The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
R Moliner - One of the best experts on this subject based on the ideXlab platform.
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Catalytic Decomposition of biogas to produce hydrogen rich fuels for si engines and valuable nanocarbons
International Journal of Hydrogen Energy, 2013Co-Authors: S De Llobet, J L Pinilla, R Moliner, I Suelves, J Arroyo, F Moreno, M Munoz, Carlos Monne, Ignacio Camean, Alberto RamosAbstract:Abstract Catalytic Decomposition of Biogas (CDB), producing simultaneously syngases (SG), with high hydrogen contents, for spark ignition (SI) engines and bio-carbon nanofibers (BCNFs) to be further used as precursor of synthetic graphite, is presented as an alternative to the usual direct combustion. Synthetic biogas mixtures were decomposed in the presence of a Ni catalyst at different temperatures and the SG thus produced were further tested as fuel in a specifically designed SI engine, whereas the BCNFs were subjected to heat treatment to graphitize. The influence of CDB process conditions on product yields and properties, the effect of SG composition/quality in SI engine performance and emissions, as compared with the use of raw biogas and the influence of BCNFs characteristics on the structural and textural properties of the graphitic materials have been studied. The syngases presented better combustion characteristics than biogas resulting in higher engine brake thermal efficiencies and lower exhaust emissions. Furthermore, high added value graphite-like materials, with a crystalline structure similar to that of oil-derived graphite which is currently commercialized to be used as anode in rechargeable lithium-ion batteries, were prepared.
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ni and fe based catalysts for hydrogen and carbon nanofilament production by Catalytic Decomposition of methane in a rotary bed reactor
Fuel Processing Technology, 2011Co-Authors: J L Pinilla, R Moliner, I Suelves, R Utrilla, M J Lazaro, Ana B GarciaAbstract:Abstract Four catalysts, consisting of Ni, Ni:Cu, Fe or Fe:Mo as the active phase and Al2O3 or MgO as a textural promoter, were tested for the Catalytic Decomposition of methane in a rotary bed reactor, obtaining both CO2-free hydrogen and carbon nanostructures in a single step. Hydrogen yields of up to 14.4 Ndm3 H2·(h·gcat)− 1 were obtained using the Ni-based catalysts, and methane conversions above 80% were observed with the Fe-based catalysts. In addition to hydrogen production, the Ni-based catalysts allowed the large-scale production of fishbone-like carbon nanofibres, whereas the use of the Fe-based catalysts promoted the production of carbonaceous filaments having a high degree of structural order, consisting of both chain-like carbon nanofibres and carbon nanotubes.
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hydrogen production by thermo Catalytic Decomposition of methane regeneration of active carbons using co2
Journal of Power Sources, 2007Co-Authors: J L Pinilla, I Suelves, R Utrilla, M E Galvez, M J Lazaro, R MolinerAbstract:Abstract Thermo-Catalytic Decomposition of methane using carbons as catalyst is a very attractive process for free CO 2 –hydrogen production. One of the main drawbacks for the sustainability of the process is catalyst deactivation. In this work, regeneration of a deactivated active-carbon catalyst has been studied using CO 2 as activating agent under different regeneration conditions. It has been stated that during the regeneration stage, a compromise between the regeneration of the initial properties of the catalyst and the burn-off is needed in order to keep the sustainability of the process. Three deactivation–regeneration cycles have been performed for two sets of regeneration conditions. A progressive decreasing in the burn-off, surface area and surface oxygenated groups after each Decomposition/regeneration cycle is observed. It can be explained considering that the carbon removed during the regeneration steps is not the carbon deposited from methane but the remaining initial catalyst, which is less resistant to gasification. The implication is that after three cycles of Decomposition/regeneration, most of the carbon sample consists of carbon formed during the process since the initial catalyst has been gasified.
