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RMN+ECI2D:ING+FWI:AGH:YMO:CLO:DFA:JEC; International audience; Herein, we report the molecular-level structuration of two full photosystems into conjugated porous organic polymers. The strategy of heterogenization gives rise to photosystems which are still fully active after 4 days of continuous illumination. Those materials catalyse the carbon dioxide photoreduction driven by visible light to produce up to three grams of formate per gram of catalyst. The covalent tethering of the two active sites into a singleframework is shown to play a key role in the visible light activation of the catalyst. The unprecedented long-term efficiency arises from an optimal photoinduced electron transfer from the light harvesting moiety to the catalytic site as anticipated by quantum mechanical calculations and evidenced by in-situ ultrafast time-resolved spectroscopy.

fff; International audience; Hydrocracking converts heavy feeds mainly into middle distillate products. Co-processing these bio-feeds with vacuum gas oil is a possible production route for biofuels. Stabilized bio-liquid from fast pyrolysis and hydrothermal liquefaction bio-crude were mixed with vacuum gas oil (10–20 wt%) and hydrocracked over a bifunctional catalyst. The impact of the bio-liquids on conversion and middle distillate selectivity were investigated. The liquid products were analyzed by several methods such as 2-dimensional gas chromatography coupled with simulated distillation to obtain quantitative distribution of monoaromatics, polyaromatics and saturated hydrocarbons. A quantification study of different types of carbons was performed by 13C NMR and showed the evolution of products. The nature of bio-liquid impacts slightly on the conversion and gas production but not on the selectivity of middle distillates and naphtha. This is explained by a decoupled hydrodeoxygenation and hydrocracking process. This also resulted in a high hydrodesulfurization conversion.

International audience; Bifunctional catalysis combining acidic catalysts and sulfide active phases is usually related to hydrocracking catalysts which balances the hydrogenation function of a NiMo (NiW) alumina supported sulfide catalysts and the acidic function of a zeolite. The discovery of sulfur-resistant catalysts for selective ring opening (SRO) is an important challenge for refiners, considering the future legislation on cetane index of diesel fuels. In the present work, we studied the properties of various transition metal sulfides (TMS) supported on Y zeolite in gas-phase decalin hydroconversion at high hydrogen pressure (5 MPa) in the presence of 0.8% H2S concentration. This screening shows high activities for noble metal based sulfides with a mechanism which proceeds by skeletal isomerization induced by the zeolite. Catalytic activity was improved by the use of ternary sulfides such as Ni1-xRuxS2 or NiRh2S4 on Y zeolites. High decalin conversion levels can be reached below 250°C with more of 20% of ring opening products and thanks to the use of comprehensive GC, a detailed mechanism of the SRO of decalin is given.

International audience; Direct C–H functionalization catalyzed by a robust and recyclable heterogeneous catalyst is highly desirable for sustainable fine chemical synthesis. Bipyridine units covalently incorporated into the backbone of a porous organic polymer were used as a porous macroligand for the heterogenization of a molecular nickel catalyst. A controlled nickel loading within the porous macroligand is achieved, and the nickel coordination to the bipyridine (bpy) sites is assessed at the molecular level using IR and solid-state NMR spectroscopy. The heterogenized Ni-bpy catalyst was successfully applied to the direct and fully selective C2 arylation of benzothiophenes, thiophene, and selenophene, as well as for the arylation of free NH-indole. Recyclability of the catalyst was achieved by employing hydride activators to reach a cumulative turnover number of more than 300 after seven cycles of catalysis, which corresponds to a total productivity of 12 g of 2-phenylbenzothiophene, chosen as model target biaryl, per gram of catalyst.

International audience; The valorization of lignin coming from pulp industry or bio-ethanol refineries into renewable chemicals is one of the great challenges of the biorefinery concept. Among the several processes proposed to depolymerize lignin, catalytic hydroconversion appeared efficient to get high liquid yield and can provide targeted aromatic monomers. A new semi-continuous set-up consisting in a batch reactor opened on the gas-phase was implemented to carry out the catalytic lignin liquefaction into phenolic and deoxygenated aromatic compounds with continuous H2 feeding. The interest of this equipment is the continuous removing of light products and water from the reacting mixture whereas the hydrogen donor solvent is reintroduced in the reactor via a reflux/condensing system. A Co-promoted Mo sulfide catalyst was used and thanks to efficient separation and extensive analysis, the components of the different gaseous, liquid and solid fractions obtained were identified and quantified. The evolution of the various fractions in function of the time and the deep investigation of the composition, allowed to propose a reaction scheme for the lignin depolymerization in those operating conditions.

