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In this study, the role of the noble metals Pt and Rh (0.5 wt.%) for the selective reduction of NO into N 2 is evaluated by the transient TAP technique and in-situ spectroscopy using a commercial stable ceria support (denoted as CZ) and applying isotopically labelled 15 NO and 18 O 2 . The transient operation was mimicked by multi-pulse oxidation (using O 2 or NO) and reduction cycles (using CO, H 2 , C 3 H 6 and C 3 H 8 ), while following quantitatively the catalyst and reactants response. Pt and Rh significantly lowered the temperature of CZ reduction. CO and H 2 only reduce the surface of CZ, while a 2.5 times deeper reduction was achieved by the hydrocarbons C 3 H 6 and C 3 H 8 , removing also lattice oxygen. Pt and Rh also promoted carbon deposition after surface reduction. Rh was a more active promoter than Pt, while propene was more reactive than propane over both metals. During the NO reduction the pre-reduced CZ support became gradually re-oxidised and after filling 70–80% of the oxygen vacancies the NO started to appear in the product mixture. In the presence of carbon deposits the lattice oxygen of the CZ reacted with the carbon keeping the CZ in a reduced state, extending the NO decomposition process as long as the carbon was present. The reduction of NO over pre-reduced noble metal/CZ showed a selective formation N 2 , while N 2 O and NO 2 were never observed. During the NO reduction process some unidentified N-species remained on the catalyst, the amount depending on the type of catalyst, but finally all nitrogen was released as N 2 . The presence of the noble metal led less unidentified N-species on the CZ surface and to a faster N 2 formation rate than that over the bare CZ. [ABSTRACT FROM AUTHOR]

This study reports a method to determine the absolute crystallinity of partly crystalline brookite TiO 2 photocatalysts. A natural, a commercial and various home-prepared brookite powders were characterized by X-ray diffraction analysis, Raman spectroscopy, scanning electron microscopy, UV–vis diffuse reflectance spectroscopy and nitrogen adsorption measurements. The absolute crystallinity was calculated from the ratio between the full width at half maximum intensity of the (121) X-ray diffraction peaks of the brookite samples and the (111) peak of CaF 2 as internal standard. The photocatalytic activity of the powders was tested employing the photodegradation of 4-nitrophenol as well as the selective oxidation of 4-methoxybenzyl alcohol to 4-methoxybenzaldehyde ( p -anisaldehyde) under UV irradiation. The results indicated that crystallinity positively influenced the photooxidation of 4-nitrophenol and 4-methoxybenzyl alcohol but reduced the selectivity toward the synthesis of p -anisaldehyde. [ABSTRACT FROM AUTHOR]

CoMo-catalysts modified by boron were studied. Boron was added to alumina support by kneading. Supports and catalysts were characterized by nitrogen adsorption, XPS, IR-spectroscopy of adsorbed CO. Catalysts were tested in hydrotreating of straight-run diesel fuel with 5 vol.% catalytic cracking gasoil (initial S content was 2750 ppm). It is found that boron has no significant influence on textural characteristics of catalysts. However, it increases slab length and visualization degree of active component, while stacking number remains unchanged (preferential formation of monolayers). Difference in morphology is caused by changes of Lewis acidity and generation of Brønsted acid sites. It is found that all catalysts with boron provide production of ultra-low sulfur diesel fuels (less than 10 ppm). The catalyst with a boron content of 2 wt.% combines high activity in HDS and HDN. [ABSTRACT FROM AUTHOR]

Abstract: A ferromagnetic γ-Al2O3-supported iron catalyst has been prepared and its activity and stability in catalytic wet peroxide oxidation (CWPO) have been compared with those of a previous iron-based conventional catalyst using the same support. Both catalysts were characterized by nitrogen adsorption–desorption isotherms, ICP, TXRF, XRD, XPS, elemental analysis and Mössbauer spectroscopy. The behavior of these catalysts in CWPO of chlorophenols has been related with the nature of the dominant iron species (magnetite or hematite). The results showed that the magnetic catalyst improved significantly the decomposition of H2O2 leading to an increased degradation and mineralization of chlorophenols. Complete conversion of those target pollutants and more than 75% TOC reduction were achieved after 4h under stoichiometric H2O2 dose, 100mgL−1 initial chlorophenol concentration, 1gL−1 catalyst, pH 3 and 50°C temperature. Moreover, complete dechlorination of all the chlorophenols tested was achieved, being the residual organic by-products short-chain acids without significance in terms of ecotoxicity. The catalyst showed a remarkable stability in long-term continuous experiments with limited Fe leaching, below 5% of the initial loading after 100h on stream. An additional clear advantage of the new catalyst is its easy separation and recovery from the reaction medium by applying an external magnetic field. [Copyright &y& Elsevier]

Abstract: The transesterification of soybean oil with methanol to biodiesel using lanthanum doped zinc aluminate with spinel structure as catalyst is studied. The catalyst was characterized by X-ray diffraction (XRD), N2 adsorption/desorption, temperature programmed desorption of CO2 (CO2-TPD) and infrared spectroscopy of CO2 adsorption (CO2-IR). The results of CO2-IR show that the basic sites of La doped zinc aluminate are surface isolated O2− anions and OH− groups. The results of CO2-TPD show that the total amount of basic sties of the catalyst improves with the increase of the La doping amount until which is to 18.5wt%. Doping La also enlarges the pore volume and diameter of zinc aluminate. It gets the largest pore volume (0.30cm3 g−1) and pore diameter (7.9nm) when doped with 5.5wt% La. Zinc aluminate doped with 5.5wt% La (5.5% La/ZnAl2O4) exhibits the highest activity, with which the biodiesel yield exceeds 95% at 160°C, 2.0MPa and 0.9h−1. Furthermore, the transesterification reaction of about 500h in a fixed-bed reactor was carried out over 5.5% La/ZnAl2O4 catalyst. No deactivation and leaching of catalyst components were happened on the catalyst in reaction. [Copyright &y& Elsevier]

