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International audience; Mesoporous TiO2 films with enhanced photocatalytic activity in both UV and visible wavelength ranges were developed through a non-conventional atomic layer deposition (ALD) process at room temperature. Deposition at such a low temperature promotes the accumulation of by-products in the amorphous TiO2 films, caused by the incomplete hydrolysis of the TiCl4 precursor. The additional thermal annealing induces the fast recrystallisation of amorphous films, as well as an in situ acidic treatment of TiO2. The interplay between the deposition parameters, such as purge time, the amount of structural defects introduced and the enhancement of the photocatalytic properties from different mesoporous films clearly shows that our easily upscalable non-conventional ALD process is of great industrial interest for environmental remediation and other photocatalytic applications, such as hydrogen production.

In this study, we investigated the beneficial properties of ZnO nanowires grown via a MOCVD (Metal Organic Chemical Vapor Deposition) process for the photocatalytic treatment of a solution containing seven xenobiotics that are commonly found in waste or surface water. A physicochemical characterization of the ZnO nanowires was performed to highlight the advantages of the high-temperature gas-phase MOCVD process for the synthesis of photocatalytic ZnO materials. In addition, the photocatalytic degradation of carbamazepine, diclofenac, lidocaine, metoprolol, propranolol, sulfadimidine and atenolol was studied for the first time using a one-step experiment under a low power 365 nm UV light (2.28 mW cm −2 ). We determined the fast photodegradation kinetics of all of the xenobiotics present in the solution. These results support the use of photocatalytic methods for the removal and degradation of xenobiotics.

Co-KIT-6 mesoporous materials with Ia3d symmetry and Si/Co ratios of 50, 25, and 10 were prepared using hydrothermal one-pot synthesis. The Co-KIT-6 mesoporous materials were characterized by X-ray diffraction, N2 adsorption–desorption isotherms, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared, and X-ray photoelectron spectroscopy. The physicochemical characterization results show that all of the samples have well-ordered cubic mesostructures and that the structural integrity is preserved for nSi/nCo ratios as high as 10. It was found that most of the cobalt ions exist as isolated framework species, but for Co-KIT-6 with an nSi/nCo ratio of 10, the presence of extra-framework species/small cobalt oxide clusters cannot be excluded. The ability of these catalysts was tested by examining the conversion of the reaction of methylcyclopentane with hydrogen at atmospheric pressure and temperatures between 200 and 450 °C. The catalytic results show that their catalytic activity increases significantly with increasing cobalt content. The active sites, tetrahedrally coordinated Co and isolated atomic Co sites, were responsible for the endocyclic C C bond rupture between substituted secondary–tertiary carbon atoms, whereas the small clusters serve as active sites for the successive C C bond rupture. The ring-opening selectivity can be improved by increasing the density of isolated cobalt atom sites at low reaction temperatures.

Anatase TiO2 films with unusual domains-like morphology were obtained by postdeposition annealing of amorphous TiO2 films deposited by atomic layer deposition (ALD). Such particular morphology was observed only for TiO2 films deposited using TiCl4 precursor in a nonconventional ALD regime where the reaction byproducts or nonreacted precursors are incorporated into the film and induce an explosive recrystallization upon annealing. This recrystallization leads to the formation of micrometric single crystal domains. The investigation of domains by electron backscatter diffraction shows the formation of a significant amount of highly reactive anatase crystalline facets such as (111) that contradicts fundamental crystal growth rules. The stabilization of (111) facets in films without additional seed layers has a strong interest for photocatalysis-based applications for environmental remediation or hydrogen production.

Resume Cette revue resume le statu quo et les perspectives quant a la reaction de methanation. La methanation du CO2, incluant les reacteurs, les mecanismes, la thermodynamique et la desactivation des catalyseurs, est presentee. Cette reaction sert a la comprehension fondamentale de la catalyse heterogene et est utilisee dans divers procedes industriels, y compris l'elimination des composes oxo (COx) dans le gaz d'alimentation pour la synthese d'ammoniac, dans le cadre de la gazeification du charbon, et peut etre utilise pour produire du methane a partir du gaz de synthese, et pour la synthese Fischer–Tropsch. En outre, la methanation du CO2 est devenue d'interet en tant que systeme de stockage d'energie renouvelable basee sur le processus power to gas par GNS de production (gaz naturel synthetique) integrant l'electrolyse de l'eau et la methanation du CO2 comme un moyen tres efficace pour stocker l'energie produite par les energies renouvelables. L'efficacite et l'efficience des centrales power to gas depend fortement du processus de methanation du CO2.

Surface-phosphated NiO catalysts with different phosphorus contents were prepared and used for ethane oxidative dehydrogenation (ODH) in the temperature range from 300 to 425 °C. The catalysts were characterized by nitrogen adsorption at −196 °C, XRD, ICP-OES, XPS, TEM, and Raman spectroscopy. They were also characterized by in situ electrical conductivity measurements at various temperatures and oxygen partial pressures, and the temporal response of the electrical conductivity to sequential exposure to air, an ethane–air mixture (reaction mixture) and pure ethane was recorded under conditions similar to those employed in the catalytic experiments. Adding increasing amounts of phosphorus to NiO changes its physicochemical characteristics; specifically, both the concentration and mobility of the surface lattice O− species in the NiO material decrease considerably, affecting its catalytic performance in ethane ODH. Thus, increasing the P content in NiO leads to a decrease in its catalytic activity with an increase in its ODH selectivity at the expense of total oxidation selectivity in the temperature range studied.

