Nanocátalysts for oxygen removal from biomass derived biofuel

The use of bio-energy as a renewable alternative to fossil fuels is nowadays attracting more and more attention. Bio-fuel from biomass seems to be a potential energy substitute for fossil fuels since it is a renewable resource that could contribute to sustainable development and global environmental preservation and it appears to have significant economic potential. Liquid fuels can be obtained from fast pyrolysis of lignocellulosic biomass, where fast pyrolysis is a promising route because the process takes place at moderate temperatures, in absence of air and with a short hot vapor residence time. However, these liquid fuels have poor quality due to their low volatility, high viscosity, low heating value, a high oxygen content and poor chemical stability. This high oxygen is due to the presence of oxygen-containing compounds such as alcohols, aldehydes, ketones, furans and phenols. In this sense, catalytic hydrodeoxygenation (HDO) is one the most efficient processes to remove oxygen from these liquid fuels. In this context, the catalyst design is of upmost importance to achieve a high degree of deoxygenation, and bifunctional catalysts are required to achieve high degrees of activity. Noble metal and non-noble metal based catalysts will be evaluated in HDO of model molecules in order to get further insight about the important role of the active phase. Transition metal phosphides have shown excellent catalytic performances due to their good hydrogen transfer properties that diminishes the amount of metal exposed, avoiding, as much as possible, the deactivation, and modifies the electronic density of the catalyst leading to solids that favors the HDO. In addition these phosphides show bifunctional catalytic properties (metallic sites for hydrogenation and acid sites for cracking, methyl transfer reaction, dehydration and isomerization).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Role of Mo in catalysts based on noble metals in hydrodeoxygenation reactions

The use of bio-energy as a renewable alternative to fossil fuels is nowadays attracting more and more attention. The bio-fuel from biomass seems to be a potential energy substitute for fossil fuels since it is a renewable resource that could contribute to sustainable development and global environmental preservation and it appears to have significant economic potential1. The problem is its high oxygen content, which gives undesirable properties for combustion. To remove oxygen, catalytic hydrodeoxygenation (HDO) reactions are carried out. Monometallic Mo/Si, Pt/Si as well as bimetallic PtMo/Si catalysts were prepared and evaluated in the hydrodeoxygenation (HDO)reaction of dibenzofurane (DBF) as a model molecule in biomass derived bio-oil.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Au-Cu/SBA(Ti) based catalysts for photocatalytic applications

Comunicación a congresoIn this work, it has been synthesized several Au and Au-Cu alloy photocatalysts supported on two different mesoporous supports: a non-commercial SBA-15 and a post-synthesis TiO2 modified SBA-15 (TiSBA-15), with which a high dispersion of TiO2 species have been achieved maintaining the SBA-15 structure. In addition, it has also been obtained highly dispersed Au nanoparticles confined in SBA-15 pore channels, as can be observed in Figure 1. The photocatalysts have been preliminary tested in the preferential CO oxidation in a H2-rich stream (CO-PROX) at room temperature and atmospheric pressure under simulated solar light irradiation. In spite of the very low gold and copper loading (1.5 wt% and 0.5wt% respectively), the catalysts resulted active and selective in the low temperature photo-CO-PROX.Universidad de Málaga, Campus de Excelencia Internacional Andalucía Tec

Synthesis of porous graphene/TiO2 by use of recycled graphite

Graphene-based nanomaterials are a kind of new technological materials with high interest for physicists, chemists and materials scientists. Graphene is a two-dimensional (2-D) sheet of carbon atoms in a hexagonal configuration with atoms bonded by sp2 bonds. These bonds and this electron configuration provides the extraordinary properties of graphene, such as very large surface area, a tunable band gap, high mechanical strength and high elasticity and thermal conductivity [1]. Graphene has also been investigated for preparation of composites with various semiconductors like TiO2, ZnO, CdS aiming at enhanced photocatalytic activity for their use for photochemical reaction as water splitting or CO2 to methanol conversion [2-3]. In this communication, the synthesis of porous graphene@TiO2 obtained from a powder graphite recycled, supplied by ECOPIBA, is presented. This graphite was exfoliated, using a nonionic surfactant (Triton X-100) and sonication. Titanium(IV) isopropoxide was used as TiO2 source. After removing the surfactant with a solution HCl/n-propanol, a porous solid is obtained with a specific area of 358 m2g-1. The solid was characterized by XRD, FTIR, XPS, EDX and TEM. Figure 1 shows the graphene 2D layer bonded with nanoparticles of TiO2. When a water suspension of this material is exposed with UV-vis radiation, water splitting reaction is carried out and H2/O2 bubbles are observed (Figure 2)Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Synthesis and characterization of silver vanadates thin films for photocatalytic applications