Abstract: Sulfonic acid functionalized mesoporous SBA-15 catalysts have been studied in the microwave-assisted transesterification of soybean oil with 1-butanol in order to produce low freezing point biodiesel. Small-angle powder XRD and nitrogen adsorption analysis revealed the formation of mesoporous materials with high surface area and uniform porosity. Catalytic activity was found to be largely dependent on the acid strength rather than the number of acid sites. Propyl-SO3H and arene-SO3H functionalized SBA-15 catalysts showed high activity and stability in transesterification reactions whereas perfluoro-SO3H functionalized SBA-15 catalyst exhibited a complete loss of activity after recycling due to complete leaching of perfluoro-SO3H groups in the reaction medium. The results over arene-SO3H functionalized catalysts showed that the optimal loading of arene-SO3H groups is approximately 15% (molar percent of functional group to total silicon) and the optimal oil to alcohol molar ratio is 1:6. Increases in catalyst to oil weight ratio and reaction temperature significantly enhance the reaction rates. Simultaneous transesterification and esterification of soybean oil with up to 20 wt% oleic acid over arene-SO3H functionalized catalyst indicated that this catalyst could be a promising candidate for processing low quality feedstocks containing high fraction of free fatty acids. Further modification of Ar-SO3H SBA-15 catalyst with hydrophobic groups did not significantly improve its catalytic performance. [Copyright &y& Elsevier]

Abstract: The catalytic N2O decomposition was investigated over a series of Cu x Ce1−x O y mixed oxides with different Cu/Ce molar ratios. Effects of synergy over mixed oxides of CeO2 and CuO were observed significantly, the catalyst of Cu0.67Ce0.33O y exhibited the high activity among the Cu–Ce–O mixed oxides for N2O decomposition. Characterizations of XRD, N2-adsorption, XPS, and H2-TPR were applied to correlate their properties with the corresponding catalytic performance, and reveal the synergetic effect between CuO and CeO2 for N2O decomposition. In situ DRIFTS investigation confirmed the presence of CuI species that was closely related with the activity of Cu x Ce1−x O y catalyst. The synergy of Cu x Ce1−x O y promoted the stability and the ability to regenerate the active CuI site. [Copyright &y& Elsevier]

Abstract: A gas bubble-templating method has enabled synthesis of a diverse portfolio of hollow transition-metal sulfides microspheres (e.g., CdS, ZnS, CuS and Bi2S3) by a general one-step route. The products were characterized by X-ray powder diffraction, scanning and transmission electron microscopy, high-resolution transmission electron microscopy, energy dispersive spectroscopy analysis, N2 adsorption and UV–vis diffuse reflectance spectroscopy. The shell of all hollow spheres is composed of single-crystal metal sulfide nanoparticles and the shell thickness can be readily controlled by changing the deposition time. These hollow microspheres are envisioned to have broad applications in catalysis, Li-ion batteries, microreactors, biomedicines, etc. As an example, here, we demonstrate that the prepared CdS and ZnS hollow sub-micrometer spheres are excellent photocatalysts with higher photodegradation efficiency of potential polluting agents than that of commercial CdS, ZnS and TiO2 P25 under visible light and UV light illumination, respectively. [Copyright &y& Elsevier]

Abstract: Fenton-like degradation of 2,4-dichlorophenol (2,4-DCP) in aqueous solution was investigated over Fe3O4 magnetic nanoparticles (MNPs) as catalyst. The obtained samples were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption–desorption isotherms, and physical property measurement system (PPMS). The catalytic results showed that Fe3O4 MNPs presented good properties for the degradation and mineralization of 2,4-DCP, achieving complete decomposition of 2,4-DCP and 51% of TOC removal after 180min at reaction conditions of H2O2 12mM, Fe3O4 MNPs 1.0g/L, 2,4-DCP 100mg/L, pH 3.0 and T 30°C. The effect of different reaction parameters such as initial pH, H2O2 dosage, Fe3O4 MNPs addition, initial concentration of 2,4-DCP and temperature on two-stage first-order kinetics of 2,4-DCP degradation was studied. A high utilization efficiency of H2O2 calculated as 73% was observed. According to the analyses of iron leaching, reactive oxidizing species and degradation intermediates, a possible mechanistic steps of 2,4-DCP degradation dominated by ons (especially by free bulk solution) were proposed. Besides, stability and reusability of Fe3O4 MNPs were tested. [Copyright &y& Elsevier]

Abstract: Cerium-doped MCM-41 (Ce-MCM-41) was prepared by a hydrothermal method and its catalytic activity for ozonation of p-chlorobenzoic acid (p-CBA) in aqueous solution was studied. For comparison, cerium-loaded MCM-41 (Ce/MCM-41) was prepared by a dipping method. Ce-MCM-41 was characterized by the low and wide angle X-ray powder diffraction (XRD), nitrogen adsorption–desorption, transmission electron microscopy (TEM) and ultraviolet–visible diffuse reflection spectrum (UV–vis DRS). The results showed that the material retained the highly ordered mesopore structure of MCM-41 and had a surface area of 852m2 g−1. Cerium was incorporated into the framework of MCM-41, locating at tetrahedrally coordinated sites. The cerium doping content, initial pH of aqueous solution and reaction temperature played important roles in catalytic ozonation of p-CBA. Under the chosen conditions (1.39mgl−1 ozone dosage, 10mgl−1 p-CBA solution and 1gl−1 catalyst dosage), the high mineralization rate (86%) was achieved by Ce-MCM-41/O3 process at 60min reaction time, only 52% by O3 alone. The combination of Ce-MCM-41 and O3 exhibited a significant synergetic effect. Ce-MCM-41 showed the better activity and stability than cerium-loaded MCM-41(Ce/MCM-41) during catalytic ozonation of p-CBA, its cerium leaching was greatly reduced (only 0.085mgl−1) and below detection limit after being reused, compared with that of Ce/MCM-41 (0.44mgl−1) with the presence of the same theoretical cerium content. TOC removal rate slightly decreased from 86% to 81% and kept stable after Ce-MCM-41 being re-utilized two times, which illustrated that Ce-MCM-41 was a kind of promising catalyst for ozonation of p-CBA. The addition of Ce-MCM-41 significantly improved ozone decomposition into HOus solution and reduced ozone concentration in equilibrium. [Copyright &y& Elsevier]

Abstract: Mono- and bimetallic Rh and Pt based NO x storage-reduction (NSR) catalysts, where the noble metals were deposited on the Al2O3 support or BaCO3 storage component, have been prepared using a twin flame spray pyrolysis setup. The catalysts were characterized by nitrogen adsorption, CO chemisorption combined with diffuse reflectance infrared Fourier transform spectroscopy, X-ray diffraction, and scanning transmission electron microscopy combined with energy dispersive X-ray spectroscopy. The NSR performance of the catalysts was investigated by fuel lean/rich cycling in the absence and presence of SO2 (25ppm) as well as after H2 desulfation at 750°C. The performance increased when Rh was located on BaCO3 enabling good catalyst regeneration during the fuel rich phase. Best performance was observed for bimetallic catalysts where the noble metals were separated, with Pt on Al2O3 and Rh on BaCO3. The Rh-containing catalysts generally showed much higher tolerance to SO2 during fuel rich conditions and lost only little activity during thermal aging at 750°C. [Copyright &y& Elsevier]

