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Paul T Williams - One of the best experts on this subject based on the ideXlab platform.
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Hydrogen and Carbon Nanotubes from Pyrolysis-Catalysis of Waste Plastics: A Review
Waste and Biomass Valorization, 2021Co-Authors: Paul T WilliamsAbstract:More than 27 million tonnes of waste plastics are generated in Europe each year representing a considerable potential resource. There has been extensive research into the production of liquid fuels and aromatic chemicals from pyrolysis-catalysis of waste plastics. However, there is less work on the production of hydrogen from waste plastics via pyrolysis coupled with Catalytic Steam Reforming. In this paper, the different reactor designs used for hydrogen production from waste plastics are considered and the influence of different catalysts and process parameters on the yield of hydrogen from different types of waste plastics are reviewed. Waste plastics have also been investigated as a source of hydrocarbons for the generation of carbon nanotubes via the chemical vapour deposition route. The influences on the yield and quality of carbon nanotubes derived from waste plastics are reviewed in relation to the reactor designs used for production, catalyst type used for carbon nanotube growth and the influence of operational parameters. Graphic Abstract
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hydrogen from waste plastics by two stage pyrolysis low temperature plasma Catalytic processing
Energy & Fuels, 2020Co-Authors: Idris Aminu, Mohamad A Nahil, Paul T WilliamsAbstract:Hydrogen was produced from waste plastic (polyethylene) using a novel two-stage pyrolysis–low-temperature (250 °C) plasma Catalytic Steam Reforming process. Pyrolysis of the polyethylene generated pyrolysis gases, which were Catalytically Steam-reformed in the presence of low-temperature non-thermal plasma (dielectric barrier discharge) to produce hydrogen gas. In the absence of a catalyst, increasing the plasma power resulted in a significant increase in the hydrogen yield. Different catalysts (Ni/Al2O3, Fe/Al2O3, Co/Al2O3, and Cu/Al2O3) were incorporated in the discharge region of the plasma reactor, and Ni/Al2O3 produced the highest yield of hydrogen at 1.5 mmol g–1plastic. The addition of Steam to the plasma Catalytic process was investigated at different Steam weight hourly space velocities (WHSVs) using the Ni/Al2O3 catalyst. The addition of Steam to promote Catalytic Steam Reforming reactions resulted in a marked increase in the hydrogen yield, producing the highest hydrogen yield of 4.56 mmol g–1plastic at a WHSV of 4 g h–1 g–1catalyst.
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co pyrolysis Catalytic Steam Reforming of cellulose lignin with polyethylene polystyrene for the production of hydrogen
Waste Disposal & Sustainable Energy, 2020Co-Authors: Kaltume Akubo, Mohamad A Nahil, Paul T WilliamsAbstract:Co-pyrolysis of biomass biopolymers (lignin and cellulose) with plastic wastes (polyethylene and polystyrene) coupled with downstream Catalytic Steam Reforming of the pyrolysis gases for the production of a hydrogen-rich syngas is reported. The catalyst used was 10 wt.% nickel supported on MCM-41. The influence of the process parameters of temperature and the Steam flow rate was examined to optimize hydrogen and syngas production. The cellulose/plastic mixtures produced higher hydrogen yields compared with the lignin/plastic mixtures. However, the impact of raising the Catalytic Steam Reforming temperature from 750 to 850 °C was more marked for lignin addition. For example, the hydrogen yield for cellulose/polyethylene at a catalyst temperature of 750 °C was 50.3 mmol g−1 and increased to 60.0 mmol g−1 at a catalyst temperature of 850 °C. However, for the lignin/polyethylene mixture, the hydrogen yield increased from 25.0 to 50.0 mmol g−1 representing a twofold increase in hydrogen yield. The greater influence on hydrogen and yield for the lignin/plastic mixtures compared to the cellulose/plastic mixtures is suggested to be due to the overlapping thermal degradation profiles of lignin and the polyethylene and polystyrene. The input of Steam to the catalyst reactor produced Catalytic Steam Reforming conditions and a marked increase in hydrogen yield. The influence of increased Steam input to the process was greater for the lignin/plastic mixtures compared to the cellulose/plastic mixtures, again linked to the overlapping thermal degradation profiles of the lignin and the plastics. A comparison of the Ni/MCM-41 catalyst with Ni/Al2O3 and Ni/Y-zeolite-supported catalysts showed that the Ni/Al2O3 catalyst gave higher yields of hydrogen and syngas.
