Chemical and morphological characterization of soot and soot precursors generated in an inverse diffusion flame with aromatic and aliphatic fuels

Knowledge of the chemical and physical structure of young soot and its precursors is very useful in understanding the paths leading to soot particle inception. This paper presents chemical and morphological characterization of the products generated in ethylene and benzene inverse diffusion flames (IDF) using different analytical techniques. The trend in the data indicates that the soot precursor material and soot particles generated in the benzene IDF have a higher degree of complexity than the samples obtained in the ethylene IDF, which is reflected by an increase in the aromaticity of the chloroform extracts observed by {sup 1}H NMR and FT-IR, and shape and size of soot particles obtained by TEM and HR-TEM. It is important to highlight that the soot precursor material obtained at the lower positions in the ethylene IDF has a significant contribution of aliphatic groups, which play an important role in the particle inception and mass growth processes during the early stages of soot formation. However, these groups progressively disappear in the samples taken at higher positions in the flame, due to thermal decomposition processes. (author)

[1]  M. Guillén,et al.  Characterization of coal tar pitches with different softening points by 1H NMR: Role of the different kinds of protons in the thermal process , 1998 .

[2]  S.Win Lee,et al.  NMR method for determination of aromatics in middle distillate oils , 1999 .

[3]  Kazuhiro Akihama,et al.  Microstructure of diesel soot particles probed by electron microscopy: First observation of inner core and outer shell , 1997 .

[4]  K. Sattler,et al.  Clustering at high temperatures: carbon formation in combustion , 2002 .

[5]  A. Ciajolo,et al.  Similarities and dissimilarities in n-hexane and benzene sooting premixed flames , 2007 .

[6]  Michael Frenklach,et al.  Reaction mechanism of soot formation in flames , 2002 .

[7]  Linda G. Blevins,et al.  The existence of young soot in the exhaust of inverse diffusion flames , 2002 .

[8]  J. T. Mckinnon,et al.  Infrared analysis of flame-generated PAH samples , 1996 .

[9]  William J. Grieco,et al.  Formation mechanism of polycyclic aromatic hydrocarbons and fullerenes in premixed benzene flames , 1999 .

[10]  Robert J. Santoro,et al.  Generation of CO and smoke during underventilated combustion , 1994 .

[11]  D. E. Rosner,et al.  Soot volume fraction and temperature measurements in laminar nonpremixed flames using thermocouples , 1997 .

[12]  A. F. Sarofim,et al.  Fossil fuel combustion , 1990 .

[13]  Juntao Wu.  SOOT ABATEMENT USING FUEL ADDITIVES , 2004 .

[14]  H. F. Calcote.  Mechanisms of soot nucleation in flames—A critical review , 1981 .

[15]  A. Ciajolo,et al.  Correlations of the Spectroscopic Properties with the Chemical Composition of Flame-Formed Aromatic Mixtures , 2000 .

[16]  E. Eddings,et al.  Average structural analysis of the extractable material of young soot gathered in an ethylene inverse diffusion flame , 2007 .

[17]  Mark Mikofski.  Flame Structure and Soot Formation in Inverse Diffusion Flames (Ph.D. Dissertation) , 2005 .

[18]  Henning Bockhorn,et al.  Soot Formation in Combustion: Mechanisms and Models , 1994 .

[19]  R. Fletcher,et al.  Laser microprobe analysis of soot precursor particles and carbonaceous soot , 1995 .

[20]  E. Eddings,et al.  FT-IR and 1H NMR characterization of the products of an ethylene inverse diffusion flame , 2006 .

[21]  Robert A. Fletcher,et al.  The evolution of soot precursor particles in a diffusion flame , 1998 .

[22]  A. Ciajolo,et al.  Distribution of soot molecular weight/size along premixed flames as inferred by size exclusion chromatography , 2007 .

[23]  Angela Violi,et al.  Modeling of soot particle inception in aromatic and aliphatic premixed flames , 2004 .

[24]  Jack B. Howard,et al.  Formation of polycyclic aromatic hydrocarbons and their growth to soot—a review of chemical reaction pathways , 2000 .

[25]  Henning Bockhorn,et al.  Soot Formation in Combustion , 1994 .

[26]  S. D. Stasio,et al.  Comparative NEXAFS Study on Soot Obtained from an Ethylene/ Air Flame, a Diesel Engine, and Graphite , 2006 .

[27]  Michael P. Tolocka,et al.  Chemical species associated with the early stage of soot growth in a laminar premixed ethylene–oxygen–argon flame , 2005 .

[28]  A. Carlos Fernandez-Pello,et al.  Structure of laminar sooting inverse diffusion flames , 2007 .

[29]  Ian M. Kennedy,et al.  Models of soot formation and oxidation , 1997 .

[30]  Viswanath R. Katta,et al.  Dynamics of an inverse diffusion flame and its role in polycyclic-aromatic-hydrocarbon and soot formation , 2005 .

[31]  Eui Ju Lee,et al.  The evolution of incipient soot particles in an inverse diffusion flame of ethene , 2005 .

[32]  D. E. Rosner,et al.  Experimental studies of soot particle thermophoresis in nonisothermal combustion gases using thermocouple response techniques , 1985 .

[33]  A. Ciajolo,et al.  Spectroscopic and compositional signatures of pah-loaded mixtures in the soot inception region of a premixed ethylene flame , 1998 .