Abstract: Silica-supported MoP catalysts were prepared by temperature-programmed reduction (H2-TPR) at 550, 600 and 700°C of the corresponding dried or calcined substrates. Two catalysts were prepared by using two different synthetic approaches. A MoP catalyst was prepared using the method described in the literature that uses ammonium phosphate (NH4H2PO4) and ammonium heptamolybdate ((NH4)6Mo7O24·4H2O) precursors, calcination and subsequent H2-TPR at high temperature. A new synthetic approach was carried out to prepare another MoP catalyst using ammonium molybdate ((NH4)2MoO4) and phosphorous acid (H2PO3H) as precursors and subsequent H2-TPR. The catalytic activity was evaluated in the individual and simultaneous hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) reactions performed in a flow reactor under a hydrogen pressure of 3.0MPa. The fresh reduced and spent catalysts were characterized by ICP, N2 adsorption–desorption isotherms at −196°C, XRD, HRTEM, NH3-TPD, XPS and elemental chemical CNHS analysis. The silica-supported MoP catalysts prepared by the new synthetic method were more active in the HDS of DBT than the catalyst prepared by reduction of calcined substrate. The catalyst characterization results showed that the lower reduction temperature required to form the MoP species is responsible for the enhancement in catalytic performance. The key factors influencing on the catalytic activity are: a large specific surface area, high acidity and good dispersion of MoP phase on the support substrate. Activity measurements in simultaneous HDN–HDS showed that quinoline conversion is enhanced in the presence of a small amount of DBT whereas the HDS of DBT reaction does not appear to be inhibited by a small amount of quinoline added to the feed. [Copyright &y& Elsevier]

Abstract: A novel hydrothermal approach is developed for the first time to synthesize hierarchical BiVO4/Bi2O2CO3 nanocomposites with reactive crystalline facets using urea as a morphology mediator. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, N2 absorption–desorption isotherms and UV–visible diffuse reflectance spectroscopy. The photocatalytic activity of the as-prepared samples was evaluated towards degradation of Rhodomine B (RhB) by visible-light. Our results indicate that both physical parameters and associated photocatalytic activity of BiVO4/Bi2O2CO3 nanocomposites can be tuned by urea concentration and reaction time in the synthesis process. With increasing urea concentration, the specific surface area, pore volume and average pore size increase. Compared to BiVO4 and Bi2O2CO3 bulk counterpart, BiVO4/Bi2O2CO3 nanocomposites show enhanced photocatalytic degradation activity of RhB. The mechanisms for the formation of BiVO4/Bi2O2CO3 nanocomposites and enhanced photoreactivity are discussed. [Copyright &y& Elsevier]

Abstract: The aim of the present research is to determine the optimum hydrothermal synthesis procedure for using TiO2-based one-dimensional materials as photocatalysts for air treatment applications, in order to enhance their mineralization capacity. The prepared samples were thoroughly characterized by means of TEM, N2 adsorption–desorption isotherms, XRD and Raman spectroscopy. Trichloroethylene (TCE) was selected as a convenient model volatile organic compound (VOC) due to its elevated reactivity. In this study, it is described how the selection of the synthesis parameters (TiO2 precursor, hydrothermal treatment conditions, washing procedure or calcination temperature) allows modulating the nanotubes physicochemical characteristics and, thus, photoactivity. The optimization process led to nanotubes with remarkable photocatalytic performance, with high TCE conversion and selectivity to CO2, which can be favourably compared to that of the benchmark photocatalyst Degussa P25. [Copyright &y& Elsevier]

Abstract: Santa Barbara Amorphous (SBA-15) mesoporous materials decorated with vary amount of TiO2 (7–31% TiO2/SBA-15) were prepared by the post-synthesis method from previously synthesized SBA-15 and their photocatalytic activity toward the degradation of methylene blue (MB) was measured. Nonionic surfactant was used as liquid template and tetraethyl orthosilicate (TEOS) as SiO2 precursor for the synthesis of mesoporous silica SBA-15. The synthesized x% TiO2/SBA-15 materials were characterized by N2 adsorption–desorption isotherms, X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy (UV–vis DRS), micro-Raman spectroscopy, infrared spectroscopy of framework vibration (IR-KBr) and X-ray photoelectron spectroscopy (XPS). The x% TiO2/SBA-15 photocatalysts were found to be more active than pure anatase titania and this increase was linear with TiO2 loading. The highest activity of 31% TiO2/SBA-15 sample was explained in terms of the combined factors such as a high crystallinity of anatase phase, preservation of a high surface area, a large amount of the surface hydroxyl groups, and a larger accessibility of photo-oxidative sites. A linear correlation between the apparent first order rate constants (k app) and the amount of TiO2 species located within porous structure of the SBA-15 substrate was found. [Copyright &y& Elsevier]

Abstract: A conceptual air purifier harvesting fluorescent room lights was tested in this study. Visible photocatalysis was applied to facilitate the degradation of volatile organic compounds (VOCs) on a highly efficient visible light photocatalyst, Pt/N-TiO2 synthesised via a sol–gel process. The as-prepared photocatalyst was characterised by many techniques, such as XRD, XPS, UV–vis DRS, N2 adsorption and SEM, etc. XPS spectra revealed that platinum was at a chemical state of 2+, while nitrogen existed as NO x species. The unique chemical compositions made the photocatalyst respond to visible light with a band gap of 2.69eV, and present a broad absorption shoulder extended further into infrared region. The photocatalytic activities under irradiations of λ >387, 430 and 490nm were evaluated by photodegradation of phenol solutions. Under UV–vis light, the Pt/N-TiO2 exhibited 5.5 times higher activity than Degussa P25. Various gaseous pollutants were degraded by employing the Pt/N-TiO2 in a batch reactor. The capability of photodegradation of VOCs under room lights was also proven by the decomposition of gaseous toluene in a continuous reactor using fluorescent lamps (6×10W). The mechanism of the enhanced activity in degradation of VOCs and potential application were discussed. [Copyright &y& Elsevier]

