Low Amount Of Carbon Research Articles

Effect of Torrefied Wood Biomass under an Oxidizing Environment in a Downdraft Gasification Process

The effect of composition and heating value of torrefied biomass under an oxidizing atmosphere at different conditions (180, 210, and 240 °C during 30, 75, and 120 minutes) was studied relative to downdraft gasification performance. An extended model for gasification in thermochemical equilibrium was used to evaluate the effect of pretreated biomasses, fuel-to-air equivalence ratio, and char byproduct production on the producer gas composition, reaction temperature, cold gas efficiency (CGE), and the engine fuel quality (EFQ). The model was validated with experimental data, reaching a global relative error of 8.5%. For raw or torrefied biomasses, with regard to char production, the CGE decreases if char increases; this is due to the fact that the process tends to combustion regimes when a lower amount of carbon is involved in the gasification reaction. Otherwise, the CGE and EFQ increase (up to 80% and 2.5 MJ/kg, respectively) if fuel-to-air ratio increases. With regard to the torrefied biomass, it is highlighted that CGE and EFQ increase from 77% to 82% and from 2.2 MJ/kg to 2.5 MJ/kg, respectively, when the torrefaction conditions (temperature and/or time) increase. This behavior is related to the increase of the autothermal zones in the gasification process and due to the higher heating value of torrefied biomass.

Sustainable power generation with large gas engines

Large gas engines will play a significant role in distributed power generation for the energy supply of the future. The lower amount of carbon in natural gas in comparison with other fossil fuels can be used to bridge the gap between a carbon‐based and a carbon‐free energy supply. The main objective of this paper is to provide an overview of the technological challenges the next generation of gas engines will face. Improvements in robustness and dynamic behavior will allow gas engines to meet the high transient requirements for the future power supply. The great fluctuations in gas quality anticipated with grid gas and liquefied natural gas impose high demands on both the transient behavior and the knock resistance of the engine. Technologies that enhance fuel flexibility by enabling sustainable power and heat generation using hydrogen‐rich syngas from biomass and the efficient use of waste gases will be key. The most important technological components that maximize power output and efficiency as well as transient operation at very low emission levels are discussed. An advanced development methodology is applied in order to deal with the requirements presented by the technological challenges. The main future goals of gas engine development will be described by use of examples to illustrate the application of the methodology.In summary, the research and technological developments presented in this paper will support the transition from conventional to carbon‐free fuel for reliable and sustainable power generation that meets future requirements for large gas engines.

Reduction behaviour of agglomerated iron ore nuggets by devolatisation of high-ash, high-volatile lignite coal for pig iron production

High-quality coking coals all over the world are gradually approaching extinction. These days, steel industries are trying to focus more on the utilisation of non-coking grades of coal. The present work involving high-ash, high-volatile lignite coal can be used indirectly in iron-making processes. Direct use is not possible due to low amount of carbon and high value of ash. High ash content leads to huge sulphur content, and this leads to high cost involvement in secondary processes. On the other hand, huge amount of iron ore fines are generated during mechanised mining, sizing, screening, transportation, beneficiation and sintering processes. Iron ore nuggets are formed from inferior quality iron ore fines using suitable binders with the applied pressure. Mechanical properties of iron ore nuggets are also assessed through shatter and abrasion test. A furnace was designed, to indirectly utilise high-ash, high-volatile lignite coal, for pre-reduction iron ore nuggets. Iron ore nuggets were partly reduced by CO, H2 and fine carbon produced from volatilisation of coal. Optimized pre-reduced nuggets, having high mechanical stability was directly charge in the raising hearth furnace for pig iron production.

