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  • UV to far-IR reflectance spectra of carbonaceous chondrites - I. Implications for remote characterization of dark primitive asteroids targeted by sample-return missions

     Trigo-Rodríguez, José María; Moyano Cambero, Carles E.; Llorca Pique, Jordi; Fornasier, Sonia; Barucci, Maria Antonietta; Belskaya, Irina N.; Martins, Zita; Rivkin, Andrew S.; Dotto, Elisabetta; Madiedo, José María; Alonso Azcárate, Jacinto
    Monthly notices of the Royal Astronomical Society
    Date of publication: 2014-01-01
    Journal article

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    We analyse here a wide sample of carbonaceous chondrites from historic falls (e.g. Allende, Cold Bokkeveld, Kainsaz, Leoville, Murchison, Murray, Orgueil and Tagish Lake) and from NASA Antarctic collection.With the analysis of these meteorites we want to get new clues on the role of aqueous alteration in promoting the reflectance spectra diversity evidenced in the most primitive chondrite groups. The selected meteorite specimens are a sample large enough to exemplify how laboratory reflectance spectra of rare groups of carbonaceous chondrites exhibit distinctive features that can be used to remotely characterize the spectra of primitive asteroids. Our spectra cover the full electromagnetic spectrum from 0.2 to 25 µm by using two spectrometers. First one is an ultraviolet (UV)-near-infrared (NIR) spectrometer that covers the 0.2-2 µm window, while the second one is an attenuated total reflectance infrared spectrometer covering the 2-25 µm window. In particular, laboratory analyses in the UV-NIR window allow obtaining absolute reflectance by using standardized measurement procedures. We obtained reflectance spectra of specimens belonging to the CI, CM, CV, CR, CO, CK, CH, R and CB groups of carbonaceous chondrites plus some ungrouped ones, and it allows identifying characteristic features and bands for each class, plus getting clues on the influence of parent body aqueous alteration. These laboratory spectra can be compared with the remote spectra of asteroids, but the effects of terrestrial alteration forming (oxy)hydroxides need to be considered. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

  • Conversion of glycerol over 10%Ni/y-Al2O3 catalyst

     Miranda Morales, Bárbara C.; Chimentao, Ricardo J; Santos, Jeannette B O; Gispert Guirado, Francesc; Llorca Pique, Jordi; Medina Cabello, Francisco; Lopez Bonillo, Francisco; Sueiras, Jesus Eduardo
    Applied catalysis B. Environmental
    Date of publication: 2014-04-05
    Journal article

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    The conversion of glycerol in gas phase and atmospheric pressure has been investigated over 10wt.% Ni/¿-Al2O3 catalyst. The catalysts were prepared with nickel nitrate and pre-treated with hydrogen in the range of 623-1073K. The resultant catalysts were characterized by N2-physisoption, H2-chemisorption, X-ray diffraction (XRD), TGA-MS, TEM, RAMAN, NH3-TPD, XPS, TPO-MS and XANES. The stability and the catalytic behavior of the catalysts were affected by the reduction pre-treatment. Glycerol reaction pathways were proposed based on dehydration, dehydrogenation and hydrogenolysis steps. The main products identified were: hydroxyacetone, pyruvaldehyde, pyruvic acid, lactic acid, lactide, acetaldehyde and methane. The number of exposed Ni atoms and the degree of reduction of the NiO species affected the hydrogenolysis reaction of glycerol to CH4 affecting the catalytic stability. The catalyst was deactivated by coke formation, by transformation of Ni phase to nickel carbide (Ni3C), as well as by oxidation of the Ni phase during the reaction. In addition, Raman analysis revealed two types of carbonaceous deposits over the used samples: on the Ni species and on the support. The regeneration treatment by oxidation-reduction reactivated the catalyst successfully. © 2013 Elsevier B.V.

  • Shape-dependent activity of ceria in soot combustion

     Aneggi, Eleonora; Wiater, Dawid; de Leitenburg, Carla; Llorca Pique, Jordi; Trovarelli, Alessandro
    ACS Catalysis
    Date of publication: 2014-01
    Journal article

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    In this study, a series of conventional polycrystalline ceria and single-crystalline ceria nanorods and nanocubes were prepared by hydrothermal methods, and their structural, redo; and morphological properties were investigated using XRD, SEM, HRTEM, BET, temperature-programmed reduction, and oxygen storage capacity measurements. According to HRTEM, they are characterized by exposure of different surfaces: {100} surface for nanocubes; {100}, {110}, and in part {111} for nanorods; and mainly {1 1 1} for conventional polycrystalline ceria, with a morphology dominated by {111}-enclosed octahedral particles. The presence of more-reactive exposed surfaces affects the reaction of soot oxidation positively, with an increase in activity in nanoshaped materials compared with conventional ceria. Thermal aging, although detrimental for surface area, is shown to affect morphology by promoting irregular truncation of edges and corners and development of more reactive surface combinations in all crystal shapes. It is likely that thermal treatment, starting from either cubes or octahedral particles, induces the formation of a similar particle geometry whose activity is dependent on the type of plane exposed and by the number an extension of edge and corners, thus linking reactivity of octahedral particles in conventional ceria powders with that of cubes in nanoshaped materials. The results indicate that soot oxidation is also a surface-dependent reaction, and catalyst design for this purpose should allow for surface structure morphology and its evolution against temperature.

  • Room-temperature Suzuki-Miyaura reaction catalyzed by Pd supported on rare earth oxides: Influence of the point of zero charge on the catalytic activity

     Amoroso, Francesco; Colussi, Sara; del Zotto, Alessandro; Llorca Pique, Jordi; Trovarelli, Alessandro
    Catalysis letters
    Date of publication: 2013-06-01
    Journal article

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    Five Pd/REO (rare earth oxide) compounds (Pd/La2O3, Pd/CeO2, Pd/Pr6O11, Pd/Sm2O 3, and Pd/Gd2O3) have been successfully used as precatalysts in the Suzuki-Miyaura C-C cross-coupling reaction of aryl bromides with arylboronic acids in ethanol/water at r.t. All Pd/REO showed high activity and selectivity. The effective catalyst arises from palladium leaching from the REO support. We have demonstrated that the activity of each Pd/REO (the decreasing order is Pd/La2O3 > Pd/Pr6O 11 > Pd/Gd2O3 > Pd/Sm2O 3 » Pd/CeO2) is strictly related to the corresponding PZC (point of zero charge) value. Accordingly, it can be reasonably argued that the metal is released in solution in the form of Pd2+, and higher is the amount of positive charge on the surface in catalytic conditions, higher is the concentration of Pd2+ ions in solution and faster is the formation of the coupling product. Also the recycling of each Pd/REO is strictly connected with the PZC value of the REO support. As a matter of fact, Pd/CeO2, which has the lowest PZC value (6.7), shows the best reusability, according to its lower tendency to release Pd2+ ions in solution

  • A general approach to fabricate fe3O4 nanoparticles decorated with Pd, Au, and Rh: Magnetically recoverable and reusable catalysts for Suzuki C-C cross-coupling reactions, hydrogenation, and sequential reactions

     Gonzàlez de Rivera, Ferran; Angurell Purroy, Inmaculada; Rossell Abrodos, Marta-Dacil; Erni, Rolf P.; Llorca Pique, Jordi; Jimenez Divins, Nuria; Müller Jevenois, Guillermo; Seco García, Miquel Angel; Rossell Alfonso, Josep Oriol
    Chemistry: a european journal
    Date of publication: 2013-09-02
    Journal article