Abstract: This article presents preparation, characterization and evaluation of heterogeneous Titanium based alumina mesoporous silica catalysts for the photo degradation of chlorophenols in aqueous solution. For more economic application, a series of silica, Al2O3–SiO2 and TiO2–Al2O3–SiO2 are prepared using linear alkylbenzene sulfonic acid as a novel structure directing agent. Two Ti–Al–SiO2 samples were prepared by direct synthesis using different titanium sources. The prepared samples are characterized by combination of various physicochemical techniques, such as XRD, N2 physisorption, FT-IR, UV–vis, SEM and TEM. The prepared mesoporous materials are applied in the presence of UV irradiation for photodegradation of chlorophenols as pollutants in water. The results reveal that the photodegradation process of 4-chlorophenol (4-CP) is completed within 40min, while reach 67.3% for 2-chlorophenol (2-CP) within 130min. Moreover, the titanium precursor species and the catalyst dosage (0.1–0.4g/l) affect the photocatalytic activity of prepared catalysts for 2-chlorophenol degradation. Finally, the concentration of acetate and chloride ions formed during the degradation process can also affect the activity of the prepared catalysts. [Copyright &y& Elsevier]

Abstract: This work reports the synthesis and characterization of a cerium phosphate supported gold catalyst as well as its catalytic activity for the oxidation of CO. A precipitation method in the presence of an organic modifier followed by a hydrothermal treatment was used for the support synthesis, resulting in high surface area nanometric particles. Gold/cerium phosphate catalyst with a 1% (w/w) nominal gold content was characterized using XRF, XRD, N2 adsorption–desorption measurements, TEM and DRIFTS-MS. The catalyst shows good catalytic activity at low temperature. The activity is related to the generation of oxygen vacancies in the support caused by the elimination of structural oxygen. In situ studies revealed that the reaction of the oxygen vacancies with gaseous oxygen resulted in the formation of peroxo species. These species are responsible for the activity detected at room temperature in both the catalyst and the support. Moreover, the presence of carbonate and hydrogen carbonate acting as reaction intermediates have been observed. [Copyright &y& Elsevier]

Abstract: Three-dimensionally ordered macroporous (3DOM) praseodymium (Pr)-modified Ce-Zr solid solutions were successfully prepared by colloidal crystal templating method. They were characterized by the techniques of SEM, XRD, UV-Raman, N2 adsorption, and H2-TPR. 3DOM samples showed higher catalytic activities for soot combustion than corresponding disordered macroporous (DM) ones, which benefits from the enhanced contact efficiency between soot and ordered macroporous structure. In addition, the effects of Ce/Zr ratio on the phase composition and catalytic performances of Ce-Zr-O and Pr-Ce-Zr-O samples for soot oxidation were investigated. The results indicate that the phase compositions of Pr-modified ceria-zirconia solid solutions are similar to those of corresponding ceria-zirconia samples, and cubic–tetragonal phases coexist in the samples with moderate zirconia content, which is favorable for soot combustion. Furthermore, the effects of thermal and hydrothermal treatments on the catalytic properties for soot oxidation of 3DOM CeO2, Ce0.7Zr0.3O2 and Ce0.6Zr0.3Pr0.1O2 were comparatively studied. Compared with 3DOM bare CeO2, 3DOM Ce-Zr-based solid solutions, especially Pr-modified Ce-Zr solid solution Ce0.6Zr0.3Pr0.1O2 exhibited the highest thermal and hydrothermal stability because it possesses the lowest mobility of lattice oxygen among the three samples. [Copyright &y& Elsevier]

Abstract: Nanostructured photocatalysts, that can effectively photodegrade the industrial dyes drimaren red and drimaren navy (Clariant Produkte), were obtained by the structural reconstruction of MgAlLDH and MgFeAlLDH anionic clays in NiSO4 aqueous solution. X-ray diffraction (XRD), energy dispersive X-ray (EDX) mapping, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), N2 adsorption at 77K and UV–vis analysis were adopted to investigate the structure, surface, micromorphology and photoresponsive properties of the reconstructed clays, as oposed to the as-synthesized clays. Results show that MgAlLDH and MgFeAlLDH reconstruction in NiSO4 aqueous solution gives rise to nanostructured enssembles defined by high density nanoparticles of oxidized nickel deposited on the larger LDHs flakes. IR spectroscopy (FTIR) results indicate that SO4 2− replaced CO3 2− in the interlayer space of the reconstructed clays. It was found that the dyes’ photodegradation is greatly enhanced by the deposition of nanosized nickel on the surface of the clay but is also influenced by the specific composition of the parent clay. [Copyright &y& Elsevier]

Abstract: Selective oxidation of glycerol with molecular oxygen was studied over different functionalized MWNTs supported Pt catalysts in base-free aqueous solution. N2 adsorption, IR, Raman and SEM–EDS analysis confirmed that the tubular structure of MWNTs is stable during HNO3 and H2O2 pretreatment and the surface of MWNTs was successfully functionalized by HNO3, H2O2 and NH2–CH2–CH2–SH. XRD, SEM and TEM analysis demonstrated that unique sized Pt particles formed on S-pretreated MWNTs. Pt/S-MWNTs catalyst with small Pt particles was more active than Pt/MWNTs, Pt/HNO3-MWNTs and Pt/H2O2-MWNTs for glycerol oxidation in base-free aqueous solution. Free glyceric acid formed (with 68.3% selectivity and 90.4% conversion of glycerol) on Pt/S-MWNTs in base-free solution. While dihydroxyacetone formed firstly in an aqueous solution of NaOH/glycerol=2:1 and the cleavage C–C bonds (catalyzed by alkali) arise severely. [Copyright &y& Elsevier]

Abstract: Titanium dioxide nanotubes were prepared via a hydrothermal treatment of TiO2 powder (Degussa P25). Obtained samples were analyzed by various techniques, such as transmission electron microscopy (TEM) and X-ray diffraction (XRD), which revealed that the crystal structure of the obtained materials was similar to that of H2Ti2O5·H2O nanotubes, and were about 50nm in length and 20nm in diameter. Nitrogen adsorption–desorption isotherms indicated that synthesized solids are mesoporous materials with a multi-walled nanotubular structure and high specific surface area. The methanol oxidation reaction was investigated on platinum nanoparticles supported TiO2 nanotubes (XC72). The electrocatalytic activity of the catalyst was measured by cyclic voltammetry. CO stripping voltammetry in acidic solutions was investigated to study the reaction of the catalysts towards poisoning by carbonyl compounds. The results demonstrated that Pt/TiO2 nanotubes catalyst exhibits the best activity for methanol oxidation and were favorable for improving the tolerance to poisoning species. [Copyright &y& Elsevier]

