2025
Journal Articles
Viteri, Fausto; Alexandrino, Katiuska; Millera, Ángela; Bilbao, Rafael; Alzueta, María U
Polycyclic aromatic hydrocarbons formed during the pyrolysis of dimethoxymethane (DMM). Comparison with other oxygenated additives Journal Article
In: Fuel, vol. 383, pp. 133750, 2025, ISSN: 0016-2361.
@article{viteri_polycyclic_2025,
title = {Polycyclic aromatic hydrocarbons formed during the pyrolysis of dimethoxymethane (DMM). Comparison with other oxygenated additives},
author = {Fausto Viteri and Katiuska Alexandrino and Ángela Millera and Rafael Bilbao and María U Alzueta},
url = {https://www.sciencedirect.com/science/article/pii/S0016236124028990},
doi = {10.1016/j.fuel.2024.133750},
issn = {0016-2361},
year = {2025},
date = {2025-03-01},
urldate = {2025-03-01},
journal = {Fuel},
volume = {383},
pages = {133750},
abstract = {The influence of the temperature (1075 – 1475 K) and inlet concentration of fuel (33,333 and 50,000 ppmv) on the formation of the 16 EPA-priority Polycyclic Aromatic Hydrocarbons (PAH) from the pyrolysis of dimethoxymethane (DMM) was analyzed. PAH were detected in different phases (gas phase, adsorbed on soot, and stuck on the reactor walls) and quantified by gas chromatography-mass spectrometry (GC–MS). Additionally, the toxicity of the PAH samples, expressed as B[a]P-eq, was analyzed in all experiments. A comparison with the results obtained from the pyrolysis of other oxygenated compounds was also performed and similar behaviors were observed. The main results showed that, at low temperatures, the highest concentrations of PAH were found in the gas phase, while at high temperatures were found on soot. For both inlet concentrations of DMM, the light PAH, such as naphthalene and acenaphthylene, were found in major concentrations, in all phases and temperatures. The heavy PAH, such as fluoranthene and pyrene, increased its concentration on soot at highest temperatures. The highest formation of soot was obtained at 1475 K and follows the trend: 2,5DMF < tert-butanol < 2MF < 2butanol < iso-butanol < 1-butanol < ethanol < DMC < DMM. The highest formation of PAH was at 1275 K with the tendency: tert-butanol < 2-butanol < 1-butanol < 2,5DMF < 2MF < iso-butanol < ethanol < DMC < DMM. The highest B[a]P-eq value was found in the pyrolysis of 2,5DMF, and the lowest in the pyrolysis of DMM.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The influence of the temperature (1075 – 1475 K) and inlet concentration of fuel (33,333 and 50,000 ppmv) on the formation of the 16 EPA-priority Polycyclic Aromatic Hydrocarbons (PAH) from the pyrolysis of dimethoxymethane (DMM) was analyzed. PAH were detected in different phases (gas phase, adsorbed on soot, and stuck on the reactor walls) and quantified by gas chromatography-mass spectrometry (GC–MS). Additionally, the toxicity of the PAH samples, expressed as B[a]P-eq, was analyzed in all experiments. A comparison with the results obtained from the pyrolysis of other oxygenated compounds was also performed and similar behaviors were observed. The main results showed that, at low temperatures, the highest concentrations of PAH were found in the gas phase, while at high temperatures were found on soot. For both inlet concentrations of DMM, the light PAH, such as naphthalene and acenaphthylene, were found in major concentrations, in all phases and temperatures. The heavy PAH, such as fluoranthene and pyrene, increased its concentration on soot at highest temperatures. The highest formation of soot was obtained at 1475 K and follows the trend: 2,5DMF < tert-butanol < 2MF < 2butanol < iso-butanol < 1-butanol < ethanol < DMC < DMM. The highest formation of PAH was at 1275 K with the tendency: tert-butanol < 2-butanol < 1-butanol < 2,5DMF < 2MF < iso-butanol < ethanol < DMC < DMM. The highest B[a]P-eq value was found in the pyrolysis of 2,5DMF, and the lowest in the pyrolysis of DMM.
Ruiz-Gutiérrez, A.; Rebollo, P.; Alzueta, María U
Combustion of NH3/DME and NH3/DME/NO mixtures Journal Article
In: Fuel, vol. 381, pp. 133253, 2025, ISSN: 0016-2361.
@article{ruiz-gutierrez_combustion_2025,
title = {Combustion of NH3/DME and NH3/DME/NO mixtures},
author = {A. Ruiz-Gutiérrez and P. Rebollo and María U Alzueta},
url = {https://www.sciencedirect.com/science/article/pii/S0016236124024025},
doi = {10.1016/j.fuel.2024.133253},
issn = {0016-2361},
year = {2025},
date = {2025-02-01},
urldate = {2025-02-01},
journal = {Fuel},
volume = {381},
pages = {133253},
abstract = {The objective of this work is to study the oxidation of ammonia and dimethyl ether mixtures (NH3/DME) both in the absence and the presence of monoxide of nitrogen (NO). For this purpose, laboratory experiments have been conducted in a quartz flow reactor setup in the 875–1425 K temperature range at atmospheric pressure, modifying the oxygen excess ratio (λ), and the NH3/DME mixture ratio with and without NO. The experimental results have been simulated with a literature-based kinetic mechanism. The results show that the presence of DME and an oxygen excess ratio affect the conversion of NH3, shifting its oxidation to lower temperatures, which decrease as the DME concentration in the mixture and λ increase. Interactions between ammonia and DME seem to be important under the studied conditions, presumably involving the formation and thermal decomposition of methyl nitrite (CH3ONO). These interactions affect the oxidation of ammonia at low temperatures, consume and produce NO, which would determine the final NO emission. When there is NO in the NH3/DME mixtures, NO is reduced up to 60 %, also favouring the oxidation of ammonia, but with an almost imperceptible effect of NO in the case of DME. The addition of different concentrations of DME also affects the oxidation behaviour of ammonia in NH3/DME/NO mixtures. In general, the conversion of both NH3 and DME is highly determined by the concentration of OH radicals, although thermal decomposition is also relevant for DME.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The objective of this work is to study the oxidation of ammonia and dimethyl ether mixtures (NH3/DME) both in the absence and the presence of monoxide of nitrogen (NO). For this purpose, laboratory experiments have been conducted in a quartz flow reactor setup in the 875–1425 K temperature range at atmospheric pressure, modifying the oxygen excess ratio (λ), and the NH3/DME mixture ratio with and without NO. The experimental results have been simulated with a literature-based kinetic mechanism. The results show that the presence of DME and an oxygen excess ratio affect the conversion of NH3, shifting its oxidation to lower temperatures, which decrease as the DME concentration in the mixture and λ increase. Interactions between ammonia and DME seem to be important under the studied conditions, presumably involving the formation and thermal decomposition of methyl nitrite (CH3ONO). These interactions affect the oxidation of ammonia at low temperatures, consume and produce NO, which would determine the final NO emission. When there is NO in the NH3/DME mixtures, NO is reduced up to 60 %, also favouring the oxidation of ammonia, but with an almost imperceptible effect of NO in the case of DME. The addition of different concentrations of DME also affects the oxidation behaviour of ammonia in NH3/DME/NO mixtures. In general, the conversion of both NH3 and DME is highly determined by the concentration of OH radicals, although thermal decomposition is also relevant for DME.
2024
Journal Articles
Glarborg, Peter; Alzueta, Maria U
Decomposition of CH3NH2: Implications for CHx/NHy radical–radical reactions Journal Article
In: International Journal of Chemical Kinetics, no. n/a, pp. 1-14, 2024.