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    A facile strategy has been explored for loading noble metals onto the surface of ferrite nanoparticles with the assistance of phosphine-functionalized linkers. Palladium loading is shown to occur with participation of both the phosphine function and the surface hydroxyl groups. Hybrid nanoparticles containing simultaneously Pd and Au (or Rh) are obtained by successive loading of metals. Similarly, ferrite nanoparticles decorated with Pd, Au, and Rh have also been formed by using the same strategy. The catalytic properties of the new nanoparticles are evidenced in processes such as reduction of 4-nitrophenol or hydrogenation of styrene. Besides, the sequential process involving a cross-coupling reaction followed by reduction of 1-nitrobiphenyl has been successfully achieved by employing Pd/Au decorated nanoferrite particles. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  • Pd0.01Ru0.01Ce0.98O2-delta: A highly active and selective catalyst for the liquid phase hydrogenation of p-chloronitrobenzene under ambient conditions

     Mistri, Rajib; Llorca Pique, Jordi; Ray, Bidhan Chandra; Gayen, Arup
    Journal of molecular catalysis A. Chemical
    Date of publication: 2013-09
    Journal article

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    Nanostructured bimetal ion substituted ceria, Pd0.01Ru0.01Ce0.98O2-delta (PdRuC2), prepared for the first time by a novel solution combustion synthesis and characterized employing XRD, BET, HRTEM and XPS has been shown to be very active and selective than the monometal ion substituted analogue Pd0.02Ce0.98O2-delta (PdC2), whereas Ru0.02Ce0.98O2-delta (RuC2) is inactive towards liquid phase hydrogenation of p-chloronitrobenzene to p-chloroaniline under ambient conditions. Structural studies show metal ion substituted ceria as the predominant phase. The hydrogenation over PdRuC2 is completed beyond 75 min with 100% selectivity. Conversely, PdC2 hydrogenates similar to 40% of p-chloronitrobenzene with 82% selectivity. Increase of temperature from 35 degrees C to 80 degrees C showed a little higher activity of PdRuC2 but with a lower selectivity. The as-prepared and aged forms of PdRuC2 showed similar activity, whereas PdRuC2 heat-treated at 500 degrees C increased the conversion and the 800 degrees C heated catalyst reduced it (both similar to 2%) indicating high thermal stability. Maximum hydrogenation activity has been observed in ethanol as compared to methanol and butanol. The PdRuC2 catalyst also shows excellent hydrogenation activity towards o-, m-chloronitrobenzene and nitrobenzene. The enhancement of activity and selectivity of Pd in presence of Ru in the PdRu bimetal ionic catalyst for the hydrogenation reaction has been attributed to involvement of remarkable Ru4+-promotion in Pd0.01Ru0.01Ce0.98O2-delta.

  • Sulfonic acid-functionalized aerogels as high resistant to deactivation catalysts for the etherification of glycerol with isobutene

     González, Maria Dolores; Salagre, Pilar; Taboada Cabellos, Elena; Llorca Pique, Jordi; Molins, Elies; Cesteros, Yolanda
    Applied catalysis B. Environmental
    Date of publication: 2013-06-05
    Journal article

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    Silica aerogel and lyogel have been successfully sulfonated in one step by a simple post-synthesis method using microwaves as well as conventional heating. The use of microwaves allowed loading higher amounts of sulfonic acid groups in both silicas, according to the higher S/Si atomic ratio determined by XPS, and the higher sulfur content determined by TGA, also exhibiting lower surface area and higher acidity. Sulfonated aerogels showed higher conversion and selectivity to h-GTBE (glycerol di- and tri-ethers) than sulfonated lyogels for the acid-catalyzed etherification of glycerol with isobutene. This was attributed to the higher content of sulfonic acid groups incorporated in aerogel. Microwave-assisted sulfonated aerogel yielded 75% of selectivity to h-GTBE, which can be used as fuel additive, for practically total conversion. Interestingly, larger porosity of aerogel avoided the partial blocking of pores by reaction products observed when other micro- and mesoporous catalysts were tested for this reaction. The combination of high conversion, high selectivity to h-GTBE, practically no formation of undesired di-isobutylenes and very high resistance to catalyst deactivation makes microwave-assisted sulfonic acid functionalized aerogel a promising catalyst for this etherification reaction.

  • The Ksar Ghilane 002 shergottite-The 100th registered Martian meteorite fragment

     Llorca Pique, Jordi; Roszjar, Julia; Cartwright, Julia A.
    Meteoritic and Planetary Sciences
    Date of publication: 2013-03
    Journal article

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    We report on the discovery of a new shergottite from Tunisia, Ksar Ghilane (KG) 002. This single stone, weighing 538 g, is a coarse-grained basaltic shergottite, mainly composed of maskelynitized plagioclase (approximately 52 vol%) and pyroxene (approximately 37 vol%). It also contains Fe-rich olivine (approximately 4.5 vol%), large Ca-phosphates, including both merrillites and Cl-apatites (approximately 3.4 vol%), minor amounts of silica or SiO2-normative K-rich glass, pyrrhotite, Ti-magnetite, ilmenite, and accessory baddeleyite. The largest crystals of pyroxene and plagioclase reach sizes of approximately 4 to 5 mm. Pyroxenes (Fs26¿96En5¿50Wo2¿41). They typically range from cores of about Fs29En41Wo30 to rims of about Fs68En14Wo17. Maskelynite is Ab41¿49An39¿58Or1¿7 in composition, but some can be as anorthitic as An93. Olivine (Fa91¿96) occurs mainly within symplectitic intergrowths, in paragenesis with ilmenite, or at neighboring areas of symplectites. KG 002 is heavily shocked (S5) as indicated by mosaic extinction of pyroxenes, maskelynitized plagioclase, the occurrence of localized shock melt glass pockets, and low radiogenic He concentration. Oxygen isotopes confirm that it is a normal member of the SNC suite. KG 002 is slightly depleted in LREE and shows a positive Eu anomaly, providing evidence for complex magma genesis and mantle processes on Mars. Noble gases with a composition thought to be characteristic for Martian interior is a dominant component. Measurements of 10Be, 26Al, and 53Mn and comparison with Monte Carlo calculations of production rates indicate that KG 002 has been exposed to cosmic rays most likely as a single meteoroid body of 35¿65 cm radius. KG 002 strongly resembles Los Angeles and NWA 2800 basaltic shergottites in element composition, petrography, and mineral chemistry, suggesting a possible launch-pairing. The similar CRE ages of KG 002 and Los Angeles may suggest an ejection event at approximately 3.0 Ma.

    We report on the discovery of a new shergottite from Tunisia, Ksar Ghilane (KG) 002. This single stone, weighing 538 g, is a coarse-grained basaltic shergottite, mainly composed of maskelynitized plagioclase (approximately 52 vol%) and pyroxene (approximately 37 vol%). It also contains Fe-rich olivine (approximately 4.5 vol%), large Ca-phosphates, including both merrillites and Cl-apatites (approximately 3.4 vol%), minor amounts of silica or SiO2-normative K-rich glass, pyrrhotite, Ti-magnetite, ilmenite, and accessory baddeleyite. The largest crystals of pyroxene and plagioclase reach sizes of approximately 4 to 5 mm. Pyroxenes (Fs26–96En5–50Wo2–41). They typically range from cores of about Fs29En41Wo30 to rims of about Fs68En14Wo17. Maskelynite is Ab41–49An39–58Or1–7 in composition, but some can be as anorthitic as An93. Olivine (Fa91–96) occurs mainly within symplectitic intergrowths, in paragenesis with ilmenite, or at neighboring areas of symplectites. KG 002 is heavily shocked (S5) as indicated by mosaic extinction of pyroxenes, maskelynitized plagioclase, the occurrence of localized shock melt glass pockets, and low radiogenic He concentration. Oxygen isotopes confirm that it is a normal member of the SNC suite. KG 002 is slightly depleted in LREE and shows a positive Eu anomaly, providing evidence for complex magma genesis and mantle processes on Mars. Noble gases with a composition thought to be characteristic for Martian interior is a dominant component. Measurements of 10Be, 26Al, and 53Mn and comparison with Monte Carlo calculations of production rates indicate that KG 002 has been exposed to cosmic rays most likely as a single meteoroid body of 35–65 cm radius. KG 002 strongly resembles Los Angeles and NWA 2800 basaltic shergottites in element composition, petrography, and mineral chemistry, suggesting a possible launch-pairing. The similar CRE ages of KG 002 and Los Angeles may suggest an ejection event at approximately 3.0 Ma.

