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A series of mono- and bi-metallic copper and iron samples were prepared by impregnation method on micro-spherical silica and used for the synthesis of methanol via CO2 hydrogenation. Compared with conventional carrier oxides, micro-spherical silica has obvious advantages in terms of absorption capacity and optimal distribution of active phases on its surface, also exhibiting excellent heat resistance properties and chemical stability. The prepared catalysts were characterized by various techniques including XRF, XRD, SEM, TEM, H2-TPR and CO2-TPD techniques, while catalytic measurements in CO2 hydrogenation reaction to methanol were performed in a fixed bed reactor at a reaction pressure of 30 bar and temperature ranging from 200 to 260 °C. The obtained results revealed that the mutual interaction of copper–iron induces promotional effects on the formation of methanol, especially on systems where Fe enrichment on the silica support favours the presence of a larger concentration of oxygen vacancies, consequently responsible for higher CO2 adsorption and selective methanol production. Surface reconstruction phenomena rather than coke or metal sintering were responsible for the slight loss of activity recorded on the catalyst samples during the initial phase of reaction; however, with no appreciable change on the product selectivity.

Coatings for filtration applications based on epoxy resin mixtures with isopropanol were synthesized using the dip-coating technique. The nanomaterials used were carbon nanospheres (CNS) synthesized by chemical vapor deposition (CVD) and commercially obtained Vulcan XC-72 (VC). The permeation flux and permeability of the coatings were determined by vacuum filtration of pure water applying different working pressures obtaining maximum values of 0.5555 cm3/s and 1.19 × 10−9 m2, respectively, for the CNS6 coating at 26,664 Pa. The minimum values obtained for the permeation flux and permeability were 0.0011 cm3/s and 1.21 × 10−11 m2, for the coating CNS3 at 39,996 Pa. This study analyzed the effect of nanomaterials and the addition of isopropanol at different volumes on the permeability of the coatings. The results show that the permeability was influenced by the number of pores present rather than by their diameter. The number of pores were obtained between the ranges 1–12 μm for all the coatings. The study of computational fluid dynamics (CFD) through a free and porous medium, showed that it is possible to accurately determine flow velocities (m/s) through and inside the composite coatings. Understanding the flow behavior is a practical strategy to predict the performance of new nanocomposite coatings.

In recent years there has been a significant boom in the production of biofuels, especially biomethane, through anaerobic biodigestion, but when the substrates decompose inside the reactors, they generate hydrogen sulfide, H2S as a byproduct. On the other hand, to increase the efficiency of biodigesters it is necessary to have control of temperature. Based on our experience, one of the ways to achieve that control is to take the gas from the upper part of the reactor, pass it through a solar heat exchanger, and then inject the hot gas in the bottom of the reactor. However, gas recirculation results in corrosion of copper pipes due to the high hydrogen sulfide, H2S content of the gas stream from the reactor. For the reasons mentioned, a hybrid epoxy resin-silica coating was designed in this work that protects the copper surface against corrosion by H2S and at the same time withstands moderate temperatures. The coatings were obtained from three v/w ratios of TEOS / Resin (T/R): 0.64, 1.28 and 1.92, named as R1, R2 and R3 respectively. Silica was produced in situ by the Sol-Gel process. The coatings on copper substrates were obtained by dip-coating, annealed at 75 °C and treated at different temperatures for evaluating their resistance to temperature. The corrosion resistance of coatings to H2S was evaluated through ASTM D610−01 and ASTM D714−02 Standards. The structural characterization of the coatings was performed by FTIR, Streaming Potential, SEM and XPS. The R2 hybrid coating showed excellent resistance to temperature and H2S attack. From all the characterization carried out and taking into account the literature review, it is concluded that the Si-N bonds obtained via sol-gel in situ at relatively low temperatures (75 °C) contribute to the protection of copper foils against the effect of temperatures higher than 100 °C and to the protection of corrosion by H2S. Taking the R2 formulation, further experimentation will be carried out for coating the internal part of copper pipes of a solar heat exchanger prototype.

Cost analyses developed for fuel cells are reviewed, focusing mainly on polymer electrolyte membrane fuel cell (PEMFC) technology, because the solid polymer membrane electrolyte is robust and operates under conditions needed for most pressing applications, especially for the automotive application. Presently, PEMFC cost is still too high for large scale commercialization. The cost of electrodes and membranes contributes substantially to the total PEMFC cost which is driving research to reduce the costs of these components so the PEMFC can be introduced into large scale power markets. A scenario analysis for PEMFC costs for an automotive application illustrates that reducing the MEA cost up to 27% makes achievable the $40/kW cost target by 2020, which corresponds to a reduction in the cost of the catalyst by $3.55/kW and the membrane by $0.8/kW. The ultimate cost target for the PEMFC of 30/kW is obtained when the MEA cost is reduced by 45%, which corresponds to a projected cost reduction for catalyst cost by $6.41/kW and membrane by $1.44/kW. If these costs are met, the PEMFC would reach a price which is cost competitive to Internal Combustion Engine Vehicles which would allow the use of PEMFCs for power generation in a significant number of sectors.