The direct hydrothermal synthesis of Fe-KIT-6 mesoporous materials with Ia3d symmetry and high iron loadings is reported for the first time. The Fe-KIT-6 mesoporous materials were characterized by XRD, N 2 adsorption/desorption isotherms, SEM, FT-IR, XPS and EPR spectroscopy. The physico-chemical characterization results show that all of the samples have well-ordered cubic mesostructures and that the structural integrity is preserved for n Si / n Fe ratios as high as 10. It was found that most of the iron ions exist as isolated framework species, but for Fe-KIT-6 with an n Si / n Fe ratio of 10, the presence of extra-framework species/small iron oxide clusters cannot be excluded. The catalytic performances of these materials were tested for carbon dioxide (CO 2 ) hydrogenation and methylcyclopentane (MCP) conversion. The catalytic results show that their catalytic activity increases significantly with increasing iron content. For the MCP conversion, the ring-opening selectivity can be improved by increasing the density of isolated iron atom sites at low reaction temperatures. For the CO 2 hydrogenation, the methanation selectivity can be improved by increasing the iron active site density and employing a high reaction temperature. Specifically, the high density of iron sites at high catalyst loadings promotes the methanation reaction at the expense of the RWGS (reverse water gas shift) reaction. Thus, the Fe-KIT-6 materials appear to be suitable catalysts for MCP conversion at low temperatures and CO 2 hydrogenation at high temperatures.

This special issue of Catalysis Science & Technology pays tribute to the scientific work of François Gault.

Polyacrylamide (PAAm) was chemically modified with hydroquinone (HQ) via a homolytic route. A degree of modification of approximately 58% was obtained under optimal reaction conditions: time of 6 h, and [modifier]/[acrylamide] molar ratio of 5. PAAm and its modified form HQ–PAAm were characterized by UV–visible spectroscopy, FT–IR spectroscopy, 13C NMR spectroscopy, DSC, TGA, XRD, and SEM. A relatively lower molecular weight of the corresponding hydroquinone-functionalized form was measured. The glass transition temperature of the modified polymeric material was lower than that of the pristine one: 78.82 °C for HQ–PAAm versus 161.19 °C for PAAm. A study of Cu(II) adsorption by the cross-linked PAAm and HQ–PAAm resins was conducted by varying the following parameters: pH, time, temperature, ionic strength, sorbent mass, and initial Cu(II) concentration. The adsorption capacity of Pb(II) and Cd(II) by the different resins and their corresponding extents of desorption were estimated. The optimal conditions for metal ion uptake by polyacrylamide and its modified resin were: pH = 5.4, time = 120 min, temperature = 45 °C. The sorption extent by the modified resin was in the order Pb(II) > Cu(II) > Cd(II). The desorption of the experimented metallic ions from the resins exceeded 97%. A new way of cross-linking PAAm and its modified form is described herein.

International audience; The effect of water on NOx storage performance of a Pt/BaO/Al2O3 catalyst was investigated. The adsorption capacity of a model NOx storage-reduction system (NSR) catalyst was studied in the presence of NO, oxygen, and water in nitrogen. Fixed-bed and in situ DRIFTS adsorption tests were carried out in order to evaluate the influence of water on the adsorption capacity of the catalyst, adsorbed species on the surface of the catalyst, and stability of these species. The presence of water slightly reduces the NOx storage capacity of the NSR catalyst. A decrease of platinum oxidation activity was observed which was correlated to a slowdown of surface bidentate nitrate formation, detected by in situ DRIFTS tests. On the other hand, surface monodentate nitrates were favored and formation of bulk nitrates was not affected. A set of reactions corresponding to these observations is proposed.

The activities of Pt/WO2, Ir/WO2 and Pt–Ir/WO2 toward the conversion of methylcyclopentane (MCP) were investigated. The catalysts were prepared using impregnation and co-impregnation methods and were characterized by SEM, XRD, N2-sorption and TEM investigations. The most active catalyst toward the conversion of MCP, irrespective of the temperature, was Ir/WO2. The order of the reactivity was Ir/WO2 > Pt–Ir/WO2 > Pt/WO2. Strong metal–support interactions (SMSI) were observed for all the catalysts over the entire investigated temperature range. At 400 °C, the Pt and Pt–Ir showed 100% selectivity toward ring-enlargement reactions associated with the presence of electron-deficient adduct sites on the reducible acidic WO2 support. Ring opening occurred over all the catalysts in three positions, resulting in the formation of 2-methylpentane (2-MP), 3-methylpentane (3-MP), and n-hexane (n-H). Difficulty in breaking the secondary – tertiary carbon bonds was observed predominantly on the Ir catalyst, which opens the MCP ring via a selective mechanism.

