The purpose of this work is a construction of the basic manner of a human brain-tumor therapy by using an immunovesicle (antibody-immobilized vesicle) in DDS. The ERM5-1 cell was applied as a model cell of human brain-tumor, which was a mouse cell made by transgenic technology. The human brain-tumor cell was found to have a specific antigen of EGFR (Epidermal Growth Factor Receptor). The ERM5-1 cell has the antigen EGFR and the cell can be applied as a model cell of human brain-tumor cell. Anti-EGFR antibody was immobilized on the surface of the vesicle as follows. The human anti-EGFR antibody (IgG) was preliminary immobilized to a protein A, which has a binding site to Fc fragment of IgG. The EGFR-protein A complex was immobilized to a vesicle by means of the two-step emulsification. Thus, the human anti-EGFR antibody was successfully immobilized orientated to the outer direction of the vesicle surface. It was fluorometrically confirmed that the specific antigen-antibody affinity between the antibody of the vesicle and EGFR on the ERM5-1 cell well functioned in vitro experiments. In the vesicle, Taxsotere of anti-tumor drug was entrapped for increasing the anti-tumor effect of the vesicle. It was also confirmed from in vitro experiments that anti-tumor effect of the immunovesicle to the ERM5-1 cell was superior to a normal vesicle (non-immunovesicle). Moreover, the in vivo experiments of anti-tumor effect to the ERM5-1 cell were carried out administrating the Taxotere-entrapped immunovesicle into nude mice to which ERM5-1 cell was implanted. Superior anti-tumor effect to the ERM5-1 cell in the mice could be observed to that of the normal vesicle.

View full abstract

We have constructed a bacterial library consisting of toluene-degrading bacteria isolated from soil activated sludge, and TCE waste. The library had been subjected to large subunits of oxygenases responsible for the first oxidation of toluene. Chromosomal DNA extracts from three strains, A1071, B6122 and IB5, which had been suggested to have toluene dioxygenase (TDO) from the result of colony hybridization, showed positive signals with todC1, a large subunit of TDO of Pseudomonas putida F1, in dot hybridization analysis, and thereby, these strains were selected for the analyses of degradation kinetics of toluene and trichloroethylene (TCE). Results of degradation experiments using resting cells revealed the variety in TCE degradation ability among these strains; A1071 demonstrated degradation kinetics similar to the strain F1 while B6122 could not degrade TCE at all. The interaction between toluene and TCE was suggested to be competitive inhibition. Kinetic parameters on the competitive inhibition between toluene and TCE degradation were determined and compared among these strains.

View full abstract

Nonylphenols (NPs) have been proved to be accumulated in sediments in aquatic environments as the degradation products of non-ionic surfactants and show endocrine disruptive activity to living organisms. To elucidate the biodegradation mechanisms for NPs, we isolated five NP-degrading bacteria from activated sludge using a commercial mixture of NP isomers (Kanto Kagaku, Tokyo) as a sole carbon source. Analysis of the partial 16S rDNA sequences of the isolates revealed that one strain is a Sphingomonas sp. and other four strains are Pseudomonas spp. On a minimal medium plate containing the NP mixture, the Sphingomonas strain, named strain NP5, formed a clear zone (halo), indicating that it degraded most of the NP isomers dispersed in the plate. In order to confirm the biodegradability for the NP isomers, a NP degradation test was carried out using the cell suspension of strain NP5. GC/MS analysis showed that at least 14 NP isomers contained in the mixture disappeared completely after 7 d- incubation and some alcohols with nine carbons were detected as the metabolites. This result indicates that strain NP5 has a broad degradation range for NP isomers and release of the alkyl-chain of NP might occur during the degradation.