Polymer membranes are prepared as a composite of polybenzimidazole and non-functionalized multiwall carbon nanotubes (PBI-CNT) and polybenzimidazole (PBI) only. Each is doped with H 3 PO 4 (PA) and used as a proton exchange membrane (PEM) as the electrolyte in a fuel cell. The proton conductivities at 180 °C for the doped PBI membrane (PBIPA) and the doped PBI-CNT membrane (PBICNTPA) are 6.3 × 10 −2 and 7.4 × 10 −2 Scm −1 respectively. A single fuel cell having these membranes as electrolyte has a Pt catalyzed hydrogen gas fed anode and a similar oxygen cathode without humidification of feed gases; the cell with the PBICNTPA membrane has higher open circuit voltage (0.96 V) than that with a PBIPA membrane (0.8 V) at 180 °C. The mechanical stability of the membrane improves with CNTs addition. The tensile strength of the composite PBI-CNT membrane with 1 wt.% CNTs loading is 32% higher and the Young's Modulus is 147% higher than the values for a membrane of PBI alone. The improvement in conductivity and mechanical properties in the composite membrane due to the CNT addition indicates that a PBI-CNT membrane is a good alternative as a membrane electrolyte in a PEMFC.

UnidaddeFisicadeMaterialesCentroMixtoCSIC-UPV/EHUandDonostiaInternationalPhysicsCenter(DIPC),20018SanSebastian,SpainInthiswork,westudytheelectronicandchemicalpropertiesofagraphenesheetdopedwithSorP,bymeansofab initio calculations.Weconsiderone,twoandthreeimpurityatomsbysubstitutiononthegrapheneandobtaindopingformationenergiesof5.78,7.43and10.53eVforsulphurimpuritiesand2.73,0.54and1.82eVforphosphorousimpurities.Wefindthatdopinginducesalargelocalcurvaturethattendstoincreasethesystemlocalreactivity.Wecharacterizetheelectronicstructureby the electronic density of states, the electron localization function and the maximally localizedWannierfunctions.Somepotentialapplicationsinelectronicnanodevicesarehighlighted.

Facultad de Ingeniería Química. Doctorado en Ciencias en Ingeniería Química In this work the addition of cadmium sulfide (CdS) particles and carbon nanotubes (CNTs) to a poly(methyl methacrylate) (PMMA) matrix was analyzed. The resulting material was proposed as potential photoconductor because CNTs and CdS could enhance the electrical current, which result from the conductivity and photoconductivity of CNTs and CdS respectively. A new route of synthesis for PMMA-CdS-CNTs materials was proposed which combines sonochemistry and in-situ polymerization. In the case of CdS, the rapid motion occurring in solution for the sonochemical process inhibits agglomeration and settling of the CdS particles, remaining suspended between the chains of the growing monomer. This route of synthesis favors the dispersion of both CdS and CNTs in the polymer, producing films with CNTs and CdS particles closely spaced in the polymer matrix, and increasing the electrical conductivity of the new material when compared with PMMA-CNTs and PMMA-CdS. Based on FT-IR analysis of PMMA-CNTs materials, a displacement of about 8 cm-1 of the band assigned to carbonyl groups of the polymer relative to the spectrum of pure PMMA was found, this change has been associated with the carbon-carbon bonding and interaction between the polymer and nanotubes resulting from the opening of the ? bonds in the nanotubes. Moreover, impedance tests performed with these materials, allow obtaining a conductivity profile which change from 1x10-14 S-m to 1x10-9 S-m by increasing the concentration of CNTs from 0 to 0.5 wt%. From these results a percolation threshold level was also identified at 0.5 wt% of CNTs, which has been defined as the necessary concentration of dispersed nanotubes in a matrix which are connected or very close to each other, leading to a continuous flow of electrical current. En este trabajo se analizó la adición de partículas de sulfuro de cadmio (CdS) y nanotubos de carbono (NTsC) a una matriz de poli(metil metacrilato) (PMMA). El material resultante se propuso como potencial fotoconductor debido a que los NTsC y el CdS le pueden impartir a una matriz dieléctrica (PMMA), un aumento en la intensidad de corriente derivada de la conductividad y fotoconductividad de los NTsC y CdS respectivamente. La ruta de síntesis que se propuso en esta tesis para obtener materiales de PMMACdS- NTsC, combina el proceso de sonoquímica y la polimerización in situ. En el caso del CdS, el movimiento rápido que se produce en la solución durante el proceso de sonoquímica, inhibe que el CdS se aglomere y sedimente quedando suspendido entre las cadenas de monómero en crecimiento, favoreciendo la dispersión de estos dos nanocompuestos en el polímero y propiciando que en la película obtenida exista una proximidad entre los NTsC y el CdS, condición que propicio el incremento de la conductividad en este nuevo material comparado con materiales de PMMA-NTsC y PMMA-CdS. A partir de los análisis de FT-IR realizados a materiales de PMMA-NTsC, se encontró un desplazamiento de aproximadamente de 8 cm-1 de la banda de los grupos carbonilos del polímero respecto al espectro del PMMA puro, este cambio ha sido asociado a la unión e interacción carbono-carbono entre el polímero y los nanotubos derivado de la apertura de los enlaces ? en los nanotubos. Por otra parte, las pruebas de impedancia realizadas a estos materiales, permitieron realizar un perfil de conductividad eléctrica donde se observó que ésta pasa de 1x10-14 S-m a 1x10-9 S-m al incrementar la concentración de NTsC de 0 al 0.5% en peso.