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SSCI-VIDE+CATREN:ING+WDR:NOG:DLA:YSC; International audience; An alternative to reduce fossil fuels dependency without heavy investment on new refineries is co-processing bio-oils derived from lignocellulosic biomass with conventional fossil feedstocks. However, the integration of bio-oil in this process faces some technical difficulties such as their high oxygen content, low miscibility with hydrocarbon fuels, low chemical stability and high acidity [1]. Therefore, it is necessary to improve bio-oil quality before using it to produce fuels. One possible option to upgrade the bio-oil quality is to produce it in an integrated catalytic pyrolyser, where the biomass conversion is carried out in the presence of an heterogeneous catalyst, such as ZSM-5 [2]. However, zeolites are susceptible to the deactivation, impacting on operational costs of process and reducing its competitiveness compared with fuel production from exclusively fossil feedstocks [3]. As an alternative for traditional catalysts, metal oxides can show acidic characteristics and good resistance to coke formation. Among them, niobium-based oxides has been studied for heterogeneous catalysis [4], but it has not been widely explored for upgrading of pyrolysis vapors. Thus, the aim of this work was to evaluate the impact of different niobium-based metal mixed oxides on the conversion of wood pyrolysis vapors employing an ex-situ catalytic system. These mixed oxides with different acidities were compared to a reference catalyst (ZSM-5). Three catalysts based on niobium oxide doped with another metal oxide (W, Al or Mn) were prepared and characterized. Pyrolysis of beech wood chips and catalytic conversion of the vapors were carried out in a laboratory-scale fixed-bed reactor equipped with a semi-continuous biomass dispenser. The gas phase was analyzed on-line using a µGC. The organic and aqueous phases of condensed bio-oil were separated by centrifugation. The organic phase was characterized by Karl-Fischer titration, elemental analysis (CHNS), GC-MS and 13C-NMR.Promising results were obtained for the treatment of pyrolysis vapors. One of the prepared catalysts exhibited equivalent catalytic performances, when compared to ZSM-5, in terms of liquid phase selectivity and reduction of oxygen content in the organic phase, which is directly related to the reduction of compounds that results in instability and immiscibility for bio-oils with traditional oil feedstocks. Modifications are planned to improve the activity of these metal-mixed oxides.Acknowledgements: This project has received funding from the European Unions’ Horizon 2020 research & innovation programme under grant agreement N° 818120. References[1]Md. M. Rahman, R. Liu, and J. Cai, Fuel Processing Technology 180, 32 (2018).[2]G. Yildiz et al., Renewable and Sustainable Energy Reviews 57, 1596 (2016).[3]A. V. Bridgwater, Biomass and Bioenergy 38, 68 (2012).[4]P. Yang et al., Applied Catalysis B: Environmental 239, 114 (2018).

SSCI-VIDE+ECI2D:ING+MLU:EGI:FRM:CMI:EPU:YSC:NOG; International audience; Nickel supported on Mg-Al oxides was studied in the autothermal reforming (ATR) of model biogas at 700 degrees C. Ni/Mg0.4Al2O3.4 deactivated with time on stream and the cause of deactivation was investigated and identified. Ni was readily oxidized to NiO in the presence of O-2. While NiO was essentially inactive for the reforming reaction, this oxide was yet active for methane combustion. Exhaustion of the O-2 supply at front of the catalyst bed enabled the remaining CH4 to be steam and dry reformed on the metallic Ni left downstream. Gradual formation of NiAl2O4 spinel was also observed, likely caused by the higher temperature prevailing in the exothermic combustion zone that favors the diffusion of nickel cations into the alumina structure. In contrast to NiO, NiAl2O4 spinel was poorly active for CH4 oxidation. The frontline associated with the formation of the NiAl2O4 spinel phase eventually reached the end of the catalyst bed, resulting in a complete loss of activity. No significant coke deposition could be evidenced here. The Ni deactivation profile was adequately fitted using a methane ATR kinetic model that included a linear decrease in the number of Ni metallic sites. Addition of Rh/Mg1.1Al2O4.1 in front of a nickel-based catalyst led to a stable activity. Using this dual-bed system, no NiAl2O4 formation was identified after reaction. (C) 2016 Elsevier B.V. All rights reserved.

SSCI-VIDE+ECI2D:ING+YSC:FRM:NOG:DLR; International audience; Effect of Sn on the adsorption of H₂ and the production of methanol during syngas conversion over Co/alumina.

SSCI-VIDE+ING+NOG:DBI:YSC; International audience; Biogas is formed by anaerobic digestion of biomass and contains essentially methane and carbon dioxide. It can be reformed into syngas over Ni-based catalysts, for hydrogen production or for Fischer-Tropsch synthesis. However, the CO2/CH4 ratio in biogas is generally

SSCI-VIDE+ING+FRM:NOG:YSC; International audience; Hydrocarbons are the main reaction products of syngas conversion over cobalt-based catalysts. Methanol is also produced as a minor by-product and has been proposed to be produced via a specific reaction pathway involving formates species located at the interface with the support [1]. The poisoning of a Co/alumina catalyst with Sn was studied here and a stronger decline in methanol production was observed at higher Sn/Co ratios, similarly to the case of hydrocarbons reported earlier [2] .The addition of Sn did not prevent the formation of formates as observed by operando diffuse reflectance FT-IR spectroscopy. The reactivity of these formates measured during a chemical transient was yet markedly lowered in the presence of Sn. In addition, the presence of tin dramatically reduced the adsorption of H2 onto the catalyst. These observations can be rationalized according to the following model. Firstly, Sn poisoned sites on the cobalt nanoparticles, hindering H2 adsorption and activation, thereby limiting the subsequent hydrogenation of formates to methanol. Secondly, Sn addition could also have specifically poisoned interfacial sites, where the most reactive formates were present.These observations provide a wider understanding of the various hydrogenation pathways of CO taking place over cobalt-based catalysts.Reference:[1] D. Lorito, A. Paredes-Nunez, C. Mirodatos, Y. Schuurman, F.C. Meunier, Catal. Today, 259 (2015) 192–196. [2] A. Paredes-Nunez, D. Lorito, L. Burel, D. Motta-Meira, G. Agostini, N. Guilhaume, Y. Schuurman, F.C. Meunier, Ang. Chem. Int. Ed. 57 (2018) 547-550.