Silver vanadates thin films were deposited by a hybrid deposition system combining laser ablation and thermal evaporation. A high purity vanadium target was ablated using the third harmonic of a Nd:YAG laser whereas high purity silver pellets were evaporated. The as-deposited thin films were subjected to thermal treatments at 400 °C to obtain crystalline films. For films without Ag amorphous V2O5 thin films were deposited and as the Ag is incorporated in the material different silver vanadates were obtained. The effect of the silver load on the composition, structure, optical properties, surface morphology and photocatalytic response of the deposited films was studied. The film composition, determined by X-ray photoelectron spectroscopy, reveals Ag contents from 5.5 to 18.9 at.%. The crystalline phases formed were identified by micro-Raman Spectroscopy; the results indicate the formation of three silver vanadates depending on the silver content. The morphology was observed using scanning electron microscopy, the filmś surface changes from a smooth surface to belts covering the surface and finally Ag nanoparticles are observed at the higher Ag contens. Optical properties determined from UV–vis reveal the presence of the surface plasmon signal in films containing silver. The films were tested in the photocatalytic degradation of Malachite Green dye reaching maximum degradations degrees close to 53% under solar irradiation. Reactive species trapping experiments suggest that O2 − produced by the O2 reduction via the photogenerated electrons drives the photodegradation mechanismCB-168827 CB-240998 F. Gonzalez-Zavala thanks to CONACyT for the PhD and Beca Mixta grants, and also to the SIEA-UAEM for the beca movilidad para estudios avanzados 2016. E. Rodríguez-Castellón thanks to project CTQ2015-68951-C3-3-R of Ministerio de Economía y Competitividad (Spain) and FEDER funds

Ni-Doped Ordered Nanoporous Carbon Prepared from Chestnut Wood Tannins for the Removal and Photocatalytic Degradation of Methylene Blue

In this work, Ni-doped ordered nanoporous carbon was prepared by a simple and green one-pot solvent evaporation induced self-assembly process, where chestnut wood tannins were used as a precursor, Pluronic® F-127 as a soft template, and Ni2+ as a crosslinking agent and catalytic component. The prepared carbon exhibited a 2D hexagonally ordered nanorod array mesoporous structure with an average pore diameter of ~5 nm. Nickel was found to be present on the surface of nanoporous carbon in the form of nickel oxide, nickel hydroxide, and metallic nickel. Nickel nanoparticles, with an average size of 13.1 nm, were well dispersed on the carbon surface. The synthesized carbon was then tested for the removal of methylene blue under different conditions. It was found that the amount of methylene blue removed increased with increasing pH and concentration of carbon but decreased with increasing concentration of methylene blue. Furthermore, photocatalytic tests carried out under visible light illumination showed that purple light had the greatest effect on the methylene blue adsorption/degradation, with the maximum percent degradation achieved at ~4 h illumination time, and that the percent degradation at lower concentrations of methylene blue was much higher than that at higher concentrations. The adsorption/degradation process exhibited pseudo second-order kinetics and strong initial adsorption, and the prepared carbon showed high magnetic properties and good recyclabilityThis research was funded by Junta de Andalucía, Consejería de Transformación Económica, Industria, Conocimiento y Universidades. Project P20_00375. Partial funding for open access charge: Universidad de Málag

M/TiO2 (M = Fe, Co, Ni, Cu, Zn) catalysts for photocatalytic hydrogen production under UV and visible light irradiation

In order to improve the photocatalytic response of TiO2 to UV and visible light for hydrogen photoproduction, low cost M/TiO2 semiconductor catalysts were prepared by the impregnation method of five different first row transition metals (M = Fe, Co, Ni, Cu or Zn) on a commercial titania support. The maximum hydrogen production efficiency was achieved for the Cu/TiO2 photocatalyst, with ∼5000 and ∼220 μmol h−1 g−1 H2 production rates for UV and visible irradiation, respectively. Ni/TiO2 and Co/TiO2 also showed a significant photocatalytic activity when UV light was used. The best performing catalyst, Cu/TiO2, was characterized by TEM and XPS measurements. The data showed that Cu was highly dispersed over the TiO2 support and the copper species existed as both reduced Cu0/Cu+ and oxidized Cu2+ on TiO2. Besides, during the hydrogen production reaction, the reduced Cu was partially oxidized to Cu2+ by the transfer of photogenerated holes under UV or visible light irradiation. With UV and visible lamps, the H2 production rates were higher than those obtained with non-impregnated TiO2 by factors of 16 and 3, respectively. These results demonstrated that a Cu/TiO2 photocatalyst could be considered a promising low-cost alternative to the well-known Pt/TiO2 system for hydrogen production, making the Cu-based catalyst an ideal cost-effective candidate for this reactionThe authors would like to thank Ministerio de Economía y Competitividad of Spain (CTQ2015-68951-C3-3-R and MAT2016-80933-R), Ministerio de Ciencia, Innovación y Universidades of Spain (Project RTI2018-099668-B-C22) and FEDER fund

Total oxidation of VOCs on mesoporous iron oxide catalysts: soft chemistry route versus hard template method