View full abstract

Many kinds of volatile organic compounds (VOCs) have been treated in the biofilters based on the degradation of VOCs by the biolayer on the surface of packing media. Such a bed is easily subjected to compaction or clogging due to separation of biolayer and hence to an increase in pressure drop of gas flow. To overcome the drawbacks, our previous study has proposed the packed column containing the immobilized activated sludge gel beads together with the hollow plastic balls to avoid the bed compaction. In this study, a single VOC such as benzene, toluene or ethylbenzene is treated in the biofilter. The gel beads are the same as in our previous works on the acetaldehyde and propionaldehyde removal. The acclimation of the gel beads to the VOC is accomplished in the packed column during the earlier stage of the removal operation. The gel beads are durable, stable and reproducible for removing the VOCs for several months to one year. The rate of each VOC degradation by the gel beads is represented by the Michaelis-Menten type rate expression as in the case of the single aldehyde above. The Henry's law constant of the present VOC depends on its concentration or partial pressure in the dilute range as opposed to that of the aldehyde. The design equation similar to that in the aldehyde removal predicts the observed removal using the degradation kinetic parameters and the Henry's law constant modified considering the above concentration dependency as well as a higher affinity of the VOC to gel phase than to water.

View full abstract

Alkalophilic nylon oligomer degrading strains were isolated from wastewater of nylon factory, and from activated sludge of a sewage disposal plant. One isolate, KY5R, showed good growth on LB-NOM10 plate (LB plate containing nylon oligomer mixture, pH10), and produced a clear zone on this plate, while previously isolated Flavobacterium sp. KI72 showed no growth and no halo formation on the LB-NOM10 plate. This result suggests that the insoluble nylon oligomers are degraded at pH10 by the strain KY5R. Nucleotide sequence of the 16S rRNA of the KY5R had 98% homology to that of Agromyces mediolanus, and 2,4-diaminobutyric acid was found as a component of cell wall. From these results, we have concluded that the strain KY5R is classified as Agromyces sp. Enzyme assay using the cell extracts of KY5R suggested that strain KY5R has the exo-type Ahx-oligomer hydrolase (EII) and endo-type Ahx-oligomer hydrolase (EIII) activities, but the no Ahx-cyclic dimer hydrolase (EI) activity. Studies using the antiserum against the purified EII of KI72 showed that the EII enzyme from Agromyces sp. KY5R (A-EII) is immunologically identical to that from Flavobacterium sp. KI72 (F-EII). In addition, DNA hybridization study using the DNA probe for the EIII gene from KI72 (F-nylC) suggested that the EIII enzyme from KY5R (A-EIII) is similar to the enzyme from KI72 (F-EIII).

View full abstract

Various anaerobes were cultivated in media containing glucose. When 100 ml of thioglycollate medium containing 2.0% (w/v) glucose was used, Clostridium butyricum ATCC 859, NBRC 3315, and NBRC 13949 evolved 227-243 ml of biogas containing about 180 ml of hydrogen in one day. C. butyricum NBRC 3315 and Enterobacter aerogenes NBRC 13534 produced hydrogen in the presence of glucose or pyruvic acid. When a medium containing 0.5% (w/v) yeast extract and 2.0% (w/v) glucose, E. aerogenes NBRC 13534 evolved more biogas and hydrogen than C. butyricum NBRC 3315 in the absence of reducing agent. When E. aerogenes NBRC 13534 was cultivated under pH control at 5.0, the doubling time of the cell was longest, maximum optical density of the culture was lowest, and the rate of glucose consumption was slowest in all cultivation under pH control at 5-7. However, the rate of hydrogen accumulation was fastest and final volume of accumulated hydrogen was highest.

View full abstract

Recently, excess sludge from wastewater treatment plant has been one of the serious problems. They are disposed by landfill, incineration, bio-gas production and so on. However, these conventional methods contain drawbacks such as short of landfill, dioxin emissions or inefficient production. A countermeasure against the problems is to minimize the sludge production in the wastewater treatment process. In this study, a biochemical sludge-reduction system was proposed. The microbes were experienced in the aerobic and anaerobic conditions alternately. By the change of microbial growth condition, it is thought that obligate aerobic and anaerobic microbes are to be dead, resulting in their solubilization under alternated anaerobic and aerobic conditions, respectively. The concentrations of organic carbonaceous and nitrogenous substrates and mixed liquor suspended solid (MLSS) were more greatly reduced under the alternate aerobic-anaerobic conditions than under the continuous aerobic or anaerobic conditions. The MLSS mainly consisted of protein (more than 50%w/w) and the amount of protein in the suspension fluctuated during the cultivation without any additions of substrates. These results indicate that the microbial solubilization and utilization of protein lysate seem to take place in this system. So far, however, the effects of growth condition on the microbial viabilities in the solubilization have not been investigated. To clarify them, carboxyfluorescein diacetate (CFDA) that was substrate of intracellular esterase was used as an indicator of microbial viability. As a further experiment, the relationships between sludge solubilization, bacterial viabilities and substrate removal are to be investigated in the continuous wastewater treatment process.

