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Currently at Universidad del Cauca, Colombia
PUBLICATIONS
2013
Sánchez, Nazly E; Callejas, Alicia; Millera, Ángela; Bilbao, Rafael; Alzueta, María U
Influence of the Oxygen Presence on Polycyclic Aromatic Hydrocarbon (PAH) Formation from Acetylene Pyrolysis under Sooting Conditions Journal Article
In: Energy & Fuels, vol. 27, no. 11, pp. 7081–7088, 2013, ISSN: 0887-0624.
@article{Sanchez2013b,
title = {Influence of the Oxygen Presence on Polycyclic Aromatic Hydrocarbon (PAH) Formation from Acetylene Pyrolysis under Sooting Conditions},
author = {Nazly E Sánchez and Alicia Callejas and Ángela Millera and Rafael Bilbao and María U Alzueta},
url = {http://dx.doi.org/10.1021/ef401484s},
issn = {0887-0624},
year = {2013},
date = {2013-11-01},
journal = {Energy & Fuels},
volume = {27},
number = {11},
pages = {7081--7088},
publisher = {American Chemical Society},
abstract = {The concentration of sixteen polycyclic aromatic hydrocarbons (PAH), classified by the Environmental Protection Agency (EPA) as priority pollutants, and the soot amount obtained from acetylene conversion for different oxygen concentrations have been determined in a tubular reactor experimental system. The present work also reports concentrations of other products such as light gases, which are known as important in the soot-PAH formation process or because of their abundance in the experiment outlet gas stream. For an acetylene concentration of 30000 ppmv two types of studies have been performed namely a) the effect of reaction temperature was evaluated between 873 and 1323 K in absence and presence of oxygen (0 and 10000 ppmv) and b) the influence of the oxygen concentration between 0 and 50000 ppmv on product formation was considered for temperatures of 973 and 1223 K. Apart from CO as the main product formed from the conversion of C2H2 in the presence of oxygen, benzene, PAH, and soot are also formed in significant amounts. They are encouraged by the presence of oxygen in fuel rich conditions at the lowest temperatures studied but seem to be diminished when the temperature is increased. The results obtained at a reaction temperature of 973 K and different oxygen concentrations showed that the PAH concentration presents a maximum of around 10000 ppmv. Moreover, for a temperature of 1223 K, an increase of oxygen concentration causes a decrease of benzene/PAH/soot formation.
The concentration of sixteen polycyclic aromatic hydrocarbons (PAH), classified by the Environmental Protection Agency (EPA) as priority pollutants, and the soot amount obtained from acetylene conversion for different oxygen concentrations have been determined in a tubular reactor experimental system. The present work also reports concentrations of other products such as light gases, which are known as important in the soot-PAH formation process or because of their abundance in the experiment outlet gas stream. For an acetylene concentration of 30000 ppmv two types of studies have been performed namely a) the effect of reaction temperature was evaluated between 873 and 1323 K in absence and presence of oxygen (0 and 10000 ppmv) and b) the influence of the oxygen concentration between 0 and 50000 ppmv on product formation was considered for temperatures of 973 and 1223 K. Apart from CO as the main product formed from the conversion of C2H2 in the presence of oxygen, benzene, PAH, and soot are also formed in significant amounts. They are encouraged by the presence of oxygen in fuel rich conditions at the lowest temperatures studied but seem to be diminished when the temperature is increased. The results obtained at a reaction temperature of 973 K and different oxygen concentrations showed that the PAH concentration presents a maximum of around 10000 ppmv. Moreover, for a temperature of 1223 K, an increase of oxygen concentration causes a decrease of benzene/PAH/soot formation.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The concentration of sixteen polycyclic aromatic hydrocarbons (PAH), classified by the Environmental Protection Agency (EPA) as priority pollutants, and the soot amount obtained from acetylene conversion for different oxygen concentrations have been determined in a tubular reactor experimental system. The present work also reports concentrations of other products such as light gases, which are known as important in the soot-PAH formation process or because of their abundance in the experiment outlet gas stream. For an acetylene concentration of 30000 ppmv two types of studies have been performed namely a) the effect of reaction temperature was evaluated between 873 and 1323 K in absence and presence of oxygen (0 and 10000 ppmv) and b) the influence of the oxygen concentration between 0 and 50000 ppmv on product formation was considered for temperatures of 973 and 1223 K. Apart from CO as the main product formed from the conversion of C2H2 in the presence of oxygen, benzene, PAH, and soot are also formed in significant amounts. They are encouraged by the presence of oxygen in fuel rich conditions at the lowest temperatures studied but seem to be diminished when the temperature is increased. The results obtained at a reaction temperature of 973 K and different oxygen concentrations showed that the PAH concentration presents a maximum of around 10000 ppmv. Moreover, for a temperature of 1223 K, an increase of oxygen concentration causes a decrease of benzene/PAH/soot formation.
