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Open accessJournal ArticleDOI: 10.1021/ACS.ENERGYFUELS.0C03874

Pyrolysis and Combustion Chemistry of Pyrrole, a Reference Component for Bio-oil Surrogates: Jet-Stirred Reactor Experiments and Kinetic Modeling.

02 Mar 2021-Energy & Fuels (American Chemical Society (ACS))-Vol. 35, Iss: 9, pp 7265-7284
Abstract: Fast-pyrolysis bio-oils (FPBOs) obtained from lignocellulosic biomass are gaining attention as sustainable fuels for various applications, including the transport sector and power production. A significant fraction of bio-oils is constituted by nitrogen-containing compounds (N fuels) that should be considered when developing surrogate models for FPBOs. Moreover, the content of N fuels in FPBOs is expected to strongly contribute to the production of nitrogen oxides (NO x ) directly from fuel-bound nitrogen (fuel NO x ), in addition to the thermal NO x formation pathways typical of high-temperature combustion conditions. This work investigates the pyrolysis and combustion chemistry of pyrrole (C4H5N), a candidate reference fuel component for FPBO surrogate models. Speciation measurements in an atmospheric pressure jet-stirred reactor have been performed for both pyrolysis and oxidation conditions. Pyrolysis experiments have been performed for 1% pyrrole/helium mixtures over the temperature range T = 925-1200 K. Oxidation experiments were carried out for 1% pyrrole/oxygen/helium mixtures at three equivalence ratios (φ = 0.5, 1.0, and 2.0) over the temperature range T = 700-1200 K. These new data significantly extend the number of experimental targets for kinetic model validation available at present for pyrrole combustion. After a thorough revision of previous theoretical and kinetic modeling studies, a preliminary kinetic model is developed and validated by means of comparison to new experimental data and those previously reported in the literature. The rate of production and sensitivity analyses highlight important pathways deserving further investigations for a better understanding of pyrrole and, more in general, N fuel combustion chemistry. A critical discussion on experimental challenges to be faced when dealing with pyrrole is also reported, encouraging further experimental investigation with advanced diagnostics.

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Topics: Combustion (58%)

6 results found

Journal ArticleDOI: 10.1016/J.COMBUSTFLAME.2021.111458
Jianghui Luo1, Chun Zou1, Qianjin Lin1, Wenxiang Xia1  +2 moreInstitutions (2)
Abstract: Understanding the details of pyrrole combustion chemistry in the O2/CO2 atmosphere contributes to developing the strategies for nitrogen oxides (NOx) control during the pressurized oxy-coal combustion (POCC). However, the existing kinetic models for pyrrole oxidation lack multi-dimensional validation, and the ignition delay times (IDTs) of pyrrole in the O2/CO2 atmosphere are still scarce. This study measured the IDTs of pyrrole in O2/CO2 atmospheres at an elevated pressure of 5.2 bar, temperatures from 1271 to 1645 K, and equivalence ratios Φ = 0.5, 1.0, and 2.0 in a shock tube. The results demonstrate that the pyrrole IDTs decrease with decreasing equivalence ratio and the pyrrole mixtures in O2/CO2 atmospheres have longer IDTs than those in O2/Ar atmospheres. A pyrrole oxidation kinetic model (HUST pyrrole model) has been developed by updating 19 reactions in our previous model (HUST pyridine model). HUST pyrrole model gives a satisfactory prediction of the IDTs of pyrrole in the O2/Ar atmosphere (measured by MacNamara et al.) and O2/CO2 atmosphere (measured in this study) and the profiles of pyrrole, HCN, and NO (measured by Yamamoto et al.). The comparison of the HUST pyrrole model with the Lumbreras model (2001) was conducted by the pyrrole IDTs and profiles of HCN using the sensitivity and flux analysis. The addition of HNCPROP and modification of R665 (C3H3 + O2 = CH2CO + HCO), R1273 (AC3H4CN + H2 => ALLYLCN + H), R1251 (PYRLNE = ALLYLCN), R1238 (PYRROLE + H = PYRLYL + H2), and R1240 (PYRROLE + OH = PYRLYL + H2O) in HUST pyrrole model significantly improve the prediction performance for the pyrrole oxidation. The effects of the equivalence ratio and CO2 on the IDTs for pyrrole oxidation have been analyzed.

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Topics: Pyrrole (50%)

1 Citations

Journal ArticleDOI: 10.1080/13647830.2021.1950838
Han Li1, Wenming Yang1, Dezhi Zhou1Institutions (1)
Abstract: An innovative kinetic mechanism reduction method, Species’ Participation in Element Fluxes (SPEF), is developed in this study. It utilises species’ participation in element fluxes to evaluate the i...

