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See detailCatalytic reforming of gasification tars with bi- and trimetallic catalysts optimized with organosilane precursors
Claude, Vincent ULiege; Lambert, Stéphanie ULiege

Poster (2017, March 07)

Biomass gasification is interesting for the production of CO + H2 from wastes and catalysts are necessary for tars degradation. Catalysts were synthesized by the sol-gel process to develop γ-Al2O3 doped ... [more ▼]

Biomass gasification is interesting for the production of CO + H2 from wastes and catalysts are necessary for tars degradation. Catalysts were synthesized by the sol-gel process to develop γ-Al2O3 doped with 10%wt of nickel and 2 wt.% of a second dopant (Co, Cu, Fe, Mn, Mo). Before their adding in AlOOH sol, metallic dopants were complexed with (OCH3)3-Si-(CH2)3-NH-(CH2)2-NH2 (EDAS) to increase their dispersion by cogelation between EDAS and AlOOH clusters. These catalysts were tested at 650°C for toluene reforming. [less ▲]

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See detailReforming of toluene formed during the gasification of biomass with alumina based catalysts prepared by aqueous sol-gel processes
Claude, Vincent ULiege

Doctoral thesis (2017)

Summary in english: The gasification of biomass into bio-syngas (CO+H2) usually goes along with the formation of tars (toluene, naphthalene) which can cause technical problems at the outlet of the reactor ... [more ▼]