SSCI-VIDE+ING+NOG:YSC; International audience; This work presents kinetic studies on the hydrogenolysis of eight lignin model compounds emulating various C-O and C-C linkages under hydrothermal conditions. Reaction rate constants and apparent activation energies of bond cleavage were determined, allowing ranking the bonds reactivity. Keywords: lignin model compounds; hydrogenolysis; kinetic study.

MICROSCOPIE+ING+FRM:LBU:NOG:YSC; International audience; The nature of the surface intermediates involved in CO hydrogenation over cobalt-based catalysts is still elusive. The methanol traces observed were shown to be related to formate species, which could not yet account for hydrocarbon formation. The effect of tin on cobalt-based catalysts used for CO hydrogenation was studied by operando diffuse reflectance FT-IR spectroscopy (DRIFTS) and isotopic transient techniques to unravel the precursors of hydrocarbons. Tin was used as a modifier to obtain a poisoning effect that could help discriminating active sites. Tin was selected because this metal does not adsorb CO, hence, the carbonyl bands observed can be wholly attributed to surface cobalt atoms.The operando DRIFTS spectra measured over a fresh cobalt sample exhibited both linearly adsorbed CO (2031 cm-1) and CO adsorbed on three-fold hollow sites (1860 cm-1). The Sn-modified samples exhibited a markedly lower fraction of hollow sites. The exact fractions of linear and hollow sites could be determined using a relative molar absorption coefficient of two.Interestingly, plots of the specific rates of formation of the main hydrocarbon produced (i.e. methane, propene and methanol) against the fraction of hollow-CO revealed an essentially linear relationship (not shown). This indicates that hollow-CO are, at least, a marker of the active sites. 12CO-13CO steady-state isotopic transient kinetic analyses (SSITKA) under reaction conditions at 220°C (not shown) were used to quantify the total concentration of CO(ads), from which the hollow-CO specific concentration could be derived. Finally, the specific rate of decomposition of hollow-CO could be determined from additional DRIFTS chemical-transient experiments and shown to be similar or higher than the cumulated rates of product formation. The difference between these rates can be simply explained by the formation of all other hydrocarbons that were not quantified here.These combined operando DRIFTS and transient data indicate that the hollow-CO can be considered as active reaction intermediates leading to hydrocarbons under these conditions.[2] Other experiments have shown that linear CO were mere spectator species

SSCI-VIDE+ECI2D:ING+DLA:NOG:CGE; National audience; Les micro-algues sont des micro-organismes capables de croitre très rapidement, dans des photobioréacteursou bassins. Cette biomasse qui compte encore des milliers d’espèces inconnues, est composéede lipides, carbohydrates et protéines. Certaines micro-algues sont exploitées pour l’un de leur composantà forte valeur ajoutée comme par exemple la phycocyanine de la spiruline. Suite à l’extraction de lamolécule souhaitée, les restes des micro-algues ne sont pas exploités alors qu’ils contiennent encore deslipides et autres composés carbonés valorisables. Le projet Algoroute a comme objectif de produire un bioliantpour remplacer le bitume pétrolier (liant des enrobés routiers) à partir de ces déchets. Dans ce but,une liquéfaction hydrothermale a été effectuée sur les résidus et a conduit à l’obtention d’une phasehydrophobe dont les propriétés rhéologiques ont été mesurées.

MICROSCOPIE+ING+LBU:NOG:YSC:FRM; International audience; The nature of the surface intermediates involved in CO hydrogenation and Fischer-Tropsch synthesis is still elusive. The effect of tin on cobalt-based catalysts used for CO hydrogenation was studied by operando diffuse reflectance FT-IR spectroscopy (DRIFTS) and isotopic transient techniques (12C-13C and H-D exchanges). Tin was used as a modifier to obtain a poisoning effect that could help discriminating active sites. Tin was selected because this metal does not adsorb CO, hence, the carbonyl bands observed can be wholly attributed to surface cobalt atoms.The operando DRIFTS spectra (Fig. 1, left) measured over a fresh cobalt sample exhibited both linearly adsorbed CO (2031 cm-1) and CO adsorbed on three-fold hollow sites (1860 cm-1).1 The Sn-modified samples exhibited a markedly lower fraction of hollow sites. The exact fractions of linear and hollow sites could be determined using a relative molar absorption coefficient of 2, as reported by Weststrate et al.1Interestingly, plots of the specific rates of formation of the main hydrocarbon produced (methane and propene) and that of methanol (traces) against the fraction of hollow-CO revealed an essentially linear relationship (not shown). 12CO-13CO steady-state isotopic transient kinetic analyses (SSITKA) under reaction conditions at 220°C (not shown) were used to quantify the total concentration of CO(ads). The hollow-CO specific concentration could thus be calculated. Finally, the specific rate of decomposition of hollow-CO could be determined from additional DRIFTS chemical-transient experiments and shown to be similar or higher than the cumulated rates of product formation (Fig. 1, right).These combined operando DRIFTS and transient data indicate that the hollow-CO are active reaction intermediates leading to hydrocarbons under these conditions. These findings should help rational design of improved cobalt Fischer-Tropsch catalysts by tuning the concentration of the crucial hollow-CO reaction intermediate.

RMN+ECI2D:ING+ABZ:CLO:DLA:NOG:CMI:CGE:YSC; International audience; Catalytic fast pyrolysis (CFP) of beech wood chips was undertaken in a laboratory-scale fixed bed reactor equipped with a biomass semi-continuous dispenser. During pyrolysis, chars are retained on a quartz frit and the pyrolytic vapors are entrained through a fixed-bed catalyst to be converted. Several acidic catalysts such as zeolites H-Beta, zeolite HMFI and 5% Ni supported on HMFI were screened in this equipment. The Ni/HMFI catalyst was also tested in the presence of 1 vol.% of hydrogen in the feed stream. Mass and carbon balances were carefully checked and the gas, liquids and solids fractions were analyzed in-depth to evaluate the impact of the catalyst compared to thermal conversion. In the presence of a catalyst, with a low catalyst-to-biomass ratio of 0.1, a lower amount of bio-oil was formed but it contained less oxygen. The bio-oils were characterized by bi-dimensional GC (GCxGC) coupled with MS and FID detectors. The amount of gaseous products also increased in the presence of all catalysts. In addition of the deoxygenation, gel-permeation chromatography (GPC) showed a decrease of the highest molecular masses in the bio-oil after catalytic treatment, which confirms the conversion of some oligomers. The presence of Ni enhanced the deoxygenation reactions while the addition of H2 is also beneficial to the bio-oil composition.