The concentration of sixteen polycyclic aromatic hydrocarbons (PAH), classified by the Environmental Protection Agency (EPA) as priority pollutants, and the soot amount obtained from acetylene conversion for different oxygen concentrations have been determined in a tubular reactor experimental system. The present work also reports concentrations of other products such as light gases, which are known as important in the soot-PAH formation process or because of their abundance in the experiment outlet gas stream. For an acetylene concentration of 30000 ppmv two types of studies have been performed namely a) the effect of reaction temperature was evaluated between 873 and 1323 K in absence and presence of oxygen (0 and 10000 ppmv) and b) the influence of the oxygen concentration between 0 and 50000 ppmv on product formation was considered for temperatures of 973 and 1223 K. Apart from CO as the main product formed from the conversion of C2H2 in the presence of oxygen, benzene, PAH, and soot are also formed in significant amounts. They are encouraged by the presence of oxygen in fuel rich conditions at the lowest temperatures studied but seem to be diminished when the temperature is increased. The results obtained at a reaction temperature of 973 K and different oxygen concentrations showed that the PAH concentration presents a maximum of around 10000 ppmv. Moreover, for a temperature of 1223 K, an increase of oxygen concentration causes a decrease of benzene/PAH/soot formation.
The concentration of sixteen polycyclic aromatic hydrocarbons (PAH), classified by the Environmental Protection Agency (EPA) as priority pollutants, and the soot amount obtained from acetylene conversion for different oxygen concentrations have been determined in a tubular reactor experimental system. The present work also reports concentrations of other products such as light gases, which are known as important in the soot-PAH formation process or because of their abundance in the experiment outlet gas stream. For an acetylene concentration of 30000 ppmv two types of studies have been performed namely a) the effect of reaction temperature was evaluated between 873 and 1323 K in absence and presence of oxygen (0 and 10000 ppmv) and b) the influence of the oxygen concentration between 0 and 50000 ppmv on product formation was considered for temperatures of 973 and 1223 K. Apart from CO as the main product formed from the conversion of C2H2 in the presence of oxygen, benzene, PAH, and soot are also formed in significant amounts. They are encouraged by the presence of oxygen in fuel rich conditions at the lowest temperatures studied but seem to be diminished when the temperature is increased. The results obtained at a reaction temperature of 973 K and different oxygen concentrations showed that the PAH concentration presents a maximum of around 10000 ppmv. Moreover, for a temperature of 1223 K, an increase of oxygen concentration causes a decrease of benzene/PAH/soot formation.
Sánchez, Nazly E; Millera, Ángela; Bilbao, Rafael; Alzueta, María U
In: Journal of Analytical and Applied Pyrolysis, vol. 103, pp. 126–133, 2013, ISSN: 01652370.
