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Digital.CSIC (158.952 recursos)

Repositorio institucional del Consejo Superior de Investigaciones Científicas. Digital.CSIC es un depósito de documentos digitales, cuyo objetivo es organizar, archivar, preservar y difundir en modo de acceso abierto la producción intelectual resultante de la actividad investigadora del CSIC.

(INCAR) Artículos post-print

Mostrando recursos 1 - 20 de 41

  1. Graphene-NHC-iridium hybrid catalysts built through -OH covalent linkage

    Blanco, Matías; Álvarez Rodríguez, Patricia; Blanco Rodríguez, Clara; Jiménez, M. Victoria; Fernández-Tornos, Javier; Pérez-Torrente, Jesús J.; Oro, Luis A.; Menéndez López, Rosa María
    Graphene oxide (GO) and thermally reduced graphene oxide (TRGO) were covalently modified with imidazolium salts through their hydroxyl surface groups. The selective reaction of the -OH groups with p-nitrophenylchloroformate produced labile intermediate organic carbonate functions which were used for the covalent anchoring of a hydroxy-functionalized imidazolium salt. Nanohybrid materials containing iridium N-heterocyclic carbene (NHC)-type organometallic complexes were prepared by causing the imidazolium-functionalized materials to react with [Ir(μ-OMe)(cod)]2. The iridium content of the graphene-based hybrid catalysts, as determined by XPS and ICP-MS was the order of ∼5 and 10 wt.%, for the TRGO and GO-based materials, respectively. The graphene-supported iridium hybrid...

  2. Temperature programmed desorption as a tool for the identification of mercury fate in wet-desulphurization systems

    Rumayor Villamil, Marta; Díaz Somoano, Mercedes; López Antón, María Antonia; Ochoa González, Raquel; Martínez Tarazona, María Rosa
    In this study a thermal desorption procedure (HgTPD) was used to identify mercury species in samples of gypsum obtained from wet flue gas desulphurization plants (WFGD). Gypsum from industrial coal combustion power plants and gypsum from a laboratory device that simulates mercury retention in the WFGD process were studied. It was concluded that mercury sulphide (HgS) is the mercury species present in WFGD gypsums unless an additive is used. Mercury speciation in this kind of residue can contribute to a better understanding of the reaction and adsorption behaviour of mercury species in the WFGD process and provide a deeper knowledge...

  3. Impact of oxy-fuel combustion gases on mercury retention in activated carbons from a macroalgae waste: Effect of water

    López Antón, María Antonia; Ferrera Lorenzo, Nuria; Fuente Alonso, Enrique; Díaz Somoano, Mercedes; Suárez Ruiz, Isabel; Martínez Tarazona, María Rosa; Ruiz Bobes, Begoña
    The aim of this study is to understand the different sorption behaviors of mercury species on activated carbons in the oxy-fuel combustion of coal and the effect of high quantities of water vapor on the retention process. The work evaluates the interactions between the mercury species and a series of activated carbons prepared from a macroalgae waste (algae meal) from the agar–agar industry in oxy-combustion atmospheres, focussing on the role that the high concentration of water in the flue gases plays in mercury retention. Two novel aspects are considered in this work (i) the impact of oxy-combustion gases on the...

  4. Thermoresponsive biodegradable HEMA-lactate-Dextran-co-NIPA cryogels for controlled release of simvastatin

    Bölgen, Nimet; Aguilar, María Rosa; Fernández de Marco, M. del Mar; Gonzalo-Flores, Sandra; Villar Rodil, Silvia; San Román, Julio; Pişkin, Erhan
    NIPA and HEMA-lactate-Dextran-based biodegradable and thermoresponsive cryogels were synthesized at different compositions by cryogelation. Chemical and morphological properties of the HEMA-lactate-Dextran-co-NIPA cryogel matrices were demonstrated by FTIR, SEM, and ESEM. Thermoresponsivity of the prepared cryogels was investigated by DSC, imaging NMR, and swelling studies. For possible use of the cryogels in potential bone tissue engineering applications, either hydrophobic simvastatin was embedded, or hydrophilic simvastatin was incorporated in the cryogels. Release profiles of simvastatin delivering cryogel scaffolds depending on their composition, hydrophobicity or hydrophilicity of loaded simvastatin and the medium temperature were demonstrated.