SSCI-VIDE+CARE:ECI2D:ING+FGI:JCO:CGE:NOG:SLO:DBI; International audience;

SSCI-VIDE+ING+NOG:YSC; International audience; The catalytic conversion of eight lignin model compounds emulating various C-O and C-C bond of lignin was explored in a batch reactor with a Pt/C catalyst in ethanol/water mixtures, using ethanol as both H-donor and solvent. The order of reactivity for hydrogenolysis of C-O model bonds was found: β-O-4 > α-O-4 >> 4-O-5, the 4-O-5 bond exhibiting a very low reactivity. α-1 model C-C bonds were also cleaved by hydrogenolysis, but β-1 model C-C bonds were not. The cleavage of C-O and C-C bonds obtained by H-transfer catalysis in water-ethanol mixtures was very selective, intermediate reaction products could be detected before full reaction completion but no decomposition or degradation products.

RMN+ECI2D:ING+AMR:CLO:NOG:CMI:CGE:DLA:YSC; International audience; Fast pyrolysis of biomass yields bio-oils with high levels of oxygen-containing components, high acidity and low stability. Further upgrading of these oils is necessary before they can be used as liquid fuels. Several low-cost strategies have been proposed for reducing the oxygen and acid contents. Catalytic conversion of pyrolytic vapors allows a partial deoxygenation before vapor condensation. In this context, a semi-continuous pyrolysis test combined with a catalytic reactor was built and different acid catalysts were tested. The resulting bio-oils were characterized in depth to get more insights in the role of the catalyst on bio oil vapors conversion.

MICROSCOPIE+ING+FRM:LBU:NOG:YSC; National audience; The effect of tin on cobalt-based catalyst in CO hydrogenation reaction was studied byoperando diffuse reflectance FT-IR spectroscopy (DRIFTS). Tin was selected as a modifier as to obtain a poisoning effect that could help discriminating active sites and also because tin does not adsorb CO at the temperatures investigated. Hence, the carbonyl bands observed by FT-IR could only be attributed to CO adsorbed on cobalt atoms. Four catalysts were studied: a parent 15 wt.% Co/Al2O3 and three Co-Sn catalysts with Co/Sn molar ratios equal to 30, 60 and 120. The setup and analytical methods are identical to those described elsewhere [1]. The rate of formation of methane (main product) and that of propene (most abundant chain growth product) were monitored for the four catalysts. Increasing the tin content led to a significant activity loss (data not shown). The operandoDRIFTS spectra measured over a fresh cobalt sample exhibited both linear CO(ads), characterized by bands above ca. 2000 cm-1, and bridged/multibonded CO(ads), characterized by bands below ca. 2000 cm-1 (Fig. 1, left). The Sn-modified samples exhibited a markedly lower fraction of bands below 2000 cm-1, indicating fewer corresponding sites when Sn was present. A decomposition of the carbonyl signal was carried out to quantify the changes in the DRIFTS band signals (not shown). The band most affected by tin was that located at around 1860 cm-1, associated with bridged/multibonded CO(ads), the intensity of which decreased with increasing Sn content.Interestingly, a plot of the normalized rates of product formation against the fraction of bridged carbonyls present at the surface of the catalyst revealed an essentially linear relationship (Figure 1, right). These data strongly suggests that the sites associated with bridged CO(ads) (possibly edges or steps of cobalt nanoparticles) are the most active sites for CO hydrogenation under these conditions and, potentially, for the Fischer-Tropsch synthesis. Note that step sites had been proposed as being the most active sites for CO dissociation [2,3].

MICROSCOPIE+ING+FRM:DLR:LBU:NOG:YSC; International audience; A bridged/multi-bonded CO(ads) was rigorously identified as being a crucial surface intermediate in the formation of hydrocarbons over cobalt-based catalysts. This species, its concentration and reactivity were characterized by a combination of operando diffuse reflectance FT-IR spectroscopy, isotopic and non-isotopic transients. The corresponding specific decomposition rate was similar to the sum of the formation rates of the main reaction products methane and propene.

MICROSCOPIE+ING+FRM:APN:YSC:NOG:LBU; International audience; This work shows that it is possible to selectively poison cobalt using small concentrations of Sn. In addition, Sn appears to be preferentially titrating sites on which bridged CO(ads) are formed. This suggests that the sites associated with the bridged sites (possibly edges or steps) are the most active sites for Fischer-Tropsch synthesis. Step sites have already been proposed as being the most active sites for CO dissociation. Methanol formation fitted less the linear relationship, possibly because it does not require CO dissociation and was shown to also involve formate species, located at the interface with the metal particles and an oxidic phase (CoOx or the support).