@article{https://doi.org/10.1002/kin.21760,
title = {Decomposition of CH3NH2: Implications for CHx/NHy radical–radical reactions},
author = {Peter Glarborg and Maria U Alzueta},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/kin.21760},
doi = {https://doi.org/10.1002/kin.21760},
year = {2024},
date = {2024-09-19},
urldate = {2024-09-19},
journal = {International Journal of Chemical Kinetics},
number = {n/a},
pages = {1-14},
abstract = {Abstract Experiments on methylamine (CH3NH2$rm CH_3rm NH_2$) decomposition in shock tubes, flow reactors, and batch reactors have been re-examined to improve the understanding of hydrocarbon/amine interactions and constrain rate constants for CHx$rm CH_ x$ + NHy$rm NH_ y$ reactions. In high-temperature shock tube experiments, the rapid thermal dissociation of CH3NH2$rm CH_3rm NH_2$ provides a fairly clean source of CH3$rm CH_3$ and NH2$rm NH_2$ radicals, allowing an assessment of reactions of CH3$rm CH_3$ with NH2$rm NH_2$ and NH. At the lower temperatures in batch and flow reactors, CH3NH2$rm CH_3rm NH_2$ is mostly consumed by reaction with H to form CH2NH2$rm CH_2rm NH_2$ + H2$rm H_2$; these results are useful in determining the fate of the CH2NH2$rm CH_2rm NH_2$ radical. Interpretation of these data, along with flow reactor data for the CH3NH2$rm CH_3rm NH_2$/H system at lower temperature, indicates that at temperatures up to about 1400 K at atmospheric pressure and above 2000 K at 100 atm, the CH3$rm CH_3$ + NH2$rm NH_2$ reaction forms mainly methylamine. At sufficiently high temperature, H-abstraction to form CH4$rm CH_4$ + NH and addition–elimination to form CH2NH2$rm CH_2rm NH_2$ + H become competitive. The CH3$rm CH_3$ + NH reaction, with a rate constant close to collision frequency, forms CH2NH$rm CH_2rm NH$ + H, also leading into the hydrocarbon amine pool. Thus, methylamine can be expected to be an important intermediate in co-combustion of natural gas and ammonia, and more work on the chemistry of CH3NH2$rm CH_3rm NH_2$ is desirable.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract Experiments on methylamine (CH3NH2$rm CH_3rm NH_2$) decomposition in shock tubes, flow reactors, and batch reactors have been re-examined to improve the understanding of hydrocarbon/amine interactions and constrain rate constants for CHx$rm CH_ x$ + NHy$rm NH_ y$ reactions. In high-temperature shock tube experiments, the rapid thermal dissociation of CH3NH2$rm CH_3rm NH_2$ provides a fairly clean source of CH3$rm CH_3$ and NH2$rm NH_2$ radicals, allowing an assessment of reactions of CH3$rm CH_3$ with NH2$rm NH_2$ and NH. At the lower temperatures in batch and flow reactors, CH3NH2$rm CH_3rm NH_2$ is mostly consumed by reaction with H to form CH2NH2$rm CH_2rm NH_2$ + H2$rm H_2$; these results are useful in determining the fate of the CH2NH2$rm CH_2rm NH_2$ radical. Interpretation of these data, along with flow reactor data for the CH3NH2$rm CH_3rm NH_2$/H system at lower temperature, indicates that at temperatures up to about 1400 K at atmospheric pressure and above 2000 K at 100 atm, the CH3$rm CH_3$ + NH2$rm NH_2$ reaction forms mainly methylamine. At sufficiently high temperature, H-abstraction to form CH4$rm CH_4$ + NH and addition–elimination to form CH2NH2$rm CH_2rm NH_2$ + H become competitive. The CH3$rm CH_3$ + NH reaction, with a rate constant close to collision frequency, forms CH2NH$rm CH_2rm NH$ + H, also leading into the hydrocarbon amine pool. Thus, methylamine can be expected to be an important intermediate in co-combustion of natural gas and ammonia, and more work on the chemistry of CH3NH2$rm CH_3rm NH_2$ is desirable.
Lete, Alejandro; Raso, Raquel; García, Lucía; Ruiz, Joaquín; Arauzo, Jesús
In: Fuel, vol. 371, pp. 132001, 2024, ISSN: 0016-2361.
@article{lete_synthesis_2024,
title = {Synthesis of ketones from glycerol and 1,2-propanediol using copper and nickel catalysts: Unraveling the impact of reaction phase and active metal},
author = {Alejandro Lete and Raquel Raso and Lucía García and Joaquín Ruiz and Jesús Arauzo},
url = {https://www.sciencedirect.com/science/article/pii/S0016236124011499},
doi = {10.1016/j.fuel.2024.132001},
issn = {0016-2361},
year = {2024},
date = {2024-09-01},
urldate = {2024-09-01},
journal = {Fuel},
volume = {371},
pages = {132001},
abstract = {Catalysts based on nickel-aluminum and copper–aluminum were synthesized through the coprecipitation method with a Ni or Cu content of 28 mol%, expressed as Ni/(Ni + Al) or Cu/(Cu + Al). The catalysts were calcined at 675 °C and thoroughly analyzed using various characterization techniques (ICP-OES, N2 adsorption–desorption, NH3-TPD, CO2-TPD, XRD, H2-TPR and elemental analysis). The samples were tested in two different reaction systems, gas phase at atmospheric pressure and liquid phase at 34 absolute bar, to investigate the production of ketones from glycerol and 1,2-propanediol under reaction conditions of 227 °C and a mass of catalyst/reagent mass flow rate ratio (W/m) of 10 gCatalyst·min/gReagent. The characterization results revealed catalysts with high specific surface area and nickel and copper metallic particles, exhibiting good catalytic activity towards liquid products. Gas phase reactions favored the generation of acetol and carbon deposits, which were minimal in liquid phase reactions. The active metal played a crucial role, and it was demonstrated that copper, with a higher number of acidic sites, exhibited greater selectivity towards ketones than the nickel catalyst. The best performance was achieved by the CuAl catalyst in the gas phase reaction of glycerol, with a conversion of 67.0 ± 4.0 %, a carbon selectivity to acetol in the liquid products of 61.4 % and a yield to acetol of 119.8 mgAcetol/gGlycerol.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Catalysts based on nickel-aluminum and copper–aluminum were synthesized through the coprecipitation method with a Ni or Cu content of 28 mol%, expressed as Ni/(Ni + Al) or Cu/(Cu + Al). The catalysts were calcined at 675 °C and thoroughly analyzed using various characterization techniques (ICP-OES, N2 adsorption–desorption, NH3-TPD, CO2-TPD, XRD, H2-TPR and elemental analysis). The samples were tested in two different reaction systems, gas phase at atmospheric pressure and liquid phase at 34 absolute bar, to investigate the production of ketones from glycerol and 1,2-propanediol under reaction conditions of 227 °C and a mass of catalyst/reagent mass flow rate ratio (W/m) of 10 gCatalyst·min/gReagent. The characterization results revealed catalysts with high specific surface area and nickel and copper metallic particles, exhibiting good catalytic activity towards liquid products. Gas phase reactions favored the generation of acetol and carbon deposits, which were minimal in liquid phase reactions. The active metal played a crucial role, and it was demonstrated that copper, with a higher number of acidic sites, exhibited greater selectivity towards ketones than the nickel catalyst. The best performance was achieved by the CuAl catalyst in the gas phase reaction of glycerol, with a conversion of 67.0 ± 4.0 %, a carbon selectivity to acetol in the liquid products of 61.4 % and a yield to acetol of 119.8 mgAcetol/gGlycerol.
Alvira, Darío; Antorán, Daniel; Darjazi, Hamideh; Elia, Giuseppe Antonio; Sebastian, Victor; Manyà, Joan Josep
Sustainable conversion of vine shoots and pig manure into high-performance anode materials for sodium-ion batteries Journal Article
In: Journal of Power Sources, vol. 614, pp. 235043, 2024, ISSN: 0378-7753.
@article{alvira_sustainable_2024,
title = {Sustainable conversion of vine shoots and pig manure into high-performance anode materials for sodium-ion batteries},
author = {Darío Alvira and Daniel Antorán and Hamideh Darjazi and Giuseppe Antonio Elia and Victor Sebastian and Joan Josep Manyà},
url = {https://www.sciencedirect.com/science/article/pii/S0378775324009959},
doi = {10.1016/j.jpowsour.2024.235043},
issn = {0378-7753},
year = {2024},
date = {2024-09-01},
urldate = {2024-09-01},
journal = {Journal of Power Sources},
volume = {614},
pages = {235043},
abstract = {Sodium-ion batteries (SIBs) are considered promising candidates for future grid energy storage, with hard carbons emerging as key commercial anode materials. This study presents a novel approach to synthesize N-doped hard carbons via co-hydrothermal treatment of vine shoots and pig manure and subsequent thermal annealing of the resulting hydrochar. This method enhances the development of micro- and ultra-microporosity in the synthesized hard carbons, with nitrogen, and to a lesser extent phosphorus and sulfur, introduced as doping elements. Furthermore, the incorporation of hydrochloric acid during the hydrothermal step promotes biomass hydrolysis, leading to increased mesoporosity and the formation of microsphere clusters. In the realm of electrochemical performance, an investigation into various ester- and ether-based electrolytes has revealed NaPF6 in diglyme as the best formulation, thanks to its thinner and more stable solid electrolyte interface (SEI). Using this electrolyte, the best-performing electrode showed an initial Coulombic efficiency (ICE) of 73 %, with reversible capacities of 239, 180, 86, and 57 mAh g−1 at 0.1, 1, 5, and 10 A g−1, respectively. In addition, the electrode exhibited a remarkable capacity retention of 88 % after 250 cycles as well as a compatible behavior when paired with a NVPF-based cathode.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Sodium-ion batteries (SIBs) are considered promising candidates for future grid energy storage, with hard carbons emerging as key commercial anode materials. This study presents a novel approach to synthesize N-doped hard carbons via co-hydrothermal treatment of vine shoots and pig manure and subsequent thermal annealing of the resulting hydrochar. This method enhances the development of micro- and ultra-microporosity in the synthesized hard carbons, with nitrogen, and to a lesser extent phosphorus and sulfur, introduced as doping elements. Furthermore, the incorporation of hydrochloric acid during the hydrothermal step promotes biomass hydrolysis, leading to increased mesoporosity and the formation of microsphere clusters. In the realm of electrochemical performance, an investigation into various ester- and ether-based electrolytes has revealed NaPF6 in diglyme as the best formulation, thanks to its thinner and more stable solid electrolyte interface (SEI). Using this electrolyte, the best-performing electrode showed an initial Coulombic efficiency (ICE) of 73 %, with reversible capacities of 239, 180, 86, and 57 mAh g−1 at 0.1, 1, 5, and 10 A g−1, respectively. In addition, the electrode exhibited a remarkable capacity retention of 88 % after 250 cycles as well as a compatible behavior when paired with a NVPF-based cathode.