  5. Producción de hidrógeno y materiales de carbono nanoestructurados

    Suelves Laiglesia, Isabel; Pinilla Ibarz, José Luis; Llobet, S.; Torres, Daniel; Lázaro Elorri, María Jesús; Moliner Álvarez, Rafael
    [EN] Hydrogen is not an energy source but an energy carrier and therefore it is as clean as the process used to generate it. Industrially is mainly produced by steam reforming of methane. Hydrogen production by catalytic decomposition of methane is an interesting alternative to reforming, especially in decentralized installations where the capture and storage of CO2 would not be economically profitable. This process occurs in a single step, producing a gaseous fraction formed by hydrogen and unconverted methane and a high added value carbon. In recent years different aspects have been deeply studied: the development of catalysts, the scaling up of the process and the possible uses of the carbon materials, among...

  6. Enrichment of thallium in fly ashes in a Spanish circulating fluidized-bed combustion plant

    López Antón, María Antonia; Spears, D. Alan; Díaz Somoano, Mercedes; Díaz, Luis; Martínez Tarazona, María Rosa
    This work evaluates the behavior of thallium in a 50 MW industrial circulating fluidized-bed combustion plant (CFBC), focusing on the distribution of this element among the bottom and fly ashes separated by the solid retention devices in the plant. The results show that thallium species are mainly retained in the solid by-products and are not emitted to air with flue gases in significant amounts, proving that this technology is a more effective means of preventing thallium emissions than pulverized coal combustion technology (PCC). The mass balance of the thallium content in the solids shows that this element was retained in...

  7. Influence of a CO2-enriched flue gas on mercury capture by activated carbons

    López Antón, María Antonia; Rumayor Villamil, Marta; Díaz Somoano, Mercedes; Martínez Tarazona, María Rosa
    The main environmental problem caused by the production of energy from coal combustion is the emission of CO2. One emerging technology designed for CO2 capture is oxy-combustion. Among other issues to be solved in oxy-combustion power plants is the presence of mercury as this may damage the CO2 compression unit. Hence the study of the behavior of mercury in oxy-combustion is of great interest both from an environmental and a technological point of view. The present study performed at laboratory scale evaluates the retention of mercury in a CO2-enriched flue gas using the same activated carbon before and after it...

  8. Activated carbons from biocollagenic wastes of the leather industry for mercury capture in oxy-combustion

    López Antón, María Antonia; Rodríguez Gil, Roberto; Fuente Alonso, Enrique; Díaz Somoano, Mercedes; Martínez Tarazona, María Rosa; Ruiz Bobes, Begoña
    This study evaluates the capacity of a series of activated carbons obtained from leather industry waste to retain mercury. The behavior of these materials was compared in two simulated flue gas compositions at laboratory scale. The atmospheres were (i) a typical coal oxy-fuel combustion atmosphere and (ii) an O2 + N2 atmosphere. The activated carbons displayed different behaviors depending on their characteristics and the gas composition. The best results were obtained for the activated carbon with the highest surface area and greatest amount of micropores, sulfur and acidity character, these results being comparable to those of an activated carbon impregnated...

  9. Application of thermal desorption for the identification of mercury species in solids derived from coal utilization

    Rumayor Villamil, Marta; Díaz Somoano, Mercedes; López Antón, María Antonia; Martínez Tarazona, María Rosa
    The speciation of mercury is currently attracting widespread interest because the emission, transport, deposition and behaviour of toxic mercury species depend on its chemical form. The identification of these species in low concentrations is no easy task and it is even more complex in coal combustion products due to the fact that these products contain organic and mineral matter that give rise to broad peaks and make it difficult to carry out qualitative and quantitative analysis. In this work, a solution to this problem is proposed using a method based on thermal desorption. A sequential extraction procedure was employed for...