SSCI-VIDE+ING+MLU:FRM:NOG:YSC; International audience; Biogas is a complex gas mixture primarily composed of methane and carbon dioxide, which is produced by anaerobic digestion of biomass. Biogas can be reformed into hydrogen-rich syngas for fuel-cell applications. In this study, autothermal reforming (ATR) of model biogas was performed. Previous screening of catalysts for this reaction led to the selection of a Ni-Rh/MgAl2O4 catalyst, which showed a stable performance over more than 300 hours [1]. SiC foams are promising catalyst supports for small size ATR units. They have excellent thermal characteristics and low pressure drops, permitting a very compact reformer. For a better reformer design a kinetic model of the biogas ATR reaction is highly desirable. Several kinetic models for methane reforming are available in the literature but only a few models exist for methane ATR [2], [3]. In this study, a kinetic model was developed for the ATR of model biogas over SiC foams coated with a 15-0.05wt.% Ni-Rh/MgAl2O4 catalyst.The tested foam samples had a diameter of 2.5 cm and two different lengths were used: 2.5 and 1.4 cm (Figure 1). The carrier gas was a mixture composed of steam, CH4, CO2, O2 in a balance of inert argon. The operating variables were temperature, gas hourly space velocity as well as steam/CH4, CO2/CH4 and O2/CH4 ratios. Overall 65 experiments were performed. Figure 1: SiC foam coated with 15 wt.% Ni-0.05 wt.% Rh/MgAl2O4 catalystFig. 2 shows the effect of the inlet O2/CH4 and H2O/CH4 ratios on the catalyst performances at 650 and 700°C. The relatively low temperatures and high GHSV were chosen to ensure incomplete conversions of methane, necessary for kinetic studies. High H2/CO ratios and high methane conversions were observed even at severe GHSV conditions. At 650°C, the conversion of methane increased with the O2/CH4 ratio, since more oxygen translates into more methane burnt in CO2, and also more heat supplied to the endothermal reforming reactions. At 700°C the methane conversion was not modified with the O2/CH4 ratio but the H2/CO ratio increased with the O2/CH4 ratio. When the H2O/CH4 ratio increased, higher conversions and higher H2/CO ratios were reached. Indeed, the water gas shift reaction is greatly influenced by the inlet partial pressure of H2O Figure 2: Observed methane conversion at 700°C ( ) and 650°C ( ) as well as H2/CO ratio at 700°C ( ) and 650°C ( ) as a function of (a) the O2/CH4 ratio (H2O/CH4 fixed at 3) and (b) the H2O/CH4 ratio (O2/CH4 fixed at 0.5) during the ATR reforming of biogas (GHSV = 15000 h-1).The performance of the model was tested by using three objectives functions: the methane conversion, the temperature at the center of the catalyst foam and the H2/CO ratio at the reactor exit. Two different models were tested consisting of the same model for methane combustion combined with two different methane reforming models, one by Hou and Hughes [4] and one by Xu and Froment [5]. The latter one was also used by Halabi et al. to simulate an ATR reactor [2]. Initial simulations showed that the rate of methane combustion was too slow, giving incomplete oxygen conversion. The corresponding rate coefficient was therefore increased until a reasonable comparison with the experimental data was reached. Axial temperature gradient could not be avoided and had to be taken into account in the model. Therefore a one-dimensional pseudo-homogeneous plug-flow reactor with axial temperature gradient was applied. Initial simulations showed that the model by Xu and Froment [5] outperformed the model by Hou and Hughes [4] and further optimization was done using the Xu and Froment model with the model adequately described the measured data (Figure 3). Figure 3: Parity plot A kinetic ATR model reported in the literature has thus been successfully adapted to describe adequately the experimental ATR data over the foam catalyst. The main change concerned the higher rate of methane combustion, probably due to the presence of rhodium in our sample, which is a better combustion catalyst. Studies are ongoing on powder for comparison purposes.AcknowledgementsThe research leading to these results has received funding from the European Community's Seventh Framework Programme ([FP7/2007-2013] under grant agreement n° 325383 (BioRobur). The authors thank Alexander Khinsky and Sandro Gianelli for providing the monolith catalysts. [1] M. Luneau, Y. Schuurman, F.C. Meunier, C. Mirodatos, N. Guilhaume, Catalysis Science and Technology, 5 (2015) [2] M.H. Halabi, M.H.J.M. de Croon, J. van der Schaaf, P.D. Cobden, J.C. Schouten, Chemical Engineering Journal, 137 (2008)[3] D.L. Hoang and S.H. Chan, Applied Catalysis A: General, 268 (2004)[4] K. Hou and R. Hughes, Chemical Engineering Journal, 82 (2001)[5] J. Xu, G.F. Froment, AIChE Journal, 35 (1989)

SSCI-VIDE+ECI2D:ING+AMR:NOG:CMI:CGE:DLA:YSC; National audience; For thousands of years, pyrolysis has been applied for charcoal production but it is only during the last 30 years that fast pyrolysis was developed. The concept is the rapid heating of biomass at moderate temperatures around 500°C with short reaction times of up to 2 seconds in an oxygen-free environment to optimize the yield of liquids. Pyrolytic bio-oils contain a significant amount of reactive oxygenated species and they have to be stabilized and deoxygenized to be compatible with traditional fuels. Catalytic pyrolysis is an approach that allows a partial deoxygenation before vapor condensation.To produce upgraded bio-oils, a semi-continuous pyrolysis experiment on lab-scale was developed. It consists of a quartz tube containing two porous frits. The first retains the wood and char, while the second holds the catalyst. This reactor is placed inside a cylindrical oven. Beech wood chips are introduced into the top part of the reactor by means of a solid powder dispensing system (Parimix). A flow of nitrogen of 500 mL/min inerts the biomass injector and drives pyrolysis vapors through the catalyst fixed bed (catalyst-to-biomass ratio of 1:10). At the reactor exit a condenser collects the bio-oil at 4°C. This condenser is followed by an electrostatic trap to capture the very fine oil droplets and to protect the micro-GC used for on-line gas analysis.