Fonts, Isabel; Lázaro, Cristina; Cornejo, Alfonso; Sánchez, José Luis; Afailal, Zainab; Gil-Lalaguna, Noemí; Arauzo, Jesús
Bio-oil Fractionation According to Polarity and Molecular Size: Characterization and Application as Antioxidants Journal Article
In: Energy & Fuels, 2024, ISSN: 0887-0624, (Publisher: American Chemical Society).
@article{fonts_bio-oil_2024,
title = {Bio-oil Fractionation According to Polarity and Molecular Size: Characterization and Application as Antioxidants},
author = {Isabel Fonts and Cristina Lázaro and Alfonso Cornejo and José Luis Sánchez and Zainab Afailal and Noemí Gil-Lalaguna and Jesús Arauzo},
url = {https://doi.org/10.1021/acs.energyfuels.4c02641},
doi = {10.1021/acs.energyfuels.4c02641},
issn = {0887-0624},
year = {2024},
date = {2024-09-01},
urldate = {2024-09-01},
journal = {Energy & Fuels},
abstract = {Bio-oil obtained from biomass pyrolysis has great potential for several applications after being upgraded and refined. This study established a method for separating bio-oil into different fractions based on polarity and molecular size to extract phenolic and polyphenolic compounds with antioxidant properties. The fractions were analyzed using various spectroscopic and chromatographic techniques, such as GC/MS, FTIR, UV–vis, SEC, DOSY-NMR, 13C-NMR, and 31P-NMR. The antioxidant properties of these fractions were tested by examining their ability to improve the oxidative stability of biodiesel. The results strongly connected the bio-oil’s chemical functionalities and antioxidant power. During solvent fractionation, dichloromethane could extract phenolic structures, which were subsequently size-fractionated. The subfractions with lower molecular weight (in the order of monomers and dimers) outperformed the antioxidant potential of the crude bio-oil. Heavier subfractions from dichloromethane extraction did not show good antioxidant abilities, which was related to the low hydroxy group content. After solvent extraction, phenolic oligomers remained in the water-insoluble/dichloromethane-insoluble fraction, which showed good antioxidant potential despite its low solubility in biodiesel.},
note = {Publisher: American Chemical Society},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Bio-oil obtained from biomass pyrolysis has great potential for several applications after being upgraded and refined. This study established a method for separating bio-oil into different fractions based on polarity and molecular size to extract phenolic and polyphenolic compounds with antioxidant properties. The fractions were analyzed using various spectroscopic and chromatographic techniques, such as GC/MS, FTIR, UV–vis, SEC, DOSY-NMR, 13C-NMR, and 31P-NMR. The antioxidant properties of these fractions were tested by examining their ability to improve the oxidative stability of biodiesel. The results strongly connected the bio-oil’s chemical functionalities and antioxidant power. During solvent fractionation, dichloromethane could extract phenolic structures, which were subsequently size-fractionated. The subfractions with lower molecular weight (in the order of monomers and dimers) outperformed the antioxidant potential of the crude bio-oil. Heavier subfractions from dichloromethane extraction did not show good antioxidant abilities, which was related to the low hydroxy group content. After solvent extraction, phenolic oligomers remained in the water-insoluble/dichloromethane-insoluble fraction, which showed good antioxidant potential despite its low solubility in biodiesel.
Antorán, Daniel; Alvira, Darío; Sebastián, Víctor; Manyà, Joan Josep
Enhancing waste hemp hurd-derived anodes for sodium-ion batteries through hydrochloric acid-mediated hydrothermal pretreatment Journal Article
In: Biomass and Bioenergy, vol. 184, pp. 107197, 2024, ISSN: 0961-9534.
@article{antoran_enhancing_2024,
title = {Enhancing waste hemp hurd-derived anodes for sodium-ion batteries through hydrochloric acid-mediated hydrothermal pretreatment},
author = {Daniel Antorán and Darío Alvira and Víctor Sebastián and Joan Josep Manyà},
url = {https://www.sciencedirect.com/science/article/pii/S0961953424001508},
doi = {10.1016/j.biombioe.2024.107197},
issn = {0961-9534},
year = {2024},
date = {2024-05-01},
urldate = {2024-05-01},
journal = {Biomass and Bioenergy},
volume = {184},
pages = {107197},
abstract = {Waste hemp hurd (WHH) was used as a sustainable feedstock for producing hard carbon-based anodes for sodium-ion batteries (SIBs). Two easily scalable production pathways were tested and compared: (1) pyrolysis (at 500 °C) and subsequent annealing at 800, 1000 or 1200 °C, and (2) hydrothermal pretreatment (at 180 °C) and subsequent annealing at the above-mentioned highest temperatures. Results indicated that when a HCl (2 mol m−3) aqueous solution was used as hydrothermal medium, the textural, structural and surface chemistry features linked to the electrochemical performance of the resulting hard carbons improved. The WHH-derived electrode produced via HCl-mediated hydrothermal pretreatment and subsequent annealing at 1000 °C showed an exceptional electrochemical performance in terms of specific capacity (535 mA h g−1 at 30 mA g−1) and rate capability (372, 156, 115, and 83 mA h g−1 at 0.1, 0.5, 1, and 2 A g−1, respectively) when an ester-based electrolyte was used (NaTFSI in EC/DMC). Using an ether-based electrolyte (NaPF6 in diglyme) improved both the ICE (from 69% to 78%) and cycling stability (85% of capacity retention after 300 cycles at 1 A g−1; 91% when current rate returned to 0.1 A g−1). In summary, relatively low-cost WHH-derived carbons are able to deliver an exceptional performance, much better than that reported so far for other biomass-derived carbons, and even close to that exhibited by more expensive and complex composite and hybrid materials.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Waste hemp hurd (WHH) was used as a sustainable feedstock for producing hard carbon-based anodes for sodium-ion batteries (SIBs). Two easily scalable production pathways were tested and compared: (1) pyrolysis (at 500 °C) and subsequent annealing at 800, 1000 or 1200 °C, and (2) hydrothermal pretreatment (at 180 °C) and subsequent annealing at the above-mentioned highest temperatures. Results indicated that when a HCl (2 mol m−3) aqueous solution was used as hydrothermal medium, the textural, structural and surface chemistry features linked to the electrochemical performance of the resulting hard carbons improved. The WHH-derived electrode produced via HCl-mediated hydrothermal pretreatment and subsequent annealing at 1000 °C showed an exceptional electrochemical performance in terms of specific capacity (535 mA h g−1 at 30 mA g−1) and rate capability (372, 156, 115, and 83 mA h g−1 at 0.1, 0.5, 1, and 2 A g−1, respectively) when an ester-based electrolyte was used (NaTFSI in EC/DMC). Using an ether-based electrolyte (NaPF6 in diglyme) improved both the ICE (from 69% to 78%) and cycling stability (85% of capacity retention after 300 cycles at 1 A g−1; 91% when current rate returned to 0.1 A g−1). In summary, relatively low-cost WHH-derived carbons are able to deliver an exceptional performance, much better than that reported so far for other biomass-derived carbons, and even close to that exhibited by more expensive and complex composite and hybrid materials.
Maziarka, Przemyslaw; Kienzl, Norbert; Dieguez-Alonso, Alba; Fierro, Vanessa; Celzard, Alain; Arauzo, Pablo J.; Hedin, Niklas; Prins, Wolter; Anca-Couce, Andrés; Manyà, Joan Josep; Ronsse, Frederik
In: Energy & Fuels, 2024, ISSN: 0887-0624, (Publisher: American Chemical Society).
