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International audience; This paper reports the interaction of aromatic compounds (as phenol, ethylphenols, and guaiacol) representative of oxygenated functions of pyrolysis bio-oils, with sulfided (Co)Mo/Al2O3 catalyst in order to determine the origin of catalyst deactivation in hydrodeoxygenation (HDO) reaction. Infrared spectroscopy shows that all the studied phenolic compounds anchor on the alumina support as phenate-type species, whereas only the most basic ones (2(4)-ethylphenol and guaiacol) interact also with the sulfide phase. At 623 K (typical temperature of the HDO reactions), only phenate species on the support are formed that is confirmed by study of the catalyst tested in HDO reaction. Phenate-type species anchored on alumina hinder the accessibility of the sulfide edge sites. This shows that the nature of the oxygenated compound (basicity and nature of the substituent) as well as the surface properties of the catalyst support are crucial in the mode and extent of HDO active sites poisoning. (c) 2012 Elsevier Inc. All rights reserved.

International audience; NiMo/SiO2-Al2O3 mixed oxide supported catalysts were investigated for hydroprocessing of heavy crude oil at moderate reaction conditions. Hydrodesulfurization (HDS), hydrodemetalization (HDM), hydrodeasphaltenization (HDAs) and hydrodenitrogenation (HDN) reactions were studied as function of time-on-stream (TOS). The results indicated that HDS of crude oil corresponds to the number of active metal sites (sulfide phases) present in the catalyst, HDN is enhanced when the catalyst presents a combination of well dispersed sulfide phases and weak to moderate acidity. HDM presented a complex behavior indicating that it is affected significantly not only by the dispersion of the sulfide phase but also by the porosity and acidity of the catalyst. As expected, for HDAs both acidity and textural properties are important. The stability of the catalyst with time-on-stream was affected by coke and metals deposition. The supports and fresh catalysts were characterized by nitrogen physisorption, SEM-EDX, and FT-IR of CO and pyridine adsorption. The results confirm that NiMo/SiO2-Al2O3 catalysts are a good option for the hydrotreatment of heavy oils and that the method used here for support preparation can tune the formation of meso- or macro-porosity and the type and strength of the catalyst acid sites. (C) 2012 Elsevier B.V. All rights reserved.

International audience; BACKGROUND: Magnetic nanoparticles are of immense interest for their applications in biotechnology. This paper reports the synthesis of magnetic iron oxide nanoparticles from two different water-in-oil microemulsion systems (ME-MIONs), their characterization and also their use in purification of coagulant protein. RESULTS: ME-MIONs have demonstrated to be an efficient binder in the purification of Moringa oleifera protein when compared with the superparamagnetic iron oxide nanoparticles prepared from coprecipitation in aqueous media. The size and morphology of the ME-MIONs were studied by transmission electron microscopy (TEM) while the structural characteristics were studied by X-ray diffraction (XRD). The microemulsion magnetic iron oxide nanoparticles (ME 1-MION and ME 2-MION) obtained have a size range 7-10 nm. The protein and ME-MIONs interaction was investigated by Fourier transform infrared spectroscopy (FT-IR); the presence of three peaks at 2970, 2910 and 2870 cm(-1) respectively, confirms the binding of the protein. The purification and molecular weight of the coagulant protein was 6.5 kDa as analyzed by SDS-PAGE. CONCLUSION: The ME-MIONs have the advantage of being easily tailored in size, are highly efficient as well as magnetic, cost effective and versatile; they are, thus, very suitable for use in a novel purification technique for protein or biomolecules that possess similar characteristics to the Moringa oleifera coagulant protein. (C) 2011 Society of Chemical Industry

International audience; The adsorption of phenol on supported sulfide CoMo catalysts and on oxides is investigated using IR spectroscopy. On silica, phenol mainly interacts via hydrogen-bonding, whereas on alumina it dissociates on the acid-base pairs of this oxide leading to the formation of strongly adsorbed phenolates species. On a sulfided CoMo catalyst supported on alumina, phenol dissociates on the support but does not interact strongly with the sulfide phase. The accessibility of the various sites of the catalyst after phenol contact is investigated by CO adsorption monitored by IR spectroscopy. As expected, phenolate formation decreases the accessibility of support sites. In addition, a decrease of the sulfide site accessibility is also observed. This is indicative of an indirect poisoning of the sulfide edge sites by phenolate species anchored on the support and in the vicinity of sulfide slabs. Consequently, decreasing the amount or strength of the acid-base paired sites of the support should be a way to limit deactivation. (C) 2011 Elsevier B.V. All rights reserved.