RMN+ECI2D+LPI:DLA:CLO:CGE; International audience; The discovery of sulfur-resistant catalysts for selective ring opening (SRO) is an important challenge for refiners, considering the future legislation on cetane index of diesel fuels. In the present work, we studied the properties of RuS2 supported on several zeolites in gas-phase decalin hydroconversion at high hydrogen pressure (5 MPa) in the presence of 0.8% H2S concentration. Catalytic bifunctionality was investigated by changing the Ru loading or support acidity. The addition of RuS2 strongly improved catalytic activity of an HY zeolite, decreased coke deposition and dehydrogenation and increased selectivity towards RO products. The mechanism mainly proceeds from skeletal isomerization induced by the acidity of the zeolite but the hydrogen activation properties of RuS2 are beneficial to the activity and stability of the catalyst.

In this work, alkaline earth phosphates have been prepared by co-precipitation and evaluated in gas phase dehydration of ethyl lactate to acrylic acid and ethyl acrylate. These solids, which were previously shown to be active for the dehydration of lactic acid, appeared more efficient. Indeed, it was shown that the decarbonylation/decarboxylation route leading to acetaldehyde was strongly inhibited compared to conversion of lactic acid and molar selectivity values to dehydration products reaching 87% were obtained. Furthermore, it was shown that the deactivation of the catalysts could strongly be slowed by addition of water vapor to the feed. The reaction pathways have been studied in the presence and absence of water and it was shown that acrylic acid was mainly formed by a simultaneous dehydration/hydrolysis reaction. The characterization of the catalysts surface from the results of XPS, cross polarization NMR, DRIFT and TEM showed the presence of a surface amorphous layer containing POH species. In situ DRIFT measurements have revealed that formation of POH groups was favored under water vapor and that these species interacted with reactants or reaction products at the reaction temperature.

H4SiW12O40 heteropolyanions, WO3, TiO2 and SnO2 were supported over SiO2 at high loading by wet impregnation or grafting methods and evaluated in the dehydration of isobutanol to butenes. Their structural and textural properties were determined by different techniques such as XRD, TEM, IR, XPS and N2 liquid physisorption respectively. Most of the prepared compounds contained amorphous oxide clusters of few nanometers lying over SiO2 and were mesoporous. Their acidic properties (nature, density and strength) were investigated by pyridine and CO adsorption followed by FTIR. H4SiW12O40/SiO2 contained strong Bronsted acid sites while mostly moderate Lewis acid sites were present on TiO2/SiO2 and SnO2/SiO2. WO3/SiO2 had a mixed character with both moderate Bronsted and Lewis acid sites. The catalytic activity was related to the Bronsted acidity and the best selectivity to butenes close to 100% were obtained for the catalysts containing moderate and weak sites (WO3/SiO2 and TiO2/SiO2). Except for SnO2/SiO2 catalysts, which were unstable and unselective to dehydration products, a significant selectivity to linear butenes (ca 30%) was obtained with all the catalysts. It is proposed that this isomerisation activity is mainly related to the equilibrium between carbocations formed after E1 elimination of water. Its slight increase for H4SiW12O40/SiO2 (and to a lesser extent WO3/SiO2) was attributed to strong Bronsted acid sites able to catalyse the isomerization of isobutene to linear butenes.

Selective ring opening is an important hydrotreating process for gas oil upgrading. In this work, we have used an Ir/NaY bifunctional catalyst -highly efficient in sulfur-free conditions- as a reference system to assess the effect of H2S impurity concentration (0–1 %) on the kinetics and mechanisms of naphthene conversion under high hydrogen pressure (5 MPa). Three model naphthenic molecules (decalin, perhydroindan and butylcyclohexane) were compared to evaluate the influence of the ring size (C5 vs C6) and number (1 vs 2). The numerous reaction products were identified, quantified and classified by using two-dimensional gas chromatography (GC × GC). In the absence of sulfur, it is confirmed that C5 rings are opened faster than C6 rings, and that single-ring naphthenes are converted faster than double-ring naphthenes. The presence of H2S, even at concentrations as low as 30 ppm, drastically and irreversibly changes the dominant catalytic function (from metallic to acidic), mechanism (from dicarbene-mediated to carbocation rearrangement) and family of products (from ring-opening products to skeletal-isomerization products). Together with experiments at variable reactant conversion, these results allow us to propose mechanistic reaction schemes for the three naphthenes under similar conditions, both for sulfur-free and sulfur-rich atmospheres.