A review of cleaner intensification technologies in biodiesel production

Biodiesel is envisaged as environmentally benign fuel due to its unique properties, such as biodegradability, renewability and non-toxicity. Its utilisation leads to the reduction of sulphur oxide and greenhouse gas emissions as it produces quite lower amounts of carbon and sulphur based gases in comparison to conventional fossil fuels. This paper is a review of the recent achievements of the cleaner intensification technologies for biodiesel production. Merits and limitations of the cleaner intensification technologies have been discussed. Mechanical stirring via transesterification is the most common and extensively utilised for biodiesel production. It involves the conversion of oil to glycerol and acid alkyl ester while employing methanol. However, this process has an inherent drawback of mass transfer resistance resulting in a lower reaction rate and higher production cost. Intensification technologies have become more attractive to overcome these aforementioned problems. In a bid to increase the cost competitiveness of biodiesel production compared to diesel fuel, process intensification has been studied for numerous biodiesel processing technologies. Many researchers have resorted to several intensification technologies namely; microwave, ultrasonic cavitation and hydrodynamic cavitation reactor to eliminate the mass transfer resistance of immiscible reactants. Once the mass transfer resistance is reduced, it may lead to a shorter reaction time and lower energy consumptions compared to mechanical stirring. Recent studies reveal that microwave and ultrasonic cavitation techniques are not yet completely feasible for biodiesel production at industrial scale. On the other hand, it was found that hydrodynamic cavitation offers a number of advantages over other intensification technologies. It shows good performance with respect to product yield, reaction time, energy consumption and product quality. Furthermore, it exhibits a sustainable mean for energy recovery from renewable oils. It was concluded that more studies are needed to extend the existing information of hydrodynamic cavitation for the design of the plate geometry with respect to the methyl ester conversion. This will help to develop a sustainable and industrially viable route for energy recovery from renewable oils. Yield efficiency in relation to the method followed the order: hydrodynamic cavitation > microwave > ultrasonic cavitation > mechanical stirring.

Ways that sugarcane industry can help reduce carbon emissions in Thailand

This study aims to evaluate the energy indexes and carbon equivalences (CE) occurring in the Thai sugarcane industry so as to find a sustainable way to produce sugar and renewable energy. Data from energy consumed and produced in the cultivation field and end-user productions for the existing operations of the sugarcane industry show a Net Energy Value (NEV) gain of +120,746.4 MJ/ha-y. The positive sign indicates that the renewable energy output is more than the fossil energy input required in the production processes. Following the concept of Carbon-Balanced Model (CBM), however, the present whole-chain operations of the sugarcane industry are found to emit carbon into the atmosphere instead of reducing carbon emissions. For the production of raw sugar and bioethanol, net carbon emissions were found for existing practice equal to +61.6 kg CE/ha-y with a carbon fixation efficiency of 98.1%. About 66% of the emissions were determined to come from the agricultural phase, mostly due to application of chemical fertilizers. Should fossil-based matter used in both agricultural and industrial phases be replaced with renewable materials, the net emission is computed to be −396.0 kg CE/ha-y, resulting in a carbon fixation efficiency of 114.3%. Thus, this practice will help reduce carbon emissions from the sugarcane industry in contrast to existing practice. From cost analysis, the entire industry is found to earn annual profit about 2.6 times of the total costs. It is revealed that more profit would be gained if lower amount of carbon is emitted.

CO2 Biofixation and Growth Kinetics of Chlorella vulgaris and Nannochloropsis gaditana.

CO2 biofixation was investigated using tubular bioreactors (15 and 1.5 l) either in the presence of green algae Chlorella vulgaris or Nannochloropsis gaditana. The cultivation was carried out in the following conditions: temperature of 25 °C, inlet-CO2 of 4 and 8 vol%, and artificial light enhancing photosynthesis. Higher biofixation were observed in 8 vol% CO2 concentration for both microalgae cultures than in 4 vol%. Characteristic process parameters such as productivity, CO2 fixation, and kinetic rate coefficient were determined and discussed. Simplified and advanced methods for determination of CO2 fixation were compared. In a simplified method, it is assumed that 1 kg of produced biomass equals 1.88 kg recycled CO2. Advance method is based on empirical results of the present study (formula with carbon content in biomass). It was observed that application of the simplified method can generate large errors, especially if the biomass contains a relatively low amount of carbon. N. gaditana is the recommended species for CO2 removal due to a high biofixation rate—more than 1.7 g/l/day. On day 10 of cultivation, the cell concentration was more than 1.7 × 107 cells/ml. In the case of C. vulgaris, the maximal biofixation rate and cell concentration did not exceed 1.4 g/l/day and 1.3 × 107 cells/ml, respectively.Electronic supplementary materialThe online version of this article (doi:10.1007/s12010-016-2062-3) contains supplementary material, which is available to authorized users.

