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Two series of SBA-16-supported Co Mo W ternary sulfide catalysts with atomic ratio r = Mo/(Mo + W) ranging from 0.3 to 0.7 were prepared by the simultaneous impregnation of SBA-16 and phosphated-SBA-16 substrates with metal precursors. The samples were characterized by a variety of techniques (chemical analysis, N 2 physisorption, SEM, XRD, DRS UV–vis, TPR, TPD-NH 3 , Raman spectroscopy, HRTEM, XPS and coke burning) . The catalytic performance was evaluated in the hydrodesulphurization (HDS) of dibenzothiophene (DBT), carried out in a batch reactor at 350 °C and 3.1 MPa of total H 2 pressure. The maximum activity at the same atomic ratio r = 0.4 was observed for the catalysts supported on SBA-16 modified with phosphorous ( r = 0.4(P)). HRTEM evidenced that this was because different MoS 2 crystalline structures were formed: the P-free sample prepared with Mo/(Mo + W) atomic ratio of 0.6 ( r = 0.6) exhibited the MoS 2 -2H crystalline structure whereas the P-containing samples prepared with Mo/(Mo + W) atomic ratio of 0.4 ( r = 0.4(P)) exhibited the interplanar distance corresponding to (0 0 3) planes of MoS 2 -3R crystalline structure. Additionally, the best activity of the r = 0.4(P) sulfide catalyst was linked with the enhancement of the WS 2 species surface exposure accompanied with a larger sulfidation degree of W species (from XPS). [ABSTRACT FROM AUTHOR]

In this work, the catalytic activity of ternary Co–Mo–W/Al-SBA-16 systems was investigated in the reaction of hydrodesulfurization (HDS) of dibenzothiophene (DBT) performed in a batch reactor at 350 °C and total H 2 pressure of 33.8 bar. The synthesized materials were characterized by a variety of techniques (chemical analysis, N 2 adsorption–desorption isotherms, XRD, TPR, TPD-NH 3 , FTIR of adsorbed pyridine, DRS-UV–vis, HRTEM and XPS). By applying the direct synthesis method, high surface area substrates with Al 3+ incorporated into the silica framework. The activity results indicate that all CoMoW/Al-SBA-16 catalysts were active in the HDS of DBT, the largest activity was found in the catalyst with the highest Al-content. This behavior was explained in terms of its largest specific area and good dispersion of the metal sulfide phases having average size of 3.3 nm (from HRTEM). Moreover, FT-IR spectroscopic study of adsorbed pyridine indicated Al incorporation into a SBA-16 substrate produces both Brønsted and Lewis acidities, which are beneficial for the HDS of DBT. All catalysts showed a high selectivity towards biphenyl indicating that HDS of DBT reaction proceeds mainly via direct desulfurization (DDS) reaction pathway. [ABSTRACT FROM AUTHOR]

Abstract: P-containing SBA-16 mesoporous systems were used as supports of ternary Ni–Mo–W hydrodesulfurization (HDS) catalysts. The samples were characterized by a variety of techniques (N2 adsorption–desorption isotherms, XRD, TPR, TPD-NH3, DRS UV–vis and HRTEM). XRD profiles evidenced the formation of crystalline Mo1- x W x O3 and NiMoO4 phases on the surface of oxide catalyst precursors with high P-loadings (1.0 and 1.6wt.%). The UV–vis DRS measurements showed a substantial decrease of energy band gap after P-loading onto the SBA-16 substrate with respect to P-free sample. The sulfided catalysts were tested in separate HDS of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) reactions performed in a batch reactor at 320°C and H2 pressure of 5.0MPa. For both HDS reactions, the initial catalyst activity displayed a volcano-type curve indicating that catalyst behavior depends strongly on the phosphorous loading being all catalysts more active in the HDS of DBT then in the HDS of 4,6-DMDBT. The NiMoW/SBA-16 catalyst loaded with optimized amount of phosphorous (1.0wt.%) showed superior initial activity than the P-free counterpart. This effect was attributed to the enhancement of active phases dispersion on the support surface, as revealed by HRTEM measurements. It was found that the formation of “onion-type” Mo(W)S2 phases on the catalyst surface was detrimental for the HDS activity. At reaction time of 5h, the most active NiMoW/SBA-16 catalyst loaded with 1.0wt.% of P showed similar activity in both HDS of DBT and 4,6-DMDBT reactions. It was found that HYD route of both reactions was promoted by the support modification with P and due to inhibition of coordinatively unsaturated sites (CUSs) by competitive adsorption of products (mainly H2S). [Copyright &y& Elsevier]

Abstract: Nanostructures of tungsten trioxide (WO3) have been successfully synthesized by using an aged route at low temperature (60 °C) followed by a hydrothermal method at 200 °C for 48 h under well controlled conditions. The material was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Energy Dispersive Spectroscopy (EDS), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Specific Surface Area (SBET) were measured by using the BET method. The lengths of the WO3 nanostructures obtained are between 30 and 200 nm and their diameters are from 20 to 70 nm. The growth direction of the tungsten oxide nanostructures was determined along [010] axis with an inter-planar distance of 0.38 nm. [Copyright &y& Elsevier]