  • Bio-ethanol steam reforming and autothermal reforming in 3-m channels coated with RhPd/CeO2 for hydrogen generation

     Divins, N.J.; López, Eduardo; Rodriguez Martinez, Angel; Vega, Didac; Llorca Pique, Jordi
    Chemical engineering and processing
    Date of publication: 2013-02
    Journal article

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    A silicon micromonolith of 7 mm diameter and 0.2 mm length containing 1.5 million regular channels with a diameter of 3.3 µm was used for obtaining hydrogen through ethanol or bio-ethanol steam reforming (ESR) and oxidative steam reforming (OSR). The microchannels were coated with RhPd/CeO2 catalyst by a two-step method. First a CeO2 layer of ca. 100 nm thickness was deposited from cerium methoxyethoxide over a SiO2 layer, which was previously grown over the silicon microchannels by oxidation. Then, noble metals were grafted over the CeO2 support from chloride precursors. The unit was successfully tested for hydrogen production, achieving hydrogen rates of 180¿LH2¿cmR-3 for the steam reforming of bio-ethanol at 873 K, S/C = 2 and 0.009 s contact time. Reaction yields of 3.8 and 3.7 mol hydrogen generated per mol ethanol in feed were measured for ESR and OSR, respectively. A performance comparison was performed with a conventional cordierite monolith with the same catalyst formulation. Results show for the silicon microreactor an outstanding improvement of the specific hydrogen production rate, operating at considerably reduced residence times, due to the increase in contact area per unit volume.

    A silicon micromonolith of 7 mm diameter and 0.2 mm length containing 1.5 million regular channels with a diameter of 3.3 μm was used for obtaining hydrogen through ethanol or bio-ethanol steam reforming (ESR) and oxidative steam reforming (OSR). The microchannels were coated with RhPd/CeO2 catalyst by a two-step method. First a CeO2 layer of ca. 100 nm thickness was deposited from cerium methoxyethoxide over a SiO2 layer, which was previously grown over the silicon microchannels by oxidation. Then, noble metals were grafted over the CeO2 support from chloride precursors. The unit was successfully tested for hydrogen production, achieving hydrogen rates of 180 LH2 cmR−3 for the steam reforming of bio-ethanol at 873 K, S/C = 2 and 0.009 s contact time. Reaction yields of 3.8 and 3.7 mol hydrogen generated per mol ethanol in feed were measured for ESR and OSR, respectively. A performance comparison was performed with a conventional cordierite monolith with the same catalyst formulation. Results show for the silicon microreactor an outstanding improvement of the specific hydrogen production rate, operating at considerably reduced residence times, due to the increase in contact area per unit volume.

  • From Au(i) organometallic hydrogels to well-defined Au(0) nanoparticles

     Aguilo, Elisabet; Gavara, Raquel; Lima, Joao Carlos; Llorca Pique, Jordi; Rodriguez, Laura
    Journal of materials chemistry C
    Date of publication: 2013
    Journal article

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    The reaction of water soluble phosphine 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane (DAPTA) with [Au(C[triple bond, length as m-dash]C¿C5H4N)]n yields a luminescent water soluble phosphine gold(I) alkynyl complex [Au(4-pyridylethynyl)(DAPTA)] that leads to the formation of a luminescent hydrogel. A small variation of the phosphine structure (introduction of acetyl groups) with respect to the previously reported complex [Au(4-pyridylethynyl)(PTA)] has a clear effect on the observed properties: (i) a great increase in the hydrogel entanglement structure has been observed; (ii) the different cross-linking structures give rise to specific emission properties. The hydrogel was characterized by different techniques (1H-NMR, absorption and emission spectroscopy, optical microscopy, fluorescent microscopy (FM) and SEM). FM together with microspectrofluorimetry measurements has determined different emissive properties that vary according to the cross-linking process. Thermal treatments of the hydrogel produce well-defined metallic gold nanoparticles with a remarkable narrow size distribution, which have been characterized by SEM, TEM and X-ray photoelectron spectroscopy (XPS). At 200 °C, Au particles measuring 1.0 ± 0.2 nm were obtained. Au nanoparticles were also formed as a result of electron beam irradiation.

  • Synthesis and characterization of poly-l-leucine initialized and immobilized by rehydrated hydrotalcite: Understanding stability and the nature of interaction

     Miranda, Ronald Alexander; Finocchio, Elisabetta; Llorca Pique, Jordi; Medina, Francisco; Ramis, Gianguido; Sueiras, Jesus Eduardo; Segarra González, Anna Maria
    Physical chemistry chemical physics
    Date of publication: 2013-10-07
    Journal article

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    PLLs were synthesized by the ring-opening polycondensation (ROP) method using a-l-leucine N-carboxyanhydride (NCA) and initialized by triethylamine (Et3N), water or rehydrated hydrotalcite (HT rus). The role of temperature, different initiators and water in ROP was further investigated. In general, the initiators used in the polymerization reaction lead to PLL alpha-helical chains containing 5-40 monomers with NCA endgroups via a monomer-activated mechanism. However, the water has a twofold effect on ROP, as both a nucleophile and a base, which involves competition between two different types of initiating mechanisms (nucleophilic attack or deprotonation of the NCA monomer) in the polymerization reaction. This competition provides as a main product NCA endgroups with an alpha-helical structure and leads to the formation of the PLL cyclic-chains and beta-sheet structures which reduce the polymer Mw and the PD of the polypeptide. Furthermore, the water can hydrolyze the NCA endgroups resulting in PLL alpha-helical chains that contain living groups as the main product. On the other hand, the HTrus presents a double role: as both an initiator and a support. The polymers synthesized in the presence of HTrus presented a HT-carboxylate endgroup. The PLLs immobilized in HTrus through an anion-exchange method performed for just 30 minutes presented the PLL immobilized in the interlayer space of the HTrus. The PLL chains of the immobilized counterpart are stabilized by H-bonding with the M-OH of the HT structure. All the polypeptides and biohybrid materials synthesized have been characterized using different techniques (EA, ICP, XRD, Raman, MALDI-TOF, ESI-TOF, FT-IR at increasing temperatures, TG/DT analyses and TEM).

  • Catalytic activity and characterization of Fe-Zn-Mg-Al hydrotalcites in biohydrogen production

     Wimonsong, Pornthip; Llorca Pique, Jordi; Nitisoravut, Rachnarin
    International journal of hydrogen energy
    Date of publication: 2013-08-21
    Journal article

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    Four different M2+-Mg-Al hydrotalcite (HT) materials were investigated for their effect on biohydrogen enhancement, where M2+ is Fe and/or Zn. HTs were synthesized by the coprecipitation method and characterized by infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD). The effect of Fe-Zn-Mg-Al HTs dose (0-833 mg/L) on hydrogen production was investigated in batch tests using sucrose-fed anaerobic mixed culture at 37 °C. The best catalytic activity was observed on Mg-Al HT at 167 mg/L with the maximum hydrogen yield of 2.30 ± 0.37 mol H2/mol sucrose, which was 44% higher than the control. The major metabolites detected in the test were acetic acid (3.6 g/L), butyric acid (4.1 g/L), and lactic acid (0.5 g/L). The basic properties of the different catalysts played an important role in stimulating or inhibiting the activity of hydrogen producing bacteria. Calcined Mg-Al HT did not promote biohydrogen production, suggesting that the catalytic enhancement was related to immobilization of bacteria in the electrostatically charged HT interlayers. Copyright © 2013, Hydrogen Energy Publications, LLC.