[EN] A comparative study on the total oxidation of volatile organic compounds, VOCs, on mesoporous iron oxide catalysts prepared by soft chemistry route versus those achieved by hard template methodThe authors would like to acknowledge the DGICYT in Spain (CTQ2012-37925-C03-1, CTQ2012-37925-C03-2, CTQ2012-37925-C03-3 and CTQ2012-37984-C02-01) and FEDER for financial support. We also thank the University of Valencia and SCSIE-UV for assistance.Solsona Espriu, BE.; Garcia, T.; Sanchis Martinez, R.; Soriano Rodríguez, MD.; Moreno, M.; Rodríguez-Castellon, E.; Agouram, S.... (2016). Total oxidation of VOCs on mesoporous iron oxide catalysts: soft chemistry route versus hard template method. The Chemical Engineering Journal and the Biochemical Engineering Journal. 290:273-281. https://doi.org/10.1016/j.cej.2015.12.109S27328129

Partial oxidation of hydrogen sulphide to sulphur over vanadium oxides bronzes

[EN] Me-containing V2O5 materials (Me =Ag, Cu, Ca and Na) were prepared hydrothermally (from aqueous gels containing V2O5/H2O2/MeClx mixtures, with Me/V ratios of 0.17). The samples were finally heattreated in air or in N2 atmosphere. The heat-treated samples have been characterized by several physicochemical techniques and tested in the partial oxidation of hydrogen sulfide. According to XRD, electron paramagnetic resonance and 51V NMR results, Ag0.35V2O5 and Na0.33V2O5 (or NaV6O15) bronzes with a minority presence of V2O5 were mainly obtained in the case of Ag- and Na-containing materials in samples both heat-treated in air or in N2 atmosphere. In the case of Cu- and Ca-containing samples, V2O5 was mainly observed in samples calcined in air. However, Cu0.26V2O5 and Ca0.17V2O5 bronzes, with the minority presence of V2O5, have been observed in Cu- and Ca-containing samples heat-treated in N2. On the other hand, the catalytic behavior strongly depends on the metal promoter. Thus catalysts presenting vanadium oxide bronzes, i.e. samples presenting Ag0.35V2O5, NaV6O15, Cu0.26V2O5 or Ca0.17V2O5 shows a catalytic activity during the partial oxidation of H2S to sulfur higher than that observed over pure V2O5 or over promoted catalysts presenting mainly V2O5 (i.e. Cu- or Ca-containing samples calcined in air). Moreover, some differences in the selectivity to sulfur were observed. A higher formation of SO2 at high reaction temperature has been favored over Ag0.35V2O5-containing catalyst. This different behavior between samples could be explained by the presence of metallic Ag on the surface of Ag0.35V2O5, which was detected by XRD. Also, higher formation of SO2 is favored in the case of catalyst heat-treated in N2, in which the presence of VO2, as minority, could have a role in combustion of sulfur. Accordingly, this work should be considered as a first approach to relate catalytic activity of the Me-containing vanadium oxide bronze (containing Ag, Cu, Ca and Na) for the selective oxidation of hydrogen sulfide.The authors would like to thank the DGICYT in Spain (Projects CTQ2012-37925-0O3-01 and CTQ2012-37925-0O3-03) for financial support.Soriano Rodríguez, MD.; Vidal Moya, JA.; Rodriguez Castellon, E.; Melo Faus, FV.; Blasco Lanzuela, T.; López Nieto, JM. (2015). Partial oxidation of hydrogen sulphide to sulphur over vanadium oxides bronzes. Catalysis Today. 259:237-244. https://doi.org/10.1016/j.cattod.2015.08.009S23724425

Total Oxidation of Propane Using CeO2 and CuO-CeO2 Catalysts Prepared Using Templates of Different Nature

[EN] Several CeO2 and CuO-CeO2 catalysts were prepared using different methods, i.e., a homogeneous precipitation with urea, a nanocasting route using CMK-3 carbon as a hard template and a sol¿gel process using Poly(methyl methacrylate) (PMMA) polymer as a soft template, and tested in the total oxidation of propane. The catalysts were characterized by a number of physicochemical techniques (XRD, N2 adsorption, TPR, XPS, Raman spectroscopy) showing distinct characteristics. For each series, Cu-Ce-O catalysts with low Cu-loadings (5 wt % CuO) showed the highest activity, higher than those samples either without copper or with high Cu-loading (13 wt % CuO). The incorporation of copper leads to an increase of the concentration of bulk defects but if the Cu-loading is too high the surface area drastically falls. The highest activity in the total oxidation of propane was achieved by Cu-containing ceria catalysts synthesized using a polymer as a template, as this method yields high surface area materials. The surface area and the number of bulk/sub-surface defects of the ceria seem to be the main properties determining the catalytic activityThe authors would like to acknowledge the DGICYT in Spain CTQ2012-37925-C03-2, CTQ2015-68951-C3-1-R, CTQ2015-68951-C3-3-R. Authors from ITQ also thank Project SEV-2012-0267 for financial support. B.S, R.S and A.M.D also thank UV-INV-AE16-484416.Solsona, B.; Sanchis, R.; Dejoz, AM.; Garcia, T.; Ruiz-Rodríguez, L.; López Nieto, JM.; Cecilia, JA.... (2017). Total Oxidation of Propane Using CeO2 and CuO-CeO2 Catalysts Prepared Using Templates of Different Nature. Catalysts. 7(4):96-110. https://doi.org/10.3390/catal7040096S961107