View full abstract

Monascus purpureus CCRC31499 produced a protease when it was grown in a medium containing shrimp and crab shell powder (SCSP) of marine wastes. An extracellular protease was purified from the culture supernatant to homology. The protease had a molecular weight of 40,000 and a pI of 7.9. The optimal pH, optimum temperature, and pH stability of the protease were pH 9, 50°C, and pH 7-12, respectively. In addition to protease activity, CCRC 31499 also exhibited activity of enhancing vegetable growth in culture supernatant. This is also the first report of isolation of a protease from Monascus species.

View full abstract

Polyhydroxyalkanoate (PHA) and triacylgrycerol (TAG) production by IAR1, a novel toluene-degrading bacterium isolated from soil, was studied. When IAR1 was cultivated on acetate as the sole carbon source, PHA and TAG content attained 12% and 24% of cell dry weight (CDW), respectively. After acetate was exhausted, PHA content decreased and TAG content increased slightly. Thus, IAR1 seemed to synthesize TAG from PHA under carbon-limited condition. When IAR1 was cultivated on toluene as the sole carbon source, PHA content reached 9.3% of CDW and became constant even though toluene was supplied. On the other hand, TAG content increased throughout cultivation and reached 24% of CDW. PHA accumulated by IAR1 was a copolymer of 3-hydroxybutylate (3HB) and 3-hydroxyvalerate (3HV) (PHBV). TAG synthesis by IAR1 was inhibited by adding cerulenin and PHBV content attained 30 % of CDW. Cerulenin addition also affected PHBV composition.

View full abstract

An antifungal compound-producing bacterium was isolated and identified as a strain of Pseudomonas fluorescens K-188. P. fluorescens K-188 grown aerobically in a shrimp and crab shell powder medium produced antifungal compounds that in tests effectively inhibited several fungal phytopathogens including Fusarium solani, Trichoderma harzianum, and Pythium ultimum. Maximum inhibitory activity was obtained when P. fluorescens K-188 was grown aerobically at 37°C for 4 days in a medium consisting 1% shrimp and crab shell powder, 0.1% K₂HPO₄ and 0.05% MgSO₄·7H₂O at a pH of 7. The antifungal compounds obtained from ethanol precipitation of the culture supernatant of P. fluorescens K-188 retained more than 70% of its inhibitory activities to F. oxysporum even after being treated at 100°C for 10 min. Spore germination and germ spore elongation of F. oxysporum were inhibited by the antifungal compounds. In addition to antifungal activity. These characteristics were unique in comparison with those of other already-known Pseudomonas fluorescens.

View full abstract

The biodegradation of oil in wastewater by bioremediation method of combining Yarrowia lipolytica (Bioaugmentation) with some water-soluble vitamins (Biostimulation) was investigated. It was found that as olive oil was used only as a substrate the strain is able to grow and the degradation rate of the oil in the model wastewater is faster than that by using general activated sludge. Moreover, when the strain is added into general activated sludge, the degradation rate of oil is fast compared with the case of the strain only. As a result, it turned out that the bioaugmentation to add fat-degradating yeast into wastewater was effective. On the other hand, it is known that several kinds of vitamins are indispensable to degrade fat but those vitamins are very little in the wastewater. Then, we examined the additive effect of the vitamin to the fat degradation. When several vitamins (thiamin, pantothenic acid, biotin etc.) were added into the model wastewater, the degradation rate of oil is faster than that without vitamins. As results, it was turned out that β-oxidation and/or TCA cycle in microorganism existing in activated sludge are activated by the biostimulation method adding a small amount of vitamins into wastewater. Now, we are examining the efficient degradation of the oil into wastewater by a new bioremediation method that combines bioaugmentation with biostimulation.