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pyrolysis Catalytic Steam Reforming of agricultural biomass wastes and biomass components for production of hydrogen syngas
Journal of The Energy Institute, 2019Co-Authors: Kaltume Akubo, Mohamad A Nahil, Paul T WilliamsAbstract:Abstract The pyrolysis-Catalytic Steam Reforming of six agricultural biomass waste samples as well as the three main components of biomass was investigated in a two stage fixed bed reactor. Pyrolysis of the biomass took place in the first stage followed by Catalytic Steam Reforming of the evolved pyrolysis gases in the second stage Catalytic reactor. The waste biomass samples were, rice husk, coconut shell, sugarcane bagasse, palm kernel shell, cotton stalk and wheat straw and the biomass components were, cellulose, hemicellulose (xylan) and lignin. The catalyst used for Steam Reforming was a 10 wt.% nickel-based alumina catalyst (NiAl2O3). In addition, the thermal decomposition characteristics of the biomass wastes and biomass components were also determined using thermogravimetric analysis (TGA). The TGA results showed distinct peaks for the individual biomass components, which were also evident in the biomass waste samples reflecting the existence of the main biomass components in the biomass wastes. The results for the two-stage pyrolysis-Catalytic Steam Reforming showed that introduction of Steam and catalyst into the pyrolysis-Catalytic Steam Reforming process significantly increased gas yield and syngas production notably hydrogen. For instance, hydrogen composition increased from 6.62 to 25.35 mmol g−1 by introducing Steam and catalyst into the pyrolysis-Catalytic Steam Reforming of palm kernel shell. Lignin produced the most hydrogen compared to cellulose and hemicellulose at 25.25 mmol g−1. The highest residual char production was observed with lignin which produced about 45 wt.% char, more than twice that of cellulose and hemicellulose.
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hybrid plasma Catalytic Steam Reforming of toluene as a biomass tar model compound over ni al2o3 catalysts
Fuel Processing Technology, 2017Co-Authors: S Y Liu, D H Mei, Mohamad A Nahil, Siddharth Gadkari, Paul T WilliamsAbstract:In this study, plasma-Catalytic Steam Reforming of toluene as a biomass tar model compound was carried out in a coaxial dielectric barrier discharge (DBD) plasma reactor. The effect of Ni/Al2O3 catalysts with different nickel loadings (5–20 wt%) on the plasma-Catalytic gas cleaning process was evaluated in terms of toluene conversion, gas yield, by-products formation and energy efficiency of the plasma-Catalytic process. Compared to the plasma reaction without a catalyst, the combination of DBD with the Ni/Al2O3 catalysts significantly enhanced the toluene conversion, hydrogen yield and energy efficiency of the hybrid plasma process, while significantly reduced the production of organic by-products. Increasing Ni loading of the catalyst improved the performance of the plasma-Catalytic processing of toluene, with the highest toluene conversion of 52% and energy efficiency of 2.6 g/kWh when placing the 20 wt% Ni/Al2O3 catalyst in the plasma. The possible reaction pathways in the hybrid plasma-Catalytic process were proposed through the combined analysis of both gas and liquid products.
Esteban Chornet - One of the best experts on this subject based on the ideXlab platform.
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the production of hydrogen by Steam Reforming of trap greaseprogress in catalyst performance
Energy & Fuels, 2004Co-Authors: Stefan R. Czernik, Richard J French, And Kimberly A Magrinibair, Esteban ChornetAbstract:Most hydrogen is currently produced via the Steam Reforming of natural gas. An environmentally preferable option is to produce hydrogen from renewable materials. Waste vegetable oil from food processing (“trap grease”) is a low-cost, widely available renewable material that currently has no commercial use. In this work, we produced hydrogen via the fluidized-bed Catalytic Steam Reforming of trap grease using commercial and experimental Ni/Al2O3 catalysts under conditions similar to those of commercial natural gas Reforming operationstemperatures in excess of 800 °C, molar Steam-to-carbon ratio of five, and a methane-equivalent volumetric space velocity of ∼1000 h-1. During operation for 150 h, yields of 25 g of hydrogen per 100 g of trap grease were obtained. The process performance decreased with time, because of catalyst attrition and deactivation. We succeeded in extending the catalyst time-on-stream through the use of a laboratory-prepared attrition-resistant catalyst. Another strategy used was a two-...
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hydrogen by Catalytic Steam Reforming of liquid byproducts from biomass thermoconversion processes
Industrial & Engineering Chemistry Research, 2002Co-Authors: Stefan R. Czernik, Calvin J. Feik, Richard J French, Esteban ChornetAbstract:Biomass, a product of photosynthesis, is a renewable resource that can be used for sustainable production of hydrogen. We propose an approach that combines production of hydrogen with valuable coproducts and shows promising economics. The concept is based on a two-stage process: fast pyrolysis of biomass to generate bio-oil, followed by Catalytic Steam Reforming of the bio-oil, or a fraction thereof, to produce hydrogen. The preferred option is separation of the bio-oil into a lignin-derived fraction, which could be used for producing phenolic resins or fuel-blending components, and a carbohydrate-derived material, which would be reformed to produce hydrogen. The coproduct strategy can also be applied to residual fractions derived from pulping operations or ethanol production and to effluents from other biomass conversion technologies such as transesterification of vegetable oils or food processing residues. In addition, all of the biomass-derived liquids can be coprocessed with natural gas to produce hy...