@article{maziarka_part_2024,
title = {Part 1─Impact of Pyrolysis Temperature and Wood Particle Length on Vapor Cracking and Char Porous Texture in Relation to the Tailoring of Char Properties},
author = {Przemyslaw Maziarka and Norbert Kienzl and Alba Dieguez-Alonso and Vanessa Fierro and Alain Celzard and Pablo J. Arauzo and Niklas Hedin and Wolter Prins and Andrés Anca-Couce and Joan Josep Manyà and Frederik Ronsse},
url = {https://doi.org/10.1021/acs.energyfuels.4c00937},
doi = {10.1021/acs.energyfuels.4c00937},
issn = {0887-0624},
year = {2024},
date = {2024-05-01},
urldate = {2024-05-01},
journal = {Energy & Fuels},
abstract = {Pore size distribution is a key parameter in the performance of biobased pyrolytic char in novel applications. In industrial-scale production, the size of feedstock particles typically exceeds a few millimeters. For such particle sizes, it is a challenge to tailor the final properties of the char based only on the process conditions (experimental and modeling-wise). Pyrolysis studies of single particles larger than a few millimeters provide data sets useful for modeling and optimization of the process. Part 1 of this research focused on the pyrolysis of single particles of beech wood, secondary cracking, and its effect on the char porous texture. It contains a quantitative assessment of the effects of five conversion temperatures (from 300 to 840 °C) and two particle dimensions (Ø8 × 10 mm and Ø8 × 16 mm) on the composition of the pyrolysis vapors and pore morphology of the char. Results from real-time temperature and mass changes are presented along with release profiles of 15 vapor constituents measured by infrared spectroscopy. Furthermore, characterization of the collected bio-oil (using GC-MS/FID) and the textural hierarchical structured char (through N2 and CO2 adsorption, Hg porosimetry, and scanning electron microscopy (SEM)) was performed. Cracking of vapors above 500 °C was compound-specific. The polyaromatic hydrocarbons (PAHs) yield, between 680 and 840 °C, increased 5 times for 10 mm particles and 9 times for 16 mm ones. Besides temperature, PAH yield was suspected to correlate with particle length and PAHs/soot deposition in the micropores. Results showed that the macropores accounted for over 80% of the total pore volume, regardless of the temperature and particle length. Increasing the particle length by 60% caused a reduction in the specific surface area (ca. 15% at 840 °C) of the resulting char, mainly due to a reduction in microporosity. Based on the findings, the production conditions for a specific char application are suggested. The obtained data will be used in Part 2 of this research, devoted to subsequent CFD modeling of the process.},
note = {Publisher: American Chemical Society},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Pore size distribution is a key parameter in the performance of biobased pyrolytic char in novel applications. In industrial-scale production, the size of feedstock particles typically exceeds a few millimeters. For such particle sizes, it is a challenge to tailor the final properties of the char based only on the process conditions (experimental and modeling-wise). Pyrolysis studies of single particles larger than a few millimeters provide data sets useful for modeling and optimization of the process. Part 1 of this research focused on the pyrolysis of single particles of beech wood, secondary cracking, and its effect on the char porous texture. It contains a quantitative assessment of the effects of five conversion temperatures (from 300 to 840 °C) and two particle dimensions (Ø8 × 10 mm and Ø8 × 16 mm) on the composition of the pyrolysis vapors and pore morphology of the char. Results from real-time temperature and mass changes are presented along with release profiles of 15 vapor constituents measured by infrared spectroscopy. Furthermore, characterization of the collected bio-oil (using GC-MS/FID) and the textural hierarchical structured char (through N2 and CO2 adsorption, Hg porosimetry, and scanning electron microscopy (SEM)) was performed. Cracking of vapors above 500 °C was compound-specific. The polyaromatic hydrocarbons (PAHs) yield, between 680 and 840 °C, increased 5 times for 10 mm particles and 9 times for 16 mm ones. Besides temperature, PAH yield was suspected to correlate with particle length and PAHs/soot deposition in the micropores. Results showed that the macropores accounted for over 80% of the total pore volume, regardless of the temperature and particle length. Increasing the particle length by 60% caused a reduction in the specific surface area (ca. 15% at 840 °C) of the resulting char, mainly due to a reduction in microporosity. Based on the findings, the production conditions for a specific char application are suggested. The obtained data will be used in Part 2 of this research, devoted to subsequent CFD modeling of the process.
Maziarka, Przemyslaw; Kienzl, Norbert; Dieguez-Alonso, Alba; Prins, Wolter; Arauzo, Pablo J.; Skreiberg, Øyvind; Anca-Couce, Andrés; Manyà, Joan Josep; Ronsse, Frederik
In: Energy & Fuels, 2024, ISSN: 0887-0624, (Publisher: American Chemical Society).
@article{maziarka_part_2024-1,
title = {Part 2─Tailoring of Pyrolytic Char Properties with a Single Particle CFD Model with a Focus on the Impact of Shrinking, Vapor Cracking, and Char Permeability},
author = {Przemyslaw Maziarka and Norbert Kienzl and Alba Dieguez-Alonso and Wolter Prins and Pablo J. Arauzo and Øyvind Skreiberg and Andrés Anca-Couce and Joan Josep Manyà and Frederik Ronsse},
url = {https://doi.org/10.1021/acs.energyfuels.4c00942},
doi = {10.1021/acs.energyfuels.4c00942},
issn = {0887-0624},
year = {2024},
date = {2024-05-01},
urldate = {2024-05-01},
journal = {Energy & Fuels},
abstract = {The prediction of the structural properties of biobased carbonaceous materials of pyrolytic origin (chars) with only base feedstock properties and process conditions still poses a challenge that hinders char tailoring for novel applications. CFD modeling of single biomass particle conversion can help solve this issue since it allows for the quantification of relations between parameters that are difficult to measure. A model for char tailoring must include a validated representation of the structural changes coupled to all other relevant phenomena occurring during conversion. Part 2 of this study focuses on finding the description of the mentioned aspects to achieve the highest precision of prediction of the structural changes in char by a CFD model. The investigation in Part 2 is composed of three cases focused on accurate description and prediction of (1) bulk density and porosity, (2) secondary vapor reactions on yields and soot formation, and (3) permeability, as well as the outflux and conversion of evolved vapors. The experimental results from Part 1 and the literature data were used to find appropriate descriptions of phenomena and assess the accuracy of the model. The model results indicate that for both particle lengths (10 and 16 mm), a high accuracy of prediction of base structural parameters was achieved. The average prediction error for temperatures between 400 and 840 °C of bulk density was 31 ± 15 kg/m3, and the porosity was 1.8 ± 1.1 vol %. The results also show a low error in the prediction of bulk product yields (dry basis) over the mentioned temperature range, which were: for char 2.8 ± 1.1 wt %, for the condensable fraction 6.5 ± 3.3 wt %, and for the pyrolysis gas 4.1 ± 1.9 wt %. The distribution of secondary char formation was found to be nonuniform below 500 °C. The changes in permeability had a minor influence on the vapor outflux but a non-negligible effect on the soot formation, especially at 840 °C. The results indicate a need for further improvement of the primary degradation model to increase the accuracy of the effect of soot formation on the char structure.},
note = {Publisher: American Chemical Society},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The prediction of the structural properties of biobased carbonaceous materials of pyrolytic origin (chars) with only base feedstock properties and process conditions still poses a challenge that hinders char tailoring for novel applications. CFD modeling of single biomass particle conversion can help solve this issue since it allows for the quantification of relations between parameters that are difficult to measure. A model for char tailoring must include a validated representation of the structural changes coupled to all other relevant phenomena occurring during conversion. Part 2 of this study focuses on finding the description of the mentioned aspects to achieve the highest precision of prediction of the structural changes in char by a CFD model. The investigation in Part 2 is composed of three cases focused on accurate description and prediction of (1) bulk density and porosity, (2) secondary vapor reactions on yields and soot formation, and (3) permeability, as well as the outflux and conversion of evolved vapors. The experimental results from Part 1 and the literature data were used to find appropriate descriptions of phenomena and assess the accuracy of the model. The model results indicate that for both particle lengths (10 and 16 mm), a high accuracy of prediction of base structural parameters was achieved. The average prediction error for temperatures between 400 and 840 °C of bulk density was 31 ± 15 kg/m3, and the porosity was 1.8 ± 1.1 vol %. The results also show a low error in the prediction of bulk product yields (dry basis) over the mentioned temperature range, which were: for char 2.8 ± 1.1 wt %, for the condensable fraction 6.5 ± 3.3 wt %, and for the pyrolysis gas 4.1 ± 1.9 wt %. The distribution of secondary char formation was found to be nonuniform below 500 °C. The changes in permeability had a minor influence on the vapor outflux but a non-negligible effect on the soot formation, especially at 840 °C. The results indicate a need for further improvement of the primary degradation model to increase the accuracy of the effect of soot formation on the char structure.
Cordoba-Ramirez, Marlon; Chejne, Farid; Alean, Jader; Gómez, Carlos A.; Navarro-Gil, África; Ábrego, Javier; Gea, Gloria
Experimental strategy for the preparation of adsorbent materials from torrefied palm kernel shell oriented to CO2 capture Journal Article
In: Environmental Science and Pollution Research, 2024, ISSN: 1614-7499.