The effect of high-pressure sulfidation on (Co)Mo/Al2O3 catalysts was studied by means of IR spectroscopy of adsorbed CO and thiophene hydrodesulfurization (HDS). A new IR cell, called CellEx, was designed in order to characterize catalysts sulfided in situ under H2S/H2 flow with pressure varying from 0.1 up to 4.0 MPa. On Mo/Al2O3, high sulfidation pressure changes neither the HDS rate nor the MoS2 site concentration. Conversely on CoMo catalyst, sulfidation under high pressure leads to a marked increase of the thiophene HDS activity and of the Co-promoted site concentration as well as to some changes in the local structure of CoMoS sites. Study of CoMo catalyst, in the new IR cell, CellEX that allows in situ sulfidation under high-pressure, shows that sulfidation pressure increases HDS activity in parallel to the CoMoS concentration.

International audience; The richness of titanium dioxide sol–gel syntheses described in literature provided a set of four different morphologies of pure anatase nanoparticles to study the impact of the exposed surfaces on the photocatalytic efficiency of the corresponding material. The selection of the experimental parameters such as the temperature, the heating method or organic additives allowed the synthesis of pure anatase materials with significantly different shapes. A thorough microscopic study of these particles gave the exposed crystallographic faces. The photocatalytic activity of the different materials was estimated following the degradation of the rhodamine B dye under UV-light and significantly different behaviors were observed. In the applied photodegradation conditions, two samples were shown to be more efficient than the reference photocatalyst P25. The rationalization of these results was done through the study of the oxide surface properties, using FT-IR spectroscopy with pyridine as a surface probe and the EPR analysis of photogenerated radicals under UV light. The most efficient photocatalyst for rhodamine B degradation was found to be the morphology presenting the stronger acidic surface sites.

International audience; Bismuth vanadate has attractive photocatalytic properties under visible light. The influence of structure and morphology of BiVO4 nanomaterials on its photocatalytic properties in the UV and the visible domain was investigated. The selection of different sets of synthetic parameters in aqueous solutionpH or the use of organic additivesallowed the formation of tetragonal zircon, tetragonal scheelite, and monoclinic scheelite structure and different morphologies of that last phase. First, the tetragonal zircon was found to be the only inactive structure. Then, the best material for photocatalytic degradation of rhodamine B in solution and stearic acid deposited directly on the photocatalyst is the coreshell tetragonal zircon-monoclinic scheelite system prepared in the presence of sodium dodecyl sulfate. The enhanced properties are explained by the presence of strong surface acidic sites corresponding to the presence of surface sulfate residues rather than to the specific morphology of the material. Additionally, an EPR study on the ability of BiVO4 to generate active surface radical showed that hydroxyl radicals are not generated and that superoxide ion concentration under irradiation is close to the detection threshold. Depending on the selected irradiation wavelength, bismuth vanadate may present a better photocatalytic activity than titanium oxide. It is shown to be equivalent to bismuth tungstate under blue light.

FT-IR spectroscopy and multivariate analysis have been used to investigate four closely related species of an important bacteria genus: Enterococcus . Since some species belonging to this genus are highly pathogen, and some others present technological interest in food industry, their differentiation is an essential task. The aim of this work was to discriminate Enterococcus strains (9 E. faecalis , 12 E. faecium , 4 E. durans and 1 E. hirae ) at the species and strain level, using FT-IR spectroscopy. Experiments were performed in two different laboratories with a good reproducibility, and were checked against a molecular biology technique, ribotyping. Discrimination at the species level was correct with both methods. Regarding the strain level, more than half the E. faecalis and E. faecium strains were differentiated by FT-IR spectroscopy, which confirms to be a rapid and promising method in microbiology.