  • Hydrogen from bioethanol. Remewable yydrogen technologies. Chapter 7

     Llorca Pique, Jordi
    Date of publication: 2013-05-01
    Book chapter

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    Experimental analysis of a degraded open-cathode PEM fuel cell stack  Open access

     Strahl, Stephan; Gasamans Rodríguez, Noemí; Llorca Pique, Jordi; Husar, Attila Peter
    Iberian Symposium on Hydrogen Fuel Cells and Advanced Batteries
    Presentation's date: 2013
    Presentation of work at congresses

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    The well-known challenges to be overcome in PEM fuel cell research are their relatively low durability and high costs for the platinum catalysts. Thus, this work focuses on factors that impact durability and the links to the fuel cell performance. Therefore a degraded, open-cathode, 20-cell, PEM fuel cell stack, which was used in a laboratory test station for characterization experiments, was analyzed experimentally. Voltage transients during external perturbations, such as changing temperature, humidity and stoichiometries show that degradation affects individual cells quite differently throughout the lifetime of the stack. Electrochemical impedance spectroscopy (EIS) data presents non-reversible catalyst layer and membrane degradation of several cells. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) are in progress in order to validate the results of the electrical analysis and elucidate catalyst and membrane degradation.

  • Gold nanoclusters for efficient removal of organic pollutants at room temperature

     Santiago, Marta; Blázquez, Zaira; Galindo, Edurne; Alves, Leonor; Llorca Pique, Jordi; Mendoza Gomez, Ernesto
    Submarine Air Monitoring and Air Purification
    Presentation's date: 2013-10-15
    Presentation of work at congresses

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    Preserving air quality of an enclosed space such as a submarine is a major challenge yet to be addressed. Currently, CO-H2 burners are employed to maintain a breathable air environment inside the submarine through catalytic conversion of contaminants being present in the air thereof into CO2 + H2O. These burners use a mixture of manganese and copper oxides referred to as hopcalite. Unfortunately, this catalyst presents a reasonable oxidation activity only above 150ºC as it suffers from strong inhibition by the presence of moisture. Furthermore, at such high operating temperatures, partial oxidation of hydrocarbons over the hopcalite may generate toxic by-products such as HF and HCl. Herein, we present a novel catalyst based on gold nanoclusters capable of eliminating massive amounts of organic pollutants at room temperature even in the presence of moisture.

  • Ethanol catalytic membrane reformer for direct PEM FC feeding

     Koch, Reinhold; López, Eduardo; Riera Colomer, Jordi; Allué Fantova, Miguel; Jossen, Andreas; Jimenez Divins, Nuria; Llorca Pique, Jordi
    International journal of hydrogen energy
    Date of publication: 2013
    Journal article

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    In this paper an ethanol reformer based on catalytic steam reforming with a catalytic honeycomb loaded with RhPd/CeO2 and palladium separation membranes with an area of 30.4 cm2 has been used to generate a pure hydrogen stream of up to 100 ml/min to feed a PEM fuel cell with an active area of 5 cm2. The fuel reformer behavior has been extensively studied under different temperature, ethanol¿water flow rate and gas pressure at a fixed S/C ratio of 1.6 (molar). The hydrogen yield has been controlled by acting upon the ethanol¿water fuel flow and gas pressure. A mathematical model of the ethanol reformer has been developed and an adaptive and predictive control has been implemented on a real time system to take account of its nonlinear behavior. With this control the response time of the reformer can be reduced by a factor of 7 down to 8 s. The improved dynamics of the controlled reformer match better the quickly changing hydrogen demands of fuel cells. They reached a magnitude where costly hydrogen buffers between the reformer and the fuel cell can be omitted and an electric buffer at the output of the fuel cell is sufficient.

    In this paper an ethanol reformer based on catalytic steam reforming with a catalytic honeycomb loaded with RhPd/CeO2 and palladium separation membranes with an area of 30.4 cm2 has been used to generate a pure hydrogen stream of up to 100 ml/min to feed a PEM fuel cell with an active area of 5 cm2. The fuel reformer behavior has been extensively studied under different temperature, ethanol–water flow rate and gas pressure at a fixed S/C ratio of 1.6 (molar). The hydrogen yield has been controlled by acting upon the ethanol–water fuel flow and gas pressure. A mathematical model of the ethanol reformer has been developed and an adaptive and predictive control has been implemented on a real time system to take account of its nonlinear behavior. With this control the response time of the reformer can be reduced by a factor of 7 down to 8 s. The improved dynamics of the controlled reformer match better the quickly changing hydrogen demands of fuel cells. They reached a magnitude where costly hydrogen buffers between the reformer and the fuel cell can be omitted and an electric buffer at the output of the fuel cell is sufficient.

  • PdCu alloy nanoparticles on alumina as selective catalysts for trichloroethylene hydrodechlorination to ethylene

     Meshesha, B.T.; Barrabes, Noelia; Llorca Pique, Jordi; Dafinov, Antonio; Medina, Francisco; Foettinger, Karin
    Applied catalysis A. General
    Date of publication: 2013-02-26
    Journal article

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    PdCu bimetallic catalysts supported on alumina were prepared by different common impregnation protocols and by a polyol nanoparticles synthesis route. These materials were studied in order to establish the relationship between structure, particle size, Pd–Cu interaction and catalytic activity/selectivity in the hydrodechlorination of trichloroethylene (TCE) in gas phase. The surface properties and the interaction between Cu and Pd in the bimetallic particles, as well as their catalytic behaviour are strongly influenced by the preparation protocol. Depending on the synthesis, PdCu alloy formation or isolated phases were observed. The presence of isolated Pd particles leads to high ethane selectivity, whereas upon alloy formation or strong interaction between Pd and Cu a higher ethylene yield was obtained. By the nanoparticles polyol synthesis, Pd-Cu alloy formation was obtained, leading to total selectivity to ethylene in the TCE hydrodechlorination reaction. On the Pd monometallic catalysts larger particle size resulted in higher levels of ethylene formation.

  • Purificación del aire mediante conjuntos estables de átomos de oro

     Santiago Redondo, Marta; Mendoza Gomez, Ernesto; Llorca Pique, Jordi
    Dyna
    Date of publication: 2013-06-04
    Journal article

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  • From Au(i) organometallic hydrogels to well-defined Au(0) nanoparticles

     Aguiló Linares, Elisabet; Gavara, Raquel; Lima, João Carlos; Llorca Pique, Jordi; Rodríguez Raurell, Laura
    Journal of materials chemistry C
    Date of publication: 2013-07-16
    Journal article

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    The reaction of water soluble phosphine 3,7-diacetyl-1,3,7-triaza-5- phosphabicyclo[3.3.1]nonane (DAPTA) with [Au(CC-C5H 4N)]n yields a luminescent water soluble phosphine gold(i) alkynyl complex [Au(4-pyridylethynyl)(DAPTA)] that leads to the formation of a luminescent hydrogel. A small variation of the phosphine structure (introduction of acetyl groups) with respect to the previously reported complex [Au(4-pyridylethynyl)(PTA)] has a clear effect on the observed properties: (i) a great increase in the hydrogel entanglement structure has been observed; (ii) the different cross-linking structures give rise to specific emission properties. The hydrogel was characterized by different techniques ( 1H-NMR, absorption and emission spectroscopy, optical microscopy, fluorescent microscopy (FM) and SEM). FM together with microspectrofluorimetry measurements has determined different emissive properties that vary according to the cross-linking process. Thermal treatments of the hydrogel produce well-defined metallic gold nanoparticles with a remarkable narrow size distribution, which have been characterized by SEM, TEM and X-ray photoelectron spectroscopy (XPS). At 200°C, Au particles measuring 1.0 ± 0.2 nm were obtained. Au nanoparticles were also formed as a result of electron beam irradiation