View full abstract

To stabilize the lipase activity of Rhizopus oryzae cells as whole-cell biocatalysts, the effect of cell-membrane fatty acid composition on biodiesel-fuel production was investigated. The fatty acid composition of the cell membrane was easily controllable by addition of various fatty acids to the culture medium. Oleic or linoleic acid-enriched cells showed higher initial methanolysis activity than saturated fatty acid-enriched cells, among which palmitic acid-enriched cells exhibited significantly greater enzymatic stability than unsaturated fatty acid-enriched cells. It was assumed that fatty acids significantly affect the permeability and rigidity of the cell membrane, and that higher permeability and rigidity lead to increases in methanolysis activity and enzymatic stability, respectively. When the optimal fatty acid ratio of 0.67, indicated by R_f [= oleic acid/ (oleic acid + palmitic acid)], was adopted for repeated methanolysis reactions, both methanolysis activity and enzymatic stability were maintained at significantly elevated levels, with methyl ester content of around 55% even in the tenth batch cycles.

View full abstract

Batch fermentation by Streptococcus bovis was carried out in order to investigate the characteristics of L-lactic acid fermentation from raw cassava as a substrate in tofu liquid waste (TLW) as a fermentation medium. The use of raw cassava-TLW system is intended to produce low cost L-lactic acid for the production of polylactic acid, a polymer used as biodegradable plastic, since raw cassava is an inexpensive raw material and TLW is cost-free. The raw cassava was compared to glucose and to tapioca and the TLW was compared to the standard basal medium, trypro-soya broth (TSB) at the 1% w/w sugar concentration. In order to maintain pH not to be lower than 5.0, 2 mol equivalent calcium carbonate (CaCO₃) were added at initial fermentation. The results revealed that the maximum of L-lactic acid concentrations (C_La) obtained with addition CaCO₃ in TSB and in TLW were 2.2 times and 1.6 times, respectively higher than that in TSB without CaCO₃ addition. The maximum of L-lactic acid concentrations obtained with TLW were about 75 ± 5% of those obtained with TSB. The L-lactic acid productivities (P_La) with TLW were 1/3∼1/2 of those in TSB. Furthermore, experiments were also carried out in TLW at various sugar concentrations: 5, 10, 15, 20% w/w to investigate its effect on the L-lactic acid production. The maximum L-lactic acid concentrations was found to be (in decreasing order): raw cassava (6.66% w/w) > tapioca (5.36% w/w) > glucose (3.41% w/w) were reached at 10% w/w of sugar concentration.

View full abstract

Conversion of food wastes into L(+)-lactic acid by simultaneous saccharification and fermentation (SSF) was investigated. The process involves saccahrification of food wastes by a commercial amyloytic enzyme preparation (a mixture of amyloglucosidase, -amylase and protease) and fermentation by a lactic acid bacterium. Several microorganisms, such as a L. delbreukii, L. helveticus, L. salivarius, L. casei and L. lactis, were tested for their L(+)-lactic acid productivity. Among the microorganisms tested, L. casei produced the most pure L(+)-lactic acid(over 91% of total lactic acid produced) with a total lactic acid yield of 78%. L. delbreukii produced the highest total lactic acid yield(99%) with about 60% of L(+)-lacitic acid purity. In the SSF with no nitrogen supplements, 27 g/L(yield 27%) of L(+)-lactic acid was produced from 100 g/L food waste.

View full abstract

Two extracellular proteases (FI and FII) were purified from the culture supernatant of Bacillus cereus YQ308. The molecular weights of FI and FII were 29,000 and 50,000, respectively, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The optimum pH and optimum temperature of FI were pH 7, 50°C; those of FII were pH8, 50°C. Antifungal activity of FI protease was found when using assay based upon inhibition of spores germination and hyphal extension of the fungal Pythium ultimum. This is the first report of the isolation of an antifungal protease from Bacillus species.

