Scientific Papers in SCI

2012


Title: Effect of deposition of silver on structural characteristics and photoactivity of TiO2-based photocatalysts
Author(s): Melian, EP; Diaz, OG; Rodriguez, JMD; Colon, G; Navio, JA; Macias, M; Pena, JP
Source: Applied Catalysis B-Environmental, 127 (2012) 112-120

abstract | fulltext

The homemade bare TiO2 photocatalyst obtained in a previous work was modified with nanosized silver particles by liquid impregnation and photodeposition methods to obtain different noble metal loadings (0.3–1 at.%). Characterization of the synthesized photocatalysts was carried out by the BET method, XPS, TEM, SEM-EDX, XRD and diffuse reflectance measurements. Photocatalytic activity of these silver-deposited TiO2 nanoparticles was tested by photocatalytic degradation of phenol as a reference model representing phenolic pollutants. The noble metal content on the TiO2 surface affected the efficiency of the photocatalytic process, and the photocatalytic activity of noble metal-modified TiO2 was considerably better than that of bare TiO2. Phenol decomposition rate was higher with TiO2 modified by the liquid impregnation method than with TiO2 modified by the photodeposition method.

October, 2012 | DOI: 10.1016/j.apcatb.2012.08.007

Title: Insights towards the influence of Pt features on the photocatalytic activity improvement of TiO2 by platinisation
Author(s): Murcia, JJ; Navio, JA; Hidalgo, MC
Source: Applied Catalysis B-Environmental, 126 (2012) 76-85

abstract | fulltext

The influence of Pt features, such as particle size, dispersion, oxidation state and amount of metal, on the improvement of the photoactivity of TiO2 for phenol and methyl orange degradation was studied.

The size of Pt deposits was precisely controlled by changing deposition time under medium light intensity during the photodeposition, with sizes ranging from 3 to 6 nm. Pt oxidation state was also strongly dependent on the photodeposition time.

Photocatalytic activity results showed that the fraction of metallic platinum (Pt0) was the crucial factor for the improvement of the activity. When the fraction of Pt0 was similar, metal deposit size became the dominant parameter influencing the activity.

The influence of the substrate to be degraded (phenol or methyl orange) was also studied.

September, 2012 | DOI: 10.1016/j.apcatb.2012.07.013

Title: Selective photooxidation of alcohols as test reaction for photocatalytic activity
Author(s): Lopez-Tenllado, F. J.; Marinas, A.; Urbano, F. J.; Colmenares, J. C.; Hidalgo, M. C.; Marinas, J. M.; Moreno, J. M.
Source: Applied Catalysis B-Environmental, 128 (2012) 150-158

abstract | fulltext

Twenty-four different titania-based systems synthesized through the sol–gel process varying the precursor (titanium isopropoxide or tetrachloride) and/or the ageing conditions (magnetic stirring, ultrasounds, microwave or reflux) were tested for liquid-phase selective photooxidation of 2-butenol (crotyl alcohol) to 2-butenal (crotonaldehyde) and gas-phase selective photooxidation of 2-propanol to acetone. To the best of our knowledge, the former process is suggested for the first time as test reaction for photocatalytic activity. Interestingly, both test reactions (despite having very different reactant/catalyst ratio and contact times) showed quite similar results in terms of influence of the precursor (titanium isopropoxide leading to better results than titanium tetrachloride) and the metals (the presence of iron, palladium or zinc being detrimental to activity whereas zirconium and especially gold improved the results as compared to pure titania). To our mind, these results give validity to both processes as test reactions for a fast screening of catalysts for photocatalytic tranformations. Finally, some gold-containing solids even improved photocatalytic activity of Degussa P25.