Summary in english: The gasification of biomass into bio-syngas (CO+H2) usually goes along with the formation of tars (toluene, naphthalene) which can cause technical problems at the outlet of the reactor. The reforming of these tars via primary catalysts (inside the reactor) or secondary catalysts (outside the reactor) currently appears as the most interesting way from practical and economical point of views. The use of catalysts made of metallic nanoparticles deposited on y-Al2O3 is an efficient combination for tar reforming applications. During this project, an aqueous sol-gel method for the synthesis of y-Al2O3 supports is developed. In the aim of developing catalysts with metallic nanoparticles finely dispersed, supports of y-Al2O3 are modified with a functionalized silicon precursor (3-(2-aminoethylamino)propyltrimethoxysilane, EDAS). The addition of EDAS modifies the properties of y-Al2O3. Samples prepared with other silicon precursors (non-functionalized or functionalized with other chains than the ones of EDAS) highlight that the reactivity of the precursor influences the crystallinity of the support. The presence of a functionalized chain modifies the shape of the crystallites, which leads to a narrower pore size distribution centered on 4 nm and to a higher specific surface area of the support. In order to orientate the project towards the development of either primary or secondary catalysts, catalytic tests are performed with 8000 ppmv of toluene under primary conditions (T = 750-850 °C) with either y-Al2O3 or olivine supports, doped with either 2 wt. % Ni or 10 wt. % Fe. The olivine, known as primary catalyst of reference, shows better performances. In the case of y-Al2O3, the low loading of Ni leads to the formation of a spinel of NiAl2O4 which shows low reducibility, and the doping with Fe favors the y-Al2O3 to a-Al2O3 phase transition of the support. Therefore, the next studies focuse on the development of 10 wt. % Ni/y-Al2O3 catalysts tested in secondary conditions. The reduction of catalysts entirely composed of NiAl2O4 only starts at T = 680 °C during H2- TPR measurements. However, these samples are reduced during the catalytic reforming of 24.000 ppmv of toluene at T = 650 °C. It is demonstrated that under these conditions, toluene is a better reducing agent than H2 or CO, and that the reduction of NiAl2O4 oxide with toluene enables its conversion with a very little formation of coke. For bulk NiO, reduced at low temperatures (T ~ 450 °C), the catalyst does not take advantage of the anti-coking effect brought by the phenomenon of special reduction by toluene, which leads to a quick deactivation of the catalyst by formation of carbon deposit. The addition of a surfactant (stearic acid) during the aqueous sol-gel synthesis efficiently modifies the morphology (mesopores, macropores) of Ni/y-Al2O3 catalysts. Despite a much higher catalytic activity, attributed to a better diffusion of the gaseous reagents, the sample shows a much higher sensibility towards deactivation by coking. It is hypothesized that this weakness is the consequence of the combination of several facts: loss of balance between the reaction rates of toluene cracking and the rates of dissociation-migration of the HO* and O* species + better reducibility of the catalyst, which avoids the phenomenon of special reduction by toluene + presence of large pores, which do not prevent the growth of filamentous carbon. A vast screening of catalysts composed of 10 % Ni/y-Al2O3 and doped with metals (Cu, Mn, Fe, Mo or Mn) or oxides (CaO, K2O, MgO or CeO2) is performed. The samples doped with Mn, Mo, Ca ou K show the most interesting catalytic activities and resistances against coking. It is to notice that, for an identical amount, the samples doped with two different elements (Co+Mo, Mn+Mo, Ca+K or Ce+K) show better catalytic performances compared to those doped with only one type of dopant. The tests of the best catalysts in long-term conditions (30 h) or in presence of H2S are promising. Hence, these catalysts might be adequate for industrial applications. Résumé français: La gazéification de biomasse en bio-syngas (CO+H2) s’accompagne généralement de formation de goudrons (toluène, naphtalène) qui peuvent causer des problèmes techniques en aval du réacteur. Le reformage de ces goudrons via un catalyseur primaire (à l’intérieur du réacteur) ou secondaire (en sortie du réacteur) apparaît actuellement comme la méthode la plus intéressante d’un point de vue pratique et économique. L’utilisation de catalyseurs constitués de nanoparticules métalliques supportées sur y-Al2O3 est une association efficace pour le reformage catalytique de goudrons. Une méthode de synthèse de support y-Al2O3 par voie sol-gel aqueuse est mise au point durant ce projet. Dans l’optique de synthétiser des catalyseurs composés de nanoparticules métalliques finement dispersées, des supports en y-Al2O3 sont modifiés avec un précurseur de silice fonctionnalisé : l’EDAS (3-(2-aminoéthylamino)propyltriméthoxysilane). L’addition d’EDAS modifie les propriétés texturales du support y-Al2O3. Des échantillons préparés avec d’autres types de précurseurs de silice (non-fonctionnalisés ou fonctionnalisés avec d’autres chaînes que celle présente dans l’EDAS) mettent en évidence le fait que la réactivité du précurseur de silice influence la cristallinité du support. La présence d’une chaîne fonctionnalisée modifie quant à elle la forme des cristallites d’alumine, menant ainsi à une distribution de taille de mésopores plus étroite et centrée à 4 nm et une plus grande surface spécifique du support. Afin de déterminer quel type de catalyseurs synthétiser (primaires ou secondaires), le reformage catalytique de 8000 ppmv de toluène en conditions primaires (T = 750-850 °C) est effectué avec des supports constitués de γ-Al2O3 ou d’olivine, dopés avec 2 % Ni ou 10 % Fe. L’olivine, catalyseur primaire de référence, présente de meilleurs résultats pour le reformage du toluène. Dans le cas de y-Al2O3, le faible dopage en Ni conduit à la formation d’un spinelle NiAl2O4 difficile à réduire, et le dopage avec Fe favorise la transition de phase de y-Al2O3 vers a-Al2O3. Les travaux suivants sont donc axés sur le développement de catalyseurs de type 10 % Ni/y-Al2O3 testés en conditions secondaires. La réduction de catalyseurs constitués d’une unique phase de NiAl2O4 ne s’initie qu’à partir de T = 680 °C lors de mesures en température programmée sous H2 (TPR). Cependant, ceux-ci sont réduits lors du reformage catalytique de 24.000 ppmv de toluène à T = 650 °C. Il est démontré que dans ces conditions, le toluène est un meilleur agent réducteur que H2 ou CO, et que la réduction des espèces NiAl2O4 par le toluène permet de convertir celui-ci en syngas tout en prévenant la formation de coke. Lors de la présence de NiO réduit à plus basse température (T ~ 450 °C), le catalyseur ne tire pas avantage du phénomène de réduction spécial des oxydes métalliques par le toluène, ce qui entraîne ainsi la désactivation rapide du catalyseur par cokage. L’ajout d’un surfactant (acide stéarique) lors de la préparation par voie sol-gel aqueuse s’avère efficace afin de modifier la morphologie (mésopores, macropores) de catalyseurs Ni/y-Al2O3. Malgré une activité catalytique nettement plus élevée, attribuée à une meilleure diffusion des réactifs, l’échantillon montre des tendances beaucoup plus importantes à se désactiver par cokage. On émet l’hypothèse que cette faiblesse est due à une combinaison de plusieurs faits: déséquilibre entre la réaction de cracking du toluène et les réactions de dissociation-migration des espèces HO* et O* + meilleure réductibilité empêchant de tirer avantage du phénomène de réduction spécial par le toluène + présence de larges pores ne restreignant pas la croissance de carbone filamentaire. Un large screening de catalyseurs 10 % Ni/y-Al2O3 dopés avec des métaux (Cu, Mn, Fe, Mo ou Mn) ou des oxydes (CaO, K2O, MgO ou CeO2) est effectué. Les échantillons contenant les éléments Mn, Mo, Ca ou K s’avèrent les plus intéressants de par leur activité catalytique et leur résistance au cokage. Pour une même quantité massique ajoutée, les échantillons constitués d’associations de dopants (Co+Mo, Mn+Mo, Ca+K ou Ce+K) affichent de meilleures performances catalytiques que ceux effectués avec un seul dopant. Les résultats obtenus avec les meilleurs catalyseurs lors de tests catalytiques de longue durée (30 h) ou en présence de H2S sont prometteurs. Ceci porte à croire que ces catalyseurs pourraient convenir à une application industrielle. [less ▲]