View full abstract

To produce L-lactic acid efficiently by batch fermentation using Rhizopus oryzae in airlift fermentor, 5 kg/m³ of activated carbon, which was used for post treatment of fermentation broth, was added to fermentation medium. Fermentation broth was decolorized simultaneously with fermentation by activated carbon to obtain clearer fermentation broth. By adding activated carbon from lignite, the cells formed smaller pellets and productivity was improved from 0.824 kg/m³ to 1.10 kg/m³. Further, productivity was improved up to 1.37 kg/m³ by increasing the addition amount of activated carbon to 20 kg/m³ though it was ineffective when adding more. From these results, it was suggested that activated carbon from lignite is effective in enhancing the cell activity for R. oryzae like biological activated carbon.

View full abstract

The recent developments in high-throughput technologies such as cDNA and oligo nucleotide microarray have enabled us to simultaneously analyze thousands of gene expressions. Gene clustering is one of the most important analyses for DNA microarray data. Many of the clustering methods require the whole expression time course profiles, however, most predominant information is time period of onset of each gene. In the gene network or circuit, gene switches for expression are turned on or off according to their demand. It should be effective to cluster the gene expression data based on expression profile considering both onset and cessation of each gene, however, there are few reports on such clustering methods. In this study, we estimated timing of gene expression onset and its cessation by simultaneous differential equation model. Since many of the values of parameters on mRNA transcription rate, mRNA decay rate, onset and cessation time of gene and cessation are all still unknown, we optimize these parameter-values for experimental data. Then we compare clustering result using estimated parameter-values and all expression time course profiles. In the next, we examined the influence of noise upon clustering result and evaluated the clustering result by Wilcoxon signed rank test. Clustering result shows that estimated parameter-values realized the almost same result as that of whole time course data. Furthermore, clustering method using estimated parameter-values was more noise tolerance than that using whole time course data. (p=0.005) These results suggest that, the clustering method using the estimated onset time and cessation is useful analysis method to cluster the experimental data.

View full abstract

Highly selective base-pairing rules in DNA can be utilized as a tool for forming nano architecture. Holliday Junction, where two different DNA double strands intersect and replace each complement strand, is an important artificial motif for forming two-dimensional "plane" conformation of DNA. In this study, we controlled the growth of the DNA "plane" conformation by changing temperature. A set of DNA single chains were cooled from 90°C to 4°C for10 minutes, to form the DNA "plane" conformation. The influence of the cooling procedure on the DNA conformation was observed by AFM (atomic force microscope), and it is found that the DNA "plane" conformation is strongly dependent on the cooling process. Further, we assembled gold nano particle using the DNA conformation, and observed the assembly of gold nano particle on the DNA conformation by AFM and TEM (transmission electron microscopy).

View full abstract

The effect of Nafion content and loading method in the catalyst layer of cathode for Direct Methanol Fuel Cell (DMFC) was investigated. The impedance of full cell and cathode are determined by ac impedance spectroscopy. The Nafion content improved the current density at cell voltage of 0.4 V up to 258 mA/cm² at a content of 1.0 mg/cm² in comparison with 128 mA/cm² at a content of 0.5 mg/cm². The increase in Nafion content was decreased the diameter of arc at the low frequency. The optimum value of Nafion content was 1.0mg/cm². For the spray method electrode (SME), the cell performance and cathode performance using a dynamic hydrogen electrode (DHE) as a reference electrode was improved in comparison with those of the PME electrode by decreasing cathode potential. From the cathode ac impedance measurements, the diffusion resistance of the SME electrode was decreased compared with that of the PME electrode. The higher cell performance was mostly dependent on the diffusion resistance. The SME with porous structure and thin catalyst layer were showed by SEM and BET adsorption measurement. In addition, the structural model of cathode has been developed and experimentally verified with which fundamental calculations of the DMFC were carried out. The model provides information concerning on the influence of the operating and structural parameters.