  10. Gaseous mercury behaviour in the presence of functionalized styrene–divinylbenzene copolymers

    Díaz Somoano, Mercedes; Popa, Adriana; Rumayor Villamil, Marta; López Antón, María Antonia; Martínez Tarazona, María Rosa; Illia, Gheorghe
    Two styrene-6.7 % divinylbenzene copolymers functionalized with aminophosphonate groups and phosphonic acid groups by means of “one-pot” reactions were evaluated for gaseous mercury removal. The results were compared with those obtained using a commercial activated carbon. These materials exhibit a significant capacity for mercury oxidation (13–25 %) with low mercury capture (9–30 μg g–1). The mercury retention capacity was observed to decrease when acid gases are present in the gas atmosphere. The highest retention capacity corresponded to the highest oxidation ratio and was obtained using the AMINOPHOS sample. These results suggest a mercury oxidation and a subsequent chemical adsorption mechanism...

  11. Ni-MoS2 supported on carbon nanofibers as catalysts for the hydroprocessing of heavy oil fractions

    Pinilla Ibarz, José Luis; Purón, H.; Torres, Daniel; Millan, M.; Suelves Laiglesia, Isabel
    [EN] In this work, fishbone carbon nanofibers (CNF) were functionalised in acidic media obtaining CNF with different surface chemistry, and subsequently used as support for NiMo catalysts. Resulting catalysts were composed by CNF coaxially coated by Ni-decorated MoS2 slabs with different length and stacking degree as a function of the functionalisation treatment. Catalysts were evaluated in the hydroprocessing of a vacuum residue. Catalysts prepared with the support functionalised with the least severe treatment, showing short and less stacked MoS2 slabs, yielded the best asphaltenes conversion. CNF supported catalysts presented low tendency to coke formation and relatively high heteroatoms (sulfur and metals) removal efficiency, comparable to a NiMo/ Al2O3 catalyst used for benchmarking purposes. This was attributed...

  12. Impact of a semi-industrial coke processing plant in the surrounding surface soil. Part II: PAH content

    García Fernández, Roberto; Díaz Somoano, Mercedes; Calvo Díez, Montserrat; López Antón, María Antonia; Suárez, Sonia; Suárez Ruiz, Isabel; Martínez Tarazona, María Rosa
    Topsoil samples taken from different areas of a disused experimental coking plant were analysed in order to determine their polycyclic aromatic hydrocarbon (PAH) concentration. The variation in concentrations as a function of distance from the coking oven battery was studied and a reduction in PAH concentration as the distance to the coking ovens' battery increases was observed. Two exceptions are the area in the vicinity of the tar distillation section of the plant, with a strong contribution from high temperature tar, and the area where hot coke was taken out of the ovens, with lower concentrations than expected, as a...

  13. Impact of a semi-industrial coke processing plant in the surrounding surface soil: Part I: Trace element content

    Díaz Somoano, Mercedes; López Antón, María Antonia; Suárez Ruiz, Isabel; Calvo Díez, Montserrat; Suárez, Sonia; García Fernández, Roberto; Martínez Tarazona, María Rosa
    Soil pollution by anthropogenic activities is an important environmental issue especially in industrialized countries. The objective of this study is to evaluate the environmental impact of a coal conversion plant on the surrounding soil by measuring the spatial distribution of particulate organic carbon and determining the concentration of trace elements (part I) and PAHs (part II). The results indicate that the surface soil presents an increase in the content of organic particulates with values exceeding 80% vol. at the centre of the coking plant facilities. The concentrations rapidly decrease as the distance from the plant increases. Although concentrations of As,...

  14. Differential partitioning and speciation of Hg in wet FGD facilities of two Spanish PCC power plants

    Ochoa González, Raquel; Córdoba, Patricia; Díaz Somoano, Mercedes; Font, Oriol; López Antón, María Antonia; Leiva, C.; Martínez Tarazona, María Rosa; Querol, Xavier; Fernández Pereira, C.; Tomás, A.; Gómez, P.; Mesado, P.
    This paper evaluates the speciation and partitioning of mercury in two Spanish pulverised coal combustion power plants (PP1 and PP2), equipped with wet limestone-based flue gas desulphurisation facilities (FGD) operating with forced oxidation and re-circulation of FGD water streams. These plants are fed with coal (PP1) and coal/pet-coke blends (PP2) with different mercury contents. The behaviour, partitioning and speciation of Hg were found to be similar during the combustion processes but different in the FGD systems of the two power plants. A high proportion (86–88%) of Hg escaped the electrostatic precipitator in gaseous form, Hg2+ being the predominant mercury species...