@article{cordoba-ramirez_experimental_2024,
title = {Experimental strategy for the preparation of adsorbent materials from torrefied palm kernel shell oriented to CO2 capture},
author = {Marlon Cordoba-Ramirez and Farid Chejne and Jader Alean and Carlos A. Gómez and África Navarro-Gil and Javier Ábrego and Gloria Gea},
url = {https://doi.org/10.1007/s11356-024-32028-3},
doi = {10.1007/s11356-024-32028-3},
issn = {1614-7499},
year = {2024},
date = {2024-02-01},
urldate = {2024-02-01},
journal = {Environmental Science and Pollution Research},
abstract = {In this study, an experimental strategy to obtain biochar and activated carbon from torrefied palm kernel shell as an efficient material for CO2 removal was evaluated. Biochar was obtained by slow pyrolysis of palm kernel shell at different temperatures (350 °C, 550 °C, and 700 °C) and previously torrefied palm kernel shell at different temperatures (220 °C, 250 °C, and 280 °C). Subsequently, activated carbons were prepared by physical activation with CO2 from previously obtained biochar samples. The CO2 adsorption capacity was measured using TGA. The experimental results showed that there is a correlation between the change in the O/C and H/C ratios and the functional groups –OH and C=O observed via FTIR in the obtained char, indicating that both dehydration and deoxygenation reactions occur during torrefaction; this favors the deoxygenation reactions and makes them faster through CO2 liberation during the pyrolysis process. The microporous surface area shows a significant increase with higher pyrolysis temperatures, as a product of the continuous carbonization reactions, allowing more active sites for CO2 removal. Pyrolysis temperature is a key factor in CO2 adsorption capacity, leading to a CO2 adsorption capacity of up to 75 mg/gCO2 for biochar obtained at 700 °C from non-torrefied palm kernel shell (Char700). Activated carbon obtained from torrefied palm kernel shell at 280 °C (T280-CHAR700-AC) exhibited the highest CO2 adsorption capacity (101.9 mg/gCO2). Oxygen-containing functional groups have a direct impact on CO2 adsorption performance due to electron interactions between CO2 and these functional groups. These findings could provide a new experimental approach for obtaining optimal adsorbent materials exclusively derived from thermochemical conversion processes.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this study, an experimental strategy to obtain biochar and activated carbon from torrefied palm kernel shell as an efficient material for CO2 removal was evaluated. Biochar was obtained by slow pyrolysis of palm kernel shell at different temperatures (350 °C, 550 °C, and 700 °C) and previously torrefied palm kernel shell at different temperatures (220 °C, 250 °C, and 280 °C). Subsequently, activated carbons were prepared by physical activation with CO2 from previously obtained biochar samples. The CO2 adsorption capacity was measured using TGA. The experimental results showed that there is a correlation between the change in the O/C and H/C ratios and the functional groups –OH and C=O observed via FTIR in the obtained char, indicating that both dehydration and deoxygenation reactions occur during torrefaction; this favors the deoxygenation reactions and makes them faster through CO2 liberation during the pyrolysis process. The microporous surface area shows a significant increase with higher pyrolysis temperatures, as a product of the continuous carbonization reactions, allowing more active sites for CO2 removal. Pyrolysis temperature is a key factor in CO2 adsorption capacity, leading to a CO2 adsorption capacity of up to 75 mg/gCO2 for biochar obtained at 700 °C from non-torrefied palm kernel shell (Char700). Activated carbon obtained from torrefied palm kernel shell at 280 °C (T280-CHAR700-AC) exhibited the highest CO2 adsorption capacity (101.9 mg/gCO2). Oxygen-containing functional groups have a direct impact on CO2 adsorption performance due to electron interactions between CO2 and these functional groups. These findings could provide a new experimental approach for obtaining optimal adsorbent materials exclusively derived from thermochemical conversion processes.
Alzueta, Maria U; Mercader, Victor D; Cuoci, Alberto; Gersen, Sander; Hashemi, Hamid; Glarborg, Peter
Flow Reactor Oxidation of Ammonia–Hydrogen Fuel Mixtures Journal Article
In: Energy & Fuels, vol. 38, no. 4, pp. 3369–3381, 2024, ISSN: 0887-0624, (Publisher: American Chemical Society).
@article{alzueta_flow_2024,
title = {Flow Reactor Oxidation of Ammonia–Hydrogen Fuel Mixtures},
author = {Maria U Alzueta and Victor D Mercader and Alberto Cuoci and Sander Gersen and Hamid Hashemi and Peter Glarborg},
url = {https://doi.org/10.1021/acs.energyfuels.3c03929},
doi = {10.1021/acs.energyfuels.3c03929},
issn = {0887-0624},
year = {2024},
date = {2024-02-01},
urldate = {2024-02-01},
journal = {Energy & Fuels},
volume = {38},
number = {4},
pages = {3369–3381},
abstract = {Hydrogen-assisted oxidation of ammonia under flow reactor conditions was investigated through experiments and chemical kinetic modeling. Novel experiments, conducted in a tubular laminar flow reactor as a function of the NH3/H2 ratio, stoichiometry, and temperature (725–1475 K), were analyzed along with literature results from tubular and jet-stirred flow reactors. Ignition and oxidation of NH3 is strongly promoted by the presence of H2 under all conditions investigated. In general, the behavior is captured well by the kinetic model. With an increasing fraction of H2 in the fuel mixture, the generation of chain carriers gradually shifts from being controlled by the amine reaction subset to being dominated by the oxidation chemistry of H2, which is known more accurately. However, under reducing conditions, the H2 consumption rate is strongly underpredicted. This shortcoming suggests that the thermochemistry of amine radicals and/or the formation of higher amines need further assessment. The present analysis shows that for lean oxidation of NH3/H2 mixtures in tubular flow reactors, data obtained at higher temperatures, particularly for NO formation, may be strongly affected by the reaction during preheating or by mixing (dependent on reactor design) in the inlet section prior to the isothermal zone. Modeling predictions for the high pressure, medium-temperature ignition conditions in a large diesel engine indicate that NH3/H2 fuel mixtures may still require a cofuel to secure stable ignition.},
note = {Publisher: American Chemical Society},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Hydrogen-assisted oxidation of ammonia under flow reactor conditions was investigated through experiments and chemical kinetic modeling. Novel experiments, conducted in a tubular laminar flow reactor as a function of the NH3/H2 ratio, stoichiometry, and temperature (725–1475 K), were analyzed along with literature results from tubular and jet-stirred flow reactors. Ignition and oxidation of NH3 is strongly promoted by the presence of H2 under all conditions investigated. In general, the behavior is captured well by the kinetic model. With an increasing fraction of H2 in the fuel mixture, the generation of chain carriers gradually shifts from being controlled by the amine reaction subset to being dominated by the oxidation chemistry of H2, which is known more accurately. However, under reducing conditions, the H2 consumption rate is strongly underpredicted. This shortcoming suggests that the thermochemistry of amine radicals and/or the formation of higher amines need further assessment. The present analysis shows that for lean oxidation of NH3/H2 mixtures in tubular flow reactors, data obtained at higher temperatures, particularly for NO formation, may be strongly affected by the reaction during preheating or by mixing (dependent on reactor design) in the inlet section prior to the isothermal zone. Modeling predictions for the high pressure, medium-temperature ignition conditions in a large diesel engine indicate that NH3/H2 fuel mixtures may still require a cofuel to secure stable ignition.
Marrodán, Lorena; Pérez, Teresa; Alzueta, María U
Conversion of methylamine in a flow reactor and its interaction with NO Journal Article
In: Combustion and Flame, vol. 259, pp. 113130, 2024, ISSN: 0010-2180.
@article{marrodan_conversion_2024,
title = {Conversion of methylamine in a flow reactor and its interaction with NO},
author = {Lorena Marrodán and Teresa Pérez and María U Alzueta},
url = {https://www.sciencedirect.com/science/article/pii/S0010218023005059},
doi = {10.1016/j.combustflame.2023.113130},
issn = {0010-2180},
year = {2024},
date = {2024-01-01},
urldate = {2024-01-01},
journal = {Combustion and Flame},
volume = {259},
pages = {113130},
abstract = {The conversion of methylamine (CH3NH2, 1000 ppm) has been studied in an atmospheric-pressure flow reactor from both experimental and modeling points of view. Several values of the oxygen excess ratio (λ), from pyrolysis to fuel-lean conditions, have been tested, and a large number of different species have been quantified experimentally by three different diagnostic techniques: gas chromatography, Fourier Transform Infra-red spectroscopy (FTIR) and an infra-red NO analyzer. For the first time, the influence of NO addition (500 and 1000 ppm) on the stoichiometric oxidation of methylamine has also been experimentally evaluated, and the main products of such interaction have been identified. Results indicate that, unlike the little influence of oxygen availability on methylamine conversion, the presence of different concentrations of NO promotes methylamine oxidation at lower temperatures. A literature mechanism has been validated against the present experimental data since previous experimental works under these conditions are scarce. The largest discrepancies have been found for the formation of NH3 and NO as oxidation products, which are under and overestimated by the model, respectively, and under pyrolysis conditions, where modification of the kinetic parameters for the reaction CH2NH2 ⇌ CH2NH + H from the original mechanism notably improves the agreement between experimental and simulated results.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The conversion of methylamine (CH3NH2, 1000 ppm) has been studied in an atmospheric-pressure flow reactor from both experimental and modeling points of view. Several values of the oxygen excess ratio (λ), from pyrolysis to fuel-lean conditions, have been tested, and a large number of different species have been quantified experimentally by three different diagnostic techniques: gas chromatography, Fourier Transform Infra-red spectroscopy (FTIR) and an infra-red NO analyzer. For the first time, the influence of NO addition (500 and 1000 ppm) on the stoichiometric oxidation of methylamine has also been experimentally evaluated, and the main products of such interaction have been identified. Results indicate that, unlike the little influence of oxygen availability on methylamine conversion, the presence of different concentrations of NO promotes methylamine oxidation at lower temperatures. A literature mechanism has been validated against the present experimental data since previous experimental works under these conditions are scarce. The largest discrepancies have been found for the formation of NH3 and NO as oxidation products, which are under and overestimated by the model, respectively, and under pyrolysis conditions, where modification of the kinetic parameters for the reaction CH2NH2 ⇌ CH2NH + H from the original mechanism notably improves the agreement between experimental and simulated results.