International audience; NiMo/SiO2-Al2O3 spent catalysts were obtained after the hydroprocessing of Maya crude oil in a fixed-bed up-flow reactor. The textural properties, metal content, carbon deposition and sulfide phase of spent catalysts were studied and compared with those of fresh catalysts. Scanning electron microscopy was used to study the deposit of nickel and vanadium, and the total metal content was determined by atomic absorption. The sulfide phase was analyzed with the use of infrared spectroscopy technique. Moreover, the catalytic activity of spent catalysts was evaluated with cumene hydrocracking and compared with the catalytic activities of fresh catalysts. The characterization results show that the silica-alumina NiMo catalysts are more sensitive to metal deposition than carbon deposition because of their porous structure which provokes pore mouth plugging and the decrease of the NiMoS active sulfide phase. The results show that optimizing the catalyst resistance to deactivation requires a trade-off between the support acidity and macro-mesoporosity. (C) 2013 Elsevier B.V. All rights reserved.

The aim of this work is to review the last 10 years articles about Fourier transform infrared spectroscopy (FTIR) as a tool for characterization of microorganisms. Various FTIR techniques like transmission, attenuated total reflection, microspectroscopy, have been used to characterize bacteria, yeast or other microorganisms. Chemometric methods as hierarchical cluster analysis (HCA), principal component analysis (PCA) or artificial neural network (ANN) are rapidly reminded. Publications are then listed, according to the purposes of the studies: taxonomical classification, discrimination according to susceptibility to antibiotic, etc.

The capacity of FTIR spectroscopy for identification and classification of lactic acid bac- teria has been proved on brewery strains and more recently by ourselves on dairy strains. During our study, we underlined that IR spectra give very informative data which can be used for old or more recent taxonomical purposes. We tried to illustrate this aspect with two examples: the distinction between Streptococcus thermophilusand Streptococcus salivarius, the taxonomic range of Lactobacillus casei, paracasei, zeae and rhamnosus. The interest of this tool for taxonomic studies will be discussed. taxonomy / FTIR spectroscopy / Streptococcus / Lactobacillus

The potentiality of FTIR spectroscopy for the identification of lactic acid bacteria (LAB) used in the dairy industry was tested. For this purpose, spectra of different strains were recorded using standardized conditions. These strains were species of Lactobacillus (12 species, 3 sub- species), Lactococcus (4 species, 3 subspecies), Leuconostoc (3 species, 3 subspecies), Weissella (1 species) and Streptococcus (2 species) involved in the soft cheese industry . Spectral libraries were then established by statistical analysis. Reference strains were then tested on these libraries, and 100% of correct identifications were obtained at the genus and species level, 86% at the subspecies level. Well-identified strains were included in libraries. Wild isolates ( n = 48) previously identified by biochemical tests and RAPD method were then tested. We obtained 100% at the genus level and 69% at the species level of correlation between FTIR and other methods. Finally, spectra of reference strains performed in other laboratories were tested with the same method, and the results tallied with official identification in 100% of the cases at the genus level and in 41% of the cases at the species level. These results concerning a few strains allow us to plan the development of a more complete database for rapid identification of LAB.

International audience; The hydrodeoxygenation of model phenol compounds (phenol and 2-ethylphenol) was carried over unpromoted Mo/Al2O3 and promoted CoMo/Al2O3 catalysts. Hydrodeoxygenation proceeds by two pathways:– hydrogenation of the aromatic ring followed by Csp3-O bond cleavage (HYD pathway, (hydrogenation of the aromatic ring followed by Csp3-O bond cleavage));– direct cleavage of the Csp2-O bond (DDO Pathway).Both routes were favored by the presence of Co on the catalyst, while the presence of the alkyl substituent on the phenolic ring favors the DDO route but inhibits the HYD pathway. IR (InfraRed) spectroscopy shows that while phenol mostly dissociates on these catalysts, a significant fraction of 2-ethylphenol remains non dissociated. The adsorption energies of both reactants and possible reaction intermediates on promoted and non-promoted sulfide phases as computed by DFT (Density-Functional Theory) confirm these findings and allow rationalizing the catalytic activity trends observed experimentally.