Abstract: The present study was focused on the influence of physico-chemical properties of TiO2 on a photocatalytic generation of useful C1–C3 hydrocarbons (mainly methane) and hydrogen from aqueous solution of acetic acid under N2 atmosphere. The photocatalysts applied in the study were prepared from a crude TiO2 obtained by the sulphate technology. The crude TiO2 was calcined at the temperatures of 600, 700 or 800°C in air atmosphere. Moreover, two commercially available photocatalysts, Aeroxide® P25 and VP TiO2 P90 (Evonik, Germany) were also used in the experiments. The photocatalysts were characterized by UV–vis/DR and FTIR spectroscopy, N2 adsorption–desorption at 77K and XRD measurements. The main gaseous products of CH3COOH decomposition were CH4 and CO2. Moreover, small amounts of ethane, propane and hydrogen were detected in the gaseous phase. The main by-products identified in the liquid phase were methanol, ethanol, acetone, acetaldehyde and methyl acetate. The most active photocatalyst towards hydrocarbons and H2 generation was TiO2 calcined at 700°C. The catalyst was composed mainly of anatase (94%) with crystallite size of 32nm and exhibited BET surface area of 30m2/g. After 27h of the process conducted with this catalyst the concentrations of CH4, CO2, C2H6, C3H8 and H2 amounted to 2.92, 2.68, 0.25, 0.08 and 0.22mmol/g of photocatalyst, respectively. It was found that the main parameters responsible for the photoactivity of the photocatalysts were crystallite size of anatase, phase composition and activity towards hydroxyl radicals formation. [Copyright &y& Elsevier]

Abstract: A series of Zr,Al-pillared interlayered clays (Zr,Al-PILCs) have been prepared and characterized by X-ray diffraction, elemental analysis, FT-IR and N2-adsorption/desorption analyses, 27Al NMR(MAS), FT-IR spectroscopy using pyridine, PhCN and CDCl3 as probe molecules. It was found that textural and physicochemical properties of Zr,Al-PILCs depend on Zr content in clay. The relationship between the acid–base properties and catalytic performances of Zr,Al-PILCs was revealed in the synthesis of propylene glycol methyl ether from methanol and propylene oxide. The results show that the conversion of propylene oxide and the selectivity to 1-methoxy-2-propanol decrease with increasing the amount of zirconium in Zr,Al-PILCs due to the change in acid–base properties. [Copyright &y& Elsevier]

Abstract: Destruction of chlorinated aromatic compounds was carried out over mesoporous Cu x Mg1−x Al2O4 spinel oxides with x =0, 0.2, 0.5 and 0.8, which were prepared by the coprecipitation method. All the catalyst samples were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and nitrogen adsorption–desorption isotherms. The performances of these catalysts on the decomposition of hexachlorobenzene (HCB) and the catalytic formation of polychlorinated dibenzodioxin and dibenzofuran (PCDD/F) were evaluated in a closed system. The activities of these catalysts for dechlorination of HCB increased with increasing the magnesium content in them. The Cu0.2Mg0.8Al2O4 presented a higher catalytic activity for the hydrodechlorination of HCB than CuO, Al2O3, as well as the other Cu x Mg1−x Al2O4 spinels. More than 99% dechlorination efficiency of HCB was achieved at low temperatures (≤300°C) for a short time (30min) under air atmosphere over Cu0.2Mg0.8Al2O4 spinel. In comparison to air atmosphere, nitrogen atmosphere seemed to be more beneficial for the dechlorination of HCB with a dechlorination efficiency of 90% at 250°C for 10min. For the Cu0.2Mg0.8Al2O4 catalyst, the I-TEQ of PCDD/F formed was 4.5pg/g, far below the value of 15122.5pg/g on CuO. The Cu0.2Mg0.8Al2O4 catalyst inhibited the chlorination reaction and enhanced the dechlorination reaction. The catalytic behavior including catalytic dechlorination of HCB and catalytic formation of PCDD/F related to the physical characteristics of Cu x Mg1−x Al2O4 spinel was discussed. [ABSTRACT FROM AUTHOR]

Abstract: A series of MgO–ZrO2 mixed oxides with different nominal Mg/(Mg+Zr) atomic ratios (0, 0.1, 0.3, 0.5, 0.75, 0.85 0.92) were prepared by co-precipitation and calcined at 873K. The catalytic activity in aldol condensation of furfural with acetone was tested in aqueous medium. These solids were systematically characterized by XRD, TEM, XPS, N2 adsorption–desorption isotherms and thermal analysis. Mg x Zr1−x O2−x solid solution with cubic ZrO2 structure was the only phase observed for the mixed solids with Mg/(Mg+Zr) atomic ratio ≤0.3, which had very low activity. Two different phases were observed in solids with a nominal Mg/(Mg+Zr) atomic ratio ≥0.5: cubic MgO and c-Mg x Zr1−x O2−x . Moreover, the relative concentration of the latter phase decreases as the Mg concentration increases. Zr4+ cations are present at the surface of the c-MgO, the concentration of which is lower in the Mg-richer samples. No significant differences were found between the overall catalytic activity of these samples. Therefore, three different active surface sites can be found in these solids: Mg–O–Mg sites co-existing with Mg–O–Zr sites at the surface of c-MgO, and Mg–O–Zr sites at the surface of c-Mg x Zr1−x O2−x . The Mg–O–Zr sites on c-MgO are much more active than the other two sites, which show similar intrinsic activity. The overall activity of each catalyst depends on the amount of each of these surface sites and on their intrinsic activity. Reutilization tests and characterization of the used catalysts suggests that the most probable causes of deactivation are fouling and/or poisoning of the surface sites by furfural derived heavy compounds, leaching of Mg2+ and Zr4+ cations, or hydration of the Mg oxide. [Copyright &y& Elsevier]