Lete, Alejandro; García, Lucía; Ruiz, Joaquín; Arauzo, Jesús
Catalytic Conversion of 1,2-propanediol to 2-propanone: An Exploratory Study Journal Article
In: Chemical Engineering Transactions, vol. 109, pp. 133–138, 2024, ISSN: 2283-9216.
@article{lete_catalytic_2024,
title = {Catalytic Conversion of 1,2-propanediol to 2-propanone: An Exploratory Study},
author = {Alejandro Lete and Lucía García and Joaquín Ruiz and Jesús Arauzo},
doi = {10.3303/CET24109023},
issn = {2283-9216},
year = {2024},
date = {2024-01-01},
urldate = {2024-01-01},
journal = {Chemical Engineering Transactions},
volume = {109},
pages = {133–138},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Alzueta, María U; Pérez, Teresa; Marrodán, Lorena
Oxidation of methylamine (CH3NH2)/CH4/NO mixtures in an atmospheric-pressure flow reactor Journal Article
In: Proceedings of the Combustion Institute, vol. 40, no. 1, pp. 105456, 2024, ISSN: 1540-7489.
@article{alzueta_oxidation_2024,
title = {Oxidation of methylamine (CH3NH2)/CH4/NO mixtures in an atmospheric-pressure flow reactor},
author = {María U Alzueta and Teresa Pérez and Lorena Marrodán},
url = {https://www.sciencedirect.com/science/article/pii/S1540748924002645},
doi = {10.1016/j.proci.2024.105456},
issn = {1540-7489},
year = {2024},
date = {2024-01-01},
urldate = {2024-01-01},
journal = {Proceedings of the Combustion Institute},
volume = {40},
number = {1},
pages = {105456},
abstract = {The oxidation of methylamine (CH3NH2) and methane mixtures has been studied by experiments in a flow reactor at atmospheric pressure and temperatures of 350–1450 K. In addition to temperature, stoichiometry (ranging from fuel-rich to fuel-lean conditions) and the presence of NO have been evaluated. Several diagnostic techniques have been used to experimentally quantify many different species: gas chromatography, Fourier Transform Infra-red spectroscopy (FTIR) and an infra-red NO analyzer. Results show a negligible influence of stoichiometry both on the conversion of MEA and CH4 in the absence of NO, while the presence of NO acts to inhibit the conversion of CH4 with no appreciable influence on MEA conversion. This indicates the complex interaction occurring in the MEA/CH4/NO mixtures, for which the mechanism is not able to properly predict the conversion of CH4 in the presence of NO, while the rest of compounds are well reproduced both in the absence and presence of NO. This fact, together with the probable formation of species containing C and N, due to the presence of additional unidentified species and the deep analysis of the mass balances carried out, supports the idea of the formation of C-N species, not clearly identified so far. The literature mechanism used in simulations has provided good results in reproducing most of the species and conditions considered. The largest discrepancy has been observed for CH4 conversion in the presence of NO, supporting the existence of missing interactions in the mechanism.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The oxidation of methylamine (CH3NH2) and methane mixtures has been studied by experiments in a flow reactor at atmospheric pressure and temperatures of 350–1450 K. In addition to temperature, stoichiometry (ranging from fuel-rich to fuel-lean conditions) and the presence of NO have been evaluated. Several diagnostic techniques have been used to experimentally quantify many different species: gas chromatography, Fourier Transform Infra-red spectroscopy (FTIR) and an infra-red NO analyzer. Results show a negligible influence of stoichiometry both on the conversion of MEA and CH4 in the absence of NO, while the presence of NO acts to inhibit the conversion of CH4 with no appreciable influence on MEA conversion. This indicates the complex interaction occurring in the MEA/CH4/NO mixtures, for which the mechanism is not able to properly predict the conversion of CH4 in the presence of NO, while the rest of compounds are well reproduced both in the absence and presence of NO. This fact, together with the probable formation of species containing C and N, due to the presence of additional unidentified species and the deep analysis of the mass balances carried out, supports the idea of the formation of C-N species, not clearly identified so far. The literature mechanism used in simulations has provided good results in reproducing most of the species and conditions considered. The largest discrepancy has been observed for CH4 conversion in the presence of NO, supporting the existence of missing interactions in the mechanism.
García-Ruiz, Pedro; Salas, Iris; Casanova, Eva; Bilbao, Rafael; Alzueta, María U
Experimental and Modeling High-Pressure Study of Ammonia–Methane Oxidation in a Flow Reactor Journal Article
In: Energy & Fuels, vol. 38, no. 2, pp. 1399–1415, 2024, ISSN: 0887-0624, (Publisher: American Chemical Society).
@article{garcia-ruiz_experimental_2024,
title = {Experimental and Modeling High-Pressure Study of Ammonia–Methane Oxidation in a Flow Reactor},
author = {Pedro García-Ruiz and Iris Salas and Eva Casanova and Rafael Bilbao and María U Alzueta},
url = {https://doi.org/10.1021/acs.energyfuels.3c03959},
doi = {10.1021/acs.energyfuels.3c03959},
issn = {0887-0624},
year = {2024},
date = {2024-01-01},
urldate = {2024-01-01},
journal = {Energy & Fuels},
volume = {38},
number = {2},
pages = {1399–1415},
abstract = {The present work deals with an experimental and modeling analysis of the oxidation of ammonia–methane mixtures at high pressure (up to 40 bar) in the 550–1250 K temperature range using a quartz tubular reactor and argon as a diluent. The impact of temperature, pressure, oxygen stoichiometry, and CH4/NH3 ratio has been analyzed on the concentrations of NH3, NO2, N2O, NO, N2, HCN, CH4, CO, and CO2 obtained as main products of the ammonia–methane mixture oxidation. The main results obtained indicate that increasing either the pressure, CH4/NH3 ratio, or stoichiometry results in a shift of NH3 and CH4 conversion to lower temperatures. The effect of pressure is particularly significant in the low range of pressures studied. The main products of ammonia oxidation are N2, NO, and N2O while NO2 concentrations are below the detection limit for all of the conditions considered. The N2O formation is favored by increasing the CH4/NH3 ratio and stoichiometry. The experimental results are simulated and interpreted in terms of an updated detailed chemical kinetic mechanism, which, in general, is able to describe well the conversion of both NH3 and CH4 under almost all of the studied conditions. Nevertheless, some discrepancies are found between the experimental results and model calculations.},
note = {Publisher: American Chemical Society},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The present work deals with an experimental and modeling analysis of the oxidation of ammonia–methane mixtures at high pressure (up to 40 bar) in the 550–1250 K temperature range using a quartz tubular reactor and argon as a diluent. The impact of temperature, pressure, oxygen stoichiometry, and CH4/NH3 ratio has been analyzed on the concentrations of NH3, NO2, N2O, NO, N2, HCN, CH4, CO, and CO2 obtained as main products of the ammonia–methane mixture oxidation. The main results obtained indicate that increasing either the pressure, CH4/NH3 ratio, or stoichiometry results in a shift of NH3 and CH4 conversion to lower temperatures. The effect of pressure is particularly significant in the low range of pressures studied. The main products of ammonia oxidation are N2, NO, and N2O while NO2 concentrations are below the detection limit for all of the conditions considered. The N2O formation is favored by increasing the CH4/NH3 ratio and stoichiometry. The experimental results are simulated and interpreted in terms of an updated detailed chemical kinetic mechanism, which, in general, is able to describe well the conversion of both NH3 and CH4 under almost all of the studied conditions. Nevertheless, some discrepancies are found between the experimental results and model calculations.