@article{Sanchez2013a,
title = {Polycyclic aromatic hydrocarbons (PAH), soot and light gases formed in the pyrolysis of acetylene at different temperatures: Effect of fuel concentration},
author = {Nazly E Sánchez and Ángela Millera and Rafael Bilbao and María U Alzueta},
url = {http://www.sciencedirect.com/science/article/pii/S0165237012002197},
issn = {01652370},
year = {2013},
date = {2013-09-01},
journal = {Journal of Analytical and Applied Pyrolysis},
volume = {103},
pages = {126--133},
abstract = {The effect of different inlet hydrocarbon concentrations (10,000, 20,000 and 30,000ppmv) and reaction temperatures (873–1323K) on PAH and soot formation from acetylene pyrolysis has been studied. 16 PAH considered by Environmental Protection Agency (EPA) as priority pollutants, together with light gases present at the outlet gas stream, have been quantified. Soot formed was collected on a filter at the reactor outlet. PAH found in the different phases (at the gas phase, adsorbed on soot, and/or stuck on reactor walls) were analysed by means of gas chromatography–mass spectrometry (GC–MS). Increasing fuel concentration and reaction temperature resulted in the increase in soot production together with decrease in the light gases at the reactor outlet. The acetylene conversion and the hydrogen concentration increased with the temperature, whereas benzene and the total PAH quantified showed a maximum around 1123 and 1223K, respectively. In all cases, the concentration of products such as hydrogen, benzene, PAH and soot at the reactor outlet and the acetylene conversion increased with the reactant concentration. The temperature, at which the benzene showed a maximum concentration, was similar to the temperature where soot and PAH started to be formed. This suggests that benzene consumption leads to form PAH, which subsequently form soot, by following the well-known HACA (hydrogen abstraction/acetylene addition) mechanism.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The effect of different inlet hydrocarbon concentrations (10,000, 20,000 and 30,000ppmv) and reaction temperatures (873–1323K) on PAH and soot formation from acetylene pyrolysis has been studied. 16 PAH considered by Environmental Protection Agency (EPA) as priority pollutants, together with light gases present at the outlet gas stream, have been quantified. Soot formed was collected on a filter at the reactor outlet. PAH found in the different phases (at the gas phase, adsorbed on soot, and/or stuck on reactor walls) were analysed by means of gas chromatography–mass spectrometry (GC–MS). Increasing fuel concentration and reaction temperature resulted in the increase in soot production together with decrease in the light gases at the reactor outlet. The acetylene conversion and the hydrogen concentration increased with the temperature, whereas benzene and the total PAH quantified showed a maximum around 1123 and 1223K, respectively. In all cases, the concentration of products such as hydrogen, benzene, PAH and soot at the reactor outlet and the acetylene conversion increased with the reactant concentration. The temperature, at which the benzene showed a maximum concentration, was similar to the temperature where soot and PAH started to be formed. This suggests that benzene consumption leads to form PAH, which subsequently form soot, by following the well-known HACA (hydrogen abstraction/acetylene addition) mechanism.
Sánchez, Nazly E; Salafranca, Jesús; Callejas, Alicia; Millera, Ángela; Bilbao, Rafael; Alzueta, María U
In: Fuel, vol. 107, pp. 246–253, 2013, ISSN: 00162361.
@article{Sanchez2013c,
title = {Quantification of polycyclic aromatic hydrocarbons (PAHs) found in gas and particle phases from pyrolytic processes using gas chromatography–mass spectrometry (GC–MS)},
author = {Nazly E Sánchez and Jesús Salafranca and Alicia Callejas and Ángela Millera and Rafael Bilbao and María U Alzueta},
url = {http://www.sciencedirect.com/science/article/pii/S0016236113000744},
issn = {00162361},
year = {2013},
date = {2013-05-01},
journal = {Fuel},
volume = {107},
pages = {246--253},
abstract = {The outlet stream from combustion processes is a complex mixture of compounds which depends on the specific operating conditions. Thermochemical processes operating under rich fuel conditions enhance the formation of polycyclic aromatic hydrocarbons (PAHs) and soot. PAH play an important role in soot formation, but they can appear adsorbed on soot surface as well as at the gas phase due to their different volatility and molecular weight. Both PAH (the gas phase and adsorbed PAH) fractions are important when considering the total characterization from pyrolytic processes, mainly for determining the emission levels of 16 Environmental Protection Agency (EPA) priority PAH. In this way, an optimized method capable to determine the aromatic compounds in the gas and particle phases in combustion exhaust gases is needed. The method here presented allows the collection and quantification of both the PAH adsorbed on soot and present at the gas phase of the exhaust gases of thermochemical processes. It involves PAH characterization by combining classical