Search results for "Aerobic oxidation"
showing 10 items of 35 documents
Direct Methane Oxidation on La1-xSrxCr1-yFeyO3-δ perovskite-type oxides as Potential Anode for Intermediate Temperature Solid Oxide Fuel Cells
2016
Abstract La1−xSrxCr1−yFeyO3−δ (x = 0, 0.1, 0.15, 0.2; y = 0, 0.3, 0.5) perovskite-type oxide powders were synthesized by solution combustion synthesis and characterized by X-ray diffraction, X-ray photoelectron spectroscopy and H2-temperature programmed reduction. Selected compositions were studied by CH4-temperature programmed reduction in the absence and in the presence of H2S. Temperature programmed oxidation and structural characterizations were performed in order to discriminate the nature of residual deposits on the catalyst surface. The study about reduction in different methane-based mixture revealed that total and partial methane oxidation occurred in the range ∼450–1000 °C indepen…
Methane oxidation in a boreal climate in an experimental landfill cover composed from mechanically–biologically treated waste
2007
The present study evaluated microbial methane (CH4) oxidation in a boreally located outdoor landfill lysimeter (volume 112 m3, height 3.9 m) filled with mechanically-biologically treated waste (MBT residual) and containing a cover layer made from the same MBT residual. The calculations based on gas emission and pore gas measurements showed that, between April and October 2005, a significant proportion (96%) of the methane produced (23 l CH4 m(-2) d(-1)) in the lysimeter was oxidized. Methane was oxidized mainly at the depths of 35-75 cm, as indicated by the upward decrease both in the methane concentration and in the methane-to-carbon dioxide ratio in the pore gas. Lower methane oxidation (…
Water chemistry and abiogenic methane content of a hyperalkaline spring related to serpentinization in the Argolida ophiolite (Ermioni, Greece)
2018
Abstract Hyperalkaline mineral springs related to active continental serpentinization are a theme of growing interest since they may contain significant amounts of abiotic gas and have important implications for energy resource exploration, subsurface microbiology and astrobiology. We report the discovery of a new hyperalkaline (pH∼12) spring issuing in the Agioi Anargyroi monastery at Ermioni (Greece), connected to serpentinization of peridotites of the Argolis ophiolite. Two water samples have been collected from separated springs and analysed for the chemical composition of major, minor and trace elements, and isotopic composition (2H and 18O) of water by IC, ICP-OES, ICP-MS and IRMS, an…
Green and Direct Synthesis of Benzaldehyde and Benzyl Benzoate in One Pot
2018
High yields of valued benzaldehyde and benzyl benzoate are obtained in one pot starting from benzyl alcohol using oxygen as only oxidant under mild conditions (2 bar O2, 100 °C) along with an ultralow amount (0.02 mol %) of Au nanoparticles heterogenized over a spherical ORMOSIL mesoporous support. The process is remarkably selective and the catalyst is stable.
Mechanically-biologically treated municipal solid waste as a support medium for microbial methane oxidation to mitigate landfill greenhouse emissions.
2005
The residual fraction of mechanically-biologically treated municipal solid waste (MBT residual) was studied in the laboratory to evaluate its suitability and environmental compatibility as a support medium in methane (CH(4)) oxidative biocovers for the mitigation of greenhouse gas emissions from landfills. Two MBT residuals with 5 and 12 months total (aerobic) biological stabilisation times were used in the study. MBT residual appeared to be a favourable medium for CH(4) oxidation as indicated by its area-based CH(4) oxidation rates (12.2-82.3 g CH(4) m(-2) d(-1) at 2-25 degrees C; determined in CH(4)-sparged columns). The CH(4) oxidation potential (determined in batch assays) of the MBT re…
Pd/Co3O4 catalyst for CH4 emissions abatement: study of SO2 poisoning effect
2007
A catalyst with 0.7 wt% Pd load supported over Co3O4 oxide was investigated in the methane oxidation by operating under CH4/O2 stoichiometric conditions. The effect of the noble metal addition on the activity of bare Co3O4 was evaluated. Samples were characterized by BET, XRD, TPR and XPS analyses. The SO2 poisoning of Pd catalyst and Co3O4 was studied by performing CH4 oxidation tests under stoichiometric conditions in SO2 (1 ppm or 10 ppm). Experiments evidenced that in our conditions the low amount of SO2 doesn’t influence the Pd behaviour, whereas in presence of 10 ppm of SO2 some deactivation occurs that becomes more evident above 450 °C at which the catalyst doesn’t reach 100% of meth…
A genetic link between synsedimentary tectonics-expelled fluids, microbial sulfate reduction and cone-in-cone structures
2018
14 pages; International audience; The late Jurassic (Tithonian) marlstones of the Boulonnais area (English Channel, France) contains diagenetic carbonate beds and nodules. Some nodules exhibit cone-in-cone structures on their lower face. We studied such nodules using various techniques of imaging and chemical (major and trace-elements) and isotopic analyses (Ccarb, Corg, O and S stable isotopes). We interpret the cone-in-cone to be the end product of carbonate-nodule formation during early diagenesis. The diagenetic carbonate precipitation was induced by microbial activity (bacteria and(?) archeae) fueled by upward-migrating fluids. Fluid expulsion was itself triggered by synsedimentary fau…
Photocatalytic partial oxidation of limonene to 1,2 limonene oxide
2018
The silylation of crystalline TiO2 P25, commonly used for photocatalytic degradation of pollutants, results in an exceptionally selective catalyst for the aerobic limonene epoxidation to 1,2-limonene oxide under solar light irradiation. The hypothesized mechanism involves the singlet oxygen generated through energy transfer from the excited TiO2 to adsorbed O2 molecules. The reaction product is the valued precursor of bio-based poly(limonene carbonate), a thermoplastic polymer of superior thermal and optical properties whose industrial production is in need of an efficient green synthesis of limonene oxide.
Co3O4 particles grown over nanocrystalline CeO2: influence of precipitation agents and calcination temperature on the catalytic activity for methane …
2015
Crystalline cobalt oxides were prepared by a precipitation method using three different precipitation agents, (NH4)(2)CO3, Na2CO3 and CO(NH2)(2). Cobalt oxide nanoparticles corresponding to a Co3O4 loading of 30 wt% were also deposited over high-surface area nanocrystalline ceria by the same precipitation agents. The effect of calcination temperature, 350 or 650 degrees C, on the morphological and structural properties was evaluated. Characterization by BET, XRD, SEM, TEM, Raman spectroscopy, H-2-TPR, XPS and NH3-TPD was performed and the catalytic properties were explored in the methane oxidation reaction. The nature of the precipitation agent strongly influenced the textural properties of…
Geochemistry and mineralogy of sediments and authigenic carbonates from the Malta Plateau, Strait of Sicily (Central Mediterranean): Relationships wi…
2010
Abstract A mud volcano field was recently discovered within the Malta Plateau in the Strait of Sicily (Central Mediterranean Sea). Box-core sediments and associated authigenic carbonates have been collected in water depths of 140–170 m from two distinctive sectors of the area, and analyzed for major, trace and rare earth elements, stable isotopes, and mineralogy. Relative homogeneity in the mineralogy and geochemistry of bulk sediments, and 210Pb activity distributions, argue against an active mud ejection activity. In the Malta Plateau western sector, the sediments show high concentrations of Fe, As, Sb, and Mo, exceeding the background values estimated for the Strait of Sicily. Active flu…