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66 results found

Open access
01 Jan 2016-
Abstract: Information document of the Scoping meeting on collaboration between Regional Seas Programmes and Regional Fisheries Bodies in the Southwest Indian Ocean

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Topics: Sustainable development (61%)

10,594 Citations

Journal ArticleDOI: 10.1063/1.477924
Abstract: The recently introduced complete basis set, CBS-Q, model chemistry is modified to use B3LYP hybrid density functional geometries and frequencies, which give both improved reliability (maximum error for the G2 test set reduced from 3.9 to 2.8 kcal/mol) and increased accuracy (mean absolute error reduced from 0.98 to 0.87 kcal/mol), with little penalty in computational speed. The use of a common method for geometries and frequencies makes the modified model applicable to transition states for chemical reactions.

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2,227 Citations

Journal ArticleDOI: 10.1002/KIN.20802
Abstract: A detailed chemical kinetic mechanism has been developed to describe the oxidation of small hydrocarbon and oxygenated hydrocarbon species. The reactivity of these small fuels and intermediates is of critical importance in understanding and accurately describing the combustion characteristics, such as ignition delay time, flame speed, and emissions of practical fuels. The chosen rate expressions have been assembled through critical evaluation of the literature, with minimum optimization performed. The mechanism has been validated over a wide range of initial conditions and experimental devices, including flow reactor, shock tube, jet-stirred reactor, and flame studies. The current mechanism contains accurate kinetic descriptions for saturated and unsaturated hydrocarbons, namely methane, ethane, ethylene, and acetylene, and oxygenated species; formaldehyde, methanol, acetaldehyde, and ethanol.

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Topics: Combustion (56%), Flame speed (55%), Methane (50%)

763 Citations

Journal ArticleDOI: 10.1016/S0360-1285(02)00031-X
Abstract: Understanding of the chemical and physical processes that govern formation and destruction of nitrogen oxides (NO x ) in combustion of solid fuels continues to be a challenge. Even though this area has been the subject of extensive research over the last three decades, there are still unresolved issues that may limit the potential of primary measures for NO x control. In most solid fuel fired systems oxidation of fuel-bound nitrogen constitutes the dominating source of nitrogen oxides. The present paper reviews some fundamental aspects of fuel nitrogen conversion in these systems, emphasizing mostly combustion of coal since most previous work deal with this fuel. However, also results on biomass combustion is discussed. Homogeneous and heterogeneous pathways in fuel NO formation and destruction are discussed and the effect of fuel characteristics, devolatilization conditions and combustion mode on the oxidation selectivity towards NO and N 2 is evaluated. Results indicate that even under idealized conditions, such as a laminar pulverized-fuel flame, the governing mechanisms for fuel nitrogen conversion are not completely understood. Light gases, tar, char and soot may all be important vehicles for fuel-N conversion, with their relative importance depending on fuel rank and reaction conditions. Oxygen availability and fuel-nitrogen level are major parameters determining the oxidation selectivity of fuel-N towards NO and N 2 , but also the ability of char and soot to reduce NO is potentially important. The impact of fuel/oxidizer mixing pattern on NO formation appears to be less important in solid-fuel flames than in homogeneous flames.

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Topics: Solid fuel (62%), Hydrogen fuel (62%), Combustion (60%) ... show more

720 Citations

Open accessReportDOI: 10.2172/925269
A. Burcat, B. Ruscic1Institutions (1)
29 Jul 2005-
Abstract: The thermochemical database of species involved in combustion processes is and has been available for free use for over 25 years. It was first published in print in 1984, approximately 8 years after it was first assembled, and contained 215 species at the time. This is the 7th printed edition and most likely will be the last one in print in the present format, which involves substantial manual labor. The database currently contains more than 1300 species, specifically organic molecules and radicals, but also inorganic species connected to combustion and air pollution. Since 1991 this database is freely available on the internet, at the Technion-IIT ftp server, and it is continuously expanded and corrected. The database is mirrored daily at an official mirror site, and at random at about a dozen unofficial mirror and 'finger' sites. The present edition contains numerous corrections and many recalculations of data of provisory type by the G3//B3LYP method, a high-accuracy composite ab initio calculation. About 300 species are newly calculated and are not yet published elsewhere. In anticipation of the full coupling, which is under development, the database started incorporating the available (as yet unpublished) values from Active Thermochemical Tables. The electronic version nowmore » also contains an XML file of the main database to allow transfer to other formats and ease finding specific information of interest. The database is used by scientists, educators, engineers and students at all levels, dealing primarily with combustion and air pollution, jet engines, rocket propulsion, fireworks, but also by researchers involved in upper atmosphere kinetics, astrophysics, abrasion metallurgy, etc. This introductory article contains explanations of the database and the means to use it, its sources, ways of calculation, and assessments of the accuracy of data.« less

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702 Citations

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