Trimetallic CoNiMo hydrodesulfurization (HDS) catalysts were herein synthesized on Al 2 O 3 support through an incipient wetness co-impregnation procedure using ammonium heptamolybdate and cobalt (and nickel) acetate as precursors. CoNiMo catalysts were obtained by adding in a small proportion of nickel with a molar amount representing between 1 and 10% of the total Co atomic loading. This addition of low amounts of nickel allows keeping the (Co + Ni)/(Co + Ni + Mo) molar ratio close to the optimum value of 0.3. The as-formed catalysts were labeled as CoNixMo/Al 2 O 3 with x the relative stoichiometry of Ni compared to Co. Catalysts were then characterized by N 2 adsorption-desorption isotherms, X-ray diffraction, ICP-OES spectroscopy, Raman spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. Catalysts were tested in the HDS of dibenzothiophene (DBT). Results show a significant impact of adding small amounts of nickel to alumina-supported Co-promoted MoS 2 on the final HDS activity. While up to CoNi 0.03 Mo/Al 2 O 3 , the resulting HDS activity is hardly influenced by the addition of nickel, a strong beneficial effect is observed for CoNi0.05Mo/Al 2 O 3 with activity reaching a value of 7.2 × 10−7 mol.g cat −1.s−1. Increasing further, the amount of nickel abruptly decreased the DBT HDS activity. Interpretation of these results is then provided considering the additional role of nickel for improving the intrinsic activity of the HDS sites. Image 1 • The influence of incorporating low amounts of nickel into cobalt-promoted MoS 2 catalysts was herein evaluated. • HDS optimum efficiency is reached for the CoNi 0.05 Mo/Al 2 O 3 catalysts. • The CoNi 0.1 Mo/Al 2 O 3 catalyst with the richest Ni content shows the lowest HDS activity. • TOF values allowed us to analyze the incorporation of nickel into Co-promoted MoS 2 slabs. [ABSTRACT FROM AUTHOR]

In the field of heterogeneous photocatalysis, catalyst concentration is one of the main parameters that restricts light availability, specifically in photocatalytic annular slurry reactors design. Therefore, data that describes the dependence of energy on both, distance and catalyst concentration is needed. This paper proposes the local relative light intensity (LRLI) as a quantity that represents the residual energy on radial distance. Experimental measurements of LRLI were made from 0 mm to 25 mm, using two commercial TiO2 powders in a wide range of concentration (200 to 1000 mg/L). Results show that residual energy was less than 80% at 6 mm from the source, for both catalysts in all concentrations. Furthermore, a forward-scattered behavior was detected, the LRLI profiles (LRLI vs radial distance) followed an exponential decay model. All profiles were correlated as a catalysts concentration function. Information obtained was used to develop a methodology to calculate the LRLI values at any radial distance for a settle catalyst concentration. The calculated values of LRLI approaches real data with a relative local accumulated error less than 10% for both catalysts. This methodology may be applied to calculate the energy available in any TiO2/UV-A annular slurry system. [ABSTRACT FROM AUTHOR]

This article is focused on the problem of the inhibition of the hydrodeoxygenation (HDO) reaction by competitive adsorption of the S-containing compounds on the active sites. The phosphorous effect during co-processing of pyrolysis bio-oils and S-content model compounds over sulfide NiMo/P/HMS-Al catalysts was investigated. A series of NiMo catalysts supported on mesoporous P (x) /HMS-Al materials were prepared and characterized by several techniques. Guaiacol (GUA) was considered as a pyrolysis bio-oils model compound, while the dibenzothiophene (DBT) was used as a model molecule of S-content. The activity test revealed that support modification with 1.1 wt% of P (NM-P1.1) decreased the inhibition of HDO reaction by co-adsorption of DBT on the active sites. With the most active NM-P1.1 catalyst, the formation of a less susceptible to coke formation product (phenol) was favored. The main superiority of sulfided NM-P1.1 catalyst comes from the support decoration with P 2 O 5 nanoparticles leading to its highest Brønsted acidity, the surface enrichment with metal sulfide species as well as with the diminishing of Al leaching from the framework of support during the HDO reaction. The activity tests demonstrated that support modification with phosphorous is an efficient method to solve the problem of the HDS inhibition by the HDO reaction. Unlabelled Image • The NiMoP/HMS-Al 1.1 wt% of P loaded exhibited the best HDO activity and stability during simultaneous HDO and HDS reactions • P loaded is effective method for diminishing the inhibition of HDO reaction by co-adsorption of S-containing compound • Surface P 2 O 5 nanoparticles decoration is effective for lowering Al leaching from the support framework during HDO reaction [ABSTRACT FROM AUTHOR]