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renewable hydrogen production by Catalytic Steam Reforming of peanut shells pyrolysis products
2002Co-Authors: Robert J Evans, Calvin J. Feik, Richard J French, Steven D Phillips, Esteban Chornet, Stefan Czernik, Jalal Abedi, Yaw D Yeboah, Danny Day, Jan HowardAbstract:Catalytic Steam Reforming OF PEANUT SHELLS PYROLYSIS PRODUCTS Although the adhesive byproduct option remains viable, commercial deployment opportunities are still not near term. Hence, other opportunities had to be developed based on the co-product strategy. The conversion of biomass to activated carbon is an alterative route to hydrogen with a valuable co-product as outlined in Figure 1. Slow pyrolysis is used in the first step of the activated carbon process to maximize the yield of charcoal and organic vapors are produced as a by-product in 25% yield. Southwest Georgia was identified as an excellent opportunity because of the importance of agriculture, the forest product industry and the need for zero emission transportation fuels in the Atlanta area. Scientific Carbons Inc. in Blakely GA uses pelletized peanut shells as the feed material for the production of activated carbon. They feed up to 1000 kg/hour of the densified peanut shells to a two-stage process producing activated carbon. The vapor by-products from the first stage, pyrolysis, are currently used as fuel for Steam generator. Robert J. Evans, Esteban Chornet, Stefan Czernik, Calvin Feik, Richard French, Steven Phillips, Jalal Abedi, Yaw D. Yeboah, Danny Day, Jan Howard, Dennis McGee, and Matthew J. Realff
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engineering scale up of renewable hydrogen production by Catalytic Steam Reforming of peanut shells pyrolysis products
2002Co-Authors: Robert J Evans, Calvin J. Feik, Richard J French, Esteban Chornet, Stefan Czernik, Steven D PhillipsAbstract:Renewable hydrogen may be produced in the near term at a cost that is competitive with natural gas Reforming by integrating hydrogen production with existing industrial utilization of agricultural residues. A team of government, industrial, and academic organizations is developing a Steam Reforming process to be demonstrated on the gaseous byproducts from a process for making activated carbon from densified peanut shells [1]. The thermochemical user’s facility (TCUF) at NREL was the site for the initial shakedown of the scaled up reactor. It was interfaced with a 20-kg/hour fluidized-bed fast pyrolysis system to take advantage of process chemical analysis and computer control and monitoring capabilities. This paper reports the results from the shake down phase of this engineering demonstration project. After an initial problem with the heaters that required modification to the heater control strategy, the system passed mechanical shakedown tests and was integrated with the TCUF fluid bed pyrolysis system. The new control system developed to protect the reactor is based on 30 heater-monitoring thermocouples to prevent overheating in the case of heater malfunction. The 30-cm, Catalytic, Steam-Reforming reactor was then successfully operated on methane and peanut shell pyrolysis products. Experiments with peanut pyrolysis vapor Reforming duplicated the results in a 5-cm bench scale unit with the aqueous fraction of wood pyrolysis oil. This is the first time that the whole pyrolysis vapors have been processed in the fluid bed Reforming process. Although peanut shells have a unique composition, containing high levels of lignin and protein, no problems were encountered in the Reforming of the vapors. The only other significant problem uncounted was the plugging of the reformer distribution plate by fine char that acted as a nucleus for vapor deposition, slowly plugging the reactor. A hot gas filter was installed to remove the char and the reactor was operated for 30 hours without plugging
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Catalytic Steam Reforming of bio oils for the production of hydrogen effects of catalyst composition
Applied Catalysis A-general, 2000Co-Authors: L Garcia, Richard J French, Stefan Czernik, Esteban ChornetAbstract:Abstract Catalytic Steam Reforming of condensable vapors (i.e. bio-oils) derived from pyrolysis of biomass is a technically viable process for hydrogen production. In this study the aqueous fraction of bio-oil, generated from fast pyrolysis, was Catalytically Steam reformed at 825 and 875°C, high space velocity (up to 126,000 h−1) and low residence time (26 ms). Using a fixed-bed micro-reactor interfaced with a molecular beam mass spectrometer (MBMS), a variety of research and commercial nickel-based catalysts were tested. The catalysts were prepared by impregnation of an α-Al2O3 support with nickel and additives. Since the main constraint in Reforming bio-oils is catalyst deactivation caused by carbon deposition, two strategies were applied to improve the performance of the catalysts. The first approach aimed at enhancing Steam adsorption to facilitate the partial oxidation, i.e. gasification of coke precursors. The second one attempted to slow down the surface reactions leading to the formation of the coke precursors due to cracking, deoxygenation, and dehydration of adsorbed intermediates. Magnesium and lanthanum were used as support modifiers to enhance Steam adsorption while cobalt and chromium additives were applied to reduce coke formation reactions. The cobalt-promoted nickel and chromium-promoted nickel supported on MgO-La2O3-α-Al2O3 catalysts showed the best results in the laboratory tests. At the reaction conditions progressive catalyst deactivation was observed leading to a decrease in the yields of hydrogen and carbon dioxide and an increase in carbon monoxide. The loss of activity also resulted in the formation of higher amounts of methane, benzene and other aromatic compounds. Commercial catalysts that were developed for Steam Reforming of natural gas and crude oil fractions proved to be more efficient for hydrogen production from bio-oil than most of the research catalysts mainly due to the higher water–gas shift activity.