Direct hydrothermal synthesis (HT), template ion-exchange (TIE) and molecular dispersion (MD) approaches were used to introduce manganese species into MCM-48-type mesoporous materials. The tungsten was highly dispersed within the channels of mesoporous MnMCM-48 samples by chemical grafting (CG) via a liquid–solid reaction. The prepared manganesosilicate and tungstenomanganesosilicate MCM-48-type mesoporous materials were characterized by physico-chemical techniques, including TEM, N2 sorption, XRD, XPS, UV-Vis and elemental analysis. The physico-chemical characterization revealed that all of the samples retained a high surface area, a regular cubic mesoporosity and that the Mn and W were highly dispersed. The higher unit cell parameter/pore wall thickness values of the MnMCM-48 and WMnMCM-48 samples relative to that of pure MCM-48 indicate the incorporation of Mn and W into the framework/channels of MCM-48. The Mn and W species existed as isolated sites in the framework/extra-framework or as monomolecular species. No bulk manganese or tungsten was observed outside the MCM-48-type mesoporous materials. The coexistence of Mn2+, Mn3+ or/and W6+ was evidenced by XPS and UV-Vis spectroscopic measurements. The catalytic activities of these samples were studied with respect to the conversion of methylcyclopentane (MCP) in reductive media as a function of Mn loading and reaction temperature (200–500 °C). Whatever the manganese content and irrespective of the temperature of reaction, the MnMCM-48 mesoporous samples did not exhibit catalytic activity, which suggests that the electrophilic manganese oxygen species, operative over all the samples, were inactive sites for the conversion of MCP. The addition of tungsten favored catalytic activity. When the WMnMCM-48 was not calcined, only the methane (C1) cracking product was observed to be formed by successive rupture of C–C bonds starting at 400 °C. When the WMnMCM-48 was calcined, ring-opening products formed by the C–C rupture, at substituted and unsubstituted carbon atoms, were observed starting at 400 °C. This behavior is associated with a symbiotic process between the MnMCM-48 support and the W nanoparticles.

Fe-TUD-1 catalysts with Si/Fe ratios of 85, 65 and 45 were prepared via hydrothermal one-pot synthesis. The samples were characterized by XRD, N2 physisorption, UV–vis and XPS spectroscopies, which show the incorporation of Fe3 + in tetrahedral coordination. The ability of these catalysts was tested by examining the conversion of the reaction of methylcyclopentane (MCP) with hydrogen at atmospheric pressure and temperatures between 200 and 400 °C. The active sites, tetrahedrally coordinated Fe and isolated atomic Fe sites, were responsible for the endocyclic C C bond rupture between substituted secondary-tertiary carbon atoms, while the small clusters serve as active sites for the successive C C bond rupture.

An investigation of the selective ring-opening of methylcyclopentane (MCP) was conducted for the first time on Pt/TiO2, Ir/TiO2 and Pt–Ir/TiO2 catalysts with low amounts of noble metals (0.5 wt%) over a temperature range of 180–400 °C under hydrogen at atmospheric pressure. The catalysts were prepared by impregnation or co-impregnation and characterized by different physico-chemical techniques, including SEM, XRD, H2-TPR, N2-sorption, TEM and elemental analysis. The metallic particles were highly dispersed on the TiO2 support at isodispersion of ~1 nm. The particles exhibited icosahedral Mackay structures limited by (111) planes. The catalytic results show that the activity in the MCP was strongly influenced by the intrinsic nature of the metal and by the temperature. The most active catalyst was Ir/TiO2. The order of the reactivity as a function of the temperature and total conversion was Ir/TiO2 180 °C (α = 2 %) > Pt–Ir/TiO2 220 °C (α = 27.8 %) > Pt/TiO2 260 °C (α = 9.9 %). Under these conditions, all of the catalysts exhibited the ability to open the ring of MCP with an atom economy, without unwanted products of cracking and ring-enlargement reactions. The synergy between Pt–Ir bimetallic particles was assessed by the total conversion of MCP, whereas the ring-opening results indicated that the reaction took place on Ir sites. These results suggest that the bimetallic catalyst contained separate entities of two metals. Increased reaction temperatures led to reduced reaction selectivity with respect to ring-opening of MCP versus the cracking side reaction.

Mo, Fe and Mo–Fe catalysts were prepared by the solid–solid method and systematically characterized by XRD, SEM, TEM, N2 sorption, H2-TPR, UV–vis, XPS and EPR physico-chemical techniques. The dispersion and the nature of the metal species depended strongly on the metal content. At low metal contents, isolated tetrahedrally coordinated metal entities and small nanoclusters were observed, whereas aggregates were formed at high metal loadings. The superior catalytic performance in the ring opening of MCP has been attributed to the highly dispersed isolated tetrahedral entities and highly dispersed small FeOx nanoclusters. The aggregates favor the cracking reactions.