2023
Journal Articles
Alzueta, María U; Salas, Iris; Hashemi, Hamid; Glarborg, Peter
CO assisted NH3 oxidation Journal Article
In: Combustion and Flame, vol. 257, pp. 112438, 2023, ISSN: 0010-2180.
@article{alzueta_co_2023,
title = {CO assisted NH3 oxidation},
author = {María U Alzueta and Iris Salas and Hamid Hashemi and Peter Glarborg},
url = {https://www.sciencedirect.com/science/article/pii/S0010218022004552},
doi = {10.1016/j.combustflame.2022.112438},
issn = {0010-2180},
year = {2023},
date = {2023-11-01},
urldate = {2023-11-01},
journal = {Combustion and Flame},
volume = {257},
pages = {112438},
series = {James A. Miller Special Commemorative Issue},
abstract = {In the present work, experimental results from the literature on the effect of CO on the NH3 oxidation in the absence and presence of NO are supplemented with novel flow reactor results and interpreted in terms of a detailed chemical kinetic model. The kinetic model provides a satisfactory prediction over a wide range of conditions for oxidation in flow reactors and for flame speeds of CO/NH3. With increasing levels of CO, the generation of chain carriers gradually shifts from being controlled by the amine reaction subset to being dominated by the oxidation chemistry of CO, facilitating reaction at lower temperatures. At elevated temperature, presence of CO causes a change in selectivity of NH3 oxidation from N2 to NO. The present work provides a thorough evaluation of the amine subset of the reaction mechanism for the investigated conditions and offers a kinetic model that reliably can be used for post-flame oxidation modeling in engines and gas turbines fueled by ammonia with a hydrocarbon or alcohol as co-fuel.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In the present work, experimental results from the literature on the effect of CO on the NH3 oxidation in the absence and presence of NO are supplemented with novel flow reactor results and interpreted in terms of a detailed chemical kinetic model. The kinetic model provides a satisfactory prediction over a wide range of conditions for oxidation in flow reactors and for flame speeds of CO/NH3. With increasing levels of CO, the generation of chain carriers gradually shifts from being controlled by the amine reaction subset to being dominated by the oxidation chemistry of CO, facilitating reaction at lower temperatures. At elevated temperature, presence of CO causes a change in selectivity of NH3 oxidation from N2 to NO. The present work provides a thorough evaluation of the amine subset of the reaction mechanism for the investigated conditions and offers a kinetic model that reliably can be used for post-flame oxidation modeling in engines and gas turbines fueled by ammonia with a hydrocarbon or alcohol as co-fuel.
Alzueta, María U; Abián, María; Elvira, I.; Mercader, Víctor D; Sieso, L.
Unraveling the NO reduction mechanisms occurring during the combustion of NH3/CH4 mixtures Journal Article
In: Combustion and Flame, vol. 257, pp. 112531, 2023, ISSN: 0010-2180.
@article{alzueta_unraveling_2023,
title = {Unraveling the NO reduction mechanisms occurring during the combustion of NH3/CH4 mixtures},
author = {María U Alzueta and María Abián and I. Elvira and Víctor D Mercader and L. Sieso},
url = {https://www.sciencedirect.com/science/article/pii/S0010218022005405},
doi = {10.1016/j.combustflame.2022.112531},
issn = {0010-2180},
year = {2023},
date = {2023-11-01},
urldate = {2023-11-01},
journal = {Combustion and Flame},
volume = {257},
pages = {112531},
series = {James A. Miller Special Commemorative Issue},
abstract = {The interaction between NH3, CH4 and NO under different conditions of interest for combustion applications is analyzed, from both experimental and kinetic modeling points of view. Reduction of NO by reburn and by SNCR (selective non-catalytic reduction) strategies is evaluated, through an extense systematic study of the influence of the main variables of interest for NO reduction, by means of laboratory flow-reactor experiments at atmospheric pressure. Variables analyzed include: temperature in the 700 to 1500 K range, air stoichiometry from fuel-rich (λ = 0.31) to fuel-lean conditions (λ = 2.21), NH3/CH4 ratio in the 0.4 to 10.78 range, NH3/NO ratio in the 0.49 to 2.60 range the, and CH4/NO ratio in the 0.37 to 1.98 range, dilution level, and bath gas by using nitrogen and argon, the latter to allow the precise determination of nitrogen balances. Results are interpreted using a literature reaction mechanism, together with reaction pathway analysis tools, and the main findings are discussed. Results indicate that ammonia promotes the conversion of methane, while methane inhibits the conversion of ammonia, due to the competition for radicals of both components in the mixture. The interaction of ammonia and methane implies that the reduction of NO by NH3/CH4 mixtures is comparatively lower than the reduction obtained by NH3 and CH4 independently. Implications for practical applications of the reduction of NO by the studied mixtures are discussed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The interaction between NH3, CH4 and NO under different conditions of interest for combustion applications is analyzed, from both experimental and kinetic modeling points of view. Reduction of NO by reburn and by SNCR (selective non-catalytic reduction) strategies is evaluated, through an extense systematic study of the influence of the main variables of interest for NO reduction, by means of laboratory flow-reactor experiments at atmospheric pressure. Variables analyzed include: temperature in the 700 to 1500 K range, air stoichiometry from fuel-rich (λ = 0.31) to fuel-lean conditions (λ = 2.21), NH3/CH4 ratio in the 0.4 to 10.78 range, NH3/NO ratio in the 0.49 to 2.60 range the, and CH4/NO ratio in the 0.37 to 1.98 range, dilution level, and bath gas by using nitrogen and argon, the latter to allow the precise determination of nitrogen balances. Results are interpreted using a literature reaction mechanism, together with reaction pathway analysis tools, and the main findings are discussed. Results indicate that ammonia promotes the conversion of methane, while methane inhibits the conversion of ammonia, due to the competition for radicals of both components in the mixture. The interaction of ammonia and methane implies that the reduction of NO by NH3/CH4 mixtures is comparatively lower than the reduction obtained by NH3 and CH4 independently. Implications for practical applications of the reduction of NO by the studied mixtures are discussed.
Villasana, Yanet; Armenise, Sabino; Ábrego, Javier; Atienza-Martínez, María; Hablich, Karina; Bimbela, Fernando; Cornejo, Alfonso; Gandía, Luis M.
Exploring a Low-Cost Valorization Route for Amazonian Cocoa Pod Husks through Thermochemical and Catalytic Upgrading of Pyrolysis Vapors Journal Article
In: ACS Omega, vol. 8, no. 40, pp. 37610–37621, 2023, (Publisher: American Chemical Society).
@article{villasana_exploring_2023,
title = {Exploring a Low-Cost Valorization Route for Amazonian Cocoa Pod Husks through Thermochemical and Catalytic Upgrading of Pyrolysis Vapors},
author = {Yanet Villasana and Sabino Armenise and Javier Ábrego and María Atienza-Martínez and Karina Hablich and Fernando Bimbela and Alfonso Cornejo and Luis M. Gandía},
url = {https://doi.org/10.1021/acsomega.3c06672},
doi = {10.1021/acsomega.3c06672},
year = {2023},
date = {2023-10-01},
urldate = {2023-10-01},
journal = {ACS Omega},
volume = {8},
number = {40},
pages = {37610–37621},
abstract = {Ecuador as an international leader in the production of cocoa beans produced more than 300 000 tons in 2021; hence, the management and valorization of the 2 MM tons of waste generated annually by this industry have a strategic and socioeconomic value. Consequently, appropriate technologies to avoid environmental problems and promote sustainable development and the bioeconomy, especially considering that this is a megadiverse country, are of the utmost relevance. For this reason, we explored a low-cost pyrolysis route for valorizing cocoa pod husks from Ecuador’s Amazonian region, aiming at producing pyrolysis liquids (bio-oil), biochar, and gas as an alternative chemical source from cocoa residues in the absence of hydrogen. Downstream catalytic processing of hot pyrolysis vapors using Mo- and/or Ni-based catalysts and standalone γ-Al2O3 was applied for obtaining upgraded bio-oils in a laboratory-scale fixed bed reactor, at 500 °C in a N2 atmosphere. As a result, bimetallic catalysts increased the bio-oil aqueous phase yield by 6.6%, at the expense of the organic phase due to cracking reactions according to nuclear magnetic resonance (NMR) and gas chromatography–mass spectrometry (GC–MS) results. Overall product yield remained constant, in comparison to pyrolysis without any downstream catalytic treatment (bio-oil ∼39.0–40.0 wt % and permanent gases 24.6–26.6 wt %). Ex situ reduced and passivated MoNi/γ-Al2O3 led to the lowest organic phase and highest aqueous phase yields. The product distribution between the two liquid phases was also modified by the catalytic upgrading experiments carried out, according to heteronuclear single-quantum correlation (HSQC), total correlation spectroscopy (TOCSY), and NMR analyses. The detailed composition distribution reported here shows the chemical production potential of this residue and serves as a starting point for subsequent valorizing technologies and/or processes in the food and nonfood industry beneficiating society, environment, economy, and research.},
note = {Publisher: American Chemical Society},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Ecuador as an international leader in the production of cocoa beans produced more than 300 000 tons in 2021; hence, the management and valorization of the 2 MM tons of waste generated annually by this industry have a strategic and socioeconomic value. Consequently, appropriate technologies to avoid environmental problems and promote sustainable development and the bioeconomy, especially considering that this is a megadiverse country, are of the utmost relevance. For this reason, we explored a low-cost pyrolysis route for valorizing cocoa pod husks from Ecuador’s Amazonian region, aiming at producing pyrolysis liquids (bio-oil), biochar, and gas as an alternative chemical source from cocoa residues in the absence of hydrogen. Downstream catalytic processing of hot pyrolysis vapors using Mo- and/or Ni-based catalysts and standalone γ-Al2O3 was applied for obtaining upgraded bio-oils in a laboratory-scale fixed bed reactor, at 500 °C in a N2 atmosphere. As a result, bimetallic catalysts increased the bio-oil aqueous phase yield by 6.6%, at the expense of the organic phase due to cracking reactions according to nuclear magnetic resonance (NMR) and gas chromatography–mass spectrometry (GC–MS) results. Overall product yield remained constant, in comparison to pyrolysis without any downstream catalytic treatment (bio-oil ∼39.0–40.0 wt % and permanent gases 24.6–26.6 wt %). Ex situ reduced and passivated MoNi/γ-Al2O3 led to the lowest organic phase and highest aqueous phase yields. The product distribution between the two liquid phases was also modified by the catalytic upgrading experiments carried out, according to heteronuclear single-quantum correlation (HSQC), total correlation spectroscopy (TOCSY), and NMR analyses. The detailed composition distribution reported here shows the chemical production potential of this residue and serves as a starting point for subsequent valorizing technologies and/or processes in the food and nonfood industry beneficiating society, environment, economy, and research.