J Arauzo - One of the best experts on this subject based on the ideXlab platform.
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Catalytic Steam Reforming of the aqueous fraction of bio oil using ni ce mg al catalysts
Applied Catalysis B-environmental, 2017Co-Authors: Fernando Bimbela, L Garcia, Javier Abrego, R Puerta, J ArauzoAbstract:Abstract The performance of different Ni/Mg-Al catalysts modified with Ce was evaluated in the Catalytic Steam Reforming of aqueous fractions of bio-oil from biomass pyrolysis. The effects of several preparation methods for incorporating Ce as a modifier (co-precipitation, impregnation and direct thermal decomposition of the salt precursors), the Ce content (0–5 wt.%) and the feed streams (three different aqueous fractions from bio-oil) on the catalyst performance were examined, and it was found that the stability and activity of the catalysts were significantly influenced by all these factors. In general, the addition of Ce to a reference Ni/Mg-Al catalyst improved the overall carbon conversion to gas and the yield to H2 as well as enhancing the catalyst stability in the Steam Reforming of aqueous fractions of bio-oils. The best preparation method was impregnation and the optimal Ce content was found to be 0.5 wt.%. Much higher initial carbon conversion to gas and initial H2 yields was obtained using bio-oils derived from pine than those derived from poplar. A very low coke formation, 103 mg C/(g of catalyst · g of organics in the aqueous fraction reacted), was achieved using the optimized catalyst, 0.5 wt.% Ce prepared by impregnation.
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hydrogen production from pine and poplar bio oils by Catalytic Steam Reforming influence of the bio oil composition on the process
International Journal of Hydrogen Energy, 2015Co-Authors: Javier Remon, L Garcia, Francois Broust, Ghislaine Volle, J ArauzoAbstract:Abstract The Catalytic Steam Reforming of four different aqueous fractions of bio-oil has been carried out in a fixed bed reactor at 650 °C and atmospheric pressure using a Ni–Co/Al–Mg catalyst, employing a spatial time of 4 g catalyst min/g organics. The chemical analysis of the aqueous fractions revealed that the source of biomass (pine or poplar sawdust) and the pyrolysis unit significantly influenced the chemical composition of these liquids. Depending on their chemical composition, the initial H 2 yield varied from 0.101 to 0.182 g H 2 /g organics and the initial CO 2 yield from 0.814 to 1.28 g CO 2 /g organics during their Catalytic Reforming. Regarding Catalytic stability, higher catalyst deactivation took place during the Reforming of the two pine bio-oil aqueous fractions. The Reforming results of the four aqueous fractions have been correlated to their chemical compositions using statistical empirical additive models developed using the Bayesian Information Criterion (BIC). This strategy enabled the identification of the chemical compounds responsible for the most significant variations observed during the Reforming of the liquids. The different proportions of acetic acid and furfural in the liquids had the greatest impact on the Reforming results. Acetic acid was identified as a compound with low reactivity and low coke formation. In contrast, furfural was found to have high reactivity and a high tendency to produce coke in the Reforming process. Additional Reforming experiments conducted with acetic acid, phenol, furfural, levoglucosan and guaiacol helped to confirm and explain the results obtained during the Catalytic Steam Reforming of the aqueous fractions.