SSCI-VIDE+ING+APN:DLR:NOG:YSC:FRM; International audience; 1.IntroductionSynthetic fuels and base chemicals can be obtained from both fossil and renewable sources through the conversion of synthesis gas (syngas). Biomass-derived syngas contain significant concentrations of chlorine that may contaminate downstream catalysts. Rytter and co-workers reported that the presence of Cl introduced ex situ during cobalt-based catalyst preparation decreased the metal surface without, surprisingly, affecting activity, thus increasing the turnover frequency [1]. Davis and co-workers investigated the effect of alkali and chloride addition to a Fischer-Tropsch slurry phase reactor using a Co-based catalyst and noted a marked deactivation by halides and potassium [2]. The authors related the metallic cobalt poisoning to a blocking effect of metal sites by halides and potassium in agreement with results of H2 chemisorption obtained ex situ on used cobalt FT catalysts [2]. We report herein an operando diffuse reflectance FT-IR spectroscopy (DRIFTS) study in which the hydrogenation of CO is monitored in the presence of 150 ppm of chlorine. DRIFTS enables monitoring the state of the cobalt surface, which is typically covered with various carbonyl species under reaction conditions [3].2.ExperimentalThe preparation of the 14 wt.% Co/Al2O3 catalyst, experimental setup, DRIFTS cell and procedures are described in details elsewhere [3]. The hydrogenation of CO was performed at atmospheric pressure using a modified high temperature DRIFT cell. The reactor effluent was quantified using a 2 m-pathlength FT-IR gas cell. Methane, ethane, propene and methanol were the main reaction products in the present conditions and were quantified, while higher hydrocarbons were not monitored. The chlorine was introduced via a saturator held at -70°C containing trichloroethylene (TCE). Differential conditions were used, to ensure that the catalyst bed remained gradientless.3.Results and discussionThe rates of formation of the main products sharply decreased upon the introduction of the chlorinated compound, typically showing a 10-fold drop. The IR signal of CO(ads) could be essentially decomposed into three bands, whether chlorine was present or not. The effect of chlorine was strongest for a surface carbonyl “B” characterized by a band located at ca. 1881 cm-1, likely a bridged species formed on edges, steps and defect sites. The corresponding C-O bond strength increased by about 15 ± 8 kJ/mol in the presence of chlorine, based on a calibration curve presented elsewhere [3]. Two other linear carbonyl species (noted L1 and L2) were affected by chloride addition, albeit to a lesser extent.It must be stressed that the relative decrease of the overall carbonyl band area was far lower than that of the activity, suggesting that each chlorine atoms poisoned several surface sites and/or selectively poisoned the most active sites. The most active sites were likely those associated with the bridged CO(ads) “B”, which displayed the highest intensity loss.The effect of Cl was partly and slowly reversible. Surprisingly, the chlorine poisoning hardly affected the position of the main on-top CO(ads) IR band, in contrast to the effect of surface coverage when CO was removed from the feed.This effect is consistent with chlorine decreasing the electronic density at the cobalt metallic centers, which in turn limited the electronic back-donation from cobalt to the antibonding molecular orbitals of the adsorbed CO [3].Assuming that the rate-determining step of the hydrogenation reaction was the C-O bond dissociation of CO(ads), the operando DRIFTS data indicated that the loss of activity was in part related to the decrease of the concentration of the carbonyl species. In addition, the electronic density removed by chlorine from the metallic cobalt limited the electronic back-donation to CO(ads) and thus limited the weakening of the C-O bond, therefore providing another cause for the observed rate decrease 4.ConclusionsOur operando DRIFTS investigation showed that chlorine strongly poisoned the activity of cobalt for CO hydrogenation. The effect is both site poisoning and electronic.The most active sites are suggested to be those associated with bridged CO(ads) absorbing at ca. 1881 cm-1, the heat of adsorption of which is increased by about 15 kJ/mol in the presence of chlorine.5. References[1] Ø. Borg, N. Hammer, B. C. Enger, R. Myrstad, O. A. Lindvåg, S. Eri, T. H. Skagseth, E. Rytter, J. Catal. 279 (2011) 163.[2] M. K. Gnanamani, V.R.R. Pendyala, G. Jacobs, D.E. Sparks, W.D. Shafer, B.H. Davis, Catal. Lett. 144 (2014) 1127.[3] A. Paredes-Nunez, D. Lorito, Y. Schuurman, N. Guilhaume, F.C. Meunier, J. Catal. 329 (2015) 229–236.

SSCI-VIDE+ECI2D:ING+AMR:NOG:CMI:CGE:DLA:YSC; International audience; The attractive valorization of biomass by fast pyrolysis is facing the drawback of the oxygen content and acidity of the bio oil which induce a high cost of the further upgrading processes for biofuels production. Therefore, several strategies have been proposed for removing at a low cost much of the oxygen and acids. Thus, catalytic pyrolysis can be directly performed in the reactor [ ] or in a close coupled reactor which performs the conversion of the pyrolytic gases after filtration. In the present work, we have built a falling reactor which performs the pyrolysis with a close fixed bed containing the catalyst. Recovery of the bio oils fractions, gases, chars leads to a mass balance higher than 95%. A screening of acidic catalysts (zeolites, silica alumina) has been performed in this test. In depth characterization of liquids and solids was done.