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See detailEthylene polymerization and hydrodechlorination of 1,2-dichloroethane mediated by nickel(II) covalently anchored to silica xerogels
Mahy, Julien ULiege; Claude, Vincent ULiege; Sacco, Luigi et al

in Journal of Sol-Gel Science and Technology (2017), 81(1), 59-68

Ni/SiO2 cogelled xerogel catalysts have been prepared in ethanol containing nickel acetylacetonate, tetraethoxysilane (TEOS), an aqueous ammonia solution of 0.54 mol L-1 and either a commercial sylilated ... [more ▼]

Ni/SiO2 cogelled xerogel catalysts have been prepared in ethanol containing nickel acetylacetonate, tetraethoxysilane (TEOS), an aqueous ammonia solution of 0.54 mol L-1 and either a commercial sylilated ligand, 3-(2-aminoethyl)aminopropyltrimethoxysilane (EDAPMS), or a home-made new silylated pyrazolypyridine ligands, respectively 2-[4-[3-(trimethoxysilyl)propyl]-3,5-dimethyl-1H-pyrazol-1-yl]pyridine (MS-PzPy) and 2-[4-[3-(trimethoxysilyl)propyl]-3,5-dimethyl-1H-pyrazol-1-yl]-6-methylpyridine (MS-PzPyMe), able to form a chelate with a metal ion such as Ni2+. All samples form homogeneous and very highly dispersed Ni/SiO2 cogelled xerogel catalysts. The resulting catalysts are composed of nickel nanoparticles with a diameter of about 2.8 nm, located inside primary silica particles exhibiting a monodisperse microporous distribution. The silylated organic ligand has a strong influence on the textural properties of cogelled xerogel catalysts, both before and after calcination and reduction steps. Changing the nature of the silylated ligand permits tailoring textural properties such as pore volume, pore size and surface area. Homogenous nickel complexes synthesized from pyrazolylpyridine derivatives are inactive for ethylene polymerization. In opposite, heterogenous nickel-based catalysts onto silica xerogel synthesized from pyrazolylpyridine derivatives bearing a tethered trialkoxysilyl group allow increasing ethylene polymerization activity. Although nickel nanoparticles are located inside the silica crystallites, their complete accessibility, via the micropore network, has been shown. For 1,2-dichloroethane hydrodechlorination over Ni/SiO2 catalysts, the conversion of 1,2-dichloroethane is high at the temperature of 350°C and mainly ethane is produced. [less ▲]