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production of a hydrogen rich gas from fast pyrolysis bio oils comparison between homogeneous and Catalytic Steam Reforming routes
International Journal of Hydrogen Energy, 2014Co-Authors: Javier Remon, Francois Broust, J Valette, Y Chhiti, I Alava, A R Fernandezakarregi, J Arauzo, L GarciaAbstract:Abstract The aim of the present work is to produce hydrogen from biomass through bio-oil. Two possible upgrading routes are compared: Catalytic and non-Catalytic Steam Reforming of bio-oils. The main originality of the paper is to cover all the steps involved in both routes: the fast pyrolysis step to produce the bio-oils, the water extraction for obtaining the bio-oil aqueous fractions and the final Steam Reforming of the liquids. Two reactors were used in the first pyrolysis step to produce bio-oils from the same wood feedstock: a fluidized bed and a spouted bed. The mass balances and the compositions of both batches of bio-oils and aqueous fractions were in good agreement between both processes. Carboxylic acids, alcohols, aldehydes, ketones, furans, sugars and aromatics were the main compounds detected and quantified. In the Steam Reforming experiments, Catalytic and non-Catalytic processes were tested and compared to produce a hydrogen-rich gas from the bio-oils and the aqueous fractions. Moreover, two different Catalytic reactors were tested in the Catalytic process (a fixed and a fluidized bed). Under the experimental conditions tested, the H 2 yields were as follows: Catalytic Steam Reforming of the aqueous fractions in fixed bed (0.17 g H 2 /g organics) > non-Catalytic Steam Reforming of the bio-oils (0.14 g H 2 /g organics) > non-Catalytic Steam Reforming of the aqueous fractions (0.13 g H 2 /g organics) > Catalytic Steam Reforming of the aqueous fractions in fluidized bed (0.07 g H 2 /g organics). These different H 2 yields are a consequence of the different temperatures used in the Reforming processes (650 °C and 1400 °C for the Catalytic and the non-Catalytic, respectively) as well as the high spatial velocity employed in the Catalytic tests, which was not sufficiently low to reach equilibrium in the fluidized bed reactor.
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ni al coprecipitated catalysts modified with magnesium and copper for the Catalytic Steam Reforming of model compounds from biomass pyrolysis liquids
Applied Catalysis B-environmental, 2012Co-Authors: F Bimbela, L Garcia, De Chen, J Ruiz, J ArauzoAbstract:Abstract Ni/Al coprecipitated catalysts modified with magnesium and copper have been prepared by a constant pH technique and tested in the Catalytic Steam Reforming of model compounds (acetic acid, acetol and butanol) from biomass pyrolysis liquids at 650 °C and atmospheric pressure. Catalysts with different copper contents, reduced at 650 °C for 1 h, were tested in the Steam Reforming of acetic acid with a Steam/carbon (S/C) molar ratio of 5.6. The best performance and the highest hydrogen yield in these conditions were achieved with the 5% Cu catalyst. This catalyst reduced at 650 °C during 10 h showed a high activity, close to the thermodynamic equilibrium, and a stable performance during 12 h in the Steam Reforming of acetic acid with a S/C = 5.6, using a short space time of 1.00 g catalyst min/g acetic acid. Copper as a promoter produces counterbalanced effects: a decrease in the initial Reforming activity and an enhancement of the catalyst stability. The initial Steam Reforming activity decreased and the CH 4 yield increased concurrently with increasing the copper content, because of the Ni dilution effect. Copper has a positive effect inhibiting the formation of encapsulating coke, identified as the cause for deactivation in acetic acid Steam Reforming with a Steam-to-carbon molar ratio (S/C) of 5.6. However, such a positive effect of copper has not been observed in acetic acid Steam Reforming with S/C = 14.7 or in the Steam Reforming of acetol and butanol.
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hydrogen from aqueous fraction of biomass pyrolysis liquids by Catalytic Steam Reforming in fluidized bed
Energy, 2011Co-Authors: J A Medrano, L Garcia, M Oliva, J Ruiz, J ArauzoAbstract:Sustainable pathways for producing hydrogen as a synthesis intermediate or as a clean energetic vector will be needed in the future. Renewable biomass resources should be taken into account in this new scenario. Processing through a pyrolysis step, optimized to high liquid production (bio-oil), increases the energy bulk density of biomass for transportation. Steam Reforming of the aqueous fraction is an alternative process that increases the hydrogen content of the syngas. However, the thermochemical conversion of organic compounds derived from biomass involves drawbacks such as coke formation on the catalysts. This work studies the performance of Ni–Al catalysts modified with Ca or Mg in the Steam Reforming of the aqueous fraction of pyrolysis liquids and the resulting coke deposits. The catalyst composition influenced the quantity and type of coke deposits. Calcium improved the formation of carbonaceous products leading to lower H2/CO ratios while magnesium improved the WGS (water gas shift) reaction. The strategy of reducing the space velocity resulted in a low coke removal although the addition of small quantities of oxygen decreased the coke content of the catalyst by more than 50% weight. Greater efficiency and further catalyst development are needed to improve the energetic requirements of the process.
L Garcia - One of the best experts on this subject based on the ideXlab platform.