Alvira, Darío; Antorán, Daniel; Vidal, Mariano; Sebastián, Víctor; Manyà, Joan Josep
Vine Shoots-Derived Hard Carbons as Anodes for Sodium-Ion Batteries: Role of Annealing Temperature in Regulating Their Structure and Morphology Journal Article
In: Batteries & Supercaps, vol. n/a, no. n/a, pp. e202300233, 2023, ISSN: 2566-6223, (_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/batt.202300233).
@article{alvira_vine_nodate,
title = {Vine Shoots-Derived Hard Carbons as Anodes for Sodium-Ion Batteries: Role of Annealing Temperature in Regulating Their Structure and Morphology},
author = {Darío Alvira and Daniel Antorán and Mariano Vidal and Víctor Sebastián and Joan Josep Manyà},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/batt.202300233},
doi = {10.1002/batt.202300233},
issn = {2566-6223},
year = {2023},
date = {2023-08-02},
urldate = {2023-08-02},
journal = {Batteries & Supercaps},
volume = {n/a},
number = {n/a},
pages = {e202300233},
abstract = {Sodium-ion batteries (SIBs) are considered one of the most promising large-scale and low-cost energy storage systems due to the abundance and low price of sodium. Herein, hard carbons from a sustainable biomass feedstock (vine shoots) were synthesized via a simple two-step carbonization process at different highest temperatures to be used as anodes in SIBs. The hard carbon produced at 1200 °C delivered the highest reversible capacity (270 mAh g−1 at 0.03 A g−1, with an acceptable initial coulombic efficiency of 71 %) since a suitable balance between the pseudographitic domains growth and the retention of microporosity, defects, and functional groups was achieved. A prominent cycling stability with a capacity retention of 97 % over 315 cycles was also attained. Comprehensive characterization unraveled a three-stage sodium storage mechanism based on adsorption, intercalation, and filling of pores. A remarkable specific capacity underestimation of up to 38 % was also found when a two-electrode half-cell configuration was employed to measure the rate performance. To avoid this systematic error caused by the counter/reference electrode polarization, we strongly recommend the use of a three-electrode setup or a full-cell configuration to correctly evaluate the anode response at moderate and high current rates.},
note = {_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1002/batt.202300233},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Sodium-ion batteries (SIBs) are considered one of the most promising large-scale and low-cost energy storage systems due to the abundance and low price of sodium. Herein, hard carbons from a sustainable biomass feedstock (vine shoots) were synthesized via a simple two-step carbonization process at different highest temperatures to be used as anodes in SIBs. The hard carbon produced at 1200 °C delivered the highest reversible capacity (270 mAh g−1 at 0.03 A g−1, with an acceptable initial coulombic efficiency of 71 %) since a suitable balance between the pseudographitic domains growth and the retention of microporosity, defects, and functional groups was achieved. A prominent cycling stability with a capacity retention of 97 % over 315 cycles was also attained. Comprehensive characterization unraveled a three-stage sodium storage mechanism based on adsorption, intercalation, and filling of pores. A remarkable specific capacity underestimation of up to 38 % was also found when a two-electrode half-cell configuration was employed to measure the rate performance. To avoid this systematic error caused by the counter/reference electrode polarization, we strongly recommend the use of a three-electrode setup or a full-cell configuration to correctly evaluate the anode response at moderate and high current rates.
Afailal, Zainab; Gil-Lalaguna, Noemí; Macías, Robert J.; Gonzalo, Alberto; Sánchez, José Luis
Production of Antioxidant Additives and High-quality Activated Biochar from Pyrolysis of Argan Shells Journal Article
In: BioEnergy Research, 2023, ISSN: 1939-1242.
@article{afailal_production_2023,
title = {Production of Antioxidant Additives and High-quality Activated Biochar from Pyrolysis of Argan Shells},
author = {Zainab Afailal and Noemí Gil-Lalaguna and Robert J. Macías and Alberto Gonzalo and José Luis Sánchez},
url = {https://doi.org/10.1007/s12155-023-10652-0},
doi = {10.1007/s12155-023-10652-0},
issn = {1939-1242},
year = {2023},
date = {2023-08-01},
urldate = {2023-08-01},
journal = {BioEnergy Research},
abstract = {An integral valorization route based on a pyrolysis process has been proposed to find sustainable applications for argan shells focused on the simultaneous production of activated biochar and antioxidant additives from bio-oil. The bio-oil obtained in the pyrolysis process was furtherly upgraded (hydrothermal treatment and extraction process) to obtain antioxidant additives. On the other hand, the biochar obtained in the pyrolysis was used as a feedstock to produce high-quality activated biochar (by physical activation with CO2). The increase in the pyrolysis temperature (350–550 °C) hardly affected the pyrolysis products distribution (biochar yields of 28–34 wt.% and bio-oil yields between 51 and 55 wt.%), but it led to a slight decrease in the content of phenolic monomers extracted from bio-oil (from 63 wt.% at 350 °C to 53 wt.% at 550 °C). When these extracted fractions were blended with biodiesel (<1 wt.%), improvements of up to 300% in biodiesel oxidation stability were attained. The hydrothermal treatment of the bio-oil did not show noteworthy effects either on the production or antioxidant performance of the extracted fractions if compared with the fractions extracted from the raw bio-oil. Regarding the valorization of argan shells biochar, the activated biochar prepared from it showed considerable potential as an adsorbent material for CO2 (125 mg of CO2 per g of the activated biochar) or phenols (complete removal of 99.6% in 4 h of contact time). It was characterized by a high BET surface area (up to 1500 m2/g), a high carbon content (up to 95 wt.%), low ash content (around 2 wt.%), and a pH of around 8.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
An integral valorization route based on a pyrolysis process has been proposed to find sustainable applications for argan shells focused on the simultaneous production of activated biochar and antioxidant additives from bio-oil. The bio-oil obtained in the pyrolysis process was furtherly upgraded (hydrothermal treatment and extraction process) to obtain antioxidant additives. On the other hand, the biochar obtained in the pyrolysis was used as a feedstock to produce high-quality activated biochar (by physical activation with CO2). The increase in the pyrolysis temperature (350–550 °C) hardly affected the pyrolysis products distribution (biochar yields of 28–34 wt.% and bio-oil yields between 51 and 55 wt.%), but it led to a slight decrease in the content of phenolic monomers extracted from bio-oil (from 63 wt.% at 350 °C to 53 wt.% at 550 °C). When these extracted fractions were blended with biodiesel (<1 wt.%), improvements of up to 300% in biodiesel oxidation stability were attained. The hydrothermal treatment of the bio-oil did not show noteworthy effects either on the production or antioxidant performance of the extracted fractions if compared with the fractions extracted from the raw bio-oil. Regarding the valorization of argan shells biochar, the activated biochar prepared from it showed considerable potential as an adsorbent material for CO2 (125 mg of CO2 per g of the activated biochar) or phenols (complete removal of 99.6% in 4 h of contact time). It was characterized by a high BET surface area (up to 1500 m2/g), a high carbon content (up to 95 wt.%), low ash content (around 2 wt.%), and a pH of around 8.