Abstract: In this work, three AlFePILCs prepared from different host clays were synthesized, characterized and tested in the catalytic wet hydrogen peroxide oxidation of 4-chlorophenol. Two reference clays, with widely different cation exchange capacities (1.2meq/g for SAz-1 and 0.87meq/g for SWy-2), and a Romanian montmorillonite (Mt) were used for the preparation of the catalysts, their structural and textural properties being determined by X-ray diffraction and nitrogen adsorption-desorption isotherms. The catalyst based on SAz-1 has a more ordered structure and a higher surface area than the other two catalysts, prepared from SWy-2 and Mt, and this was attributed to its higher layer charge. The 4-chlorophenol oxidation proceeds with the formation of 4-chlorocatechol (main reaction intermediate) and hydroquinone. Other chlorinated benzenediols and triols as well as dimerization products have been also identified by derivatization and GC–MS analysis. All the catalysts allowed the total elimination of 4-chlorophenol and significant removal efficiencies for the total organic carbon, of 60, 52 and 45%, for Mt, SWy-2 and SAz-1 based catalysts, respectively. The iron leaching was very low, but the most active catalyst produced the higher amount of dissolved iron (1ppm), as compared with AlFePILCs based on SWy-2 and SAz-1 (0.5ppm). To explain the differences in the catalytic properties, Mössbauer and diffuse-reflectance UV–vis spectroscopies were used to investigate the nature of the active sites. Both methods suggested the presence of two iron species: low-nuclearity ferric oxides and well-ordered hematite-like nanoparticles. The low-nuclearity ferric oxides seem to be responsible for the iron leaching and for the differences in the catalytic activity. [ABSTRACT FROM AUTHOR]

Abstract: Multi-walled carbon nanotubes (MWNT) supported platinum catalysts were employed to study the support functionalization on their catalytic performances. The MWNT were subjected to HNO3 functionalization, in which oxygen containing groups (OCGs) were introduced to improve Pt dispersion. The MWNT supports were characterized by nitrogen physisorption and NEXAFS, and the Pt supported on differently functionalized MWNT characterized by X-ray absorption, TEM and both hydrogen and CO chemisorption. Compared to the as received MWNT supports, Pt dispersion is improved on the HNO3 treated MWNT supports, but the turnover frequency (TOF) of aqueous phase reforming decreases by half. The TOF can be recovered by removing the OCGs via high temperature annealing. To further investigate the OCGs effect, different probe reactions, including both steam reforming and liquid phase reforming of hydrocarbon oxygenates and dehydrogenation of alkanes in the liquid and gas phases, have been performed on the MWNT supported catalysts with different OCGs. A comparison of these reaction results suggests that OCGs are only detrimental to reactions in a binary mixture with two components of different hydrophilicity due to their competitive adsorption on the catalyst supports. [ABSTRACT FROM AUTHOR]

Abstract: Vanadia supported on zeolites were prepared and characterized by N2 physisorption, FTIR, XRPD, and NH3-TPD methods. The influence of the Si/Al ratio on the total surface acidity of the catalysts as well as the optimum V2O5 content were studied and compared with the catalytic activity in the selective catalytic reduction (SCR) of NO with ammonia. The SCR activity was found to correlate directly with the total acidity of the catalysts and showed high poisoning resistivity after doping with potassium oxide (100μmol/g). The poisoning resistance was due to unique combination of high surface area, acidity and micropore structure of the support. Apparently the support hosted the potassium oxide on the acid sites, thereby protecting the active vanadium species from poisoning. Zeolite based catalysts might therefore prove useful for SCR of NO in alkali- containing flue gases from, e.g. biomass fired power plants. [Copyright &y& Elsevier]

Abstract: Pure TiO2 and various silver-enriched TiO2 powders were prepared by the sol–gel process controlled in the reverse micellar environment. The catalysts were tested in CO2 photocatalytic reduction and characterized by X-ray diffraction (XRD), nitrogen adsorption measurement and UV–vis. Methane and methanol were the main reduction products. The yield of methane and methanol increases when modifying the TiO2 by silver incorporation is caused by two mechanisms: up to 5% of Ag in TiO2 the Ag impurity band inside the TiO2 bandgap decreases the absorption edge and increases so the electron–hole pair generation, above 5% of Ag in TiO2 Ag metallic clusters are formed in TiO2 crystals with Shottky barrier at the metal–semiconductor interface, which spatially separates electron and holes and increases their lifetime (decreases probability of their recombination). [Copyright &y& Elsevier]

Abstract: The photoisomerization of norbornadiene using M–Ti–MCM-41 (M=V, Fe and Cr) has been studied to develop an alternative for solar energy accumulation and high energy aerospace fuel synthesis. The photocatalysts were prepared via hydrothermal method and characterized by EDX, XRD, N2 adsorption–desorption, TEM, UV–vis, XPS and IR. With the same Si/M ratio in starting materials, the final concentration of V in the photocatalyst is significantly lower than that of Fe and Cr. V5+ and Fe3+ ions are highly dispersed in Si–O framework with tetrahedral coordination when the metal content is low, and the ordered structure is well retained. However, some species in higher coordination and polymerized environments present with increasing metal content, and the ordered structure becomes to collapse. Cr ions are difficult to get into the framework with various species like extraframework Cr6+ and bulk Cr2O3 formed, also the ordered structure is greatly destroyed. Under UV irradiation, the transition metal ions can improve the photoisomerization activity, with the order of V>Fe>Cr. The activities of V– and Fe–Ti–MCM-41 rise with the increase of Si/M ratio, whereas the performance of Cr–Ti–MCM-41 is irregular. The photocatalysts do not exhibit any activity under visible light, regardless of their absorption in visible-light region. The activity is closely related to the extent of dispersion and local structure of metal ions, about which an indirect excitation process of Ti–O species is suggested. [Copyright &y& Elsevier]

Abstract: Na-montmorillonite (Na-mmt) and different pillared interlayered clays (Al-PILC, Zr-PILC, Ti-PILC and Al2O3/Ti-PILC) supported CrCe catalysts for the deep oxidation of nitrogen-containing VOCs (NVOCs) are synthesized and characterized by a combination of X-ray diffraction, N2 adsorption/desorption, high resolution transmission electron microscopy, temperature-programmed reduction, temperature-programmed desorption and adsorption capacity tests techniques. The results indicate that a porous structure named “house of cards” forms during the pillaring and calcination processes. Both porous structure and acidity play important roles in deep oxidation of NVOCs. The mesoporous structure and the proper acid sites improve the catalytic activity of supported CrCe catalysts. Among all these catalysts, CrCe/Ti-PILC and CrCe/Al2O3/Ti-PILC exhibit higher catalytic activity than other catalysts. N-butylamine and ethylenediamine with –NH2 groups are easier to be destructed may be involved in the stronger adsorption on the acid sites of the catalysts. Much too strong adsorption of ethylenediamine on the acid sites leads to a lower activity compared with n-butylamine. Acetonitrile with C≡N bond and little interaction with acid sites is the most difficult to be decomposed. All the catalysts show a good control quality of NO x , and the yield of NO x is limited within 2% during the whole experimental temperature range. [Copyright &y& Elsevier]