View full abstract

To know the movement of water in Polymer Electrolyte Fuel Cell (PEFC) is important for deciding the optimum shape of the cell and the optimum operating condition. And it is well known that PEFC shows the best performance under moderate relative humidity condition. However, the experimental measurement is difficult because of the flow through the complex geometry of diffusion layer. Therefore, in order to know the movement of water in PEFC, microscopic analysis was performed by lattice gas automata (LGA) method. The influence of gas diffusion prevention by water was investigated. In addition, the relationship between reaction time and reaction quantity for PEFC with dry membrane was investigated. A reaction quantity, which had increased due to membrane getting more wet by generation water, decreased due to gas diffusion prevention by water, and after a while, it settled into steady state. According to the channel configuration, a distribution of water was observed in the diffusion layer and a distribution of oxygen and hydrogen reaction quantity was affected. Moreover, since the influence of gas diffusion prevention by water in the cathode side was more extremely than that in anode side, it was shown that concentration overpotential of cathode side affects a cell performance greatly.

View full abstract

This paper proposes novel types of electrodes available for proton exchange membrane fuel cells (PEMCs), in which three-dimensional channels of carbon fibers (CFs), carbon-nanotubes (CNTs) and a polymer-electrolyte (PE) are connected with one another. A particular feature of fabricating a type of electrode is physical coating of CFs with CNTs. A suspension of CVD-synthesized CNTs was sprayed onto/into a gas-diffusion electrode (carbon paper consisting of three-dimensional network of CFs) heated at a temperature well above the boiling point of the matrix solvent. Not only CFs at the top surface of but also those inside the carbon paper were coated uniformly with dense and extremely thin (< 1 µm) layers of CNTs. Then, PE channels were formed within the CNT layers by means of a dip coating technique. CFs could also be chemically coated with CNTs by a novel CVD method applying forced flow of H₂ gas containing carbon and catalyst sources through the carbon paper. CNTs with lengths up to several micron meters were formed with a population density of 10⁹ cm^-2 or even higher. Employing CNTs not particulate but fibrous in shape is expected to maximize the efficiency of contact among Pt catalyst, PE and the gas phase inside the electrode, eliminating negative factors limiting performance of current PEFCs such as low utilization efficiency of Pt catalysts and suppressed diffusion of reactant/product gases through the catalyst layer.

View full abstract

A numerical simulation study of fluid flow, heat and mass transfer in a proton exchange membrane (PEM) fuel cell was performed. The three-dimensional continuity, Navier-Stokes, energy and diffusion equations were discretized by the finite volume technique on the staggered mesh and solved by the SIMPLE algorism. The electrochemical reaction at the catalyst layer was considered in the calculation. Effects of flow rate configuration and arrangement of flow channels on current density distribution were discussed to optimize the fuel cell design with high-energy efficiency and high power density performance. Numerical simulation results show that the insufficient inlet gas flow rate induces low performance of fuel cell, especially, in the serpentine flow structure.

View full abstract

A numerical study on the water management in a proton exchange membrane fuel cell (PEMFC) was performed. Both the one-dimensional numerical analysis in membrane-electrode assembly (MEA) and the three-dimensional numerical analysis in cathode side flow channel were carried out for discussion of water transport. In order to find the operating condition without dehydration of the water and/or flooding of the electrodes induced by an imbalance between production and removal rates of water, the effects of the operating pressure, and the thickness of membrane and the gas diffusion layer (GDL) on the cell performance were investigated by using numerical analysis of the MEA. The calculation results show that water behavior in the membrane depends on the pressure difference between the anode and cathode sides, and thickness of membrane as well as current density. The calculation results of three-dimensional analysis in separator show the gas flow distribution affects vapor concentration and current density distribution.