Influence of process parameters on the surface integrity of micro-holes of SS304 obtained by micro-EDM

The present research deals with the evaluation of surface integrity of micro-holes machined in stainless steel (SS304) sheet, using ultrasonic vibration-assisted micro-EDM process. Experimental results showed that pulse duration, gap voltage, and the application of ultrasonic vibration significantly affected the surface integrity in terms of the changes in recast layer thickness, micro-hardness, and the chemical composition of the machined surface. It is observed that the thickness of the recast layer is in the range of 6–23 µm, but the recast layer thickness was less with application of the ultrasonic vibration of the work piece. The heat-affected zone (HAZ) could not be observed both in FESEM and optical images. The micro-hardness in the HAZ was found in the range of 146–238 HV. The lower values of the micro-hardness were obtained with the application of vibration to the work piece. The changes in the chemical composition of the edge of the fabricated micro-holes were analyzed through EDS test, and it was found that lower amounts of carbon, oxygen, and tungsten were present in the machined surfaces.

Energy Dissipation in Very High Cycle Fatigue for Polycrystalline Pure Copper and Armco Iron

This paper aims at a deeper understanding of microplastic mechanisms leading to crack initiation in ductile metals in Very High Cycle Fatigue (VHCF). Fatigue tests were conducted using an ultrasonic technique at loading frequency of 20 kHz. The microplastic mechanisms are revealed via observations of slip markings at the specimen surface and self-heating measurements due to intrinsic dissipation. Pure copper and Armco iron (which contains a very low amount of carbon) were investigated. Both are single-phase ductile materials but the crystallographic structure of copper is face-centered cubic while it is body centered cubic for Armco iron. A good correlation was found between slip markings initiation and dissipation for both materials. The dissipation for both materials is of the same order of magnitude but the location, the morphology and the evolution over cycles of slip markings were found different.

Manejo post incendio de bosques mediterráneos: almacenamiento de carbono en áreas regeneradas en el este de la Península Ibérica

El manejo de las masas forestales incendiadas debe incluir un seguimiento desde el primer momento tras el incendio, optimizando la implementación de medidas urgentes que aseguren unas condiciones mínimas para la regeneración natural del ecosistema. Sin embargo, ante una regeneración excesiva, se deben plantear tratamientos selvícolas tempranos como apoyo a la recuperación del ecosistema. En este trabajo se discuten los efectos del clareo temprano en dos zonas incendiadas y regeneradas de manera natural situadas en el este peninsular, una en el sur de Albacete con masas de pino carrasco (Pinus halepensis Mill.) quemadas en el verano de 1994, y otra al este de Cuenca, con masas de carrasca (Quercus ilex L. ssp. ballota (Desf.) Samp), quemadas repetidamente en los veranos de 1993 y 2001. El objetivo de este estudio es monitorizar la recuperación de biomasa y el almacenamiento de carbono de estas masas naturales, mediante muestreo directo en campo y por cálculo de existencias obtenidas de bases de datos públicas. El método directo mostró que la disminución del carbono almacenado en las especies estudiadas fue debido a la reducción inicial del número de árboles, que en los encinares no se había recuperado totalmente en 2010 (dos años después del tratamiento y nueve tras incendio). En 2010, dieciséis años después del incendio y seis tras el tratamiento silvícola, obtuvimos que en el pinar, los clareos de alta intensidad mejoraron la capacidad de la masa arbórea para almacenar carbono. Además, los valores de carbono almacenado en la biomasa arbórea en áreas no tratadas eran comparables a los valores del Tercer Inventario Forestal Nacional. Por tanto, se pone de relieve el interés del uso de la implementación de esta herramienta de manejo selvícola en un manejo forestal adaptativo y se propone la inclusión de masas jóvenes en regeneración dentro de los cálculos de almacenaje de carbono, al menos a niveles provinciales y regionales.

