bearing species at intermediates and high temperatures, respectively. Introducing the newly constructed aniline sub-mechanism in NOx + benzene kinetic model from the literature (i.e., CERCK model) alters predicted concentrations of principal N species within factors of 1.2- 2 between 1100–1300 K. It is hoped that reaction rate constants and mechanistic pathways presented herein to improve the predictive performance of kinetic models that address NOx and HCN emission from flames of ammonia and aromatic-containing fuels in general.
AB - Ammonia and cyclic aromatic compounds are principal products from combustion of various fractions of biomass. Yet, kinetic mechanistic models on formation of NOx from biomass de-couple the oxidation mechanism of ammonia from that of aromatic molecules. Literature kinetic models do not consider a plausible formation of aniline as the initial product from the interaction of amine radicals and benzene molecules (as the simplest aromatic molecule). Such reaction acts a sink for NH2 radicals, and thus may alter the yields of NOx and HCN. To fill in this gap, this study reports production pathways of aniline from NH2 + benzene reactions, maps out unimolecular decomposition pathways of aniline and its derived anilino radical into, and explores the effect of the title reaction on the yields of small nitrogenated species from co-combustion of ammonia and benzene. We find that anilino radical to preferentially decompose into iso-HNC and a cyclopentadienyl radical. The resonance-stabilized structure of the anilino radical enables it to undergo bimolecular reaction with the aniline molecule to generate N-analogous compounds of dioxins, namely diphenylamine, carbazole, and phenazine. Detail kinetic modeling discloses that decomposition of aniline initiates at 1100 K with ammonia and HCN signify the most abundant N-bearing species at intermediates and high temperatures, respectively. Introducing the newly constructed aniline sub-mechanism in NOx + benzene kinetic model from the literature (i.e., CERCK model) alters predicted concentrations of principal N species within factors of 1.2- 2 between 1100–1300 K. It is hoped that reaction rate constants and mechanistic pathways presented herein to improve the predictive performance of kinetic models that address NOx and HCN emission from flames of ammonia and aromatic-containing fuels in general.
KW - Ammonia
KW - Aniline
KW - Kinetic model
KW - Reactions mechanisms
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U2 - 10.1016/j.combustflame.2021.02.011
DO - 10.1016/j.combustflame.2021.02.011
M3 - Article
AN - SCOPUS:85101928201
SN - 0010-2180
VL - 228
SP - 433
EP - 442
JO - Combustion and Flame
JF - Combustion and Flame
ER -