View full abstract

Nafion-112 is a membrane applied to PEM(Proton Exchange Membrane) fuel cells. In the recent research for PEM fuel cells, it has been found that their performance is decreased in the presence of ammonia contained in the feed gas of H². In the pores of Nafion-112, there are side chains terminating in sulfonic acid dissociative groups. In the case where such dissociative groups exist on the solid surface contacting with a solution, electric double layers (EDL) may be formed in the pores of membrane, and then an electro-osmotic flow is generated by applying an electric field. In this work, we have confirmed the generation of an electro-osmotic flow across Nafion-112 membrane in the presence of ammonia. In our experiments, several NH₃ solutions and NaOH solutions at different concentrations were prepared in order to measure the electro-osmotic flow rate through the membrane. As the result, the electro-osmotic flow rate was increased with the increasing of the solution pH without showing any appreciable dependency on the cation substance, NH₄⁺ or Na⁺ contained in the solution. In PEM fuel cells, protons migrate from anode to cathode through the pores of the membrane to generate electric power. We conclude that the decrease in the performance of PEM fuel cells might be caused by the prevention of proton migration due to electro-osmotic flow.

View full abstract

One of the major issues in the direct methanol fuel cells (DMFC) is water management in the cathode. Then, we evaluated the effluent water amount of the cathode by changing the air flow velocity and the influence of water flooding on the cell performance. From characterization of cathode flooding by I-V measurement, AC impedance measurement and effluent water amount measurement, it was confirmed that the amount of effluent water was dependent on air flow velocity, and even low flow rate could control the flooding by a suitable design of the flow channel.

View full abstract

The crosslinked sulfonated polyimides with different sulfonation degree by a sulfonated diamine were prepared by polycondensation reaction in m-cresol using various crosslinkers with various chain length. The preparation of crosslinked sulfonated polyimides was characterized and confirmed by NMR and FT-IR. Each sulfonated polyimide membranes were investigated by ion exchange capacity, methanol permeability, water vapor sorption, water uptake, and proton conductivity to observe the effect of crosslinkers having different chain length.

View full abstract

The reaction of carbon dioxide catalytic reforming with methane is an attractive conversion technology because of the possibility of enhancing natural gas utilization with the sequestration of CO₂. However, this reaction is a highly energy consuming and coke forming process. These problems may be overcomed the electrocatalytic reforming of CO₂ with CH₄ in a solid oxide fuel cell (SOFC) membrane reactor system, which generates high electrical power and synthesis gases. The single cell included catalyst electrode (NiO-MgO, NiO-YSZ-MgO), counter electrode ((La, Sr) MnO₃) and Y₂O₃ stabilized ZrO₂ (YSZ) electrolyte was prepared by a tape casting method. The reaction rates of CO₂ and CH₄, and the electrochemical properties were investigated by an on-line GC and Impedance-analyzer under open- and closed- circuit conditions, respectively. It was found that reaction rates of CO₂ and CH₄ under the closed- circuit condition were more stable than those of the open-circuit. It was concluded that the stability of catalyst electrode was dependent on the reaction of oxygen ion transferred from the cathode with the surface carbon formed in the internal CO₂ reforming by CH₄ in SOFC system.

View full abstract

The surface modification was carried out to fabricate nano-scale Pt-Ru layer on the anode of direct methanol fuel cell using a sputter-deposition technique. The platinum and ruthenium was sputter-deposited on the surface of catalyst layer with different Pt-Ru compositions in 30-nm thicknesses. Electrochemical tests in a single DMFC were conducted at the typical temperature (80°C) under an ambient pressure and show improvements in the cell performances with the surface modification. The best composition and the suitable amounts of Pt-Ru bimetallic layer were investigated by analyzing the polarization curves and impedance measurements of cell. X-ray photoelectron spectroscopy (XPS) was carried out to determine the surface chemical composition of the Pt-Ru sputtered layer.