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Catalytic Steam Reforming of the aqueous fraction of bio oil using ni ce mg al catalysts
Applied Catalysis B-environmental, 2017Co-Authors: Fernando Bimbela, L Garcia, Javier Abrego, R Puerta, J ArauzoAbstract:Abstract The performance of different Ni/Mg-Al catalysts modified with Ce was evaluated in the Catalytic Steam Reforming of aqueous fractions of bio-oil from biomass pyrolysis. The effects of several preparation methods for incorporating Ce as a modifier (co-precipitation, impregnation and direct thermal decomposition of the salt precursors), the Ce content (0–5 wt.%) and the feed streams (three different aqueous fractions from bio-oil) on the catalyst performance were examined, and it was found that the stability and activity of the catalysts were significantly influenced by all these factors. In general, the addition of Ce to a reference Ni/Mg-Al catalyst improved the overall carbon conversion to gas and the yield to H2 as well as enhancing the catalyst stability in the Steam Reforming of aqueous fractions of bio-oils. The best preparation method was impregnation and the optimal Ce content was found to be 0.5 wt.%. Much higher initial carbon conversion to gas and initial H2 yields was obtained using bio-oils derived from pine than those derived from poplar. A very low coke formation, 103 mg C/(g of catalyst · g of organics in the aqueous fraction reacted), was achieved using the optimized catalyst, 0.5 wt.% Ce prepared by impregnation.
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hydrogen production from pine and poplar bio oils by Catalytic Steam Reforming influence of the bio oil composition on the process
International Journal of Hydrogen Energy, 2015Co-Authors: Javier Remon, L Garcia, Francois Broust, Ghislaine Volle, J ArauzoAbstract:Abstract The Catalytic Steam Reforming of four different aqueous fractions of bio-oil has been carried out in a fixed bed reactor at 650 °C and atmospheric pressure using a Ni–Co/Al–Mg catalyst, employing a spatial time of 4 g catalyst min/g organics. The chemical analysis of the aqueous fractions revealed that the source of biomass (pine or poplar sawdust) and the pyrolysis unit significantly influenced the chemical composition of these liquids. Depending on their chemical composition, the initial H 2 yield varied from 0.101 to 0.182 g H 2 /g organics and the initial CO 2 yield from 0.814 to 1.28 g CO 2 /g organics during their Catalytic Reforming. Regarding Catalytic stability, higher catalyst deactivation took place during the Reforming of the two pine bio-oil aqueous fractions. The Reforming results of the four aqueous fractions have been correlated to their chemical compositions using statistical empirical additive models developed using the Bayesian Information Criterion (BIC). This strategy enabled the identification of the chemical compounds responsible for the most significant variations observed during the Reforming of the liquids. The different proportions of acetic acid and furfural in the liquids had the greatest impact on the Reforming results. Acetic acid was identified as a compound with low reactivity and low coke formation. In contrast, furfural was found to have high reactivity and a high tendency to produce coke in the Reforming process. Additional Reforming experiments conducted with acetic acid, phenol, furfural, levoglucosan and guaiacol helped to confirm and explain the results obtained during the Catalytic Steam Reforming of the aqueous fractions.
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production of a hydrogen rich gas from fast pyrolysis bio oils comparison between homogeneous and Catalytic Steam Reforming routes
International Journal of Hydrogen Energy, 2014Co-Authors: Javier Remon, Francois Broust, J Valette, Y Chhiti, I Alava, A R Fernandezakarregi, J Arauzo, L GarciaAbstract:Abstract The aim of the present work is to produce hydrogen from biomass through bio-oil. Two possible upgrading routes are compared: Catalytic and non-Catalytic Steam Reforming of bio-oils. The main originality of the paper is to cover all the steps involved in both routes: the fast pyrolysis step to produce the bio-oils, the water extraction for obtaining the bio-oil aqueous fractions and the final Steam Reforming of the liquids. Two reactors were used in the first pyrolysis step to produce bio-oils from the same wood feedstock: a fluidized bed and a spouted bed. The mass balances and the compositions of both batches of bio-oils and aqueous fractions were in good agreement between both processes. Carboxylic acids, alcohols, aldehydes, ketones, furans, sugars and aromatics were the main compounds detected and quantified. In the Steam Reforming experiments, Catalytic and non-Catalytic processes were tested and compared to produce a hydrogen-rich gas from the bio-oils and the aqueous fractions. Moreover, two different Catalytic reactors were tested in the Catalytic process (a fixed and a fluidized bed). Under the experimental conditions tested, the H 2 yields were as follows: Catalytic Steam Reforming of the aqueous fractions in fixed bed (0.17 g H 2 /g organics) > non-Catalytic Steam Reforming of the bio-oils (0.14 g H 2 /g organics) > non-Catalytic Steam Reforming of the aqueous fractions (0.13 g H 2 /g organics) > Catalytic Steam Reforming of the aqueous fractions in fluidized bed (0.07 g H 2 /g organics). These different H 2 yields are a consequence of the different temperatures used in the Reforming processes (650 °C and 1400 °C for the Catalytic and the non-Catalytic, respectively) as well as the high spatial velocity employed in the Catalytic tests, which was not sufficiently low to reach equilibrium in the fluidized bed reactor.
