Hydrodesulfurization and hydrodenitrogenation reactions must take place on different sites. The addition of Ir and Pt improves the catalytic behavior of the RuS2 catalyst Display omitted
•RuS2/SBA is ...active in simultaneous hydrodesulfurization and hydrodenitrogenation.•The hydrodesulfurization reaction is not inhibited under the presence of quinoline.•The hydrodenitrogenation reaction is improved in the presence of dibenzothiophene.•Hydrodesulfurization and hydrodenitrogenation on RuS2/SBA occur on different sites.•The presence of Ir and Pt improves the catalytic behavior of RuS2 catalyst.
Simultaneous hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) reactions over RuS2/SBA and the effect of feed composition and the presence of Pt or Ir in the catalyst formulation have been studied. Activity tests were carried out in a flow reactor under a hydrogen pressure of 3.0MPa and WHSV 32h−1. The catalysts were characterized by X-ray diffraction (XRD), N2 adsorption desorption isotherms at −196°C, CO chemisorption, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy of adsorbed CO at low temperature. Characterization results reveal that under the presence of noble metals the dispersion of the RuS2 phase is not affected, the RuS2 coordinatively unsaturated sites (CUS) are in a very sulfided ambient and their population increases; while the noble metals are poorly sulfided and undergo reduction upon reaction. The evaluation of HDN and HDS activity for RuS2/SBA when both (dibenzothiophene) DBT and (quinoline) Q were present in the feed has highlighted the high activity of the RuS2 phase in hydrotreating. The HDS reaction is hardly affected by the presence of Q molecules, with only the hydrogenation (HYD) sites responsible for cyclohexylbenzene (CHB) formation being anyhow altered. HDN results improve in the presence of DBT, even showing high HDN conversion when Q is present in great quantities. These catalytic results strongly suggest that the HDN and HDS reactions must take place on different sites. CO-FTIR spectroscopy results have evidenced that N-containing molecules block the CUS sites responsible for CO adsorption although when S-containing molecules are present, N-containing molecules should be easily transformed since CO-adsorption sites are again available. The addition of small quantities of iridium and platinum to ruthenium sulfide improves the catalytic behavior of the RuS2 catalyst. This is probably due to the greater number of CUS sites and Ir and Pt acting as active hydrogen suppliers. Moreover, these noble metals can act as real active sites where the DBT HDS reaction takes place.
A freeze-drying precursor method was used to obtain submicrometric powders of ceria-based materials such as Ce1−xGdxO2−δ (x=0, 0.01, 0.05, 0.10 and 0.20), 80%CeO2–20%ZrO2, 80%CeO2–20%Al2O3 and ...(1−y)Ce0.99Gd0.01O2−δ–(y)Al2O3 (y=0.01, 0.02, 0.05, 0.10 and 0.30) at temperatures as low as 400°C. The phase formation and evolution with the temperature was studied by X-ray diffraction (XRD). Also, temperature programmed reduction (TPR) was performed to investigate the reducibility of the ceramic powders. It was observed that after reduction of the ceria-based materials the fluorite structure of the samples was retained. The TPR profiles showed two peaks which are associated to the surface and bulk ceria reduction processes. Likewise, after the TPR measurements the resulting powders have showed high phase stability and reproducibility. XPS results confirmed the reduction of Ce4+ to (Ce3++Ce4+) ratio with alumina doping.
Functionalized TiO2 nanoparticle, which have added phosphates, sulfates and GABA in its surface as toxic agent against Nosocomial Infections.
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•Four Cu/TiO2 nanoparticles ...functionalized using phosphates, sulfates and organic compounds on the external and internal surface were prepared.•The chemical state of central metal and the surface composition of nanoparticles were characterized by XPS.•XPS results indicated that Cu1+ and Ti3+were stabilized inside the network at room temperature.•The four studied nanobiocatalysts degraded the DNA and Escherichia coli.
New copper compounds were proposed as alternative toxic agents against Nosocomial Infections (NI); in contrast with other copper complexes reported in the literature, they were inorganic nanobiocatalysts. The design of diverse Cu species such as Cu(0), Cu(I) and Cu(II) over TiO2 has enabled us to induce hydrogen bonds in the nanoparticle network. The main objective of this research is to use copper instead of silver to avoid the high cost at industrial level, of the use of silver. Four Cu/TiO2 precursors were used and these were functionalized using phosphates, sulfates and organic compounds on the external and internal surface (Cu/TiO2-F). The chemical state of central metal and the surface composition were studied by XPS and the materials were analyzed by Electronic Paramagnetic Resonance and UV–vis spectroscopies, and finally they were microbiologically tested against E. Coli.
Solid acid catalysts based on WO
-SiO
and WO
-ZrO
-SiO
were prepared by one-pot non-hydrolytic sol-gel method and tested in the gas phase glycerol dehydration to acrolein. Their structural and ...textural characteristics were determined by X-ray diffraction (XRD), N
adsorption, X-ray energy dispersive spectroscopy (XEDS), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Their acid characteristics were studied by both temperature programmed desorption of ammonia (NH
-TPD) and FTIR of adsorbed pyridine. Under our operating conditions, all the catalysts were active and selective in the transformation of glycerol to acrolein, which was always the main reaction product. The high selectivity to acrolein is achieved on catalysts presenting a higher proportion of Brønsted acid sites. In addition, the role of oxygen in the feed on catalytic performance of these catalysts is also discussed.