  • Ethanol steam reforming over hydrotalcite-derived Co catalysts doped with Pt and Rh

     Espinal, Raul; Taboada Cabellos, Elena; Molins, Elies; Chimentao, Ricardo J; Medina, Francisco; Llorca Pique, Jordi
    Topics in catalysis
    Date of publication: 2013-12
    Journal article

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    Honeycomb structures loaded with hydrotalcite-derived cobalt catalysts doped with various amounts of Pt and Rh have been tested in the steam reforming of ethanol at 523-823 K under different operational conditions. Catalysts promoted with noble metals are significantly more active than non-promoted hydrotalcite-derived cobalt but, at the same time, they build up carbon very efficiently. Electron microscopy, magnetic measurements and X-ray photoelectron spectroscopy reveal the occurrence of metal cobalt nanoparticles in the samples promoted with noble metals after reaction. According to the TPR profiles recorded over the hydrotalcite-derived cobalt catalysts doped with Pt and Rh, it is concluded that noble metals strongly promote cobalt reduction under ethanol steam reforming (ESR) conditions. Cobalt nanoparticles thus formed are very active for ethanol reforming but, at the same time, they originate severe carbon deposition. In contrast, non-promoted hydrotalcite-derived cobalt catalysts are less active for ESR but do not form carbon due to the absence of metallic cobalt.

  • Design of linear controllers applied to an ethanol steam reformer for PEN fuel cell applications

     García, Vanesa M.; Serra Prat, Maria; Llorca Pique, Jordi; Riera Colomer, Jordi
    International journal of hydrogen energy
    Date of publication: 2013-06-01
    Journal article

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    This paper focuses on the design of a controller for a low temperature ethanol steam reformer for the production of hydrogen to feed a protonic exchange membrane (PEM) fuel cell. It describes different control structures for the reformer and treats the control structure selection of this multiple input multiple output (MIMO) system. For each considered control structure, decentralised 2 × 2 controllers with proportional integral (PI) control actions in each control loop are implemented. The tuning of the PI parameters and the performance evaluation of the different controllers are based on a non-linear simulation model. For the validation and comparison of the considered controllers, the dynamic response for different setpoint changes and initial conditions is analysed, as well as the behaviour of the controlled system against disturbances.

  • Boosted CO2 reaction with methanol to yield dimethyl carbonate over Mg¿Al hydrotalcite-silica lyogels

     Stoian, Dragos Constantin; Taboada Ceballos, Elena; Llorca Pique, Jordi; Molins Grau, Elies; Medina Cabello, Francesc; Segarra González, Anna Maria
    Chemical communications
    Date of publication: 2013-05-13
    Journal article

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    Nonimmobilized and immobilized Mg¿Al hydrotalcite-like materials on silica lyogels were prepared and activated by calcination to be tested as catalysts in the direct carboxylation reaction of methanol. The HTs supportedon silica lyogels showedan important improvement andhigh stability in the direct synthesis reaction of DMC from CO2 and MeOH.

  • Ethanol steam reforming for hydrogen generation over structured catalysts

     López Pastor, Eduardo Tommy; Jimenez Divins, Nuria; Anzola, Andrés; Schbib, Susana; Borio, Daniel O.; Llorca Pique, Jordi
    International journal of hydrogen energy
    Date of publication: 2013-04
    Journal article

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    The present paper reports on the preparation, characterization and reaction evaluation of structured catalysts toward hydrogen generation via ethanol steam reforming. To these ends, 400 cpsi cordierite monoliths were functionalized with RhePd/CeO2 catalyst. SEM, TEM and XRD showed a uniform and well-covering CeO2 layer where RhePd nanoparticles of less than 0.5 nm were anchored. The functionalized monoliths were successfully tested for synthesis gas production from ethanol steam reforming. Realistic operating conditions were selected, including temperatures between 500 and 950 K, pressures from 1 to 6 bar, undiluted ethanol:water molar ratios 1:4e1:8 (i.e., 2 S/C 4) and a wide range of feed loads. Appropriate activity and hydrogen selectivity were verified for the catalytic system, with ca. complete ethanol conversion at T > 700 K and a minor, or even negligible, generation of by-products (acetaldehyde, acetone, ethane, ethylene). Operating at 950 K and 1.5 bar, a H2 yield of 3.4 mol hydrogen per mol ethanol in feed was achieved for a liquid feed load of 0.22 mlliq/(mgcat min) (S/C ¼ 3), with 8.1% of CH4 and 8.2% of CO on dry basis. Kinetic parameters of a phenomenological set of reaction rate equations were fitted against experimental data, considering ethanol decomposition (methane formation) with subsequent methane steam reforming to both CO and CO2 and wateregas shift reaction. Copyright ª 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

  • A luminescent hydrogel based on a new Au(i) complex

     Gavara, Raquel; Llorca Pique, Jordi; Lima, Joao Carlos; Rodríguez Raurell, Laura
    Chemical communications
    Date of publication: 2013-01-04
    Journal article

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    The reaction of the water soluble phosphine 1,3,5-triaza-7-phosphaadamantane (PTA) with [Au(C[triple bond, length as m-dash]C¿C5H4N)]n yields the highly luminescent water soluble [(PTA)Au(4-pyridylethynyl)] complex. A detailed analysis of the compound shows the formation of gel structure giving rise to very long fibers, being the first example reported with such a simple structure.

    The reaction of the water soluble phosphine 1,3,5-triaza-7-phosphaadamantane (PTA) with [Au(CRC–C5H4N)]n yields the highly luminescent water soluble [(PTA)Au(4-pyridylethynyl)] complex. A detailed analysis of the compound shows the formation of gel structure giving rise to very long fibers, being the first example reported with such a simple structure.

  • Hydrogen production from bioethanol using cobalt hydrotalcites.

     Espinal Bustos, Raúl Uziel
    Defense's date: 2013-12-20
    Universitat Politècnica de Catalunya
    Theses