Pt/γ-Al 2 O 3 , Ir/γ-Al 2 O 3 and Pt-Ir/γ-Al 2 O 3 were prepared by incipient wetness impregnation and co-impregnation methods. The catalysts were characterised by the classical physico-chemical techniques of SEM, TEM, XRD, N 2 -sorption, H 2 -TPR and elemental analysis. The metallic particles were highly dispersed on the support, assuming the presence of an icosahedral Mackay structure, which is a limited only by (1 1 1) face. The performances of the catalysts were investigated in the conversion of methylcyclopentane (MCP) with hydrogen at atmospheric pressure at temperatures between 180 and 400 °C. At low temperature, only Ir/γ-Al 2 O 3 showed the ability to open MCP with an atom economy ( S RO = 100%) and without by-products from cracking and ring enlargement reactions. Ir/γ-Al 2 O 3 opened the MCP ring at the secondary–secondary positions. The Pt/γ-Al 2 O 3 and Pt-Ir/γ-Al 2 O 3 catalysts opened MCP starting at 220 °C, in the secondary–tertiary positions, with atom economy ( S RO = 100%). The synergistic effect between Ir and Pt was observed in our conditions, but the Pt and Ir particles existed also as individual entities on the support. At high temperature, all the catalysts were inactive in MCP ring opening. Cracking reactions became more pronounced with increasing temperature and parallel decreases in ring opening selectivities. The formation of benzene was observed at high temperatures only on Pt/γ-Al 2 O 3 .

The effect of the metal and reaction temperature was investigated in the conversion of MCP with hydrogen at atmospheric pressure. The highly dispersed 0.5 wt.% Pt/MoO2, 0.5 wt.% Ir/MoO2 and 0.25 wt.%–0.25 wt.% Pt–It/MoO2 metal catalysts were prepared by incipient wetness impregnation or co-impregnation methods. The most active catalyst in the conversion of MCP was Pt/MoO2 and the most selective to MCP ring opening was Ir/MoO2. At low temperature, Ir/MoO2 opened the MCP ring at the secondary–secondary position. High temperature promoted ring opening at the secondary–tertiary positions, which was attributed to the adlineation sites. At low temperatures, Pt/MoO2 and Pt–Ir/MoO2 promoted only the ring enlargement reaction while Ir/MoO2 promoted both ring opening and ring enlargement. Ring enlargement of MCP to cyclohexane and benzene was catalysed by electron deficient adduct sites, while ring opening to 2-meythylpentane (2-MP), 3-methylpentane (3-MP) and n-hexane (n-H) was catalysed by metallic sites. At high temperatures, MCP broken into C1–C5 fragments and deactivation of the catalysts was observed. The Ir/MoO2 showed the highest selectivity for cracking. The differences in selectivity were attributed to the presence of adsorbed agostic species, where the electronic environment of Ir and Pt are different.

Catalysts based on chromium supported by sulphated and unsulphated zirconia have been synthesised, in one step, by sol–gel method and dried in hypercritical solvent conditions. Comparative study of their catalytic properties shows that dispersed Cr3+ seems to be the active species in the n-hexane aromatisation reaction. However, the acidity generated by sulphate groups acts as coke eliminator of the layers deposed on the surface mainly when catalyst is calcined at high temperature.

A high dispersion of Co3O4 and Mn3O4 nanoparticles on SBA-15 mesoporous silica was carried out thanks to a two-solvent impregnation method. This kind of preparation allows a proper control of both the metal oxides loading (7 or 30 wt.%) and the particle sizes (10–12 nm). A complete set of physico-chemical characterisations of Co3O4 and Mn3O4 supported oxides on SBA-15 was realized using several techniques such as XRD, BET, TEM and XPS, to correlate the structures of the materials with their catalytic activities. Co3O4/SBA-15 and Mn3O4/SBA-15, 7% in weight, exhibit a high catalytic performance in the combustion of methane under Lower Explosive Limit (LEL) conditions, comparable to the well-known LaBO3 (B = Co or Mn) perovskite-type. The efficiency of the catalysts can be explained by the organised porous meso-structure of the SBA-15. Indeed, the mesoporous support creates a confinement medium which permits a high dispersion of metal oxide nanoparticles. The Co3O4 and Mn3O4 nanoparticles supported on SBA-15 become therefore novel efficient combustion catalysts at low metal oxides' loading.

Catalysts based on crystalline nanoparticles of Mn and Co metal oxides supported on mesoporous silica SBA-15 have been developed. These materials were characterized by XRD, BET and transmission electron microscopy (TEM) techniques. SBA-15 mesoporous silica was synthesized by a conventional sol–gel method using a tri-block copolymer as surfactant. Supported Mn3O4 and Co3O4 nanoparticles were obtained after calcination of as-impregnated SBA-15 by a metal salt precursor. The catalytic activity was evaluated in the combustion of methane at low concentration. Co3O4/SBA-15 (7 wt.%) exhibits the highest performance among the different oxides. Furthermore, this novel generation of catalysts appeared as active as conventional LaCoO3 perovskite, usually taken as reference for this reaction. Thanks to its organized meso-structures, SBA-15 material creates peculiar diffusion conditions for reactants and/or products.