International @ RAFFINAGE+RHE:MTF:PAF:CLO; International audience; A new approach has been developed to characterize bifunctional catalysts in a complex matrix of hydrotreated vacuum gas oil, 370°C+ using a batch reactor test. Triphasic reactions were carried out in a reactor equipped with a stationary basket, hydrogen injection and products sampling systems. Bifunctional catalysts containing different relative amounts of alumina-supported NiMo sulfide and zeolite were tested at 400°C under 120 bars over different reaction times. The repeatability of the test conditions was validated and the lack of mass transfer limitations at phase interfaces was confirmed. Gas and liquid samples were analyzed by one and two-dimensional gas chromatography (2D-GCGCxGC) respectively to obtain quantitative distributions of linear and branched paraffins, olefins, naphthenes and aromatics. The details of the products distribution provided by the chromatography were analyzed using model kinetic mechanisms of bifunctional catalysis. It has been established that the limiting step defining the total conversion is scission of the hydrocarbon chains on zeolite sites. The increase of the molybdenum to zeolite ratio provided an improvement of selectivity to middle distillate (150-370°C)

International audience; Since the beginning of the 2000's, comprehensive GC x GC chromatography brought a totally new way to characterize complex matrices. This disruptive technique is well adapted to fuels and rapidly gained importance in R & D laboratories of oil (and related) companies. Therefore, this analytical tool has been applied to many aspects of refining and especially the challenge of reducing the sulfur content in fuels. The present article reviews the use of comprehensive GC x GC for understanding the nature of sulfur compounds in refinery products (from gasoline to VGO) and their catalytic conversion through various catalytic processes such as HDS, AOTS, ODS. Various types of detectors (universal or specific) as well as FIT GC x GC have been applied and can be combined in order to get a better description of the S compounds in oil products.

Ferrospinels with different metals—Fe, Ni, Co, and Cu—were investigated as oxygen ion and electron carrier materials for the chemical-loop reforming of ethanol, aimed at the production of H2 with intrinsic separation from CO and CO2. The materials used showed different behaviours both during the first step of the loop—the reduction of the annealed spinel with ethanol—and the second step—the re-oxidation with steam—as well as with the increasing cycle number. The differences shown were rationalised in terms of redox behaviour, carbon residue accumulation during the cycle, and ability to restore the starting spinel structure during cycling. Mixed ferrospinels showed enhanced reducibility when compared to magnetite; however, since coke accumulation was unavoidable, the best-performing material amongst the materials tested was Co ferrite, which underwent the greatest reduction and was able to maintain it throughout repeated cycles.

RMN+ECI2D+BJF:MNG:DLA:CLO:CGE; International audience; The hydroconversion of a wheat straw soda lignin was studied in a batch reactor, in tetralin solvent, with a NiMoS/Al2O3 catalyst under H-2pressure at 350 degrees C. Gaseous, solid and liquid products wereseparated, quantified and detailed analyses were performed in order todescribe and to understand the various reactions occurring versusresidence time. In those operating conditions, the weakest beta-O-4 andalpha-O-4 ether linkages of the lignin were first cleaved. The ligninwas thus progressively converted into smaller hydrogenated anddeoxygenated fragments called lignin residues which were extensivelycharacterized by GPC and NMR. In the liquid phase, smaller monomers anddimers were identified by GC x GC/MS and quantified by GC x GC/FID. Theevolution of these molecules was investigated as a function of residencetime in order to investigate the catalytic transformation scheme oflignin. (C) 2015 Elsevier B.V. All rights reserved.

XPS:RMN+ECI2D+LMA:CLO:PAF:JMI; International audience; Four preparation methods have been developed for the synthesis of lanthanum orthophosphate catalysts, which are shown to be active and selective catalysts for the dehydration of light alcohols (C-2 to C-4). Their crystallinity, surface area, surface composition and acid-base properties appear to differ according to the preparation method used. The most important parameter influencing their catalytic properties appears to be their surface composition since this has a direct influence on their surface acidity. All of the solids presented weak and moderately strong Bronsted and Lewis acid sites, and only weak basic sites in low quantities. These acid-base properties resulted in the prevalence of an E-1-type mechanism for 1-butanol dehydration. Bronsted acid sites, which appear as the most efficient sites, are associated with the presence of an excess of phosphorus at their surface and from spectroscopic data this is attributed to (H2PO4)(-3+n) (n=1 or 2) species from spectroscopic data. The prevalence of these species and their optimum surface distribution make them extraordinarily efficient and ultra-selective for the dehydration of several alcohols. Published by Elsevier B.V.