November, 2012 | DOI: 10.1016/j.apcatb.2012.02.015

Title: Cu-modified cryptomelane oxide as active catalyst for CO oxidation reactions
Author(s): Hernandez, Willinton Y.; Centeno, Miguel A.; Ivanova, Svetlana; Eloy, Pierre; Gaigneaux, Eric M.; Odriozola, Jose A.
Source: Applied Catalysis B-Environmental, 123-124 (2012) 27-35

abstract | fulltext

Manganese oxide octahedral molecular sieves (cryptomelane structure) were synthesized by a solvent-free method and tested in the total oxidation of CO (TOX), and preferential oxidation of CO in presence of hydrogen (PROX). The influence of Cu in the cryptomelane structure was evaluated by several characterization techniques such as: X-ray fluorescence (XRF), thermogravimetric analysis (TGA), hydrogen temperature programmed reduction (TPR-H2) and X-ray photoelectron spectroscopy (XPS). The Cu-modified manganese oxide material (OMS-Cu) showed very high catalytic activity for CO oxidation in comparison to the bare manganese oxide octahedral molecular sieve (OMS). The improved catalytic activity observed in OMS-Cu catalyst was associated to a high lattice oxygen mobility and availability due to the formation of Cusingle bondMnsingle bondO bridges. In addition, under PROX reaction conditions the catalytic activity considerably decreases in the presence of 10% (v/v) CO2 in the feed while the same amount of water provokes an improvement in the CO conversion and O2 selectivity.

July, 2012 | DOI: 10.1016/j.apcatb.2012.04.024

Title: Influence of the shape of Ni catalysts in the glycerol steam reforming
Author(s): Bobadilla, L. F.; Alvarez, A.; Dominguez, M. I.; Romero-Sarria, F.; Centeno, M. A.; Montes, M.; Odriozola, J. A.
Source: Applied Catalysis B-Environmental, 123-124 (2012) 379-390

abstract | fulltext

Biomass is an alternative to replace the use of fossil fuels. Glycerol, a byproduct in the biodiesel production, can be used for obtaining hydrogen. The most efficient method for obtaining hydrogen from glycerol is the steam reforming (SR). So far all the published papers report the use of conventional catalyst. In this paper, a structured catalyst has been prepared and compared with the conventional ones (powder and spherical pellets). Results show that the structured catalyst (monolith) is more stable as formation of coke was not observed.

July, 2012 | DOI: 10.1016/j.apcatb.2012.05.004

Title: New insights into the synergistic effect in bimetallic-boron catalysts for hydrogen generation: The Co–Ru–B system as a case study
Author(s): Arzac, G. M.; Rojas, T. C.; Fernandez, A.
Source: Applied Catalysis B-Environmental, 128 (2012) 39-47

abstract | fulltext

Catalysed sodium borohydride hydrolysis is a high-potential method to produce hydrogen for portable applications. Co–B catalysts are the most chosen because they are easily prepared, cheap and efficient. The addition of small amounts of Ru produces a significant enhancement in catalytic activity.

In the present work a series of Co–Ru–B catalysts with variable Ru content was prepared, isolated and characterized. The comprehension of the synergistic effect was achieved trough the incorporation of the nanostructural dimension to the study of surface and bulk chemical states of the involved atoms along the series. It was found that up to 70% (of total metal) atomic content of Ru the catalysts can be considered isostructural to the single Co–B catalyst in the nanoscale. A structural transition occurs in the case of the pure Ru–B material to produce a boron deficient material with higher nanoparticle size. This structural transition together with Co segregation and Ru dispersion play a key role when explaining a [OH−] dependent effect.

The inexistence of borate layers in Ru rich catalysts is suggestive in the research for non deactivating catalysts.

November, 2012 | DOI: 10.1016/j.apcatb.2012.02.013

Title: LaNiO3 as a precursor of Ni/La2O3 for CO2 reforming of CH4: Effect of the presence of an amorphous NiO phase
Author(s): Rosa Pereñiguez , Victor M. Gonzalez-delaCruz, Alfonso Caballero, Juan P. Holgado,
Source: Applied Catalysis B-Environmental, 123-124 (2012) 324-32

abstract | fulltext

The objective of the present work has been the study of the physico-chemical and catalytic properties of Ni/La2O3 catalysts obtained by reduction of four LaNiO3 samples prepared by different methods. The LaNiO3 precursors as well as the resulting Ni/La2O3 catalysts, were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), temperature programmed reduction and oxidation (TPR, TPO). The catalytic performances of these systems for dry reforming of methane (DRM) were also tested. These samples show different physico-chemical properties resulting from the synthesis method used. The XAS and TPR measurements show that in all four LaNiO3 samples there is, in addition of the crystalline LaNiO3 rhombohedrical phase, a significant amount of an amorphous NiO phase, not detectable by XRD but evidenced by XAS. The amount of this NiO amorphous phase seems to play, together with some other microstructural parameters, an important role in the performance of the Ni/La2O3 samples for the DRM reaction.