The present study contemplates the application of Ru-based bimetallic alloys for hydrogen generation by hydrolysis of sodium tetrahydroborate (NaBH4). Ru and Pt, RuCu, RuPd, RuAg and RuPt (atomic ratio 1:1), PtAg, and RuxPty (atomic ratios x:y of 2:1 or 1:2), all supported over titanium oxide, were prepared. Their activity decreased in the order Ru∼Ru2Pt1 > RuPt∼Ru1Pt2 > RuPd > RuAg∼Pt > RuCu > PtAg. Alloying Ru with an inactive metal like Cu, Pd or Ag did not improve the performances of Ru. The catalytic ability of Ru2Pt1-TiO2 is in the range of the highest values reported so far in the literature with a hydrogen generation rate of 15.2 L(H2) min−1 g−1(RuPt). After separation from the reaction medium and rinsing with deionised water, the used Ru2Pt1-TiO2 catalyst was re-evaluated and almost the same catalytic activities as fresh catalyst were obtained during several cycles.

The hydrolysis of sodium tetrahydroborate is a promising way for generating hydrogen. The key element of this process is the catalyst. The present study reports the performances of Pt-based catalysts (supported over various metal oxides like TiO2 or ZrO2, with different Pt loadings, or doped with metal-‘impurities’ like Ag or Pd). TiO2 is the best support and the optimal Pt loading is 2 wt%. Addition of metal-‘impurities’ to Pt is detrimental to the performances of Pt-TiO2. However, the first results with Pt Pd-TiO2 are even, so promising for the continuation of such a study. The present paper discusses these results.

Co3O4 and Mn3O4 nanoparticles were successfully impregnated on SBA-15 mesoporous silica. A high dispersion of these metal oxide particles was achieved while using a “two-solvents” procedure, allowing a proper control of the metal oxides loading (7 wt%) and size (10–12 nm). These Co3O4 and Mn3O4 supported oxides on SBA-15 were characterised by means of XRD, BET and TEM techniques. The influence of the nature of the silica support was investigated in terms of porosity and specific surface area. Since, an improved catalytic activity was achieved over SBA-15 mesoporous silica; it appears that its organised porous meso-structure creates a confinement medium which permits a high dispersion of metal oxide nanoparticles. Supported Co3O4/SBA-15 (7 wt%) showed the highest catalytic performance in the combustion of methane under lower explosive limit conditions, comparable to perovskites. These materials become therefore novel efficient combustion catalysts at low metal loading.

Sulfadiazine, pyrimethamine, and atovaquone are widely used for the treatment of severe toxoplasmosis. Their in vitro activities have been almost exclusively demonstrated on laboratory strains belonging to genotype I. We determined the in vitro activities of these drugs against 17 strains of Toxoplasma gondii belonging to various genotypes and examined the correlations among 50% inhibitory concentrations (IC 50 s), growth kinetics, strain genotypes, and mutations on drug target genes. Growth kinetics were determined in THP-1 cell cultures using real-time PCR. IC 50 s were determined in MRC-5 cell cultures using a T. gondii -specific enzyme-linked immunosorbent assay performed on cultures. Mutations in dihydrofolate reductase (DHFR), dihydropteroate synthase (DHPS), and cytochrome b genes were determined by sequencing. Pyrimethamine IC 50 s ranged between 0.07 and 0.39 mg/liter, with no correlation with the strain genotype but a significant correlation with growth kinetics. Several mutations found on the DHFR gene were not linked to lower susceptibility. Atovaquone IC 50 s were in a narrow range of concentrations (mean, 0.06 ± 0.02 mg/liter); no mutation was found on the cytochrome b gene. IC 50 s for sulfadiazine ranged between 3 and 18.9 mg/liter for 13 strains and were >50 mg/liter for three strains. High IC 50 s were not correlated to strain genotypes or growth kinetics. A new mutation of the DHPS gene was demonstrated in one of these strains. In conclusion, we found variability in the susceptibilities of T. gondii strains to pyrimethamine and atovaquone, with no evidence of drug resistance. A higher variability was found for sulfadiazine, with a possible resistance of three strains. No relationship was found between drug susceptibility and strain genotype.

For the first time, solid acid sulphated-zirconia (ZrO 2 – SO 4 2 - , SZ) has been used as support of metal catalysts for hydrogen generation from catalytic hydrolysis of alkaline solution of sodium tetrahydroborate NaBH 4 . SZ was prepared according to an optimised one-step sol–gel method. Pt- or Ru-promoted SZs (Pt–SZ or Ru–SZ) were then got by wet impregnation. On the one hand, Pt–SZ was rather inefficient. On the other hand, Ru–SZ showed very promising hydrogen generation abilities with a hydrogen generation rate of ∼10 L(H 2 ) min −1 g −1 of Ru. This performance is one of the best ones published in the literature.