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hydrogen production by thermo Catalytic Decomposition of methane on ni based catalysts influence of operating conditions on catalyst deactivation and carbon characteristics
International Journal of Hydrogen Energy, 2005Co-Authors: I Suelves, R Moliner, M J Lazaro, Beatriz M Corbella, J M PalaciosAbstract:Abstract Thermo Catalytic Decomposition of methane to produce CO 2 -free hydrogen has been carried out in a fixed bed reactor at different operating conditions using a commercial Ni-based catalyst to study the characteristics of the carbon produced and the catalyst deactivation mechanism. At temperature of 700 ∘ C, the concentration of hydrogen was around 80%, which corresponds to a methane conversion close to the thermodynamic values. It has been shown that time for catalyst deactivation depends on the operating conditions, so that, the higher the temperature and methane flow, the shorter the life of the catalyst. At temperature of 700 ∘ C and space time of 1 s, the catalyst activity did not decay after 8 h in stream. In contrast when space time was reduced to 0.2 s, the catalyst became deactivated after 90 min while the quantity of carbon deposited was the half. Scanning electron microscope and transmission electron microscope examination has shown that the deposited carbon appears either as large filaments a few nanometres in diameter emerging from Ni particles or as uniform coatings. X-ray diffraction, Fourier transform-Raman and X-ray photoelectron spectra reveal that in both cases the carbon deposited is highly ordered graphite whose structure does not depend on the operating conditions. Formation of carbon filaments, which is desirable, is favoured by operating conditions promoting low rates of methane conversion. On the contrary, operating conditions promoting high Decomposition rates enhance coating carbon deposition and shorten the catalyst life.
I Suelves - One of the best experts on this subject based on the ideXlab platform.
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Catalytic Decomposition of biogas to produce hydrogen rich fuels for si engines and valuable nanocarbons
International Journal of Hydrogen Energy, 2013Co-Authors: S De Llobet, J L Pinilla, R Moliner, I Suelves, J Arroyo, F Moreno, M Munoz, Carlos Monne, Ignacio Camean, Alberto RamosAbstract:Abstract Catalytic Decomposition of Biogas (CDB), producing simultaneously syngases (SG), with high hydrogen contents, for spark ignition (SI) engines and bio-carbon nanofibers (BCNFs) to be further used as precursor of synthetic graphite, is presented as an alternative to the usual direct combustion. Synthetic biogas mixtures were decomposed in the presence of a Ni catalyst at different temperatures and the SG thus produced were further tested as fuel in a specifically designed SI engine, whereas the BCNFs were subjected to heat treatment to graphitize. The influence of CDB process conditions on product yields and properties, the effect of SG composition/quality in SI engine performance and emissions, as compared with the use of raw biogas and the influence of BCNFs characteristics on the structural and textural properties of the graphitic materials have been studied. The syngases presented better combustion characteristics than biogas resulting in higher engine brake thermal efficiencies and lower exhaust emissions. Furthermore, high added value graphite-like materials, with a crystalline structure similar to that of oil-derived graphite which is currently commercialized to be used as anode in rechargeable lithium-ion batteries, were prepared.
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ni and fe based catalysts for hydrogen and carbon nanofilament production by Catalytic Decomposition of methane in a rotary bed reactor
Fuel Processing Technology, 2011Co-Authors: J L Pinilla, R Moliner, I Suelves, R Utrilla, M J Lazaro, Ana B GarciaAbstract:Abstract Four catalysts, consisting of Ni, Ni:Cu, Fe or Fe:Mo as the active phase and Al2O3 or MgO as a textural promoter, were tested for the Catalytic Decomposition of methane in a rotary bed reactor, obtaining both CO2-free hydrogen and carbon nanostructures in a single step. Hydrogen yields of up to 14.4 Ndm3 H2·(h·gcat)− 1 were obtained using the Ni-based catalysts, and methane conversions above 80% were observed with the Fe-based catalysts. In addition to hydrogen production, the Ni-based catalysts allowed the large-scale production of fishbone-like carbon nanofibres, whereas the use of the Fe-based catalysts promoted the production of carbonaceous filaments having a high degree of structural order, consisting of both chain-like carbon nanofibres and carbon nanotubes.