Twentieth century carbon stock changes related to Piñon-Juniper expansion into a black sagebrush community

BackgroundIncreases in the spatial extent and density of woody plants relative to herbaceous species have been observed across many ecosystems. These changes can have large effects on ecosystem carbon stocks and therefore are of interest for regional and national carbon inventories and for potential carbon sequestration or management activities. However, it is challenging to estimate the effect of woody plant encroachment on carbon because aboveground carbon stocks are very heterogeneous spatially and belowground carbon stocks exhibit complex and variable responses to changing plant cover. As a result, estimates of carbon stock changes with woody plant cover remain highly uncertain. In this study, we use a combination of plot- and remote sensing-based techniques to estimate the carbon impacts of piñon and juniper (PJ) encroachment in SE Utah across a variety of spatial scales with a specific focus on the role of spatial heterogeneity in carbon estimates.ResultsAt a plot scale (300 m2) areas piñon juniper (PJ) encroached areas had 0.26 kg C m-2 less understory vegetation carbon compared to un-encroached sites. This lower amount of carbon was offset by an average of 1.82 kg C m-2 higher carbon in PJ vegetation and 0.50 kg m-2 of C in PJ surface-litter carbon. Soil mineral carbon stocks were unaffected by woody plant cover and density. Aboveground carbon stocks were highly dependent on PJ vegetation density. At a 300 m2 plot-scale, plots with low and high density of PJ forest had 1.40 kg C m-2 and 3.69 kg m-2 more carbon than the un-encroached plot. To examine how these 300 m2 variations influence landscape scale C estimates, historical and contemporary aerial photos were analyzed to develop forest density maps in order to estimate above ground PJ associated C stock changes in a 25 ha area. This technique yielded an average estimate of 1.43 kg m-2 of C accumulation with PJ encroachment. Combining this estimate with analysis of tree growth increments from dendrochronologies, we estimate that these PJ stands are accumulating aboveground C at an annual rate of 0.02 kg C m-2 with no slowing of this rate in healthy PJ. This result is in contrast to what has been observed in large areas of drought related PJ mortality, where C accumulation has ceased.ConclusionsThese results illustrate that the encroachment of PJ forests in SE Utah over the last century has resulted in a large (and ongoing) accumulation of carbon in PJ trees and surface litter. However, the magnitude of the increase depends to on the density of vegetation across the landscape and the health of forest stands. Both management activities that remove forest carbon and forest mortality due to drought or wildfire have the potential to quickly reverse the multi-decadal accumulation of carbon in these stands.

Anionic bulk polymerization to synthesize styrene–isoprene diblock and multiblock copolymers by reactive extrusion

ABSTRACTIn this study, styrene–isoprene diblock and multiblock copolymers were synthesized with n‐butyllithium as the initiator, in an intermeshing, corotating twin‐screw extruder. The diameter (D) of this extruder was 36 mm, and the ratio of length/diameter was 56. The weight content of polyisoprene in these copolymers was above 50% although in the past studies it had not been possible to accomplish levels higher than 30%. Gel permeation chromatography results of samples and their degraded products show that there is only one long block polystyrene in the diblock copolymer chains; while in the multiblock copolymer molecules, there is a long block and large numbers of small blocks. Dynamic mechanical analysis and transmission electron microscopy show that the two phases in the diblock copolymer are completely incompatible, leading to sharp phase separation. In the multiblock copolymer, the two phases are partly compatible without an obvious phase boundary. The successful syntheses of styrene/isoprene diblock and multiblock copolymers with high‐isoprene contents provide a novel method to synthesize polystyrene rubbers and styrene–diene–styrene thermoplastic elastomers. Traditionally, these products were mainly synthesized by solution polymerization. The present work in this article provides the possibility to synthesize them with very little or no solvent using bulk polymerization. This method fits the environmentally friendly trend to use low amounts of carbon while allowing commercial profitability. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39429.