Pure hydrogen can be catalytically generated by hydrolysis of sodium tetrahydroborate NaBH 4 . The present paper reports the kinetics of hydrolysis of aqueous alkaline solution of NaBH 4 . The investigated catalyst was 1 wt% Ru-promoted sulphated zirconia. The reaction orders for both NaBH 4 and NaOH, the reaction order for Ru and the apparent activation energy were determined. The hydrogen generation rate can be written following a power law: r = k [NaBH 4 ] 0.23 [NaOH] −0.35 [Ru] 1.27 . The activation energy for the hydrogen generation reaction is of 76 kJ mol −1 . Otherwise, the present paper shortly reviews the kinetic data that are available in the open literature and notices the discrepancies that exist for these data. The kinetic data of the present study also contribute to these discrepancies.

International audience; Interaction between a model soot (carbon black) and a model NOx storage reduction catalyst (Pt-Ba/Al2O3) is investigated as a function of the strength of the carbon–catalyst contact and the presence or not of H2O in the reactive gas flow. Experiments performed at laboratory scale, using a fixed bed reactor, revealed that the inhibiting effect of carbon on the NOx storage capacity (NSC) of the catalyst increases with the strength of carbon–catalyst contact and affects NOx adsorption on both Al sites and Ba sites, whereas the oxidative function of the catalyst (Pt sites) is not affected. In the presence of water in the reactive gas flow, it was observed that carbon prevents the inhibition of the oxidative function of the catalyst by H2O. On the other hand, the inhibiting effect of carbon on NSC decreases. Hence, a noncumulative effect of carbon and H2O impacts on NSC is observed. © 2015 American Institute of Chemical Engineers Environ Prog, 35: 14–19, 2016

It is shown that catalytic heterogeneous hydrogenation over Ru/Al2O3 of mono- and di-substituted phenols (1–4) works and provides mixtures of the two or four possible isomers. Although cis and all-cis isomers (corresponding to all-syn H2 additions) are less stable, they are always major. It is also observed that large alkyl substituents and carbomethoxy groups have a tendency to increase the diastereoselectivity and that formation of larger amounts of the trans isomers is related to the presence of an OH group thus supporting intermediate formation of the corresponding ketone as already suggested.

The present paper continues and terminates our previous studies devoted to platinum supported on sulphated zirconia (Pt/SZ). More particularly, it deals with iridium or palladium supported on SZ (Ir/SZ or Pd/SZ) which kinetic data were determined for the n -heptane conversion. Both display similar catalytic behaviours since their kinetic data follow similar evolutions with the variations of temperature and hydrogen pressure. The results suggest that the catalysis is bifunctional at 150 °C and hydrogen pressures below 101,325 Pa, while it becomes acid with the increase of both temperature and hydrogen pressure. The main difference between Ir-or-Pd/SZ and Pt/SZ is the number of functions of the active metal–proton adduct site that are involved in the reaction at 150 °C and hydrogen pressures above 101,325 Pa. The metal–proton adduct is a single active site that gathers together two functions, the metal and the acid functions.

This paper studies the isomerization mechanisms of 3-methyl(3- 13 C)pentane over Pt supported sulphated zirconias (SZs). Pt hydrogenates the reaction intermediates that desorbs, hinders successive isomerizations from occurring and reduces the isomerization steps to two (three with Pt-free SZs). The isomerization is a monomolecular process to which Pt does not participate. Lastly, it is suggested that the ratio between the proportions of methyl migration and ethyl migration could be appreciated as a catalyst intrinsic characteristic.

International audience; This paper highlights the use of Al2O3 and SnO2 films as protecting layers to tailor the optical properties and biocompatibility of ZnO nano-films. ZnO, ZnO/Al2O3 and ZnO/SnO2 nano-films have been deposited inside 3-dimensional (3D) structures such as anodic aluminium oxide (AAO) membranes via a gas phase atomic layer deposition (ALD) process. We show that ZnO/Al2O3 multilayers exhibit improved excitonic photoluminescence properties compared to ZnO only, whereas ZnO/SnO2 multilayers quench the near band edge emission signal. In addition, in vitro experiments on Caco-2/TC7 cells and Vibrio fischeri bacteria reveal that ZnO/Al2O3 and ZnO/SnO2 multilayers display enhanced biocompatibility in liquid media compared to ZnO. We attribute the improvement of the biocompatibility to a lower dissolution of the ZnO nano-film when protected by Al2O3 or SnO2.

In this work, we have evidenced the impact of stoichiometry on the photocatalytic properties of ZnO nanofilms grown by atomic layer deposition (ALD). We point out the importance of hydrogen incorporation and propose here a model explaining the presence of Zn–OH impurities in the form of a ZnOxHy amorphous matrix hosting ZnO crystallites. We evidence that this phase prevails in films grown at low temperatures and prevents the photoluminescence and photocatalytic activity of ZnO films. We also point out that high temperature ALD processes promote the preferential growth of ZnO films in the (002) orientation, leading to a significant increase of the film wettability and so their photocatalytic degradation performances.