Drastic regulations concerning sulfur content in fuels require the development of new processes in the refineries. In the case of gasoline, AOTS process based on the alkylation of thiophene by butenes was proposed. In the present work, we attempted to describe the mechanism of such a reaction with model molecules. Liquid-phase alkylation of 3-methylthiophene with 2-methyl-2-butene was performed on supported phosphoric acid. It is shown that this reaction is mainly selective to monoalkylation products. The kinetics is following an Eley–Rideal law and the reaction intermediate seems to be an ester of phosphoric acid or polyphosphate.

The H/D exchange reaction between isobutane and acidic USY zeolite was studied using mass spectrometry and in situ1H NMR. An inhibiting effect of hydrogen on this reaction was observed. The H/D exchange is enhanced by both in situ and ex situ addition of small amounts of isobutene. A kinetic isotope effect of 1.5 was found for the H/D exchange of isobutane and 2-deuterium-labeled isobutane over D2O-exchanged HUSY (DUSY), as well as nondeuterated and perdeuterated isobutane over HUSY. The occurrence of a primary kinetic isotope effect (KIE) indicates that the slow step of the H/D exchange reaction involves a cleavage of the tertiary CH (or CD) bond in isobutane. After addition of small amounts of isobutene to the feed or pretreating the catalyst with small amounts of isobutene before starting the H/D exchange reaction, the KIE still exists, suggesting that the limiting step for the H/D exchange reaction between isobutane and acidic zeolite is the hydride transfer from an alkane to the exchanged cation.

RAFFINAGE+JBI:CJN:CLO:PDE:SLO:JMI; International audience; Several techniques such as Al-27 800-MHz NMR, X-ray diffraction (XRD; powder), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), Raman spectroscopy, and electrical conductivity measurements have been applied to characterize VAlO mixed oxides used in the selective ammoxidation of propane to acrylonitrile. The results confirmed that the catalysts were nitrided when exposed to ammoxidation conditions and that the nitridation occurred only for mixed oxides. The solids corresponding to poorly crystallized x-alumina contained usual six-, five-, and four-coordinated aluminum and after testing, AlO3N species in significant amount. These results are in line with those of XPS showing besides adsorbed nitrogenous species, the presence of NH2- species allowing to propose AlO3(NH)VO5,6 as active site for catalytic nitridation. On another side, the samples prepared by a new method allowing to better disperse vanadium in the mixed oxide as shown by EPR, were shown to be more active and selective. Based on these observations, it is proposed that most selective sites for propane activation correspond to monomeric isolated species or to low-size oligomeric vanadium oxide species, which is in line with any other study of vanadium containing catalysts used for light alkanes oxidation or ammoxidation. Finally, nitrogen substitution in the bulk was shown to greatly enhance the electrical conductivity, which should facilitate the complete catalytic redox cycling.

International audience; The oligomerization of glycerol to di- and triglycerol is an attractive reaction because these products find many applications in cosmetics, food industry and polymer industry. To control the oligomerization degree, it is necessary to develop a selective catalyst. In this work, two cesium mesoporous silica (MCM-41 and SBA-15) are compared in the selective oligomerization of glycerol into di- and triglycerol. The catalysts were prepared by incipient-wetness impregnation. The results showed that the stability and the activity of catalysts depend on the support nature. The use of SBA-15 support instead of MCM-41 leads to a more stable catalyst without changing polyglycerols selectivity. Different characterizations showed that it is due to the larger wall thickness of SBA-15. This study also showed that the nature of catalyst could influence the diglycerol isomers distribution. In fact the glycerol activation inside or outside the pores can strongly modify the selectivity to linear or branched diglycerol isomers.

Pyridinium salts of H 3 PW 12 O 40 and H 3 PMo 12 O 40 were investigated by 1 H NMR and IR spectroscopies. 1 H NMR evidenced the formation of bi-pyridinium cation in the pyridinium salt of H 3 PW 12 O 40 , while a classical pyridinium cation was identified in the pyridinium salt of H 3 PMo 12 O 40 . Pyridinium and bi-pyridinium species were clearly differentiated by infra red spectroscopy: The bi-pyridinium cation is characterized by the splitting of the 8b and 19b vibration modes of the pyridinium ring.