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    El hidrógeno se perfila como un vector energético que puede ayudarnos a gestionar la energía de una manera más eficiente. El hidrógeno se puede almacenar y usar para producir electricidad en las pilas de combustible, en las que se combina con el oxígeno del aire y genera únicamente agua como subproducto. De las distintas maneras que existen para producir hidrógeno, la reacción catalítica entre el etanol y el agua (reformado) constituye una de las mejores opciones, ya que el etanol se produce fácilmente a partir de la biomasa (bioetanol) y es un substrato líquido y fácilmente manipulable. En esta tesis doctoral se ha estudiado el comportamiento de una familia de catalizadores de cobalto para llevar a cabo la producción de hidrógeno a partir de etanol y agua; concretamente, catalizadores basados en hidrotalcitas de cobalto. Existen otros catalizadores para llevar a cabo este mismo proceso, pero muchos de ellos tienen un coste elevado porque contienen metales nobles y otros se desactivan con facilidad por deposición de carbón en su superficie (los basados en níquel y cobalto). En esta tesis se demuestra que mediante un método preciso de preparación a partir de hidrotalcitas de cobalto se consiguen catalizadores de bajo coste y muy estables bajo condiciones reales de operación.El capítulo 1 es una introducción a los aspectos más destacables de la tesis doctoral, en el que se plantean los objetivos que se quieren abordar y se incluyen el estado del arte y los fundamentos en los que se basa el trabajo experimental realizado. Además de la naturaleza de los catalizadores y de las reacciones que se van a estudiar, en la introducción también se explica qué son y por qué se utilizan en esta tesis monolitos de cordierita como soportes físicos de los catalizadores y reactores catalíticos de membrana. Y es que esta tesis doctoral persigue, por un lado, la adquisición de nuevo conocimiento científico y, por otro lado, la aplicación de este conocimiento en el desarrollo de dispositivos útiles en aplicaciones reales.En los capítulos siguientes, la tesis doctoral constituye un compendio de artículos publicados en revistas internacionales de prestigio (3 artículos publicados y 1 artículo en proceso de revisión).En el capítulo 2 se describe la preparación de una familia de hidrotalcitas de cobalto con distinto contenido de cobalto, magnesio y aluminio y su comportamiento catalítico en la reacción de reformado de etanol con vapor para la producción de hidrógeno. A partir de una caracterización pormenorizada mediante distintas técnicas instrumentales, entre las que se incluyen la microscopía electrónica de barrido, microscopía electrónica de transmisión, difracción de rayos X, medidas de magnetismo a temperatura variable, espectroscopia infrarroja, análisis termogravimétricos, y experimentos in-situ con espectroscopía fotoelectrónica de rayos X, se identifican las especies químicas presentes y su estructura en los catalizadores antes, durante, y después de la reacción, poniéndose de manifiesto que la mejor formulación (la que ofrece un rendimiento a hidrógeno más elevado y sobre la que apenas se depositan residuos carbonosos) corresponde a una hidrotalcita con una relación Co:Mg:Al de 1:2:1. Asimismo se concluye que el catalizador preparado a partir de esta hidrotalcita se transforma a una mezcla de espinela de cobalto interaccionando fuertemente con MgO a escala nanométrica bajo las condiciones de reacción. Sin embargo, al realizar la reacción exclusivamente con la espinela de cobalto (preparada por separado a tal efecto) se obtiene una producción de hidrógeno menor, lo que demuestra que la hidrotalcita de cobalto usada como precursor del catalizador ejerce un control decisivo en la estructura del mismo. En el capítulo 3 se estudia la influencia del dopaje de la hidrotalcita Co:Mg:Al=1:2:1 con Pt y Rh. . Para ello se han preparado dos familias de catalizadores con distinto contenido de Pt y Rh.

  • Q-00032

     Llorca Pique, Jordi
    Participation in a competitive project

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  • CuZn/ZrO2 catalytic honeycombs for dimethyl ether steam reforming and autothermal reforming

     Ledesma Rodriguez, Cristian; Llorca Pique, Jordi
    Fuel (Guildford)
    Date of publication: 2013-02
    Journal article

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    Dimethyl ether (DME) steam reforming simulating practical applications was tested over catalytic honeycombs coated with ZrO2 and loaded with different amounts of Cu and Zn. The best catalytic performance in terms of activity and yield towards the reforming products, H2 and CO2, was exhibited by CuZn/ ZrO2 with a Cu:Zn molar ratio of 1:10, which also showed high stability. SEM and XPS characterization showed that this catalyst contains very well-dispersed copper particles in contact with ZnO. Catalytic monoliths were also tested in the DME autothermal reforming reaction, but a strong deactivation was observed, probably due to the prevalence of methoxy species that lead to the formation of methane and carbon residues, as evidenced by in situ FTIR and XPS experiments.

    Dimethyl ether (DME) steam reforming simulating practical applications was tested over catalytic honeycombs coated with ZrO2 and loaded with different amounts of Cu and Zn. The best catalytic performance in terms of activity and yield towards the reforming products, H2 and CO2, was exhibited by CuZn/ ZrO2 with a Cu:Zn molar ratio of 1:10, which also showed high stability. SEM and XPS characterization showed that this catalyst contains very well-dispersed copper particles in contact with ZnO. Catalytic monoliths were also tested in the DME autothermal reforming reaction, but a strong deactivation was observed, probably due to the prevalence of methoxy species that lead to the formation of methane and carbon residues, as evidenced by in situ FTIR and XPS experiments

  • The study of catalysts by transmission electron microscopy techniques

     Llorca Pique, Jordi
    Date of publication: 2012-09-11
    Book chapter

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  • Dels asteroides als meteorits

     Llorca Pique, Jordi
    Date of publication: 2012-04-01
    Book chapter

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  • Pt-Ag/activated carbon catalysts for water denitration in a continuous reactor: Incidence of the metal loading, Pt/Ag atomic ratio and Pt metal precursor

     Aristizabal, A.; Contreras, Sandra; Jimenez Divins, Nuria; Llorca Pique, Jordi; Medina, Francisco
    Applied catalysis B. Environmental
    Date of publication: 2012-10-30
    Journal article

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    Several Pt–Ag catalysts supported on activated carbon powder were tested in the catalytic reduction of nitrates in a continuous flow reactor. The influence of the noble metal precursor (Pt(NH3)4(NO3)2 or H2PtCl6), the Pt/Ag atomic ratio (0.3, 1.1 and 1.8) and the metal loading (3% or 1% Pt) were studied. The samples were characterized by XRD, TPR, HRTEM, XPS, H2-chemisorption and nitrogen physisorption. The results showed that the most important variables affecting the catalytic activity are the noble metal precursor and the metal loading, whereas the Pt/Ag atomic ratio does not affect significantly the catalytic behavior. The use of H2PtCl6 instead of Pt(NH3)4(NO3)2 as noble metal precursor leads to more active catalysts. The nitrate conversion is enhanced by the high metal loading (3%).

  • Stability of ruthenium catalysts supported by aerogel mixed oxides during the wet air oxidation of p-hydroxybenzoic acid in a continuous reactor

     Triki, Mohamed; Dafinov, Antonio; Llorca Pique, Jordi; Medina, Francisco
    Reaction kinetics mechanisms and catalysis
    Date of publication: 2012-12
    Journal article

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    Continuous catalytic wet air oxidation was investigated as a suitable treatment of p-hydroxybenzoic acid chosen as a phenolic compound typically found in olive mill wastewater. The reaction was conducted in a continuous reactor at 140 or 150 C and 50 bar of air using ruthenium catalysts supported by aerogel mixed oxides (Ru/CeO2–Al2O3, Ru/CeO2–TiO2). The influence of the Ru precursor and the nature of the support were studied. The results show that supported ruthenium catalysts were active to oxidize p-hydroxybenzoic acid and that the catalytic activity is very stable.

  • Hydrogen production from ethanol over Pd-Rh/CeO2 with a metallic membrane reactor

     López, Eduardo; Jimenez Divins, Nuria; Llorca Pique, Jordi
    Catalysis today
    Date of publication: 2012-10-15
    Journal article

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    The present paper reports on experimental results of an ethanol reformer equipped with a Pd-based metallic membrane toward the production of pure hydrogen, suited for PEM-fuel cell feeding. The ethanol steam reforming is conducted using a Pd–Rh/CeO2 catalyst over cordierite monoliths, which were implemented in-series into a stainless-steel membrane reactor. Inconel membranes functionalized with Pd–Ag over an adequate support were profited for hydrogen separation from the monoliths outlet. The unit was successfully tested for hydrogen production from ethanol steam reforming, achieving pure-hydrogen flowrates up to 110 mLN/min. Reaction yields of 3.1 mol hydrogen generated per mol ethanol in feed and total yields of 1.4 mol H2 permeated per mol ethanol in feed were measured, with maximum hydrogen recuperation of 70%. We discuss here the influence of the different operation parameters, as temperature, reaction (retentate) pressure, load and/or composition of the feed on the device performance. Temperatures of ca. 650 ◦C, retentate pressures of 9–11 bar and water contents in feed slightly over-stoichiometric revealed optimal for the unit operation.