The isomerization on sulphated zirconias of the 3-methyl(3-13C)pentane, molecule chosen to distinguish between the methyl and ethyl migrations, is studied. The products distribution shows 0% for the 3-methylpentane isotopomers (not detected? or not formed?), what makes the interpretations difficult. Supposing these molecules formed in low proportions but not detected, a reaction pathway involving protonated cyclopropanes is proposed: the isotopomers are obtained from one- two- or three-step reactions. However, it is envisaged the possible non-formation of these molecules and a reaction pathway involving protonated cyclopropanes, cyclobutanes and bicyclopropanes is suggested: the 13C-label scrambling would be a two-step isomerization and the other isotopomers would be formed via a one-step reaction. The relative proportions of methyl migration (MM) and ethyl migration (EM) are assessed. The MM/EM ratio could be appreciated as an intrinsic characteristic of the catalyst because of correlations with, e.g. the crystalline structure, the sulphate content and the activity. Such correlations knowledge could help preparing catalysts with high activity and selective reactivity.

Hydrogen pressure is often found to cause an inhibiting effect on the kinetics of alkane reactions on metal surfaces. The most common interpretation of such results is focussed on the degree of dehydrogenation of the active surface intermediate following a dissociative mechanism. A series of arguments will be given in favour of an associative mechanism in which the hydrocarbon reacts with an adsorbed hydrogen atom. In this mechanism, the adsorption site or “landing site” is composed of a chemisorbed hydrogen atom associated with an ensemble of “Z” potential sites. These sites are associated with the hydrogen chemisorption site. The validity of H2 adsorption to determine the metallic dispersion will be also discussed.

Preparation, textural and structural characterizations as well as acid properties of some aluminium, zirconium pillared montmorillonite (from Algerian bentonite) and including alumina or zirconium pillared montmorillonite supported palladium are reported. Heat resistant basal spacings of 1.7 nm, surface areas in the range of 250–300 m 2 /g and micropore volumes of about 0.1 cm 3 /g were obtained. The acid activation of montmorillonite prior pillaring conduces to a resulting material with significantly higher pore volume and acidity. The improvement in acidity is mainly of the Bronsted acid type. The modification of zirconium-pillared montmorillonite with sulfate ions affects the structural properties of the pillared sample but gives a material with strong acid properties and both Lewis and Bronsted acid types are enhanced. It is reported also that textural and structural properties are not affected by the impregnation of a metallic function (1 wt.% Pd loading) but the acid properties changed. The pillared montmorillonite supported palladium has more Bronsted acidity than does the pillared montmorillonite. Decomposition of isopropanol was studied on these systems at low reaction temperature.

The present work is an evaluation of 1 wt.% Pd/sulfated zirconium pillared montmorillonite catalyst in the hydroisomerization reaction of two fractions of light naphtha composed mainly of C 5 and C 6 paraffins (feeds 1 and 2). Catalyst activity test was carried out in a fixed-bed flow reactor at reaction temperature of 300 °C, under atmospheric hydrogen pressure and weight hourly space velocity of 0.825 h −1 . The reaction products showed high isomer and cyclane selectivity. Monobranched and multibranched isomers were formed as well as C5 and C6 cyclane products. After the catalytic reaction, the total amount of benzene and cyclohexane decreased by 30% for the “feed 1” and by 40% for the “feed 2” leading to methylcyclopentane formation in the products. A long-term performance test catalyst for the two light naphtha fractions was also performed and we observed an improving of the research octane number (RON) by 15–17 for, respectively, feeds 1 and 2.

Heterogeneous hydrogenations of 1-naphthol and 2-naphthol over Ru/Al 2 O 3 -9001 (from Engelhard) are presented. It was found that 1-naphthol provides almost exclusively (98–100%) the cis -decalols (OH equatorial and axial) while the 2-naphthol lead to mixtures of a cis -decalol (OH equatorial) and a trans -decalol (OH equatorial) in 1/1–1/2 ratio where the trans -decalol is major. A rapid and simple 1 H NMR method (based on analysis of the patterns and of the 3 J values obtained from the C H (OH) proton) is described, which allows unambiguous assignment of the diastereomers of 1-decalols and 2-decalols. To cite this article: A. Solladie-Cavallo et al., C. R. Chimie (2005) .

A tool for direct and quantitative determination of surface Bronsted acidity of solids in terms of number, type and force based on quantitative H/D exchange kinetic between gaseous D 2 O and the acid solid, i.e. the hydron of the –O–H acid surface groups, has been developed. This method has been applied to materials covering the whole range of acidity, from very low acidic materials (e.g. carbonaceous solids) to high acidic materials ( e.g. acidic oxides or zeolites). Calibration was performed using well-characterized zeolites with known acidities and allowed the number of surface Bronsted acid sites (in μmol/g) to be determined using the integrated surfaces of the H/D experimental exchange curve given by the direct measurement of the exchanged HDO molecule signal by mass spectrometry. The determination of the force of the acidity was directly linked to the rate constant of the first step of the H/D exchange. This method allows, after deconvolution of the H/D experimental curve, the number and force of each type of surface Bronsted acid sites to be determined.