International audience; Bismuth-based oxides have attractive photocatalytic properties under visible light. A better understanding of the origin of that good photocatalytic activity should allow its control and its optimization. In this Article, we have studied the impact of surface properties on photocatalytic activity for three bismuth-based oxides Bi2O3, BiVO4, and Bi2WO6. The surface acidity of particles was investigated by pyridine adsorption using infrared spectroscopy and the photocatalytic activity was investigated by the degradation of an aqueous solution of rhodamine B (Rho) and of stearic acid deposited on films under visible light. From the results obtained for the three bismuth-based oxides, we established a relation between surface acidity and photocatalytic mechanism of Rho degradation. The best photocatalytic efficiency for RhB and stearic acid degradation has been obtained with Bi2WO6 that also exhibits the highest surface acidity. The most acid sites promote a strong interaction with the pollutant, implying a short distance between the pollutant and the photocatalyst. Consequently, the photogenerated electrons, holes, and radicals can reach more easily the pollutant, leading to an efficient degradation under visible light. The development of strong acid solids such as Bi2WO6 emerged as promising materials for the degradation of pollutants. Because the good photocatalytic properties are related to the high acidity of Bi2WO6, we are interested in its origin using the multi site complexation model (MUSIC model). We found high acidity sites that are located on the lateral faces of the Bi2WO6 platelets (crystallographic planes (101), (10 (1) over bar), (100), and (001)).

International audience; We report the study of the impact of water on the stability of Mo and CoMo sulfide catalysts in hydrodeoxygenation of phenolic compounds. The presence of water at reaction temperature leads to an additional deactivation of the catalyst, which is fully reversible on the CoMo catalyst, but partly irreversible on non-promoted Mo catalyst. IR and HRTEM characterizations as well as DFf simulations confirm the higher sensitivity of unpromoted MoS(2) toward water and show that large amounts of water at reaction temperature lead to the exchange of an important fraction of edge sulfur atoms on non-promoted MoS(2) catalysts, hence changing the nature of the active sites. For Co-promoted catalyst, the extent of water poisoning is much lower and reversible because Co atoms prevent sulfur-oxygen exchanges. Hence, in HDO conditions, Co does not only increase the intrinsic activity of the catalyst (promotion effect) but also stabilizes the active phase in the presence of water (passivation effect). (C) 2011 Elsevier Inc. All rights reserved.

International audience

The interaction of phenol, anisole, and guaiacol, representatives of oxygenate functions present in pyrolysis bio-oils, with oxides such as silica, alumina (pure or doped with K or F), and silica−alumina is investigated by infrared spectroscopy. While phenolic type compounds mainly interact via H-bonding with silica, chemisorption is their main mode of adsorption on alumina. Besides, guaiacol interacts very strongly by forming doubly anchored phenates instead of monoanchored ones with phenol and anisole. At temperatures typical of hydrodeoxygenation (HDO) operating conditions (∼673 K), the phenate type species cover 2/3 of the alumina surface. This study clearly indicates that substantial carbon deposition could take place on alumina-supported HDO catalysts. Hence, this suggests that silica-based supports should be considered as potential candidates to design HDO catalyst with better stability.

International audience; Two series of (Co)Mo/Al(2)O(3) catalysts were compared: one set was prepared with a constant amount of Mo, and various amounts of Co (from 0 to 4.5%), the second one containing the same amount of metals, but with ethylene diamino tetraacetic acid (EDTA) addition (27 wt%). The sulfided catalysts were characterized by IR spectroscopy of adsorbed CO. IR reveals that EDTA leads to a strong increase in the concentration of Co-promoted sites. EDTA has also a significant positive effect on thiophene hydrodesulfurization at atmospheric pressure, and 2,6-dimethylaniline hydrodenitrogenation at high pressure. Combination of spectroscopic and activity data shows that EDTA chiefly increases the amount of promoted sites having lower average intrinsic activities. This decrease in intrinsic activity should be due to a change of the site structure. Two models can be proposed to account for EDTA effect on the site structure such as the formation of type II slabs or that of nitrogeno-sulfide Co-promoted sites, “CoMoSN”. (C) 2009 Elsevier B.V. All rights reserved.