Soxhlet extraction of the sample collected, followed by an extract concentration using a rotary evaporator and subsequent micro-concentration under gentle nitrogen stream before the analysis. The EPA-PAH were determined using a gas chromatograph–mass spectrometer (GC–MS). Validation tests using a fully characterized soot, the NIST (National Institute of Standards and Technology) reference material SRM 1650b, and repeatability using diesel surrogate commercial soot named Printex-U, were done. Additionally, experiments of acetylene pyrolysis were carried out and their products analyzed for determining the PAH amount. The results showed good method reliability for the determination of 16 EPA-PAH found in the outlet gases, as well as good recovery for the most of PAH and good prediction for the real samples analyzed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The outlet stream from combustion processes is a complex mixture of compounds which depends on the specific operating conditions. Thermochemical processes operating under rich fuel conditions enhance the formation of polycyclic aromatic hydrocarbons (PAHs) and soot. PAH play an important role in soot formation, but they can appear adsorbed on soot surface as well as at the gas phase due to their different volatility and molecular weight. Both PAH (the gas phase and adsorbed PAH) fractions are important when considering the total characterization from pyrolytic processes, mainly for determining the emission levels of 16 Environmental Protection Agency (EPA) priority PAH. In this way, an optimized method capable to determine the aromatic compounds in the gas and particle phases in combustion exhaust gases is needed. The method here presented allows the collection and quantification of both the PAH adsorbed on soot and present at the gas phase of the exhaust gases of thermochemical processes. It involves PAH characterization by combining classical Soxhlet extraction of the sample collected, followed by an extract concentration using a rotary evaporator and subsequent micro-concentration under gentle nitrogen stream before the analysis. The EPA-PAH were determined using a gas chromatograph–mass spectrometer (GC–MS). Validation tests using a fully characterized soot, the NIST (National Institute of Standards and Technology) reference material SRM 1650b, and repeatability using diesel surrogate commercial soot named Printex-U, were done. Additionally, experiments of acetylene pyrolysis were carried out and their products analyzed for determining the PAH amount. The results showed good method reliability for the determination of 16 EPA-PAH found in the outlet gases, as well as good recovery for the most of PAH and good prediction for the real samples analyzed.
2012
Sánchez, Nazly E; Callejas, Alicia; Millera, Ángela; Bilbao, Rafael; Alzueta, María U
Polycyclic Aromatic Hydrocarbon (PAH) and Soot Formation in the Pyrolysis of Acetylene and Ethylene: Effect of the Reaction Temperature Journal Article
In: Energy & Fuels, vol. 26, no. 8, pp. 4823–4829, 2012, ISSN: 0887-0624.
@article{Sanchez2012,
title = {Polycyclic Aromatic Hydrocarbon (PAH) and Soot Formation in the Pyrolysis of Acetylene and Ethylene: Effect of the Reaction Temperature},
author = {Nazly E Sánchez and Alicia Callejas and Ángela Millera and Rafael Bilbao and María U Alzueta},
url = {http://dx.doi.org/10.1021/ef300749q},
issn = {0887-0624},
year = {2012},
date = {2012-08-01},
journal = {Energy & Fuels},
volume = {26},
number = {8},
pages = {4823--4829},
publisher = {American Chemical Society},
abstract = {The formation of soot and polycyclic aromatic hydrocarbons (PAHs) has been studied during the pyrolysis of acetylene and ethylene at different reaction temperatures (1073?1423 K) in a tubular flow reactor at atmospheric pressure. The 16 PAHs classified by the United States Environmental Protection Agency (U.S. EPA) as priority compounds, together with light gases present at the outlet gas stream, were quantified by a chromatographic method. Soot formed was collected on a filter at the reactor outlet and later quantified. In this way, the relationship between PAH, gas, and soot formation can be discussed. The distribution of the target PAHs in the different phases (at the gas phase, adsorbed on soot, and/or sticked on reactor walls) is also analyzed. The speciation of the individual PAH compounds was achieved by a combination of Soxhlet extraction, extract concentration by a rotary evaporator, and gas chromatography coupled to mass spectrometry (GC?MS). The present study shows that, in the pyrolysis of both acetylene and ethylene, while soot formation is enhanced by increasing the temperature, the PAH yield exhibits a maximum in the evaluated temperature range, and such a maximum value depends upon the hydrocarbon used (ethylene or acetylene). However, the PAH distribution in the different phases does not seem to be influenced by hydrocarbon used. PAHs from ethylene and acetylene pyrolysis are seen to be mainly adsorbed on soot preferably than on other places, except for naphthalene (NAPH) in the pyrolysis of ethylene, in which case a higher concentration was found at the gas phase.