Abstract: The catalytic upgrading of pyrolytic vapors derived from radiata pine sawdust was carried out over mesoporous MFI zeolite synthesized using an amphiphilic organosilane. Its catalytic activity was compared with those of conventional HZSM-5 and mesoporous material from HZSM-5 (MMZZSM-5). The effect of gallium incorporation into mesoporous MFI zeolite on the product distribution and chemical composition of bio-oil was also investigated. The catalysts synthesized were characterized using ICP, XRD, N2-sorption, NH3-TPD, and H2-TPR methods. After catalytic upgrading, products were analyzed by GC–TCD, GC–FID, GC–MS, and Karl Fischer titration. The mesoporous MFI zeolite exhibited the best activity in deoxygenation and aromatization during the upgrading of pyrolytic vapors. In particular, mesoporous MFI zeolite showed high selectivity for highly valuable aromatics, such as benzene, toluene, and xylenes (BTX), even though it decreased the overall organic fraction of the bio-oil. The incorporation of gallium into the mesoporous MFI zeolite increased both the organic fraction of the bio-oil and resistance to coke deposition. Moreover, the selectivity for BTX aromatics was enhanced when the appropriate amount of gallium was introduced. [Copyright &y& Elsevier]

Abstract: The nickel active sites were introduced into TUD-1 mesoporous molecular sieve via grafting, direct synthesis, and impregnation methods. These samples were characterized using powder X-ray diffraction, N2 physisorption, H2 temperature-programmed reduction, H2 chemisorption, TG/DTA, temperature-programmed hydrogenation, Raman spectra and transmission electron microscope to give the insight of physicochemical properties. Catalytic tests probed by the carbon dioxide reforming of methane revealed that Ni-grafted TUD-1 exhibited the highest catalytic activity and long-term stability among these catalysts. Further studies implied catalytic activity, stability and carbon formation were highly sensitive to the metallic nickel particle size which was significantly affected by the introduction method of Ni active sites. Strong anchoring effect inherent to the grafting method was suggested to be the underlying reason for the small Ni particle size and improved catalytic performance. [Copyright &y& Elsevier]

Abstract: The reusability of silica functionalized with 4-ethyl-benzene sulfonic acid groups used as catalyst in biodiesel production from sunflower oil/methanol mixtures has been investigated. This material was used for four runs under batch mode operation, at different reaction temperatures (373, 423 and 473K), with a catalyst loading of 1.5wt.% referred to oil and with a methanol/oil molar ratio equal to 6. The catalyst is significantly deactivated during the first run, while the activity for the second and successive runs are very similar. Fresh and used catalysts were characterized by chemical analysis, N2 adsorption–desorption isotherms, infrared spectroscopy and evolved gas analysis by mass spectrometry. Leaching of the organosulfonic groups and adsorption of organic compounds onto the acid sites was detected in the used catalysts. Reactants and products are involved in the leaching process, although glycerine has the highest leaching capacity. The organic deposits are formed by side reactions involving reactants and/or products. The solid porous structure remained unchanged after catalyst use, indicating that sintering or other alterations of the porous network can be discarded as source of deactivation. Leaching and deposition effects occur predominantly during the first run, slowing down notably in subsequent cycles. Both leaching and organic deposits participate of the deactivation; the latter increases its impact at reaction temperatures higher than 423K. Partial catalyst regeneration by removal of the organic adsorbates could not be achieved by treatment at high temperature because the deposits and the organosulfonic acid sites were combusted simultaneously. [Copyright &y& Elsevier]

Abstract: A series of nanosized W,N-codoped and single-doped N- and W-anatase-TiO2 catalysts have been prepared by a microemulsion method and calcined at different temperatures. The activity in the sunlight selective photo-oxidation of toluene and styrene has been correlated with structural, electronic, and surface examinations of the catalysts done with the help of XRD-Rietveld, N2 physisorption, X-ray photoelectron, infrared, electron paramagnetic resonance (EPR) and UV–vis spectroscopies. Irrespective of the reaction, W,N-codoped nanocatalysts showed an enhanced photoactivity with respect to bare anatase and single-doped N-TiO2 and W-TiO2 materials. A strong W–N synergistic interaction appears to play a decisive role in driving the excellent photoactivity performance of W,N-codoped materials by affecting (i) electronic properties, particularly maximizing the anatase band gap decrease and enhancing the subsequent visible light photon absorption, and (ii) surface properties, in turn related to the formation of OH radicals upon light excitation. The maximum photoactivity is reached by calcination at 450°C and is concomitantly observed with a near complete selectivity to partial oxidation products. Higher calcination temperatures yielded solids with significantly inferior photocatalytic performance. The properties of the W–N interaction are discussed as a function of the calcination temperature. [Copyright &y& Elsevier]

Abstract: Nanotitania supported on mesoporous silica systems were synthesized by a reliable procedure based on an incipient wetness impregnation post-synthetic approach. Characterization by X-ray diffraction, N2 physisorption, TEM, X-ray photoelectron spectroscopy, ICP has been carried out in order to investigate the chemical–physical properties of the catalysts with particular attention to the chemical nature of the titanium species. The photocatalytic activity of the samples was evaluated for the degradation of NOx in the gas phase. The influence of both the textural properties and the nature of titanium species on the photocatalytic activity is discussed. [Copyright &y& Elsevier]

Abstract: The combustion of methane on model three way catalysts (TWC) Pd/CeZrO2 and Pd/LaFeO3 (2wt.% Pd) was studied under lean conditions in the temperature range between ca. 200 and 800°C to investigate the catalytic performance at and after high temperatures. The catalysts were prepared by incipient wetness impregnation and the nature and distribution of palladium species was characterized by N2-physisorption, X-ray diffraction (XRD), visible Raman spectroscopy, X-ray absorption spectroscopy (XANES and EXAFS), H2-temperature programmed reduction (H2-TPR), CO adsorption followed by diffuse reflectance infrared Fourier transform spectroscopy (CO-DRIFTS) and CO chemisorption. The behaviour of Pd during the combustion was monitored by in situ XANES spectroscopy. The characterization results indicate that the dispersion of Pd is higher in Pd/CeZrO2 than in Pd/LaFeO3. The catalytic data reveal that Pd/CeZrO2 is more active and stable compared to Pd/LaFeO3 in the whole studied temperature range. This is also true even after subjecting the catalysts to reaction at ≥800°C as evidenced by the extent of hysteresis observed in the conversion profiles. In situ XANES studies indicate that palladium had been in the oxidized state when the catalysts showed the best combustion performance. The studies also indicate that a fraction of PdO x had been reduced when the hysteresis was observed in the conversion profiles (while cooling between ca. 680 and 560°C) implying that the PdO x species are the active sites, at least at T ≤700°C. [Copyright &y& Elsevier]