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See detailAg/SiO2 and Cu/SiO2 cogelled xerogel catalysts for benzene combustion and 2-butanol deshydrogenation
Mahy, Julien ULiege; Claude, Vincent ULiege; Tasseroul, Ludivine ULiege et al

Poster (2016, June 08)

Tars are recognized as major impurities when biomass is gazified into Syngas (mixture CO + H2) or when the methane reforming was produced from sustainaible reagents [1]. Therefore, fundamental knowledge ... [more ▼]

Tars are recognized as major impurities when biomass is gazified into Syngas (mixture CO + H2) or when the methane reforming was produced from sustainaible reagents [1]. Therefore, fundamental knowledge of catalytic oxidation and deshydrogenation mechanisms can be valuable to develop effective methods to control syngas or methane pollution. A very important concern about cogelled catalysts is the accessibility of the active centers. Because the silver and copper is located inside silica particles, there is a risk that it may not be accessible. In the case of benzene oxidation, it was observed that the specific activity (mol s-1 g-1Ag) of Ag/SiO2 and Cu/SiO2 catalysts increases when the silver or copper loading decreases (Fig. 1). In fact, visual observations by TEM showed that in samples Ag0.25, Ag0.45, Ag1.05 and Cu1.00, there are not silver or copper particles located on silica particles external surface and then the metal dispersion values are greater in these samples. So, it is the proof that Ag and Cu particles located inside the silica particles are accessible for benzene in this catalytic system. In the case of 2-butanol dehydrogenation, the specific activity of Cu/SiO2 catalysts increases when the copper loading increases or when the metal dispersion values decreases (Fig. 2). However, in Cu1.00 sample, copper particles inside silica particles only are observed by TEM. It seems that these metallic particles are accessible for 2-butanol in this catalytic system. [less ▲]

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See detailCatalytic reforming of biomass gasification tars with bi- or tri-doped catalysts optimized with organosilane precursors
Claude, Vincent ULiege; Courson, Claire; Heinrichs, Benoît ULiege et al

Conference (2016, June 08)

The thermochemical method called “biomass gasification” is generating emphatic interest for the production of bio-Syngas (CO + H2) since this process presents the advantage of being renewable without ... [more ▼]

The thermochemical method called “biomass gasification” is generating emphatic interest for the production of bio-Syngas (CO + H2) since this process presents the advantage of being renewable without emitting CO2. However, in practical applications, there are still some technical problems due to high tars concentration in the outlet gas which can condensate and clog the pipes. Many studies have highlighted the fact that the tar elimination via catalytic reforming seem to be the more practical and economical solution. The required properties of the catalysts are determined by its location: inside the reactor (primary catalyst) or outside of the reactor (secondary catalyst). Primary catalysts are generally robust, non-toxic, cheap and they are almost uniquely destined to fluidized bed reactors. Secondary catalysts can be used at the exit of both fluidized and fixed bed reactors. They are characterized by a tailored mesoporous shape, a controlled active site dispersion and an adapted elemental composition [1]. In this work , we decided to focus on designing materials for secondary catalytic applications, i.e. working at relatively low temperature (~650°C) with no mechanical stress. The supports were made of γ-Al2O3 synthesized via an easy Sol-Gel method. During their synthesis, these supports were doped with 10%wt of nickel and various combinations of metallic dopants (Co, Cu, Fe, Mn, Mo) in the aim of enhancing their catalytic activities and lifetime. [less ▲]