SSCI-VIDE+ING+APN:NOG:YSC:FRM; International audience; 1.IntroductionSynthetic fuels and base chemicals can be obtained from both fossil and renewable sources through the conversion of synthesis gas (“syngas”, a mixture of carbon oxides and H2) [1]. The nature of the reaction mechanism of the Fischer-Tropsch synthesis over cobalt-based catalysts is still a debate, as well as the nature of the active sites [2,3]. IR-based techniques are useful in investigating syngas conversion because CO is both a reactant and a molecular probe often used to characterize metal surfaces. We recently reported that the most active cobalt sites were likely those associated with the formation of bridged CO(ads), which are thought to be located at the particle edges or steps [4]. This conclusion was reached by noting that the poisoning of cobalt by chloride affected more bridged CO(ads) than linear CO(ads) [4].We report herein an operando diffuse reflectance FT-IR spectroscopy (DRIFTS) study in which the hydrogenation of CO is monitored on Co and Sn-Co catalysts. Sn-modified cobalt catalysts were synthesized to obtain similar poisoning effects, using an element less volatile than chlorine. Sn does not adsorb CO at the temperatures investigated, so the carbonyl band observed in the region 2100-1700cm-1 by FT-IR could be attributed to CO adsorbed only on cobalt atoms.2.ExperimentalA 15 wt.% Co/Al2O3 catalyst used for the CO hydrogenation was prepared with the method reported by Shi et al.[5]. Commercial reagents of Co(NO3)2.6H2O, γ-alumina and citric acid were used. Two Sn-modified catalysts were prepared by adding tin (according to a yet undisclosed method) on the as-prepared 15 wt.% Co/Al2O3 catalyst, with Co/Sn molar ratios equal to 60 and 120. The hydrogenation of CO was performed using a modified high temperature DRIFT cell described in [4]. The reactor effluent was quantified using a 2m-pathlength FT-IR gas cell. The low mass of catalyst (30 mg) used in the reactor enabled to maintain low conversion and to operate essentially under differential conditions, making the DRIFTS cell a gradient-less reactor.3.ResultsThe rate of formation of methane, propene, and methanol were monitored for the three catalysts. The presence of tin lead to a significant activity loss of about 30% for the Co/Sn = 120:1 and 60% for the Co/Sn = 60:1. Such large activity losses for such low concentrations of poison suggest that most of the Sn remained at the particle surface, despite the fact that Co and Sn can form bulk alloyed phases.The operando DRIFTS spectra measured over a fresh alumina-supported cobalt sample exhibited both linear CO(ads), characterized by bands above 2000 cm-1, and bridged CO(ads), characterized by bands below 2000 cm-1. In contrast, Sn-modified sample exhibited a lower fraction of bands below 2000 cm-1, indicating that less bridged sites were available when Sn was present. A decomposition of the carbonyl signal was carried out to better characterize the changes in the DRIFTS band signal. The lowest number of Gaussian curves needed to obtain close fits of the original spectra was five (Figure 1.B). The band most affected by tin was that located at around 1860 cm-1, noted “Bridged CO(ads)”, the intensity of which decreased with increasing Sn content. It should be noted that this band may corresponds to various bridged and multi-bonded carbonyls. The plot of the relative loss of activity in product formation against the quantity of bridged carbonyls present on the surface of the catalyst appeared to yield an essentially linear relationship. 4.DiscussionThis work shows that it is possible to selectively poison cobalt using small concentrations of Sn. In addition, Sn appears to be preferentially titrating sites on which bridged CO(ads) are formed. This suggests that the sites associated with the bridged sites (possibly edges or steps) are the most active sites for Fischer-Tropsch synthesis. Step sites have already been proposed as being the most active sites for CO dissociation [6-9]. Methanol formation fitted less the linear relationship, possibly because it does not require CO dissociation and was shown to also involve formate species, located at the interface with the metal particles and an oxidic phase (CoOx or the support) [10].5.ConclusionsThe most active sites for CO hydrogenation over cobalt-based catalysts were shown to be related to sites on which CO adsorption led to bridged or multi-bonded species. Such sites could be selectively titrated by small concentrations of Sn.6.References[1] A.Y. Khodakov, W. Chu, P. Fongarland, Chem. Rev. 107 (2007) 1692-1744.[2] N. Fischer, E. van Steen, M. Claeys, J. Catal. 299 (2013) 67-80.[3] J. Schweicher, A. Bundhoo, N. Kruse. J. Am. Chem. Soc. 134 (2012) 16135-16138.[4] A. Paredes-Nunez, D. Lorito, Y. Schuurman, N. Guilhaume, F.C. Meunier, J. Catal. 329 (2015) 229–236.[5] L. Shi, C. Zeng, Q. Lin, W. Niu, N. Tsubaki, Catal. Today 228 (2014) 206-211.[6] Q. Ge, M. Neurock, J. Phys. Chem. B. 110 (2006) 15368[7] C.J. Weststrate, I.M. Ciobîca, A.M. Saib, D.J. Moodley, J.W. Niemantsverdriet, Catal. Today 228 (2014) 106.[8] P. van Helden, J.-A. van den Berg, I.M. Ciobîca, Catal. Sci. Tech. 2 (2012) 491.[9] R.A. van Santen, Acc. Chem. Res. 42 (2009) 57.[10] D. Lorito A. Paredes-Nunez, C. Mirodatos, Y. Schuurman, F. Meunier, Catal. Today, in press, doi:10.1016/j.cattod.2015.06.027.

MICROSCOPIE+ING+APN:LBU:NOG:YSC:FRM; National audience; The effect of tin on cobalt-based catalysts used for CO hydrogenation was studied by operando diffuse reflectance FT-IR spectroscopy (DRIFTS). Tin was selected as a modifier as to obtain a poisoning effect that could help discriminating active sites and also because tin does not adsorb CO at the temperatures investigated (210-230°C). Hence, the carbonyl bands observed by FT-IR could only be attributed to CO adsorbed on cobalt atoms. Four catalysts were studied: a parent 15 wt.% Co/Al2O3 and three Co-Sn catalysts with Co/Sn molar ratios equal to 30, 60 and 120. The setup and analytical methods are identical to those described elsewhere [1,2]. The rate of formation of methane, propene and methanol were monitored for the four catalysts. Increasing the tin content led to a significant activity loss. The operando DRIFTS spectrum measured over the tin-free Co/Al2O3 exhibited both linear CO(ads), characterized by bands above 2000 cm-1, and bridged and/or multibonded CO(ads), associated with bands below 2000 cm-1.The Sn-modified samples exhibited a markedly lower fraction of bands below 2000 cm-1, indicating fewer corresponding sites when Sn was present. A decomposition of the carbonyl signal was carried out to quantify the changes in the DRIFTS band signals. The band most affected by tin was that located at around 1860 cm-1, referred to as “Bridged CO(ads)”, the intensity of which decreased with increasing Sn content. Interestingly, a plot of the normalized rates of product formation against the fraction of bridged carbonyls present at the surface of the catalyst revealed an essentially linear relationship.These data strongly suggests that the sites associated with bridged CO(ads) (possibly edges or steps of cobalt nanoparticles) are the most active sites for CO hydrogenation under these conditions and, potentially, for the Fischer-Tropsch synthesis. Note that step sites have also been proposed as being the most active sites for CO dissociation [3,4].In addition, the heat of adsorption of the CO species at full coverage was estimated using an IR-based technique [5] on the four catalysts after 16 hours of stabilization under reaction conditions. These values were almost the same for all samples, ca. 80 kJ/mol, stressing the absence of any electronic effects of tin on the adsorption of CO on cobalt atoms.

National @ ING+APN:DLR:NOG:YSC:FRM; International audience; The effect of chlorine, introduced as trichloroethylene (TCE), on the CO hydrogenation activity of an alumina-supported cobalt was studied by operando diffuse reflectance FT-IR spectroscopy (DRIFTS) at atmospheric pressure. The surface of metallic cobalt was covered with CO(ads) under reaction conditions. The corresponding IR signal could be exactly decomposed into three bands, whether chlorine was present or not (data not shown). Chlorine induced a strong and partly reversible poisoning.A major effect of chlorine on the electronic structure of the cobalt particles was evidenced here, in addition to the previously reported site blocking. The carbonyl band position remained unchanged, while its intensity decreased significantly in the presence of TCE. This is in contrast to typical surface coverage effects. This difference was related to the electronic density removed by chlorine from the metallic cobalt that limited the weakening of the C-O bonds, which occured through electronic back-donation from cobalt to the CO π* anti-bonding orbital.The CO(ads) exhibiting a wavenumber at ca. 1911 cm-1 were most affected by chlorine, suggesting that those were associated with the most active sites. The 1911 cm-1 species only led to a minor dipole-dipole coupling and were thus most likely forming a mono-dimensional, or even punctual, network of CO(ads). These species were likely bridged CO adsorbed on step sites, where chlorine could preferentially adsorb. The corresponding C-O bond strength increased by about 7 kJ/mol in the presence of chlorine.Assuming that the rate-determining step of CO hydrogenation was C-O bond dissociation, these observations are consistent with chlorine main poisoning effects being both site blocking (i.e. competitive adsorption) and an electronic effect through the strengthening of the C-O bond that made CO(ads) less likely to dissociate (i.e. modification of the activation energy barrier).

