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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; 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.
Sánchez, Nazly E; Callejas, Alicia; Millera, Ángela; Bilbao, Rafael; Alzueta, María U
Formation of PAH and soot during acetylene pyrolysis at different gas residence times and reaction temperatures Journal Article
In: Energy, vol. 43, no. 1, pp. 30–36, 2012, ISSN: 03605442.
@article{Sanchez2012a,
title = {Formation of PAH and soot during acetylene pyrolysis at different gas residence times and reaction temperatures},
author = {Nazly E Sánchez and Alicia Callejas and Ángela Millera and Rafael Bilbao and María U Alzueta},
url = {http://www.sciencedirect.com/science/article/pii/S0360544211008036},
issn = {03605442},
year = {2012},
date = {2012-07-01},
journal = {Energy},
volume = {43},
number = {1},
pages = {30--36},
abstract = {The formation of polycyclic aromatic hydrocarbons (PAH)11Polycyclic aromatic hydrocarbons. and soot from the pyrolysis of acetylene was studied, taking into account the influence of the operating conditions, such as gas residence time and temperature. The influence of gas residence time was considered between 1.28 and 3.88 s for the experiments carried out under different temperatures from 1073 to 1223 K. The total PAH was calculated as the addition of PAH concentration found in different locations, namely adsorbed on soot and on the reactor walls, and at the outlet gas stream. The relationship between the PAH concentrations and their carcinogenic equivalence sum (KE)22Carcinogenic equivalence sum. was also evaluated. The results obtained showed that temperature and residence time have a high influence on pyrolysis products, especially on the PAH concentration adsorbed on soot, which exhibited the highest KE in all cases studied.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The formation of polycyclic aromatic hydrocarbons (PAH)11Polycyclic aromatic hydrocarbons. and soot from the pyrolysis of acetylene was studied, taking into account the influence of the operating conditions, such as gas residence time and temperature. The influence of gas residence time was considered between 1.28 and 3.88 s for the experiments carried out under different temperatures from 1073 to 1223 K. The total PAH was calculated as the addition of PAH concentration found in different locations, namely adsorbed on soot and on the reactor walls, and at the outlet gas stream. The relationship between the PAH concentrations and their carcinogenic equivalence sum (KE)22Carcinogenic equivalence sum. was also evaluated. The results obtained showed that temperature and residence time have a high influence on pyrolysis products, especially on the PAH concentration adsorbed on soot, which exhibited the highest KE in all cases studied.
Esarte, Claudia; Callejas, Alicia; Millera, Ángela; Bilbao, Rafael; Alzueta, María U
Characterization and reactivity with NO/O2 of the soot formed in the pyrolysis of acetylene–ethanol mixtures Journal Article
In: Journal of Analytical and Applied Pyrolysis, vol. 94, pp. 68–74, 2012, ISSN: 01652370.
@article{Esarte2012a,
title = {Characterization and reactivity with NO/O2 of the soot formed in the pyrolysis of acetylene–ethanol mixtures},
author = {Claudia Esarte and Alicia Callejas and Ángela Millera and Rafael Bilbao and María U Alzueta},
url = {http://www.sciencedirect.com/science/article/pii/S0165237011001902},
issn = {01652370},
year = {2012},
date = {2012-03-01},
journal = {Journal of Analytical and Applied Pyrolysis},
volume = {94},
pages = {68--74},
abstract = {Characterization analyses and soot–O2 and soot–NO interaction experiments have been performed for soot samples obtained in the pyrolysis of acetylene–ethanol mixtures at different temperatures from 1275 to 1475K. The objective of these analyses is to address the influence of soot formation conditions on soot properties and structure, as well as on its capability to interact with gaseous compounds. The characterization techniques used are: elemental analysis, transmission electron microscopy (TEM), Brunnauer–Emmett–Teller (BET) surface area analysis, Raman spectroscopy and X ray diffraction (XRD). The characterization of soot samples is useful to increase the database on soot composition and structure and may help to find a dependence of those characteristics with soot formation conditions and the fuel from which soot is formed. From these data it can be observed a certain degree of graphitization for the soot samples formed at higher temperatures and/or from fuel mixtures with a higher content in ethanol. The interaction of soot with NO and O2 is investigated in order to analyze the capability of soot to interact with gas reactants. Soot samples formed at the highest temperatures are less reactive towards O2 and NO than those formed at lower temperatures. Soot samples appear to be more reactive when the fuel mixture presents a lower initial volume of ethanol. These observations can be related to the higher C/H ratio, associated to slightly higher degree of ordering, for the soot samples formed in such conditions. Experimental results have also demonstrated that soot samples are more reactive towards O2 than NO, although the initial concentration of O2 is lower.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Characterization analyses and soot–O2 and soot–NO interaction experiments have been performed for soot samples obtained in the pyrolysis of acetylene–ethanol mixtures at different temperatures from 1275 to 1475K. The objective of these analyses is to address the influence of soot formation conditions on soot properties and structure, as well as on its capability to interact with gaseous compounds. The characterization techniques used are: elemental analysis, transmission electron microscopy (TEM), Brunnauer–Emmett–Teller (BET) surface area analysis, Raman spectroscopy and X ray diffraction (XRD). The characterization of soot samples is useful to increase the database on soot composition and structure and may help to find a dependence of those characteristics with soot formation conditions and the fuel from which soot is formed. From these data it can be observed a certain degree of graphitization for the soot samples formed at higher temperatures and/or from fuel mixtures with a higher content in ethanol. The interaction of soot with NO and O2 is investigated in order to analyze the capability of soot to interact with gas reactants. Soot samples formed at the highest temperatures are less reactive towards O2 and NO than those formed at lower temperatures. Soot samples appear to be more reactive when the fuel mixture presents a lower initial volume of ethanol. These observations can be related to the higher C/H ratio, associated to slightly higher degree of ordering, for the soot samples formed in such conditions. Experimental results have also demonstrated that soot samples are more reactive towards O2 than NO, although the initial concentration of O2 is lower.