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

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 (300h) under high loads of ethanol and bioethanol (0.036gEtOHmin−1, H2O:CH3CH2OH=4:1 molar). Moreover, they generate a low amount of carbon (0.0067gCgcatalyst−1h−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, <0.1wt.% Co0, suggesting that oxidized cobalt is an active species in ESR.

Enhanced electrochemical performance of

5–10nm thin rod shaped LiMnPO4 nanoparticles are synthesized by an improved thermal decomposition method. The synthesis parameters such as the concentration of surfactants, reaction temperature and time, as well as the presence of a solvent play a critical role in the formation of spherical, thin or thick nanorods, and needle-shaped particles of LiMnPO4. A washing procedure to efficiently eliminate the surfactants attached to the surface of LiMnPO4 nanoparticles is presented, avoiding thermal treatment at high temperatures. A nanocomposite LiMnPO4 electrode provides a discharge capacity of 165mAh/g at 1/40C and 66mAh/g at 1C with only 10wt% of total carbon additive. The characteristics of as-synthesized and low amount of carbon coated LiMnPO4 are described as well as their electrochemical properties.

Diversity of rock varnish bacterial communities from Black Canyon, New Mexico

Scientists vigorously debate the degree to which rock varnish is formed through the actions of microorganisms. To investigate this enigma, we utilized a three‐pronged approach that combined (1) culture‐independent molecular methods to characterize bacterial communities associated with varnish that coats the rhyolitic volcanic rocks of Black Canyon, New Mexico, and rocks with no visible varnish; (2) culturing of varnish in media supplemented with reduced forms of manganese and/or iron and no or low amounts of carbon to isolate bacteria capable of precipitating iron and/or manganese oxides; and (3) scanning electron microscopy (SEM) of varnish and nearby rock that lacks macroscopically visible varnish. Our culture‐independent studies revealed significant differences between varnish and nonvarnish communities. Chloroflexi and Ktedobacteria dominated one varnish site, while the other varnish site was dominated by Cyanobacteria. The nonvarnish sites were dominated by Actinobacteria and, to a lesser extent, Cyanobacteria and were the only samples to contain Deinococcus‐Thermus sequences. Approximately 65% of varnish cultures produced visible manganese precipitates. Most culture isolates were not closely related to known manganese oxidizers, with the exception of Bacillus spp. SEM revealed microbial morphologies and two types of varnish morphologies: (1) relatively smooth layers and (2) patches of botryoidal pinnacles, which were often associated with increased manganese concentrations. “Bare” rock showed evidence of incipient varnish. These results have important implications for the detection of life on extraterrestrial planets such as Mars, where putative varnish coatings have been observed, and represent some of the first culture‐independent characterizations of varnish communities.

Whole-cell fungal transformation of precursors into dyes

BackgroundChemical methods of producing dyes involve extreme temperatures and unsafe toxic compounds. Application of oxidizing enzymes obtained from fungal species, for example laccase, is an alternative to chemical synthesis of dyes. Laccase can be replaced by fungal biomass acting as a whole-cell biocatalyst with properties comparable to the isolated form of the enzyme. The application of the whole-cell system simplifies the transformation process and reduces the time required for its completion. In the present work, four fungal strains with a well-known ability to produce laccase were tested for oxidation of 17 phenolic and non-phenolic precursors into stable and non-toxic dyes.ResultsAn agar-plate screening test of the organic precursors was carried out using four fungal strains: Trametes versicolor, Fomes fomentarius, Abortiporus biennis, and Cerrena unicolor. Out of 17 precursors, nine were transformed into coloured substances in the presence of actively growing fungal mycelium. The immobilized fungal biomass catalyzed the transformation of 1 mM benzene and naphthalene derivatives in liquid cultures yielding stable and non-toxic products with good dyeing properties. The type of fungal strain had a large influence on the absorbance of the coloured products obtained after 48-hour transformation of the selected precursors, and the most effective was Fomes fomentarius (FF25). Whole-cell transformation of AHBS (3-amino-4-hydroxybenzenesulfonic acid) into a phenoxazinone dye was carried out in four different systems: in aqueous media comprising low amounts of carbon and nitrogen source, in buffer, and in distilled water.ConclusionsThis study demonstrated the ability of four fungal strains belonging to the ecological type of white rot fungi to transform precursors into dyes. This paper highlights the potential of fungal biomass for replacing isolated enzymes as a cheaper industrial-grade biocatalyst for the synthesis of dyes and other commercially important products. The use of immobilized fungal biomass limits free migration of cells and facilitates their reuse in a continuous system for precursor transformation.