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hydrogen production by thermo Catalytic Decomposition of methane regeneration of active carbons using co2
Journal of Power Sources, 2007Co-Authors: J L Pinilla, I Suelves, R Utrilla, M E Galvez, M J Lazaro, R MolinerAbstract:Abstract Thermo-Catalytic Decomposition of methane using carbons as catalyst is a very attractive process for free CO 2 –hydrogen production. One of the main drawbacks for the sustainability of the process is catalyst deactivation. In this work, regeneration of a deactivated active-carbon catalyst has been studied using CO 2 as activating agent under different regeneration conditions. It has been stated that during the regeneration stage, a compromise between the regeneration of the initial properties of the catalyst and the burn-off is needed in order to keep the sustainability of the process. Three deactivation–regeneration cycles have been performed for two sets of regeneration conditions. A progressive decreasing in the burn-off, surface area and surface oxygenated groups after each Decomposition/regeneration cycle is observed. It can be explained considering that the carbon removed during the regeneration steps is not the carbon deposited from methane but the remaining initial catalyst, which is less resistant to gasification. The implication is that after three cycles of Decomposition/regeneration, most of the carbon sample consists of carbon formed during the process since the initial catalyst has been gasified.
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hydrogen production by thermo Catalytic Decomposition of methane on ni based catalysts influence of operating conditions on catalyst deactivation and carbon characteristics
International Journal of Hydrogen Energy, 2005Co-Authors: I Suelves, R Moliner, M J Lazaro, Beatriz M Corbella, J M PalaciosAbstract:Abstract Thermo Catalytic Decomposition of methane to produce CO 2 -free hydrogen has been carried out in a fixed bed reactor at different operating conditions using a commercial Ni-based catalyst to study the characteristics of the carbon produced and the catalyst deactivation mechanism. At temperature of 700 ∘ C, the concentration of hydrogen was around 80%, which corresponds to a methane conversion close to the thermodynamic values. It has been shown that time for catalyst deactivation depends on the operating conditions, so that, the higher the temperature and methane flow, the shorter the life of the catalyst. At temperature of 700 ∘ C and space time of 1 s, the catalyst activity did not decay after 8 h in stream. In contrast when space time was reduced to 0.2 s, the catalyst became deactivated after 90 min while the quantity of carbon deposited was the half. Scanning electron microscope and transmission electron microscope examination has shown that the deposited carbon appears either as large filaments a few nanometres in diameter emerging from Ni particles or as uniform coatings. X-ray diffraction, Fourier transform-Raman and X-ray photoelectron spectra reveal that in both cases the carbon deposited is highly ordered graphite whose structure does not depend on the operating conditions. Formation of carbon filaments, which is desirable, is favoured by operating conditions promoting low rates of methane conversion. On the contrary, operating conditions promoting high Decomposition rates enhance coating carbon deposition and shorten the catalyst life.
J L Pinilla - One of the best experts on this subject based on the ideXlab platform.
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Catalytic Decomposition of biogas to produce hydrogen rich fuels for si engines and valuable nanocarbons
International Journal of Hydrogen Energy, 2013Co-Authors: S De Llobet, J L Pinilla, R Moliner, I Suelves, J Arroyo, F Moreno, M Munoz, Carlos Monne, Ignacio Camean, Alberto RamosAbstract:Abstract Catalytic Decomposition of Biogas (CDB), producing simultaneously syngases (SG), with high hydrogen contents, for spark ignition (SI) engines and bio-carbon nanofibers (BCNFs) to be further used as precursor of synthetic graphite, is presented as an alternative to the usual direct combustion. Synthetic biogas mixtures were decomposed in the presence of a Ni catalyst at different temperatures and the SG thus produced were further tested as fuel in a specifically designed SI engine, whereas the BCNFs were subjected to heat treatment to graphitize. The influence of CDB process conditions on product yields and properties, the effect of SG composition/quality in SI engine performance and emissions, as compared with the use of raw biogas and the influence of BCNFs characteristics on the structural and textural properties of the graphitic materials have been studied. The syngases presented better combustion characteristics than biogas resulting in higher engine brake thermal efficiencies and lower exhaust emissions. Furthermore, high added value graphite-like materials, with a crystalline structure similar to that of oil-derived graphite which is currently commercialized to be used as anode in rechargeable lithium-ion batteries, were prepared.