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See detailTailoring γ-Al2O3 supports with specific silicon precursors
Claude, Vincent ULiege; Vilaseca, Miriam; Heinrichs, Benoît ULiege et al

Poster (2016, May 13)

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See detailCatalytic reforming of biomass gasification tars with bimetallic catalysts
Claude, Vincent ULiege; Vilasecca, Miriam; Heinrichs, Benoît ULiege et al

Poster (2016, May)

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See detailOverview and Essentials of Biomass Gasification Technologies and their Catalytic Cleaning Methods
Claude, Vincent ULiege; Courson, Claire; Köhler et al

in Energy and Fuels (2016), 30(11), 8791-8814

Obtaining a tar-free biosyngas from biomass gasification processes has been the subject of many studies in the past 2 decades, and it still remains the major technologic and economic challenge ... [more ▼]

Obtaining a tar-free biosyngas from biomass gasification processes has been the subject of many studies in the past 2 decades, and it still remains the major technologic and economic challenge. Unfortunately, the countless publications about gasification technologies and different techniques permitting reduction of the tar present at the outlet of gasifier reactors usually confuse inexperienced persons who attempt to further research this subject. More than presenting the basis of biomass gasification technologies and positioning them among other bioenergies, this work mainly aims at reviewing and comparing the different methods developed in order to produce a tar-free biosyngas. In this way, biosyngas quality improvement can be obtained through different operating processes such as reactor designs, gasifying ratios, feedstock, temperature, and space ratio. Since catalytic destruction has proved to be one of the most convenient and efficient ways to eliminate undesirable tars, an important part of this work also highlights the catalytic and deactivating phenomena involved. Furthermore, this work takes inventory of numerous studies conducted to understand the influence of different properties, especially supports and active site compositions, on the tar reforming activities and lifetime of catalyst materials. Thus, this review aims at summarizing basic and more recent improvements applied to biomass gasification processes and catalytic syngas purification. [less ▲]

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See detailInfluences of the aqueous synthesis way and organosilane nature on the physico-chemical properties of porous alumina
Claude, Vincent ULiege; Vilaseca, Miriam; Tatton, Andrew ULiege et al

in European Journal of Inorganic Chemistry (2016), 2016(11), 1678-1689

The aqueous sol-gel synthesis of γ-Al2O3 modified with different silicon precursors {trimethoxysilane, triethoxysilane and N-[3-(trimethoxysilyl)propyl]ethylene diamine} has been investigated. Two ... [more ▼]

The aqueous sol-gel synthesis of γ-Al2O3 modified with different silicon precursors {trimethoxysilane, triethoxysilane and N-[3-(trimethoxysilyl)propyl]ethylene diamine} has been investigated. Two parameters have been studied: the silicon addition step and the type of silicon alkoxide. A first observation was that adding a silicon alkoxide either before or just after the precipitation step influences both the crystallinity and structure, whereas adding the alkoxide after a long agitation time only slightly modifies the support properties. It was also highlighted that due to their higher reactivity, silicon precursors with methoxy groups interact more strongly with the bulk alumina than the silicon precursors with ethoxy groups. This difference of Si location in the alumina structure permitted not only their resistance toward phase transition to be increased at high temperature, but also to stabilize them more efficiently against sintering under normal and steam conditions. Among the different silicon alkoxides tested, samples prepared with N-[3-(trimethoxysilyl)propyl]ethylene diamine showed very unusual properties. The alumina supports modified with this precursor showed grain-shaped nanocrystallites, whereas all other samples were platelet-like. As a result, this sample presented a very narrow pore diameter distribution of around 5 nm and a remarkably high specific surface area (530 m2/g). [less ▲]

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See detailLa catalyse par les céramiques
Claude, Vincent ULiege

Speech/Talk (2015)

Présentation réalisée à l'Ecole Européenne d'Ingénieurs en Génie des Matériaux, Nancy. Introduction aux procédés sol-gel pour la synthèse d'inorganique et à la catalyse hétérogène.