  15. Speciation of Cr and its leachability in coal by-products from spanish coal combustion plants

    López Antón, María Antonia; Díaz Somoano, Mercedes; Fuente Cuesta, Aida; Rubio Riesco, Aida; Martínez Tarazona, María Rosa
    This study evaluates the behaviour of total Cr and Cr (VI) during coal combustion in two Spanish power stations. The content and distribution of Cr in the feed coal and combustion wastes was determined and the Cr contents were normalized using enrichment factor indexes. The speciation of Cr in the fly ash fractions from the different hoppers of the electrostatic precipitators was established and the possibility that the Cr (VI) might lixiviate when ashes are disposed of at landfill sites was assessed. Differences in the distribution and behavior of Cr in the two power stations were observed. According to European...

  16. The stability of arsenic and selenium compounds that were retained in limestone in a coal gasification atmosphere

    Díaz Somoano, Mercedes; López Antón, María Antonia; Huggins, F.E.; Martínez Tarazona, María Rosa
    The aim of this work was to evaluate the stability of arsenic and selenium species retained in a lime/limestone mixture obtained by using limestone as a sorbent for gas cleaning in a coal gasification atmosphere. It was found that the stability of arsenic and selenium species produced by the gas–solid reactions with lime/limestone may be affected by their exposure to air and by their contact with water. The results confirm the conclusions of a previous work in which Ca(AsO2)2 and CaSe was postulated as the products of the reaction between the arsenic and selenium species present in a coal gasification...

  17. Study of boron behaviour in two spanish coal combustion power plants

    Ochoa González, Raquel; Fuente Cuesta, Aida; Córdaba, Patricia; Díaz Somoano, Mercedes; Font, Oriol; López Antón, María Antonia; Querol, Xavier; Martínez Tarazona, María Rosa
    A full-scale field study was carried out at two Spanish coal-fired power plants equipped with electrostatic precipitator (ESP) and wet flue gas desulfurisation (FGD) systems to investigate the distribution of boron in coals, solid by-products, wastewater streams and flue gases. The results were obtained from the simultaneous sampling of solid, liquid and gaseous streams and their subsequent analysis in two different laboratories for purposes of comparison. Although the final aim of this study was to evaluate the partitioning of boron in a (co-)combustion power plant, special attention was paid to the analytical procedure for boron determination. A sample preparation procedure...

  18. The influence of carbon particle type in fly ashes on mercury adsorption

    López Antón, María Antonia; Abad Valle, Patricia; Díaz Somoano, Mercedes; Suárez Ruiz, Isabel; Martínez Tarazona, María Rosa
    Recent research has shown that certain fly ash materials produced in coal combustion for power generation have an affinity for the mercury compounds present in flue gases. However, the exact nature of Hg–fly ash interactions is still unknown and the different variables that influence mercury adsorption need to be identified. In this work the microscopic components of fly ashes derived from the combustion of different types of feed blends of different coal rank and mercury adsorption were investigated. The aim of this research was to establish relationships between Hg retention and the type of unburned carbons present in various fly...

  19. Thallium in coal: Analysis and environmental implications

    López Antón, María Antonia; Spears, D. Alan; Díaz Somoano, Mercedes; Martínez Tarazona, María Rosa
    The ecotoxicological importance of thallium stems from its acute toxicity, the effects of which are as harmful to living organisms as those of lead and mercury. The main anthropogenic sources of thallium are the emissions from coal combustion processes, underlining the need to control this element in coal and coal by-products. Despite the threat posed by thallium, very little information has been published on its behaviour in coal-fired power plants or on its modes of occurrence in coal, its mobilisation and its distribution. Although thallium is highly toxic, the environmental risk presented by this element in coal utilisation have been...

  20. Analytical methods for mercury analysis in coal and coal combustion by-products

    López Antón, María Antonia; Díaz Somoano, Mercedes; Ochoa González, Raquel; Martínez Tarazona, María Rosa
    This review deals with the analysis of mercury present in different types of solid, liquid and gaseous samples involved in the coal combustion process, focusing on the specific characteristics of each type of sample and the problems typically associated with these products. The main aim of the paper is to describe the methods that, at the current stage of development, are preferable in each case (i.e. the most frequently used in most laboratories and the standard methods). The advantages and disadvantages of each method are discussed with reference to the quality of the results and the uncertainties involved in the...

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