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ni and fe based catalysts for hydrogen and carbon nanofilament production by Catalytic Decomposition of methane in a rotary bed reactor
Fuel Processing Technology, 2011Co-Authors: J L Pinilla, R Moliner, I Suelves, R Utrilla, M J Lazaro, Ana B GarciaAbstract:Abstract Four catalysts, consisting of Ni, Ni:Cu, Fe or Fe:Mo as the active phase and Al2O3 or MgO as a textural promoter, were tested for the Catalytic Decomposition of methane in a rotary bed reactor, obtaining both CO2-free hydrogen and carbon nanostructures in a single step. Hydrogen yields of up to 14.4 Ndm3 H2·(h·gcat)− 1 were obtained using the Ni-based catalysts, and methane conversions above 80% were observed with the Fe-based catalysts. In addition to hydrogen production, the Ni-based catalysts allowed the large-scale production of fishbone-like carbon nanofibres, whereas the use of the Fe-based catalysts promoted the production of carbonaceous filaments having a high degree of structural order, consisting of both chain-like carbon nanofibres and carbon nanotubes.
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hydrogen production by thermo Catalytic Decomposition of methane regeneration of active carbons using co2
Journal of Power Sources, 2007Co-Authors: J L Pinilla, I Suelves, R Utrilla, M E Galvez, M J Lazaro, R MolinerAbstract:Abstract Thermo-Catalytic Decomposition of methane using carbons as catalyst is a very attractive process for free CO 2 –hydrogen production. One of the main drawbacks for the sustainability of the process is catalyst deactivation. In this work, regeneration of a deactivated active-carbon catalyst has been studied using CO 2 as activating agent under different regeneration conditions. It has been stated that during the regeneration stage, a compromise between the regeneration of the initial properties of the catalyst and the burn-off is needed in order to keep the sustainability of the process. Three deactivation–regeneration cycles have been performed for two sets of regeneration conditions. A progressive decreasing in the burn-off, surface area and surface oxygenated groups after each Decomposition/regeneration cycle is observed. It can be explained considering that the carbon removed during the regeneration steps is not the carbon deposited from methane but the remaining initial catalyst, which is less resistant to gasification. The implication is that after three cycles of Decomposition/regeneration, most of the carbon sample consists of carbon formed during the process since the initial catalyst has been gasified.
G Van Tendeloo - One of the best experts on this subject based on the ideXlab platform.
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control of the outer diameter of thin carbon nanotubes synthesized by Catalytic Decomposition of hydrocarbons
ELECTRONIC PROPERTIES OF NOVEL MATERIALS—MOLECULAR NANOSTRUCTURES: XIV International Winterschool Euroconference, 2001Co-Authors: I Willems, A Fonseca, Zoltan Konya, Jeanfrancois Colomer, G Van Tendeloo, N Nagaraju, J B NagyAbstract:Multi-wall carbon nanotubes were produced by Catalytic Decomposition of acetylene. Co-Mo, Co-V and Co-Fe mixtures supported either on zeolite or corundum alumina were used as catalysts. When Fe or V is added to Co, the amount of carbon deposit increases. The nanotubes were characterized by both low and high resolution TEM. From histograms representing the outer diameter distributions, it is made clear that the outer diameter of the nanotubes can be controlled, choosing the appropriate catalyst.