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ni al coprecipitated catalysts modified with magnesium and copper for the Catalytic Steam Reforming of model compounds from biomass pyrolysis liquids
Applied Catalysis B-environmental, 2012Co-Authors: F Bimbela, L Garcia, De Chen, J Ruiz, J ArauzoAbstract:Abstract Ni/Al coprecipitated catalysts modified with magnesium and copper have been prepared by a constant pH technique and tested in the Catalytic Steam Reforming of model compounds (acetic acid, acetol and butanol) from biomass pyrolysis liquids at 650 °C and atmospheric pressure. Catalysts with different copper contents, reduced at 650 °C for 1 h, were tested in the Steam Reforming of acetic acid with a Steam/carbon (S/C) molar ratio of 5.6. The best performance and the highest hydrogen yield in these conditions were achieved with the 5% Cu catalyst. This catalyst reduced at 650 °C during 10 h showed a high activity, close to the thermodynamic equilibrium, and a stable performance during 12 h in the Steam Reforming of acetic acid with a S/C = 5.6, using a short space time of 1.00 g catalyst min/g acetic acid. Copper as a promoter produces counterbalanced effects: a decrease in the initial Reforming activity and an enhancement of the catalyst stability. The initial Steam Reforming activity decreased and the CH 4 yield increased concurrently with increasing the copper content, because of the Ni dilution effect. Copper has a positive effect inhibiting the formation of encapsulating coke, identified as the cause for deactivation in acetic acid Steam Reforming with a Steam-to-carbon molar ratio (S/C) of 5.6. However, such a positive effect of copper has not been observed in acetic acid Steam Reforming with S/C = 14.7 or in the Steam Reforming of acetol and butanol.
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hydrogen from aqueous fraction of biomass pyrolysis liquids by Catalytic Steam Reforming in fluidized bed
Energy, 2011Co-Authors: J A Medrano, L Garcia, M Oliva, J Ruiz, J ArauzoAbstract:Sustainable pathways for producing hydrogen as a synthesis intermediate or as a clean energetic vector will be needed in the future. Renewable biomass resources should be taken into account in this new scenario. Processing through a pyrolysis step, optimized to high liquid production (bio-oil), increases the energy bulk density of biomass for transportation. Steam Reforming of the aqueous fraction is an alternative process that increases the hydrogen content of the syngas. However, the thermochemical conversion of organic compounds derived from biomass involves drawbacks such as coke formation on the catalysts. This work studies the performance of Ni–Al catalysts modified with Ca or Mg in the Steam Reforming of the aqueous fraction of pyrolysis liquids and the resulting coke deposits. The catalyst composition influenced the quantity and type of coke deposits. Calcium improved the formation of carbonaceous products leading to lower H2/CO ratios while magnesium improved the WGS (water gas shift) reaction. The strategy of reducing the space velocity resulted in a low coke removal although the addition of small quantities of oxygen decreased the coke content of the catalyst by more than 50% weight. Greater efficiency and further catalyst development are needed to improve the energetic requirements of the process.
Richard J French - One of the best experts on this subject based on the ideXlab platform.
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production of hydrogen from plastics by pyrolysis and Catalytic Steam reform
Energy & Fuels, 2006Co-Authors: Stefan Czernik, Richard J FrenchAbstract:Thermal decomposition of the most common plastics such as polyethylene and polypropylene produces a mixture of many different hydrocarbons that can be used as a feedstock for producing hydrogen. The proposed process includes two steps: pyrolysis of plastics and Catalytic Steam Reforming of pyrolysis gases and vapors. This research provides a proof of concept supported by experiments on selected polymers performed using a microscale reactor system interfaced with a molecular beam mass spectrometer and demonstrates process performance using a two-reactor bench-scale system. From 60 g/h polypropylene fed to the system 20.5 g/h hydrogen was produced, which corresponds to 80% of the theoretical potential.