Abstract: A series of nanosized W,N-co-doped anatase TiO2 catalysts with different dopant contents has been prepared by a microemulsion method and examined in the sunlight selective photo-oxidation of toluene and styrene. The activity results have been correlated with structural, electronic, and surface examinations of the catalysts done with the help of XRD–Rietveld, N2 physisorption and NH3 chemisorption–calorimetry, XPS, Infrared, and UV–visible spectroscopies. Irrespective of the reaction, a consistent reaction rate enhancement with respect to titania (nano-TiO2, P25) references and W-doped TiO2 systems is observed for single-phase anatase W,N-co-doped samples. This is likely linked with the decrease of the band gap energy decrease and results from a combined W–N cooperative effect on structural properties of the anatase network. W,N simultaneous presence also makes a drastic effect on selectivity, maximizing the yield to partial oxidation products. This appears related with surface properties of the materials. [Copyright &y& Elsevier]

Abstract: Birnessite and cryptomelane samples have been prepared and characterised by N2 adsorption at −196°C, XRD, XRF, XPS and H2-TPR. The activity of birnessite and cryptomelane for catalysed combustion of soot under NO x /O2 gas mixtures has been studied and compared with that of some other commercially available pure manganese oxides, namely MnO, MnO2, Mn2O3, Mn3O4, and natural MnO2. Birnessite and cryptomelane are more active for soot combustion than all the commercial oxides tested. Among the manganese oxides studied, birnessite shows the highest catalytic activity, lowering the soot combustion temperature by 150°C regarding the uncatalysed reaction, and cryptomelane lowers this temperature by 120°C. The NO x removal profiles suggest that birnessite chemisorbs NO x and forms potassium nitrate, which melts and reacts with soot. On the contrary, the main soot combustion pathway for cryptomelane and for the commercial manganese oxide tested is based on the catalytic oxidation of NO to NO2. Birnessite and cryptomelane only yield CO2 as carbon-containing soot combustion product. [Copyright &y& Elsevier]

Abstract: Catalytic decomposition of N2O was studied on Na-MOR, H-MOR, and Na-MFI samples exchanged to various extents with cobalt or copper. Co-MOR samples were characterized by FTIR and volumetric measurements of NO adsorption. The most abundant species on Co-MOR was Co2+(NO)2. In agreement, the volumetric data yielded NO/Co=1.8±0.2. On Co-MOR, N2O conversion progressively increased as the cobalt content increased. All samples yielded similar apparent activation energy, E a =75±5kJmol−1. The reaction order was 0.9±0.1 for N2O, and 0.0±0.1 for O2. For samples having a Co-exchange percentage up to 61%, the turnover frequency per total Co atom was independent of the cobalt content and was significantly lower for more extensively exchanged samples. On all Co-MOR samples, the turnover frequency per isolated Co atom was nearly constant, indicating isolated Co2+ as the active site. On Cu-MOR and Cu-MFI samples, N2O conversion markedly increased with the copper content. Samples having a Cu-exchange percentage up to 62% yielded higher E a than more extensively exchanged samples (150±5kJmol−1 vs. 100±5kJmol−1). The reaction order was 0.5±0.1 for N2O, and 0.0±0.1 for O2. We conclude that in Co-MOR and Co-MFI catalysts the active site for N2O decomposition is isolated Co2+, whereas in Cu-MOR and Cu-MFI isolated Cu2+ is nearly inactive. In extensively exchanged Cu-MOR and Cu-MFI, the active site for N2O decomposition is most probably Cu1+. A similar reaction mechanism for N2O decomposition operates over Co-zeolites and extensively exchanged Cu-zeolites. [Copyright &y& Elsevier]

Abstract: This work investigates the use of calcined calcium zincate as solid base catalyst for the methanolysis of sunflower oil to FAME (biodiesel). The precursor and catalyst were characterized by XRD, XPS, SEM, EGA-MS, FTIR and N2 adsorption. The thermal treatment at temperatures as low as 400°C leads to a base catalyst which is very active and stable in biodiesel production from different vegetable oils (sunflower and soybean). The presence of carbonate on the calcium zincate, used as precursor, is negligible after remaining in contact with air for two weeks. The catalyst obtained at 400°C shows FAME yields higher than 90% after 45min of reaction, and the kinetic of the heterogeneous process (60°C, methanol:sunflower oil molar ratio of 12, 3wt.% of catalyst) is very close to that observed under homogeneous conditions (KOH dissolved in methanol). Under these experimental conditions, the catalyst is stable against lixiviation since it can be reutilized for three catalytic runs of 1h, reaching yields higher than 85%. Moreover, by increasing the acidity of the oil until 1.1° (typical value of fried oils), the catalytic performance is maintained. The presence of water has a negative influence on the catalytic activity, since the addition of a 0.2wt.% of water into the reaction medium decreases the FAME yield until 80% after 3h of reaction, although this yield is still higher than 60% after adding a 1wt.% of water. This catalyst is also very active in the transesterification of soybean oil. [Copyright &y& Elsevier]

Abstract: A series of Co–Mo–Mg/Al2O3, K–Co–Mo–Mg/Al2O3, and Co–Mo/silica catalysts were prepared and characterized by means of N2 adsorption, temperature-programmed desorption of ammonia (NH3-TPD), high-resolution transmission electron microscopy (HRTEM), and Fourier transformed infrared (FT-IR) spectra of adsorbed NO. The physicochemical properties of the catalysts were correlated with their hydrodesulfurization and olefin hydrogenation activities. The results showed that the dispersion and stacking of supported MoS2 were more important in influencing the selectivity of FCC gasoline hydrodesulfurization than the catalyst pore diameter and acidity. The compromise between the dispersion and the stacking of supported MoS2 slabs was crucial to form the sufficient and accessible Co–Mo–S phases for achieving optimal hydrodesulfurization selectivity. The present results form a fundamental basis for developing highly effective catalysts for the selective hydrodesulfurization of fluid catalytic cracking gasoline to meet the strict regulations for ultra-low sulfur gasoline. [Copyright &y& Elsevier]