The formation of soot and polycyclic aromatic hydrocarbons (PAHs) has been studied during the pyrolysis of acetylene and ethylene at different reaction temperatures (1073?1423 K) in a tubular flow reactor at atmospheric pressure. The 16 PAHs classified by the United States Environmental Protection Agency (U.S. EPA) as priority compounds, together with light gases present at the outlet gas stream, were quantified by a chromatographic method. Soot formed was collected on a filter at the reactor outlet and later quantified. In this way, the relationship between PAH, gas, and soot formation can be discussed. The distribution of the target PAHs in the different phases (at the gas phase, adsorbed on soot, and/or sticked on reactor walls) is also analyzed. The speciation of the individual PAH compounds was achieved by a combination of Soxhlet extraction, extract concentration by a rotary evaporator, and gas chromatography coupled to mass spectrometry (GC?MS). The present study shows that, in the pyrolysis of both acetylene and ethylene, while soot formation is enhanced by increasing the temperature, the PAH yield exhibits a maximum in the evaluated temperature range, and such a maximum value depends upon the hydrocarbon used (ethylene or acetylene). However, the PAH distribution in the different phases does not seem to be influenced by hydrocarbon used. PAHs from ethylene and acetylene pyrolysis are seen to be mainly adsorbed on soot preferably than on other places, except for naphthalene (NAPH) in the pyrolysis of ethylene, in which case a higher concentration was found at the gas phase.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The formation of soot and polycyclic aromatic hydrocarbons (PAHs) has been studied during the pyrolysis of acetylene and ethylene at different reaction temperatures (1073?1423 K) in a tubular flow reactor at atmospheric pressure. The 16 PAHs classified by the United States Environmental Protection Agency (U.S. EPA) as priority compounds, together with light gases present at the outlet gas stream, were quantified by a chromatographic method. Soot formed was collected on a filter at the reactor outlet and later quantified. In this way, the relationship between PAH, gas, and soot formation can be discussed. The distribution of the target PAHs in the different phases (at the gas phase, adsorbed on soot, and/or sticked on reactor walls) is also analyzed. The speciation of the individual PAH compounds was achieved by a combination of Soxhlet extraction, extract concentration by a rotary evaporator, and gas chromatography coupled to mass spectrometry (GC?MS). The present study shows that, in the pyrolysis of both acetylene and ethylene, while soot formation is enhanced by increasing the temperature, the PAH yield exhibits a maximum in the evaluated temperature range, and such a maximum value depends upon the hydrocarbon used (ethylene or acetylene). However, the PAH distribution in the different phases does not seem to be influenced by hydrocarbon used. PAHs from ethylene and acetylene pyrolysis are seen to be mainly adsorbed on soot preferably than on other places, except for naphthalene (NAPH) in the pyrolysis of ethylene, in which case a higher concentration was found at the gas phase.
The formation of soot and polycyclic aromatic hydrocarbons (PAHs) has been studied during the pyrolysis of acetylene and ethylene at different reaction temperatures (1073?1423 K) in a tubular flow reactor at atmospheric pressure. The 16 PAHs classified by the United States Environmental Protection Agency (U.S. EPA) as priority compounds, together with light gases present at the outlet gas stream, were quantified by a chromatographic method. Soot formed was collected on a filter at the reactor outlet and later quantified. In this way, the relationship between PAH, gas, and soot formation can be discussed. The distribution of the target PAHs in the different phases (at the gas phase, adsorbed on soot, and/or sticked on reactor walls) is also analyzed. The speciation of the individual PAH compounds was achieved by a combination of Soxhlet extraction, extract concentration by a rotary evaporator, and gas chromatography coupled to mass spectrometry (GC?MS). The present study shows that, in the pyrolysis of both acetylene and ethylene, while soot formation is enhanced by increasing the temperature, the PAH yield exhibits a maximum in the evaluated temperature range, and such a maximum value depends upon the hydrocarbon used (ethylene or acetylene). However, the PAH distribution in the different phases does not seem to be influenced by hydrocarbon used. PAHs from ethylene and acetylene pyrolysis are seen to be mainly adsorbed on soot preferably than on other places, except for naphthalene (NAPH) in the pyrolysis of ethylene, in which case a higher concentration was found at the gas phase.