SSCI-VIDE+ING+APN:DLR:NOG:YSC:FRM; International audience; Synthetic fuels and base chemicals can be obtained from both fossil and renewable sources through the conversion of synthesis gas. Biomass-derived syngas contain significant concentrations of chlorine that may contaminate downstream catalysts. Rytter and co-workers reported that the presence of Cl introduced ex situ during cobalt-based catalyst preparation decreased the metal surface without, surprisingly, affecting activity, thus increasing the turnover frequency [1]. Davis and co-workers investigated the effect of alkali and chloride addition to a Fischer-Tropsch slurry phase reactor using a Co-based catalyst and noted a marked deactivation by halides and potassium [2]. The authors related the metallic cobalt poisoning to a blocking effect of metal sites by halides and potassium in agreement with results of H2 chemisorption obtained ex situ on used cobalt FT catalysts [2].We report herein an operando diffuse reflectance FT-IR spectroscopy (DRIFTS) study in which the hydrogenation of CO is monitored in the presence of 150 ppm of chlorine. DRIFTS enables monitoring the state of the cobalt surface, which is typically covered with various carbonyl species under reaction conditions [3].

International audience

International @ ING+MLU:NOG:FRM:YSC; International audience; Biogas is a complex gas mixture produced from the anaerobic digestion of biomass, which contains methane and carbon dioxide as main components. It can be burnt directly, but it has a lower heating value as natural gas. Biogas can also be reformed into hydrogen, which is an essential feedstock in the chemical industry and can also be used as a fuel in fuel-cells to produce electricity. Hence, the production of hydrogen from biogas can contribute to reduce our reliance on fossil fuels and develop renewable energies.Autothermal reforming of model biogas on different nickel supported catalysts was performed at 700°C and atmospheric pressure. The carrier gas was a mixture composed of 42% steam, 14% CH4, 9% CO2, 7% O2 in a balance of inert Argon. Nickel-based catalysts are generally used for steam-reforming of methane because of their low cost and high activity. However, they are prone to oxidation, coking and sintering problems leading to catalyst deactivation. Catalysts were thus developed to prevent these issues. Nickel supported on mixed oxides, perovskites and spinels were synthesized. Long-term catalytic tests were performed in order to discriminate the catalysts resistance to deactivation. In order to save time with long-term experiments, a six parallel-flow reactor was successfully implemented to test six catalysts simultaneously under similar flow rate, temperature and feed composition. With the exception of LaNiO3, the catalysts showed the same deactivation profiles: a slow deactivation was observed followed by an abrupt loss of activity. The catalyst lifetime under time-on-stream differed depending on catalyst composition: Among the tested catalysts, nickel supported on magnesium spinel showed a high resistance to deactivation. Preliminary results showed that deactivation on the different catalysts was likely related to oxidation. Carbon was evidenced on spent catalysts, but does not appear as the main cause of deactivation.

SSCI-VIDE+ECI2D:ING+FGI:JCO:CGE:NOG:EPU:DBI; International audience; The present study is a part of an experimental microkinetic approach of the removal of NOx from coal-fired power plants by reduction with NH3 on V2O5/WO3/TiO2 catalysts (NH3-selective catalytic reduction, NH3-SCR). It is dedicated to the characterization of the heats of adsorption of molecularly adsorbed H2Oads species formed on sulfate-free and sulfated TiO2 supports. Water, which is always present during the NH3-SCR, may be in competition and/or react (formation of NH4+) with the adsorbed NH3 species controlling the coverage of the adsorbed intermediate species of the reaction. Mainly, an original experimental procedure named adsorption equilibrium infrared spectroscopy (AEIR) previously used for the adsorption of NH3 species on the same solids is adapted for the adsorption of H2O. At T-a = 300 K and for P-H2O

SSCI-VIDE+ECI2D:ING+FGI:CGE:NOG:SLO:DBI; International audience; The present article is dedicated to the measurement of the individual heats of adsorption of adsorbed NH3 species on WO3/TiO2 and V2O5/WO3/TiO2 (a catalyst for the selective catalytic reduction of NOx by NH3 on stationary sources, briefly NH3-SCR) model and commercial solids by using an original experimental procedure (adsorption equilibrium infrared spectroscopy, AEIR) developed in parts 1 [Giraud et al. J. Phys. Chem. C 2014, 118, 15664] and 2 [Giraud et al. J. Phys. Chem. C 2014, 118, 15677] for the adsorbed NH3 species on TiO, and V2O5/TiO2 solids. In agreement with the literature, Raman and Fourier transform infrared spectra indicate the presence of well-dispersed VxOy and WOz entities on the different solids. For NH3 adsorption at pressure P-a < 0.5 IrPa and temperature T-a in the range 300-673 K, the modifications of the V=O and W=O overtone IR bands indicate that these entities are involved in the adsorption of NH3, forming NH3ads-L, and NH4+ species on Lewis and Br-misted sites, respectively. For T-a = 300 K, it is shown that four adsorbed NH3 species are formed on the WOz- containing catalysts: two are adsorbed on Lewis sites, named NH3ads-L1 and NH3ads-L2, and two are adsorbed on Bronsted sites, named NH4+-1 and NH4+-2 ("1" and "2" indicate the increasing order of stability of the different species). Using the delta(as) IR band characteristic of the NH3ads-L (similar to 1600 cm(-1)) and NH4+ (similar to 1445 cm(-1)) species, it is shown that the AEIR method provides the individual heats of adsorption of the four adsorbed species at low and high coverages of their adsorption sites. For instance, on a model 0.5% V2O5/6% WO3/TiO2 catalyst the heats of adsorption of the two more stable species (which slightly change with the exact composition of the solid) at low and high coverages of the sites are 105 and 148 kJ/mol for NH3ads-L2 and 78 and 135 kJ/mol for the NH4+-2 species, respectively. These values indicate that the presence of WOz increases significantly the heat of adsorption of the NH4+ species, as compared to TiO2 and V2O5/TiO2, explaining that both NH3(ads-L2) and NH4+-2 species can be present in the experimental conditions of NH3-SCR.