Unsupported Ni/Mo(W)S2 Catalysts from Hexamethylenediammonium Thiometallates Precursors: In Situ Activation During the HDS of DBT

Unsupported Ni/MoS2 and Ni/WS2 HDS cata- lysts were prepared by in situ activation of hexamethyl- enediammonium thiometallates promoted with Ni. The method involved an aqueous solution reaction of ammo- nium thiomolybdate (ATM) or ammonium thiotungstate (ATT) with Ni(NO3)2� 6H2O and hexamethylenediamine. Ni-promoted precursors were then in situ activated during the hydrodesulfurization (HDS) of dibenzothiophene (DBT) producing Ni/MoS2 and Ni/WS2 catalysts. Solids were analyzed after the in situ activation by scanning electron microscopy, transmission electron microscopy, X- ray diffraction, and for textural properties by using the BET and BJH methods. Catalysts with relatively high surface area and type IV N2 adsorption-desorption isotherms were obtained. The use of the hexamethylene- diammonium precursor led to a significant nickel promo- tion of MoS2 and WS2 catalysts. For Ni/MoS2, the use of this carbon-containing precursor was found to be more beneficial for the final HDS catalytic activity than using the classical ammonium tetrathiomolybdate (ATM) without carbon. For Ni/WS2, compared to tetraalkylammonium thiosalts, the lower amount of carbon in excess formed during the decomposition of the hexamethylenediammo- nium precursor coupled with a lower crystallization rate of WS2 favors a correct nickel accommodation on the WS2 edges.

Utilization of High Specific Surface Area CuO−CeO2 Catalysts for High Temperature Processes of Hydrogen Production: Steam Re-forming of Ethanol and Methane Dry Re-forming

CuO-CeO(2) mixed oxide catalysts with 10, 15, and 20 mol % CuO content were prepared by the hard template method using KIT-6 silica as a template. The applied synthesis method yields solids with BET surface area in excess of 147 m(2)/g, highly porous nanocrystalline CeO(2) morphology and dispersion of CuO phase between 28 and 40%, corresponding to CuO particle size between 1.3 and 1.9 nm. Increasing the CuO content caused a decrease in dispersion of this phase and a further decrease of surface acid site abundance, determined by NH(3) chemisorption/TPD method, but improved the reducibility extent of CeO(2) (14.5, 16.1 and 24.5% for CuCe10, CuCe15, and CuCe20 catalyst, respectively) and oxygen mobility of prepared powders. It was discovered during ethanol steam re-forming experiments that increasing CuO content is favorable in terms of ethanol conversion but also causes quicker catalyst deactivation, primarily as a result of sintering and loss of CuO dispersion. Reaction temperatures in excess of 550 degrees C strongly promoted ethanol dehydratation reaction, leading to a rise in methane production and extensive coking of the catalyst surface. Coking was slower in the case of CuO-CeO(2) catalysts with a higher CuO content as a result of lower acid site abundance and more pronounced oxygen mobility. Temperatures in excess of 450 degrees C are required for any noticeable CO(2) and CH(4) conversion in methane dry re-forming reaction over CuO-CeO(2) materials. The examined materials displayed steady performance during stability tests at a reaction temperature of 650 degrees C, with catalysts containing 15 and 20 mol % CuO exhibiting the highest activity. Additionally, very low amounts of carbon were deposited on spent catalyst samples.