The formation of soot and polycyclic aromatic hydrocarbons (PAHs) has been studied during the pyrolysis of acetylene and ethylene at different reaction temperatures (1073?1423 K) in a tubular flow reactor at atmospheric pressure. The 16 PAHs classified by the United States Environmental Protection Agency (U.S. EPA) as priority compounds, together with light gases present at the outlet gas stream, were quantified by a chromatographic method. Soot formed was collected on a filter at the reactor outlet and later quantified. In this way, the relationship between PAH, gas, and soot formation can be discussed. The distribution of the target PAHs in the different phases (at the gas phase, adsorbed on soot, and/or sticked on reactor walls) is also analyzed. The speciation of the individual PAH compounds was achieved by a combination of Soxhlet extraction, extract concentration by a rotary evaporator, and gas chromatography coupled to mass spectrometry (GC?MS). The present study shows that, in the pyrolysis of both acetylene and ethylene, while soot formation is enhanced by increasing the temperature, the PAH yield exhibits a maximum in the evaluated temperature range, and such a maximum value depends upon the hydrocarbon used (ethylene or acetylene). However, the PAH distribution in the different phases does not seem to be influenced by hydrocarbon used. PAHs from ethylene and acetylene pyrolysis are seen to be mainly adsorbed on soot preferably than on other places, except for naphthalene (NAPH) in the pyrolysis of ethylene, in which case a higher concentration was found at the gas phase.
Keramiotis, Ch.; Vourliotakis, G; Skevis, G; Founti, M A; Esarte, Claudia; Sánchez, Nazly E; Millera, Ángela; Bilbao, Rafael; Alzueta, María U
Experimental and computational study of methane mixtures pyrolysis in a flow reactor under atmospheric pressure Journal Article
In: Energy, vol. 43, no. 1, pp. 103–110, 2012, ISSN: 03605442.
@article{Keramiotis2012,
title = {Experimental and computational study of methane mixtures pyrolysis in a flow reactor under atmospheric pressure},
author = {Ch. Keramiotis and G Vourliotakis and G Skevis and M A Founti and Claudia Esarte and Nazly E Sánchez and Ángela Millera and Rafael Bilbao and María U Alzueta},
url = {http://www.sciencedirect.com/science/article/pii/S036054421200179X},
issn = {03605442},
year = {2012},
date = {2012-07-01},
journal = {Energy},
volume = {43},
number = {1},
pages = {103--110},
abstract = {A study of the pyrolysis of methane mixtures in a laboratory reactor, exploring the influence of the bath gas used (N2 and CO2) and the presence of small amounts of ethane to simulate natural gas, has been carried out at atmospheric pressure and the 1250–1500 K temperature range. Exhaust gaseous species analysis was realized using a gas chromatographic system and total soot was determined by collecting and weighing it. The study can be useful for understanding and optimizing the performance of modern engines, gas turbines and some fuel cell systems where the syngas feed is obtained from the partial oxidation of different mixtures with possible formation of soot and other undesired products. Model simulations using two detailed kinetic mechanisms have been performed. Overall, experimental and computational results are in reasonable agreement, with some exceptions in some minor species. The work provides a basis for further development and optimization of existing detailed chemical kinetic schemes.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A study of the pyrolysis of methane mixtures in a laboratory reactor, exploring the influence of the bath gas used (N2 and CO2) and the presence of small amounts of ethane to simulate natural gas, has been carried out at atmospheric pressure and the 1250–1500 K temperature range. Exhaust gaseous species analysis was realized using a gas chromatographic system and total soot was determined by collecting and weighing it. The study can be useful for understanding and optimizing the performance of modern engines, gas turbines and some fuel cell systems where the syngas feed is obtained from the partial oxidation of different mixtures with possible formation of soot and other undesired products. Model simulations using two detailed kinetic mechanisms have been performed. Overall, experimental and computational results are in reasonable agreement, with some exceptions in some minor species. The work provides a basis for further development and optimization of existing detailed chemical kinetic schemes.