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See detailTailoring γ-Al2O3 supports with specific silicon precursors
Claude, Vincent ULiege; Vilaseca, Miriam; Lambert, Stéphanie ULiege

Poster (2015, September)

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See detailCatalytic epuration of biogaz
Claude, Vincent ULiege; Toye, Dominique ULiege; Heinrichs, Benoît ULiege et al

Poster (2015, May 08)

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See detailReformage catalytique du toluène
Claude, Vincent ULiege; Lambert, Stéphanie ULiege; Courson, Claire

Poster (2014, October 23)

This poster summarizes results obtained for the catalytic reforming of tar in the oultlet gas of a biomass gasifier. All samples were synthesized with aluminum nitrate and an organosilane (EDAS) in order ... [more ▼]

This poster summarizes results obtained for the catalytic reforming of tar in the oultlet gas of a biomass gasifier. All samples were synthesized with aluminum nitrate and an organosilane (EDAS) in order to enhance the metallic dispersion and surface area. Three different compositions have been studied (Al2O3-SiO2; Al2O3-SiO2+2%wt Ni; Al2O3-SiO2+10%wt Fe). The catalytic tests highlight the fact that the sample containing 2%Ni wt is the more appropriate in our conditions. [less ▲]

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See detailDevelopment of alumina xerogel catalysts for biogas cleaning
Claude, Vincent ULiege; Heinrichs, Benoît ULiege; Toye, Dominique ULiege et al

Poster (2014)

This poster resume the synthesis and characterizations of Ni/y-Al2O3 catalysts for the reforming of tars during the bio-syngas purification. The effect of an additionnal organosilane (EDAS) and a ... [more ▼]

This poster resume the synthesis and characterizations of Ni/y-Al2O3 catalysts for the reforming of tars during the bio-syngas purification. The effect of an additionnal organosilane (EDAS) and a surfactant (stearic acid) on the size,the dispersion and the sinterability of the nickel nanoparticles have been investigated. [less ▲]

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See detailEpuration catalytique de biogaz
Claude, Vincent ULiege; Lambert, Stéphanie ULiege; Heinrichs, Benoît ULiege et al

Poster (2013, November 15)

The poster presents the recent observations concerning the of Ni-Al2O3 catalysts synthesized in 2013. Particles size, surface areas and crystallinity of the samples are controlled thanks to the initial ... [more ▼]

The poster presents the recent observations concerning the of Ni-Al2O3 catalysts synthesized in 2013. Particles size, surface areas and crystallinity of the samples are controlled thanks to the initial reactives (surfactants, EDAS). [less ▲]

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See detailNi/Al2O3 xerogel catalysts for biogas cleaning
Claude, Vincent ULiege; Heinrichs, Benoît ULiege; Lambert, Stéphanie ULiege

Poster (2013, August 29)

This poster summarize the firsts results of the PhD project started on October 2012 about the catalytic purification of biogas. The aim of this project consists in the development of Ni/Al2O3 catalyst in ... [more ▼]

This poster summarize the firsts results of the PhD project started on October 2012 about the catalytic purification of biogas. The aim of this project consists in the development of Ni/Al2O3 catalyst in order to reform the tars present in the outlet gas of biomass gasifier. In order to obtain catalysts with high performance and lifetime, materials need to have optimized specific surface and metal particle dispersion. This poster investigate the effect of different surfactants (Pluronic P123; F127; stéarique acide, EDAS) on the materials properties. [less ▲]

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See detailCatalytic purification of biogas
Claude, Vincent ULiege; Lambert, Stéphanie ULiege

Poster (2012, December 05)

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See detailEpuration catalytique de biogaz
Claude, Vincent ULiege; Toye, Dominique ULiege; Heinrichs, Benoît ULiege et al

Poster (2012, November 08)

Detailed reference viewed: 23 (11 ULiège)