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evaluation of catalyst deactivation during Catalytic Steam Reforming of biomass derived syngas
Industrial & Engineering Chemistry Research, 2005Co-Authors: Richard L. Bain, Stefan R. Czernik, Calvin J. Feik, Richard J French, David Charles Dayton, Kimberly A Magrinibair, Daniel Carpenter, Steven D PhillipsAbstract:Mitigation of tars produced during biomass gasification continues to be a technical barrier to developing systems. This effort combined the measurement of tar-Reforming catalyst deactivation kinetics and the production of syngas in a pilot-scale biomass gasification system at a single steady-state condition with mixed woods, producing a gas with an H2-to-CO ratio of 2 and 13% methane. A slipstream from this process was introduced into a bench-scale 5.25 cm diameter fluidized-bed catalyst reactor charged with an alkali-promoted Ni-based/Al2O3 catalyst. Catalyst conversion tests were performed at a constant space time and five temperatures from 775 to 875 °C. The initial catalyst-Reforming activity for all measured components (benzene, toluene, naphthalene, and total tars) except light hydrocarbons was 100%. The residual steady-state conversion of tar ranged from 96.6% at 875 °C to 70.5% at 775 °C. Residual steady-state conversions at 875 °C for benzene and methane were 81% and 32%, respectively. Catalytic deactivation models with residual activity were developed and evaluated based on experimentally measured changes in conversion efficiencies as a function of time on stream for the Catalytic Reforming of tars, benzene, methane, and ethane. Both first- and second-order models were evaluated for the Reforming reaction and for catalyst deactivation. Comparison of experimental and modeling results showed that the Reforming reactions were adequately modeled by either first-order or second-order global kinetic expressions. However, second-order kinetics resulted in negative activation energies for deactivation. Activation energies were determined for firstorder Reforming reactions and catalyst deactivation. For Reforming, the representative activation energies were 32 kJ/g‚mol for ethane, 19 kJ/g‚mol for tars, 45 kJ/g‚mol for tars plus benzene, and 8-9 kJ/g‚mol for benzene and toluene. For catalyst deactivation, representative activation energies were 146 kJ/g‚mol for ethane, 121 kJ/g‚mol for tars plus benzene, 74 kJ/g‚mol for benzene, and 19 kJ/g‚mol for total tars. Methane was also modeled by a second-order reaction, with an activation energy of 18.6 kJ/g‚mol and a catalyst deactivation energy of 5.8 kJ/g‚mol.
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evaluation of catalyst deactivation during Catalytic Steam Reforming of biomass derived syngas
Industrial & Engineering Chemistry Research, 2005Co-Authors: Richard L. Bain, Calvin J. Feik, Richard J French, David Charles Dayton, Kimberly A Magrinibair, Daniel Carpenter, Stefan Czernik, Steven D PhillipsAbstract:Mitigation of tars produced during biomass gasification continues to be a technical barrier to developing systems. This effort combined the measurement of tar-Reforming catalyst deactivation kinetics and the production of syngas in a pilot-scale biomass gasification system at a single steady-state condition with mixed woods, producing a gas with an H2-to-CO ratio of 2 and 13% methane. A slipstream from this process was introduced into a bench-scale 5.25 cm diameter fluidized-bed catalyst reactor charged with an alkali-promoted Ni-based/Al2O3 catalyst. Catalyst conversion tests were performed at a constant space time and five temperatures from 775 to 875 °C. The initial catalyst-Reforming activity for all measured components (benzene, toluene, naphthalene, and total tars) except light hydrocarbons was 100%. The residual steady-state conversion of tar ranged from 96.6% at 875 °C to 70.5% at 775 °C. Residual steady-state conversions at 875 °C for benzene and methane were 81% and 32%, respectively. Catalytic ...
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the production of hydrogen by Steam Reforming of trap greaseprogress in catalyst performance
Energy & Fuels, 2004Co-Authors: Stefan R. Czernik, Richard J French, And Kimberly A Magrinibair, Esteban ChornetAbstract:Most hydrogen is currently produced via the Steam Reforming of natural gas. An environmentally preferable option is to produce hydrogen from renewable materials. Waste vegetable oil from food processing (“trap grease”) is a low-cost, widely available renewable material that currently has no commercial use. In this work, we produced hydrogen via the fluidized-bed Catalytic Steam Reforming of trap grease using commercial and experimental Ni/Al2O3 catalysts under conditions similar to those of commercial natural gas Reforming operationstemperatures in excess of 800 °C, molar Steam-to-carbon ratio of five, and a methane-equivalent volumetric space velocity of ∼1000 h-1. During operation for 150 h, yields of 25 g of hydrogen per 100 g of trap grease were obtained. The process performance decreased with time, because of catalyst attrition and deactivation. We succeeded in extending the catalyst time-on-stream through the use of a laboratory-prepared attrition-resistant catalyst. Another strategy used was a two-...
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hydrogen by Catalytic Steam Reforming of liquid byproducts from biomass thermoconversion processes
Industrial & Engineering Chemistry Research, 2002Co-Authors: Stefan R. Czernik, Calvin J. Feik, Richard J French, Esteban ChornetAbstract:Biomass, a product of photosynthesis, is a renewable resource that can be used for sustainable production of hydrogen. We propose an approach that combines production of hydrogen with valuable coproducts and shows promising economics. The concept is based on a two-stage process: fast pyrolysis of biomass to generate bio-oil, followed by Catalytic Steam Reforming of the bio-oil, or a fraction thereof, to produce hydrogen. The preferred option is separation of the bio-oil into a lignin-derived fraction, which could be used for producing phenolic resins or fuel-blending components, and a carbohydrate-derived material, which would be reformed to produce hydrogen. The coproduct strategy can also be applied to residual fractions derived from pulping operations or ethanol production and to effluents from other biomass conversion technologies such as transesterification of vegetable oils or food processing residues. In addition, all of the biomass-derived liquids can be coprocessed with natural gas to produce hy...