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control of the outer diameter of thin carbon nanotubes synthesized by Catalytic Decomposition of hydrocarbons
Chemical Physics Letters, 2000Co-Authors: I Willems, A Fonseca, Zoltan Konya, Jeanfrancois Colomer, G Van Tendeloo, N Nagaraju, J B NagyAbstract:Abstract Multi-wall carbon nanotubes have been produced by the Catalytic Decomposition of acetylene. Co–Mo, Co–V and Co–Fe mixtures supported either on zeolite or corundum alumina were used as catalysts. When Fe or V is added to Co, the carbon deposit increases. The nanotubes were characterized by both low and high resolution TEM. From histograms representing the outer diameter distributions, it is clear that the outer diameter of the nanotubes can be controlled by choosing the appropriate catalyst.
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synthesis of single wall carbon nanotubes by Catalytic Decomposition of hydrocarbons
Chemical Communications, 1999Co-Authors: Jeanfrancois Colomer, A Fonseca, J B Nagy, I Willems, Zoltan Konya, G Bister, G Van TendelooAbstract:Individual single-wall carbon nanotubes (SWNTs) and bundles can be obtained over different types of supported metal catalysts by Decomposition of ethylene, similar to the synthesis of multi-wall carbon nanotubes.
J B Nagy - One of the best experts on this subject based on the ideXlab platform.
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control of the outer diameter of thin carbon nanotubes synthesized by Catalytic Decomposition of hydrocarbons
ELECTRONIC PROPERTIES OF NOVEL MATERIALS—MOLECULAR NANOSTRUCTURES: XIV International Winterschool Euroconference, 2001Co-Authors: I Willems, A Fonseca, Zoltan Konya, Jeanfrancois Colomer, G Van Tendeloo, N Nagaraju, J B NagyAbstract:Multi-wall carbon nanotubes were produced by Catalytic Decomposition of acetylene. Co-Mo, Co-V and Co-Fe mixtures supported either on zeolite or corundum alumina were used as catalysts. When Fe or V is added to Co, the amount of carbon deposit increases. The nanotubes were characterized by both low and high resolution TEM. From histograms representing the outer diameter distributions, it is made clear that the outer diameter of the nanotubes can be controlled, choosing the appropriate catalyst.
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production of nanotubes by the Catalytic Decomposition of different carbon containing compounds
Applied Catalysis A-general, 2000Co-Authors: Klara Hernadi, A Fonseca, J B Nagy, Andrea Siska, Imre KiricsiAbstract:Carbon nanotubes were prepared in the Catalytic Decomposition of different carbon containing compounds over supported transition metal catalysts. Besides acetylene, ethylene, propylene, acetone, n-pentane, methanol, toluene, and methane were tested and each resulted in carbon nanotube formation. The quality of as-made nanotubes was investigated by TEM and was found to be at least as good as obtained in acetylene Decomposition. Ethylene and propylene showed somewhat lower reactivity in the buckytube formation with respect to acetylene, simultaneously suppressed formation of amorphous carbon on the outer surface was found.
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control of the outer diameter of thin carbon nanotubes synthesized by Catalytic Decomposition of hydrocarbons
Chemical Physics Letters, 2000Co-Authors: I Willems, A Fonseca, Zoltan Konya, Jeanfrancois Colomer, G Van Tendeloo, N Nagaraju, J B NagyAbstract:Abstract Multi-wall carbon nanotubes have been produced by the Catalytic Decomposition of acetylene. Co–Mo, Co–V and Co–Fe mixtures supported either on zeolite or corundum alumina were used as catalysts. When Fe or V is added to Co, the carbon deposit increases. The nanotubes were characterized by both low and high resolution TEM. From histograms representing the outer diameter distributions, it is clear that the outer diameter of the nanotubes can be controlled by choosing the appropriate catalyst.
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synthesis of single wall carbon nanotubes by Catalytic Decomposition of hydrocarbons
Chemical Communications, 1999Co-Authors: Jeanfrancois Colomer, A Fonseca, J B Nagy, I Willems, Zoltan Konya, G Bister, G Van TendelooAbstract:Individual single-wall carbon nanotubes (SWNTs) and bundles can be obtained over different types of supported metal catalysts by Decomposition of ethylene, similar to the synthesis of multi-wall carbon nanotubes.