Pour evaluer l'action du champ electromagnetique micro-onde sur la reaction, les proprietes et la preparation des catalyseurs, nous avons dispose d'un reacteur place dans une cavite resonnante permettant de mesurer la plupart des grandeurs experimentales importantes qui definissent la reaction et les conditions dans lesquelles l'irradiation micro-onde est effectuees. Parmi celles ci figure le champ electrique, la puissance apportee au systeme et la temperature. Les resultats obtenus pour les reactions d'hydrogenolyse du methylcyclopentane font apparaitre qu'independamment du mode de chauffage et quelle que soit la conversion, la distribution des produits formes est identique pour les deux systemes et les rapports des differents hexanes obtenus obeissent a la regle statistique d'ouverture des liaisons C-C du cycle methylcyclopentane. Par contre, lors des reactions d'isomerisation du methyl-2pentane, methyl-3pentane et n-hexane, la selectivite globale en isomeres est plus elevee lorsque la reaction a lieu en presence d'un champ micro-onde. A la suite de ces experiences il a ete demontre que le catalyseur est modifie lors de son irradiation micro-onde et que cette modification est permanente.

XPS and UPS characterization of partially reduced MoO3 by hydrogen at different temperatures enabled us to define the metallic character of MoO2. Hydrogen dissociation by this state results in the formation of Bronsted acidic group(s) Mo–OH as characterized by O 1s and catalytic properties. A bifunctional MoO2(Hx)ac phase is formed on the outermost sample surface layer. Two hydrocarbons were studied: methylcyclohexane (MCH) and n-heptane (nC7). The catalytic behavior of MCH on this system shows two different pathways depending on the reaction temperature. A selectivity close to 95% in dimethyl and ethyl-cyclopentanes (DMCP and EtCP) products were obtained at temperatures between 493 and 573 K. At higher temperatures up to 653 K, toluene is the major dehydrogenation product. The general tendency of this catalytic system seems to behave as a bifunctional; to confirm this hypothesis, an acid-supported catalyst, i.e. sulfated zirconia-supported Pt–Ir, was tested under the same experimental conditions. The possible formations of dimethyl or ethylcyclopentanes as intermediate products in the catalytic reaction of n-heptane have been explored using both catalysts.

Platinum catalyst supported on a medium surface area β-SiC was successfully used for the catalytic combustion of model carbon particles and compared to a catalyst supported on a low surface area α-SiC. The β-SiC-based catalyst showed no deactivation as a function of cycling tests while a strong deactivation was observed on the α-SiC-based catalyst. This deactivation was attributed to the progressive encapsulation of the platinum particles by a layer of silica which built up during the combustion cycle. These results render possible the use of Pt/β-SiC catalyst as a diesel carbon particle catalytic filter with continuous regeneration.

This work is focused on the catalytic behaviour of alumina supported low loaded Pt-Cu catalysts. Ethylcyclopentane is the probe molecule. In fact this molecule can lead to several primary reactions as: (i) ring opening, (ii) ring enlargement, (iii) aromatisation, and (iv) hydrocracking. Due to these various pathways we can follow the modifications of the catalytic activities as well as selectivity changes when the surface composition of the catalyst is changed. Various techniques were used to characterise these catalysts: (i) by TPR we showed that an interaction between platinum and copper is present and (ii) by hydrogen chemisorption we found that the platinum dispersion decreased from 100 to 20% when the copper content increased. The ring opening reaction is non-selective for platinum catalysts and for Pt-Cu systems with low copper content and is selective for catalysts with a high copper content. We noted that the apparent activation energy values also changed with the amount of copper which confirms the modifications in the catalytic mechanisms when changing copper concentration. We proposed that the ring enlargement reaction is similar to a bond shift reaction, when ring opening corresponds to hydrocracking reactions. Such comparative relation can help to understand the results obtained.

A new medium surface area and non-microporous TiO2–β-SiC photocatalytic material was successfully obtained according to an extension of the Shape Memory Synthesis (SMS) method, and following a three step procedure. A high surface area TiO2 supported on an activated charcoal precursor was prepared in a first step by the sol–gel precipitation of titanium tetraisopropoxide in the presence of activated charcoal powder. The second step consisted of a gas–solid reaction between this precursor and SiO vapors at 1300 °C under dynamic vacuum which formed TiC–β-SiC, by carboreduction of SiO vapors and TiO2 into β-SiC and TiC respectively. The final step was oxidation in air at temperatures ranging from 420 °C to 600 °C which produced the TiO2–β-SiC material, using the high resistance of β-SiC towards oxidation to selectively form TiO2. The gross morphology of the activated charcoal precursor was maintained during the carburization and the subsequent oxidation processes according to the SMS concept. Both TiO2 and the β-SiC semiconductor phases were in intimate contact in the same grain of catalyst, without the usually problematic post-synthesis shaping of high mechanical strength SiC-based materials and using no binder. The TiO2-to-SiC ratio could be directly tuned by adjusting the TiO2 content of the precursor, whereas the anatase-to-rutile ratio could be modified by changing the post-synthesis calcination temperature, without altering the β-SiC properties or significantly increasing the average TiO2 particle size.