A series of tetrametallic hydrotalcite with different Ni loading, were synthesized by coprecipitation method. Then, these hydrotalcites were calcined in their respective metal oxides and were used as ...catalysts in the etherification reaction for the synthesis of polyglycerols. The effect of Ni loading on the structural and textural features was investigated by various techniques such as X-ray diffraction (XRD), thermogravimetric analysis TG–DSC–MS, temperature-programmed reduction (H
2
-TPR), temperature-programmed desorption (NH
3
-TPD) and 1-butene isomerization as a model reaction to probe acid–base character of catalysts. Mixed oxides derived from hydrotalcites are found to be active and suitable, via solvent free, in the glycerol etherification reaction. A gradual enhance of glycerol conversion is revealed when increasing the Ni/Mg molar ratio and the most active catalyst found is HTc-Ni
75%
with full selectivity to diglycerol.
Highlights
The presence of Ni
2+
species modifies the amount of acid and basic sites.
The partial incorporation of Ni
2+
enhances the catalytic activity.
The glycerol etherification leads to diglycerol and triglycerols as products.
Temperatures higher than 220 °C lead to uncontrolled polymerizations.
Cobalt phosphide catalysts supporting on SiO
2
presenting different Co
x
P
y
stoichiometry were proved in hydrodeoxygenation (HDO) of two different model molecules present in biomass derived bio-oil ...such as phenol (Ph) and dibenzofuran (DBF). To investigate composition effects a series of cobalt phosphide catalysts presenting different initial P/Co atomic ratio were prepared. The catalysts were characterized by a range of techniques (N
2
physisorption, XRD, TEM, NH
3
-TPD and XPS) and tested for DBF and Ph HDO activity and selectivity. Characterization results evidenced good textural properties, high dispersion of the active phase, as well as the presence of acid sites after P and Co incorporation. The highest activity was observed for catalysts containing an intermediate P/Co content were the CoP phase was the predominat one. Those catalyst containing Co
2
P or CoP
2
phases were less active in these reactions.
Porous clay heterostructures (PCH) have been synthesized from raw bentonite, obtaining porous materials with high surface area and micro-, meso- and macroporosity. Both raw bentonite and PCH have ...been evaluated in CO2 adsorption processes at 1 bar and 25 °C. In both cases, adsorption isotherms were well fitted using the Langmuir model, obtaining an increase of the CO2 adsorption from 0.112 mmol CO2 g−1 for the raw bentonite to 0.640 mmol CO2 g−1 in the PCH. In order to improve the CO2 adsorption capacity, raw bentonite and PCH were functionalized with amine species, via grafting using 3-aminopropyltriethoxysilane (APTES) and via impregnation with polyethylenimine (PEI) or tetraethylenepentamine (TEPA). The isotherms of the amine-functionalized samples were adjusted to the Dual-Langmuir model, which assumes the coexistence of physical and chemical adsorption sites. From the profiles of the CO2 isotherms, it can been observed that grafted-PCH with APTES shows the coexistence of physical and chemical interactions, reaching 1.023 mmol CO2 g−1. The adsorption of CO2 on PCH impregnated with TEPA and mainly with PEI is governed by chemical interactions between the amine species located in the porous structure and/or on the surface of the adsorbent and the CO2 molecules, attaining maximum values of 1.644 and 1.465 mmol CO2 g−1 for TEPA and PEI, respectively.
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•Porous clay heterostructure were used as adsorbent for CO2 capture.•Porous clay heterostructure displayed higher CO2 capture values than raw bentonite.•CO2 adsorption capacity was increased by the incorporation of amine species.•Dual-Site Langmuir model revealed physical and chemical adsorption sites.•The addition of tetraethylenepentamine led to the highest CO2 adsorption at 1 bar.
In recent work J. Morales, J. Santos-Peña, Electrochem. Commun. 9 (2007) 2116, we prepared nanosized α-LiFeO
2 with increased electrochemical activity in lithium cells relative to various lithium ...ferrite polymorphs. In this work, we studied the previous electrodes in different charge states in order to obtain a more accurate picture of the phenomena occurring during cycling.
Ex
situ X-ray photoelectron spectroscopy (XPS) measurements confirmed the oxidation/reduction of iron atoms during the charge/discharge process. The electrochemical impedance spectroscopy results suggested that the electrolyte is not oxidised during the first charge, but rather than a solid electrolyte interface is formed after one cycle. Also, thermal tests revealed that Fe(IV) present in the electrodes reacted with the electrolyte to form oxidised carbon species. Finally, α-LiFeO
2 was tested as a positive electrode material in a lithium battery under different regimes. Stabilised capacities up to 150
mAh
g
−1 were obtained under a C/4 regime. This lithium ferrite is therefore an attractive alternative to LiCoO
2.
The heterostructure and compositional depth profile of low-temperature processed (Pb0.76Ca0.24)TiO3 (PCT24) ferroelectric thin films have been studied in the present work. The films were prepared by ...ultraviolet (UV) sol–gel photoannealing (also called photochemical solution deposition, PCSD) onto platinized silicon substrates and crystallized at 450 °C in air and oxygen atmospheres. Despite using such a low temperature, analysis carried out by X-ray photoelectron spectroscopy (XPS) revealed the total lack of organic rests within the bulk film. Complementary information about the heterostructure of the films was also obtained by Rutherford backscattering spectroscopy (RBS). Both analytical techniques detected the presence of a lead gradient in the films, together with small fluctuations on the concentration of this element along the bulk film. The RBS study also showed that the films of this work develop a Pt x Pb interface between the ferroelectric layer and the Pt bottom electrode. The thickness of this interlayer is much lower than that of the interface formed in PCT24 films prepared at higher temperatures (650 °C) without UV irradiation (conventional CSD). On the other hand, the low processing temperature here used minimizes the lead loss by volatilization, as deduced from the RBS simulated spectra of the films. Thus, the lead excess incorporated in the precursor solution remains in the films after the crystallization treatment. This result would suppose a significant advance toward the environmentally low-impact processing of lead-containing ferroelectric films with applications in electrical and electronic components (e.g., piezoelectric devices).
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