IR spectroscopy of probe molecules (pyridine, 2,6-dimethylpyridine, and CO) as well as high-resolution solid state NMR and especially double-resonance experiments give a new insight into the acidic sites of amorphous silica alumina (ASA). ASA samples are heterogeneous compounds that contain a silica alumina mixed phase as well as aluminum clusters and pure silica zones. The distribution of various forms depends both on the preparation method and on the Si/Al ratio. Formation of mixed phase leads to the creation of acidic hydroxyl groups of various strength, up to that present in dealuminated HY zeolite. Detailed spectroscopic analyses show that these acidic OH groups correspond to the silanol groups located in close vicinity to an Al atom in tetrahedral environment. The strength of the acidity of the OH species of ASA could be modified both by the location of the vicinal Al atom on the surface or in the bulk and by the number of aluminum atoms in the vicinity of silanol group. Cogelification of high silica-containing ASA appears as the best mean to prepare homogeneous amorphous aluminosilicate, which exhibits the strongest Bronsted acidity.

Sulfato and Thiosulfato Reducing Bacteria (SRB, TRB) can induce corrosion process on steel immersed in seawater. This phenomenon, called biocorrosion, costs approximatively 5 billion euros in France each year. We provide the first evidence that Fourier Transformed InfraRed (FTIR) spectroscopy is a competitive technique to evaluate the sulfurogen flora involved in biocorrosion in comparison with time consuming classical identification methods or PCR analyses. A great discrimination was obtained between SRB, TRB and some contamination bacteria known to be present in seawater and seem to be able to reduce sulfate under particular conditions. Moreover, this preliminary study demonstrates that FTIR spectroscopic and genotypic results present a good correlation (these results are confirmed by other data obtained before or later, data not shown here). The advantages gained by FTIR spectroscopy are to give information on strain phenotype and bacterial metabolism which are of great importance in corrosion processes.

For 10 years FTIR has been proposed as a rapid method for identification of microorganisms [1]. Several studies have been published concerning different genera of bacteria like Clostridium, Pseudomonas, Streptococcus, Enterobacteriaceae [2], Lactobacillus [3], Listeria [4], or more recently Bacillus [5] and Coryneform Bacteria [6]. We are interested in food industry, and more particularly in characterizing strains of lactic acid bacteria involved in cheese manufacturing. We propose a FTIR method for a rapid identification of these bacteria. We point out that this method is able to identify spectra of different origins.

Comparison of IR spectra of species formed from adsorption of different bases on the acidic OH groups of zeolites (HY, MFI) indicates that O3 basicity is close to that of CO. Calculations confirm such a result ; in particular they involve that the terminal oxygen atoms of ozone are the basic centers.

La presence de certaines bacteries au sein d’un biofilm peut soit accelerer un processus de corrosion deja etabli, soit creer des conditions favorables a son elaboration. Les microorganismes consideres a ce jour comme les plus agressifs pour les materiaux metalliques en milieu marin sont les Bacteries Sulfato-Reductrices (BSR) et Thiosulfato-Reductrices (BTR). Des travaux preliminaires ont montre les potentialites de la spectroscopie InfraRouge a Transformee de Fourier (IRTF) pour la discrimination de ces 2 groupes. La realisation d’une bibliotheque de spectres de reference necessite la mise en place de conditions de cultures standardisees communes a l’ensemble de la flore etudiee. Une premiere bibliotheque spectrale incluant 6 BSR et 6 BTR de collection a ete elaboree. La classification hierarchique de ces 12 souches permet d’obtenir 3 clusters distincts (un de BSR, un de BTR et un mixte), et de discriminer l’ensemble de ces souches au niveau genre (11 souches sur 12) et au niveau espece (12 souches sur 12). Dix souches isolees de l’environnement ont ete testees sur cette bibliotheque, et un debut d’identification a pu etre propose. L’enrichissement de la base de donnees initiee sera poursuivi pour ameliorer les capacites d’identification des bacteries sulfurogenes isolees de l’environnement marin.