  • Catalytic Performance of Solution Combustion Synthesized Alumina- and Ceria-Supported Pt and Pd Nanoparticles for the Combustion of Propane and Dimethyl Ether (DME)

     Colussi, Sara; Gayen, Arup; Llorca Pique, Jordi; de Leitenburg, Carla; Dolcetti, Giuliano; Trovarelli, Alessandro
    Industrial and engineering chemistry research (Online)
    Date of publication: 2012-01
    Journal article

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  • Cobalt hydrotalcites as catalysts for bioethanol steam reforming. The promoting effect of potassium on catalyst activity and long-term stability

     Espinal, Raul; Taboada, E.; Molins, E.; Chimentao, Ricardo J; Medina, Francisco; Llorca Pique, Jordi
    Applied catalysis B. Environmental
    Date of publication: 2012-10-30
    Journal article

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    Cobalt hydrotalcite-derived catalysts, doped with potassium, are active materials for the ethanol steam reforming reaction. Potassium addition reduces the acid sites number and strength. It acts as a promoter of the ethanol steam reforming (ESR); ethanol conversion is higher at lower temperature, as the amount of potassium at the surface of the catalyst increases. The catalysts are stable for long-term experiments (300 h) under high loads of ethanol and bioethanol (0.036 gEtOH min−1, H2O:CH3CH2OH = 4:1 molar). Moreover, they generate a low amount of carbon (0.0067 gC gcatalyst−1 h−1). The catalysts after reaction contain almost exclusively high spin Co2+ in cobalt oxide (or in (Co,Mg)O); only traces of metallic cobalt are identified by magnetometry, <0.1 wt.% Co0, suggesting that oxidized cobalt is an active species in ESR.

  • Cobalt hydrotalcite for the steam reforming of ethanol with scarce carbon production

     Espinal, Raul; Taboada, E.; Molins, E.; Medina, Francisco; Chimentao, Ricardo J; Llorca Pique, Jordi
    RSC Advances
    Date of publication: 2012
    Journal article

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  • Gas-phase hydrodechlorination of trichloroethylene over Pd/NiMgAl mixed oxide catalysts

     Meshesha, B.T.; Barrabes, N.; Foettinger, Karin; Chimentao, Ricardo J; Llorca Pique, Jordi; Medina, Francisco; Rupprechter, Guenther; Sueiras, J.E.
    Applied catalysis B. Environmental
    Date of publication: 2012-05-18
    Journal article

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  • Facile Synthesis of Palladium Nanoparticles Protected with Alkanethiolates Functionalized with Organometallic Fragments

     Friederici, Mario; Angurell, Inmaculada; Rosse, Oriol; Seco, Miquel; Jimenez Divins, Nuria; Llorca Pique, Jordi
    Organometallics
    Date of publication: 2012-01-23
    Journal article

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  • In situ studies of CeO 2-supported Pt, Ru, and Pt-Ru alloy catalysts for the water-gas shift reaction: Active phases and reaction intermediates

     Xu, W.; Si, Rui; Senanayake, Sanjaya D.; Llorca Pique, Jordi; Idriss, Hicham; Stacchiola, Darío J.; Hanson, Jonathan C.; Rodríguez, Jose Antonio Bertinatto
    Journal of catalysis
    Date of publication: 2012-07
    Journal article

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  • Higher activity of diesel soot oxidation over polycrystalline ceria and ceria-zirconia solid solutions from more reactive surface planes

     Aneggi, Eleonora; de Leitenburg, Carla; Llorca Pique, Jordi; Trovarelli, Alessandro
    Catalysis today
    Date of publication: 2012-12-15
    Journal article

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    High temperature treatment under air of samples of polycrystalline ceria and ceria¿zirconia is shown to induce a rearrangement of crystals, with a surface structural evolution of the oxides toward the formation of more reactive exposed planes belonging to the {1 0 0} and {1 1 0} families, associated with a decrease of the exposure of the less reactive {1 1 1} facets. This is dependent on the amount of ceria, being more evident with pure CeO2, and less important with increasing ZrO2 content. A correlation between the exposure of more reactive planes and the specific rate of carbon soot oxidation is found, in agreement with previous results obtained in monodimensional nanoshaped and polycrystalline ceria samples for CO oxidation. This suggests that Diesel soot oxidation catalysts might be designed by keeping into consideration also these effects.

  • In situ generation of hydrogen peroxide in catalytic membrane reactors

     Osegueda, O.; Dafinov, Antonio; Llorca Pique, Jordi; Medina, Francisco; Suerias, J.
    Catalysis today
    Date of publication: 2012-10-15
    Journal article

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  • Ethanol photoreaction to hydrogen over Au/TiO(2) catalysts. Investigating the synergistic effect of nanoparticles

     Waterhouse, G.I.N; Murdoch, M.; Llorca Pique, Jordi; Idriss, Hicham
    International journal of nanotechnology
    Date of publication: 2012
    Journal article

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  • Pt-Cu bimetallic catalysts obtained from layered double hydroxides by an anion-exchange route

     Barrabes, Noelia; Frare, A.; Foettinger, Karin; Urakawa, A.; Llorca Pique, Jordi; Rupprechter, Guenther; Tichit, D.
    Applied clay science
    Date of publication: 2012-11
    Journal article

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  • Modelado, análisis y control dinámico de un reformador de etanol en tres etapas para aplicaciones en pilas de combustible  Open access

     García, Vanesa Mariel
    Defense's date: 2012-04-16
    Institute of Industrial and Control Engineering (IOC), Universitat Politècnica de Catalunya
    Theses

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    This thesis presents results related to the design, modeling and control of a low temperature ethanol reformer as a source of hydrogen designed to feed a fuel cell (PEMFC). As fuel, ethanol has been selected as one of the renewable energy sources currently under study due to its interest for scientific and economic fields. The reformer has been separated into three stages in order to guarantee the maximum production of H2 and the minimum production of CO. SnO2 and Co(Fe)Na+/ZnO catalytic monoliths have been used, where in the first stage ethanol is dehydrogenated over SnO2 and, in the second stage, the reforming of acetaldehyde over Co(Fe)Na+/ZnO takes place under the presence of hydrogen, generated in stage 1. Then we add a third stage with a Fe2O3-Cr2O3 commercial catalyst to complete the WGS reaction. In addition to ensure a reducing environment in the reforming step, this configuration also allows optimizing the conditions of each stage of the reaction. Constant pressure has been imposed as a condition of the reformer design, but the variation of temperatures in each stage has been considered. In this thesis dynamic models have been developed for the reformer of ethanol with vapour at low temperatures described previously, the stationary and dynamic response has been analysed and controllers have been designed to meet the requirements of the system. Up until now there have only been a few works that address the design and implementation of controllers for fuel reformers, and none of these have used ethanol fuel. Some are in the area of automatic control and have been applied to tubular reformers but consider other type of fuel, not ethanol, for its alimentation In this thesis the mathematical model used to represent the state of the monolithic reformer has been presented, considered and implemented. Through a study of the stationary state one can validate the different hypothesis of assumed design and through an analysis of the parametric sensitivity the operational conditions for the reform process are discussed. This way the mathematic model of the reactor can be used to explore other alternatives for the operation of the reformer putting an emphasis on the influence of temperature in the second stage as this is a variable. Afterwards a study is made of the control of the models based on the balance of mass and linearised energy. In order to realise the control study the mathematic tools RGA, MRI and CN have been used. Through this analysis the control structures have been selected which will be most suitable for design controllers which can guarantee the requirements for the fuel cell.