This paper presents the catalytic activity of ruthenium phosphides supported on SBA-15 material as hydrodesulfurization (HDS) catalysts of gasoline model compounds. It was studied the influence of the P/Ru molar ratio of 0.5, 1, 2, 3, and 4.5 (samples were labeled as 0.5-P/Ru, 1-P/Ru, 2-P/Ru, 3-P/Ru and 4.5-P/Ru) in the hydrodesulfurization of 3-methyl-thiophene as a model molecule and evaluated under mild reaction conditions. The ruthenium phosphide phase was synthesized from a conventional phosphate reduction method using RuCl 3 and (NH 4) 2 HPO 4 as precursors. The catalysts were characterized by XRPD, N 2 adsorption–desorption isotherms, TEM, EDS, XPS, NH 3 -TPD, H 2 -TPD and CO chemisorption. All catalysts maintained the mesoporous structure characteristic of the SBA-15 support, although pore blockage occurred at high P loadings. TEM images and EDS mapping showed well dispersed active phosphide phases, mainly RuP and Ru 2 P, as evidenced by XRPD. 3-P/Ru catalyst became to be the most active in the HDS reaction, with a high isomerization ability, which was assigned to its medium acidity and higher amount of active species on the surface that activates H 2 species. • The ruthenium phosphide catalysts are effective for the HDS for selective sulfur removal of gasoline model compounds. • The phosphorus load leads the formation of Ru 2 P active phase, optimizing a P/Ru molar ratio of 3. • The ruthenium phosphide catalysts displayed medium acidity properties that led to a high isomerization ability. [ABSTRACT FROM AUTHOR]

This study reports the effect on catalytic activity resulting from Ni incorporation in Pt nanoparticles supported on carbon nanotubes (CNTs) for electrochemical methanol oxidation at low temperature in acidic conditions. Chemical composition, morphology and structure of the Pt 1–X Ni X /CNTs (X = 0, 0.1, 0.2, 0.3, 0.4, 0.5) catalysts were studied by EDS, SEM, XRD, TEM and TGA. The catalytic activity of the prepared materials in methanol electro-oxidation reaction was investigated by cyclic voltammetry (CV) and chronoamperometry (CA). The results of catalytic activity of the nanostructured materials showed a volcano-type relationship between the Ni relative concentration current density. The enhancement of catalytic activity was attributed to changes in surface electronic structure of Pt nanoparticles that impacted in an increment of active sites for methanol dehydrogenation and oxidation processes. On the other hand, high concentration of Ni (concentration ≥ 30 at.%) in Pt nanoparticles caused a substantial decrease of the catalytic activity due to a depletion of active sites for the methanol dehydrogenation process. The highest catalytic activity was observed when the Ni relative concentration reaches 30 at.%. [ABSTRACT FROM AUTHOR]

Abstract This work presents the results obtained from the dosimetric properties of the new radiation detectors of KMgF 3 :Tb + PTFE. The thermoluminescent material was obtained by microwave technique. The polycrystalline powder obtained was mixed with polytetrafluoroethylene resin powder in the ratio 2:3 to make dosimeters in pellet form. The thermoluminescent response of these new detectors presented a linear behavior, in the dose range between 1 and 1000 Gy 60Co gamma radiation, the repeatability test in the measurements, during ten cycles of heat treatment, irradiation and readouts, showed ± 3.7% DS, the stability test of thermoluminescent signal, during two months showed that the fading is practically null. For the results obtained, this new detector could be very useful for radiation dosimetry, in clinical applications. Highlights • The synthesis of KMgF 3 :Tb assisted via microwave was performed. • The dosimetric properties of KMgF 3 :Tb + PTFE phosphor was studied. • The material has very good reproducibility. • The TL signal is very stable. • This TL material is suitable for dosimetry. [ABSTRACT FROM AUTHOR]

A series of trimetallic Ni–Mo–W catalysts supported on cubic mesoporous silica (SBA-16) modified with Ti were prepared with the aim to study the effect of Ti incorporation method (sol-gel against pore volume post-synthesis impregnation) on the physical and chemical properties of the synthetized materials. The catalytic behavior of the sulfided catalysts was evaluated in the reaction of hydrodesulfurization (HDS) of dibenzothiophene (DBT). The catalyst characterization by variety of techniques demonstrated that one-pot synthesis led to Ti ions incorporation into SBA-16 structure and an increase of acidity whereas the post-synthesis method led to formation of octahedral Ti species decorating support's surface. The catalytic behavior was closely linked with the characteristics of their oxide precursors. The catalysts prepared by sol-gel method demonstrated to be more effective toward S-removal from DBT than the catalyst modified by post-synthesis method. The initial HDS activity of the best NiMoW/S16–Ti catalyst doubled that of NiMoW/SBA-16 and a commercial NiMo/γ-Al 2 O 3 which was linked with its better textural properties, acidity and adequate active phases dispersion. The main effect of the support modification with Ti was the enhancement of selectivity toward HYD route products. The best hydrogenation selectivity was archived by Ti incorporation via post-synthesis method which was linked to the formation of curved Mo(W)S 2 layers having a large amount of "brim" HYD sites. Image 1 • HDS activity of NiMoW catalysts was enhanced by Ti incorporation into SBA-16 framework. • The post-synthesis support's decoration with TiO 2 enhanced HYD selectivity. • The bent Mo(W)S 2 layers are formed around of TiO 2 nanoparticles. [ABSTRACT FROM AUTHOR]