July, 2012 | DOI: 10.1016/j.apcatb.2012.04.044

Title: Enhancement of Fast CO2 Capture by a Nano-SiO2/CaO Composite at Ca-Looping Conditions
Author(s): Valverde, JM; Perejon, A; Perez-Maqueda, LA
Source: Environmental Science and Technology, 46 (2012) 6401-6408

abstract | fulltext

In this paper we show the performance of a new CO 2 sorbent consisting of a dry physical mixture of a Ca-based sorbent and a SiO 2 nanostructured powder. Thermo-gravimetric analysis (TGA) performed at conditions close to the Ca-looping process demonstrate that the rate of CO 2 capture by the mixture is enhanced during the fast carbonation stage of practical interest in applications. Moreover, the residual capture capacity of the mixture is increased. SEM/EDX, physisorption, and XRD analyses indicate that there is a relevant interaction between the nanostructured SiO 2 skeleton and CaO at high temperatures, which serves to improve the efficiency of the transfer of CO 2 to small reactive pores as well as the stability of the sorbent pore structure.

June, 2012 | DOI: 10.1021/es3002426

Title: Influence of Vanadium or Cobalt Oxides on the CO Oxidation Behavior of Au/MOx/CeO2-Al2O3 Systems
Author(s): Reina, TR; Moreno, AA; Ivanova, S; Odriozola, JA; Centeno, MA
Source: Chemcatchem, 4 (2012) 512-520

abstract | fulltext

A series of V2O5- and Co3O4-modified ceria/alumina supports and their corresponding gold catalysts were synthesized and their catalytic activities evaluated in the CO oxidation reaction. V2O5-doped solids demonstrated a poor capacity to abate CO, even lower than that of the original ceria/alumina support, owing to the formation of CeVO4. XRD, Raman spectroscopy, and H2-temperature programmed reduction studies confirmed the presence of this stoichiometric compound, in which cerium was present as Ce3+ and its redox properties were avoided. Co3O4-doped supports showed a high activity in CO oxidation at subambient temperatures. The vanadium oxide-doped gold catalysts were not efficient because of gold particle agglomeration and CeVO4 formation. However, the gold–cobalt oxide–ceria/alumina catalysts demonstrated a high capacity to abate CO at and below room temperature. Total conversion was achieved at −70 °C. The calculated apparent activation energy values revealed a theoretical optimum loading of a half-monolayer.

April, 2012 | DOI: 10.1002/cctc.201100373

Title: Nanoporous silica microparticle interaction with toll-like receptor agonists in macrophages
Author(s): Cejudo-Guillen, M; Ramiro-Gutierrez, M L; Labrador-Garrido, A; Diaz-Cuenca, A; Pozo, D
Source: Acta Biomaterialia, 8 (2012) 4295-4303

abstract | fulltext

Nanoporous silica microparticles (NSiO2-MP) are considered to be potential drug delivery systems and scaffolding platforms in tissue engineering. However, few biocompatibility studies regarding NSiO2-MP interaction with the immune system have been reported. Toll-like receptors (TLR) are involved in host defence as well as autoimmune and inflammatory diseases. The results show that NSiO2-MP up to 100 μg ml−1 do not affect macrophage cell viability after 24 h cell culture. Moreover, NSiO2-MP do not compromise the cell viability of TLR-activated Raw 264.7 cells, for either cell surface TLR (TLR1/TLR2/TLR4/TLR6) or endocytic compartment TLR (TLR3/TLR7/TLR9). Furthermore, Raw 264.7 cells do not respond to NSiO2-MP exposure in terms of IL-6 or IL-10 secretion. NSiO2-MP co-treatment in the presence of TLR ligands does not impair or enhance the secretion of the pro-inflammatory cytokine IL-6 or the regulatory cytokine IL-10. Thus, NSiO2-MP do not affect macrophage polarization towards a pro-inflammatory or immunosuppressive status, representing added value in terms of biocompatibility compared with other SiO2-based micro- and nanoparticles.

December, 2012 | DOI: 10.1016/j.actbio.2012.07.026

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