SSCI-VIDE+ING+APN:DLR:NOG:YSC:FRM; International audience; Biomass-derived syngas contain significant concentrations of chlorine that may contaminate downstream Fisher-Tropsch catalysts. We report herein an operando diffuse reflectance FT-IR spectroscopy (DRIFTS) study in which the hydrogenation of CO is monitored in the presence of 150 ppm of chlorine (introduced as 50 ppm of trichloroethylene, noted “TCE”) at ambient pressure.The experimental setup was described elsewhere [1]. The rates of formation of the main products of interest sharply decreased upon the introduction of the chlorinated compound, typically showing a 10-fold drop. Interestingly, the drop in the carbonyl band area was far less marked and mostly due the removal of bridged/multi-bonded carbonyls. This suggests that each Cl atoms poisoned several surface sites and/or selectively poisoned the most active sites. The effect of Cl was partly and slowly reversible. Surprisingly, the Cl poisoning hardly affected the position of the on-top CO(ads) IR band, in contrast to the effect of surface coverage when CO was removed from the feed. In addition to site poisoning, our operando DRIFTS data highlights a strong electronic effect of Cl, which is able to counteract the effects of surface coverage of CO on the position of the IR band. Similar effects were observed on a silica-supported cobalt catalyst.

SSCI-VIDE+CDFA:ING+FBG:NOG:PFO; International audience; In the last years, water separation by hydrophilic membranes has gained huge importance in the scientific and industrial community. Hydrophilic membranes can be used for selective water pervaporation from liquid mixtures or dehydration of organic compounds and these processes can positively replace distillation due to lower energy requirement. Moreover, water is produced in various chemical reactions as a by-product; its separation by hydrophilic membranes from the reaction media can displace the equilibrium and overcome thermodynamic limitations. As example, the selective removal of H2O during dimethyl ether (DME) synthesis (carbon dioxide hydrogenation into methanol followed by its dehydration to produce DME) by means of a membrane separation process would displace the equilibriums to enhance CO2 conversion into methanol, improve DME productivity and also prevent catalyst deactivation. To develop this process, the main latch is undoubtedly the production of a membrane able to selectively separate water at high temperature and pressure from a gaseous mixture of H2O, H2, CO, CO2, CH3OH and DME. Zeolite membranes appear to offer great potential for this application in reason of their molecular sieving properties, uniform pore size distribution and wide range of hydrophilic behavior depending on their Si/Al ratio. Furthermore, it is known that they have higher thermal resistance and mechanical strength than polymeric membranes and provide higher separation factors than ceramic ones.Highly hydrophilic sodalite (SOD, Si/Al ratio of 1) membranes were produced in this work based on a new mechanical pore-plugging technique. This process involved the insertion of specific sized seeds within the pores of an asymmetric host support followed by their growth by hydrothermal synthesis steps. To obtain membranes with high water selectivity and flux, several parameters were investigated, including composition of the precursor solutions (nature and ratio of the reactants to get clear solutions, without the use of structure directing agents), hydrothermal synthesis conditions, mean pore size and nature of the support top-layer (0.1-0.5 um for TiO2 or a-Al2O3 on stainless steel) and membrane post-treatments. Zeolite seeds and/or synthesized membranes were characterized by X-ray diffraction (XRD), thermal gravimetric analysis (TGA), scanning electron microscopies (SEM), gas permeation and permporosimetry where hydrogen permeance was evaluated as a function of water P/Po up to 250°C. Results revealed that membranes obtained under optimized synthesis conditions have good H2O/H2 selectivity at high temperatures even for low water P/Po indicating their high potential to improve DME productivity industrially.

International @ INGENIERIE+SDA:NOG; International audience; We investigated the influence of the acid-base properties of TiO2-based supports on the performances of Pd-Cu catalysts for nitrates hydrogenation in water. TiO2 supports doped with Mg or Nb (1-7 wt.%) were prepared by co-hydrolysis of metal alkoxides. The surface area increased and the crystallinity decreased for Mg- and Nb-doped TiO2, all solids exhibiting mesoporosity with average pore sizes smaller than 20 nm. Mg-doping introduces a strong basic character whereas Nb-doped TiO2 becomes acidic. Pd-Cu bimetallic catalysts supported on TiO2 and Mg- or Nb-TiO2 were found very active for the catalytic hydrogenation of nitrates, but the selectivity to ammonium was high. Nb-doping slightly decreased the reactivity of nitrates, Mg-doping improved the reactivity of nitrites, but the selectivity to ammoniums was only marginally modified. The activity and products selectivity were only moderately affected by the properties of the support, which suggests that this property is not relevant to the reaction mechanism.

National @ INGENIERIE+APN:DLR:NOG:YSC:FRM; International audience; Synthetic fuels and base chemicals can be obtained from both fossil and renewable sources through the conversion of synthesis gas (syngas, a mixture of carbon oxides and dihydrogen). Understanding the selectivity pattern to various products of interest of a given catalyst is paramount to derive structure/activity relationship. Operando DRIFT (diffuse reflectance FT-IR) spectroscopy can be of help to determine the relevance of surface species in the formation of products. In the case of a Co-Mg-O sample, it was shown that the surface formates species observed by DRIFTS were irrelevant in the formation of ethane [1]. A new setup was developed combining a DRIFTS reaction cell for operando surface characterisation and an IR gas cell and mass spectrometer for the on-line analysis of the reactor cell effluents (Fig. 1). DRIFTS spectra of excellent quality (see carbonyls and formates bands in Fig. 1) could be obtained in 10 s with less than 10 mg of sample, for which the contribution of gas-phase CO could be perfectly subtracted. The IR-cell exhibited a 2 m-long pathlength that enabled measuring concentration of reaction products in the ppm range. The system could thus be operated under differential conditions and the primary reaction products could be detected. The system can be operated up to 5 bars of absolute pressure. Preliminary results collected over a Co-based catalyst (Fig. 2) show that the reaction order in CO was globally positive and methane and propene were the main reaction products, while only trace amounts of methanol were detected. The relation between the various surface species and reaction products will be discussed. 1] J. Schweicher, A. Frennet, N. Kruse, H. Daly, F.C. Meunier, J. Phys. Chem. C 114 (2010) 2248.