  • Development and numerical implementation of tritium and helium transport models in liquid metal breeders for nuclear fusion technology applications

     Fradera Fernández, Jorge
    Defense's date: 2012-01-25
    Department of Physics and Nuclear Engineering, Universitat Politècnica de Catalunya
    Theses

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  • Experimental characterization and diagonosis tools for proton exchange membrane fuel cells  Open access

     Primucci, Mauricio Ariel
    Defense's date: 2012-09-10
    Institute of Industrial and Control Engineering (IOC), Universitat Politècnica de Catalunya
    Theses

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    A fuel cell is a device that gives electric power directly from electrochemical reduction and oxidation reactions. PEM fuel cells present some properties that make them appropriate for portable and transport applications: high efficiency, no emissions, solid electrolyte, low operating temperatures and high power density. However, some technical problems can be improved, durability of the materials and the appropriate control of the operating conditions. One important aspect of the operating conditions is the water management. The right water content is needed in the electrolyte and catalyst layers to maximize the efficiency of the PEMFC by minimizing the voltage losses. Water content in the fuel cell is given basically by the generation of the water in the cathode due to the reaction, the humidity of the inlet gases and the transport trough the membrane. This thesis studies, proposes and compares different experimental characterisation methods aimed to provide performance indicators of the PEMFC water state. A systematic use of Electrochemical Impedance Spectroscopy technique is presented and its results are studied in order to analyse the influence of different operating conditions over the PEMFC response. The variables under analysis include: load current, pressure temperature and gas relative humidity. All these variables are considered with inlet gases feeding: H2/O2 and H2/Air. A set of relevant characteristics from the EIS response has been considered. Several equivalent circuits has been analysed and those that have the best fitting with the experimental EIS data are selected. When air is used as oxidant, a simple equivalent circuit with a resistance and a Warburg element is proposed. When Oxygen is used as oxidant, a more complex equivalent circuit is needed. A detailed sensitive analysis is performed indicating those parameters that best capture the influence of the operating conditions. A new experimental characterisation technique, based on the inlet gases humidification interruption is proposed. This dynamic technique combines the information extracted from EIS and the temporal response in order to study the water transport and storage effects in the PEMFC. Two advantages of this proposed technique is the simple hardware configuration used and the relative low impact on the fuel cell response, making attractive the humidification interruption as an in-situ technique. Three different sets of performance indicators are proposed as diagnosis tool. Relevant Characteristics from the EIS response, if properly monitored, can give a diagnostic of the fuel cell internal state. After an analysis, the chosen ones are: low and high frequency resistances (RLF and RHF) and the frequency of the maximum phase. These RC are helpful to determine if the PEMFC with the current operating conditions is well humidified. If the zone defined by RLF decrease, RHF slight increase and the frequency of the maximum phase increase is minimal, the cathode is optimally humidified. Equivalent Circuit are used in order to give a physical interpretation. The selected parameters as performance indicators are: membrane resistance, Rm, time constant and resistance of diffusion process (using Warburg elements: Tw and Rw). In this case, the humidification of the fuel cell is optimum if the zone where Rw and Tw decrease and Rm has slow increase is minimal. Model Based performance indicators are proposed: Rm, effective diffusion coefficient, Deff and effective active area, Aeff. The optimal humidification occurs when the zone where Deff is stationary and Rm has not changed significantly, is minimal. The parameter Aeff involved in this last diagnosis procedure can be detached from the humidification interruption test and be used to estimate the effective active area and then is also helpful to compare the PEMFC performance in different operating conditions.

    Una pila de combustible es un dispositivo que da energía eléctrica a partir de reacciones electroquímicas de reducción y oxidación. Las pilas del tipo PEMFC presentan propiedades que las hacen adecuadas para aplicaciones de transporte: alta eficiencia, cero emisiones, electrolito sólido, bajas temperaturas de operación y alta densidad de potencia. Sin embargo, algunos problemas técnicos deben ser estudiados: la durabilidad de los materiales y la correcta selección de las condiciones de funcionamiento. Una de las más importantes es la gestión del agua. Un balance adecuado del agua en la pila es necesario para maximizar la eficiencia de la PEMFC reduciendo al mínimo las pérdidas de tensión. El contenido de agua en la PEMFC viene dado por su generación en el cátodo debido a la reacción, la humedad de los gases de entrada y el transporte de agua a través de la membrana. La tesis estudia, propone y compara los diferentes métodos de caracterización experimental con el objetivo de obtener indicadores del estado del agua en la PEMFC. Se realiza un uso sistemático de la técnica “espectroscopía de impedancia electroquímica (EIS)” y el análisis de la influencia de las diferentes condiciones de operación sobre la respuesta de la PEMFC. Las variables estudiadas son: corriente de carga, presión de los gases, temperatura, humedad relativa y también la alimentación de los gases de entrada: H2/O2 y H2/aire. Se presenta un conjunto de características relevantes de la respuesta del EIS y se usan para dar valores iniciales a los circuitos equivalentes. Se estudian diferentes configuraciones de circuitos equivalentes y se seleccionan aquellos que tienen la mejor conexión con los datos experimentales. Se realiza un análisis de sensibilidad de los parámetros de los circuitos equivalentes con respecto a las diferentes condiciones de operación, para encontrar aquellos que sean útiles para representar estas variaciones. Se propone una nueva técnica experimental de caracterización, basada en la interrupción de la humidificación de los gases de entrada. Esta técnica combina la información de la respuesta temporal con la frecuencial (EIS) y es útil para analizar la influencia del agua en la respuesta de la PEMFC. Algunas ventajas de esta técnica son: la fácil implementación física y el bajo impacto sobre la respuesta de la PEMFC, lo cual convierte esta técnica en candidata para ser utilizada “In-situ”. Se proponen tres conjuntos de indicadores de comportamiento de la pila como herramientas de diagnosis. En primer lugar, se presentan las “Características Relevantes” de la respuesta de la EIS que dan un diagnóstico del estado interno de la PEMFC. De entre ellas se selecciona como indicadas: las resistencias de baja y alta frecuencia (RLF y RHF) y la frecuencia del máximo de fase. Estas características sirven para determinar la correcta humidificación de la pila en las condiciones actuales de operación. El cátodo está correctamente humidificado si la respuesta de las características, muestran que la zona definida por RLF bajando, RHF subiendo ligeramente y la frecuencia de la máxima fase está subiendo, es mínima. En segundo lugar, se usan los “Circuitos Equivalentes” para dar una interpretación física a los indicadores. Los parámetros seleccionados son: la resistencia de la membrana, Rm, la resistencia y la constante de tiempo de la difusión (Rw y Tw). En este caso, la humidificación correcta del cátodo ocurre cuando la zona donde Rw y Tw bajan y Rm sube ligeramente, es mínima. Por ultimo, se proponen indicadores de comportamiento utilizando un modelo: Rm, coeficiente de difusión efectivo, Deff y el área activa efectiva, Aeff. La humidificación óptima del cátodo ocurre cuando la zona donde Deff es estable y Rm no cambia significativamente, es mínima. El parámetro Aeff es útil para estimar el área activa efectiva aun cuando no se realice una interrupción de humidificación y para comparar la respuesta de la PEMFC bajo diferentes condiciones de operacion

  • Premi EcoEmprenedor XXI

     Llorca Pique, Jordi; Mendoza Gomez, Ernesto
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  • Premi ICREA Acadèmia

     Masoller Alonso, Cristina; Garcia Ojalvo, Jorge; Llorca Pique, Jordi
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  • Premios de la Fundación Altran 2012

     Mendoza Gomez, Ernesto; Llorca Pique, Jordi
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  • Incorporació de tècnic de gestió d'R+D+I a l'INTE

     Llorca Pique, Jordi
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