Carbon nanotube–TiO2 hybridfilms for detecting traces of O2

Hybrid titania films have been prepared using an adapted sol–gel method for obtainingwell-dispersed hydrogen plasma-treated multiwall carbon nanotubes in either puretitania or Nb-doped titania. The drop-coating method has been used to fabricateresistive oxygen sensors based on titania or on titania and carbon nanotube hybrids.Morphology and composition studies have revealed that the dispersion of low amounts ofcarbon nanotubes within the titania matrix does not significantly alter its crystallizationbehaviour. The gas sensitivity studies performed on the different samples have shown that thehybrid layers based on titania and carbon nanotubes possess an unprecedented responsivenesstowards oxygen (i.e. more than four times higher than that shown by optimized Nb-dopedTiO2 films). Furthermore, hybrid sensors containing carbon nanotubes respond atsignificantly lower operating temperatures than their non-hybrid counterparts.These new hybrid sensors show a strong potential for monitoring traces of oxygen(i.e. ≤10 ppm)in a flow of CO2, which is of interest for the beverage industry.

Effect of specific surface area on oxygen storage capacity (OSC) and methane steam reforming reactivity of CeO2

It was found from the work that the specific surface area of ceria presents an important role on the oxygen storage capacity (OSC), the reactivity toward methane steam reforming, and the resistance toward carbon formation of this material. After calcination at 900°C, ceria prepared by surfactant-assisted method (SF) was observed from the present work to have significantly higher surface area than those prepared by templating (TP) and precipitation (PP) methods; this material showed strong OSC with good reforming reactivity in terms of thermal stability and resistance toward carbon formation compared to others. In detail, the degree of OSC was measured by the number of hydrogen uptake from the temperature programmed reduction (TPR). It was found that the value of hydrogen uptake from the TPR-1 of ceria prepared by SF was 2084 mmol g−1, whereas those of ceria prepared by TP and PP were 1724 and 781 mmol g−1, respectively. In addition, it was also proven in the present work that the OSC of these materials are reversible, according to the temperature programmed oxidation (TPO) and the second time temperature programmed reduction (TPR-2) results. According to the reactivity toward methane steam reforming, after purging in 3 kPa methane and 9 kPa steam at 900°C for 8 h, the methane conversion at steady state of ceria prepared by SF was approximately 38% with very low amount of carbon formed on the surface (0.16 mmol g−1), whereas those of ceria prepared by TP and PP were 22% (with the amount of carbon formation of 0.30 mmol g−1) and 13% (with the amount of carbon formation of 0.33 mmol g−1), respectively.

Carbon and nitrogen limitation to microbial respiration and biomass in an acidic solfatara field

The solfatara field is a unique ecosystem characterized by harsh conditions such as acidic soils. We examined the respiration rate and phospholipid fatty acid (PLFA) content of solfatara soils and their responses to carbon and nitrogen addition to determine whether soil microbial respiration and biomass in a solfatara field are limited by substrate availability. Soil samples were collected from locations along a transect across a solfatara field in Oita Prefecture, Japan. The soil in the central part of the solfatara field was highly acidic (pH 2.4) and contained low amounts of carbon and nitrogen. Low basal respiration rates were detected in these soil samples. Measurements of substrate-induced respiration (SIR) and PLFA contents suggested that it was partly attributable to low microbial biomass. Addition of a carbon source (glucose) to the solfatara soil engendered a marked increase in the microbial respiration rate, whereas the nitrogen source (ammonium nitrate) application had no marked effect. Addition of both carbon and nitrogen caused a nearly eightfold increase in the microbial respiration rate and a threefold increase in the total PLFA contents. These results suggest that some acidophilic and/or acid-tolerant microorganisms exist in solfatara soil, but that their respiration and biomass are limited by low substrate availability.