View full abstract

Fuel cell has high generation efficiency so that it may replace the conventional power systems. Especially it is expected that the fuel cell is applied to the power source of portable devices such as mobile computer and cellular phone due to its scalability. To promote its applicability, high productivity of hydrogen is required. Thus we started to develop a micro methanol-reformer for hydrogen production. In the methanol decomposition, addition of water is not necessary. A reactor made of Aluminum has 50 mm diameter and 1 mm thickness. The channel before coating catalyst has 500 µm in width, 500 µm in depth and 300 mm in length. Palladium catalyst is formed on the wall of anodized Aluminum channel by impregnating acetone solution of Palladium Chloride. At first, Methanol is fed with a pump, and next, it is evaporated at 80 degree C and reformed at 250, 270, 300, 320 and 350 degree C. The concentration of product is identified by TCD gaschromatographs. In this type of reactor, the optimum temperature for reforming is exist about 320 degree C, and the concentration of hydrogen is about 45% under the methanol feed rate of 1.0ml/h.

View full abstract

To develop a non-equilibrium reactor for Fuel Cell (FC), the steam reforming of ethanol in the presence of the CO₂ absorption ceramics was carried out at the atmospheric pressure between 450°C and 650°C using a plug flow reactor, and a commercially available reforming catalyst was used. The CO₂ absorption ceramics consisted of lithium silicate powder, which was granulated and coated with alumina coarse particles. Reaction products were analyzed by gas chromatography, and the effect of the CO₂ absorption ceramics for the hydrogen selectivity was estimated. It was concluded that the steam reforming ethanol in the presence of the CO₂ absorption ceramics has high potential for a non-equilibrium reactor. The hydrogen selectivity was enhanced in the presence of the CO₂ absorption ceramics. Especially at a temperature of 550°C, the hydrogen selectivity in the presence of the CO₂ absorption ceramics was 1.6 times as high as that in the absence of the CO₂ absorption ceramics. And the CO₂ absorption ceramics shows neither catalytic poison for steam reforming reaction nor degradation under steam reforming conditions.

View full abstract

The conversion of methane for H2 production over a CoMo catalyst with several Co loadings carbided at various temperatures using two carbiding methods of different heating rates was studied. The effects of the CO₂ addition and H₂ pretreatment on the catalyst lifetime were determined. The low-temperature carbiding increased the surface area of the catalysts and produced CoMo oxycarbides decorated with pyrolytic carbons, from which hydrogen and graphite carbons were produced during the CH₄ reaction. The high-temperature carbiding produced CoMo carbides. The CoMo oxycarbides had the structure of β-Mo₂C with Co metal.

View full abstract

Efficient hydrogen evolution from decalin by heating at moderate temperatures (200-300°C) was attempted in a continuous dehydrogenation reactor with use of "superheated-liquid-film type catalysis." The effect of decalin flow rates on the catalyst layer temperature, the decalin conversions and the hydrogen evolution rates was examined experimentally and following results were obtained. The catalyst layer temperature changed from the superheated state to the boiling point of decalin with increasing of the decalin flow rates. The decalin conversions in the superheated state were higher than that in the equilibrium state and decreased as the decalin flow rates increased. On the other hand, the hydrogen evolution rates had a maximum value under the experimental conditions of flow rates adopted. It was also found that the ratio of retention volume of decalin in the catalyst layer to whole amount of catalyst was an important index to represent the state of catalysis layer.

View full abstract

A new type of static solar concentrator is proposed to match the features of the town. The concentrator consists of vertical plate solar cells and white-transparent transformable bottom plate, which is operated with external power. The bottom is turned to be a diffuse reflection white surface when the cell generates electric power, and turned to be a light transmissible transparent surface when it is at rest. The light collection of this concentrator was analyzed by using the multiple internal total reflection model and the ray tracing simulation. For the same ratio of the area of the solar cells to that of the collector surface, the collection efficiency for the proposed concentrator is about half of that of the conventional concentrator for flat plate cell, and nearly equal to that of the concentrator for the embedded spherical silicon solar cells.

View full abstract

Highly efficient dye-sensitized solar cells become feasible using single crystalline anatase titania nanowires (TiNWs) and their network structures for semiconductor thin film instead of titania nanoparticles. We used laurylamine hydrocholoride(LAHC)/ tetraisopropylorthotitanate (TIPT) modified with acetylacetone (ACA) system. TIPT-ACA solution was mixed with 0.1 M LAHC aqueous solution at 313K, and the solution was stirred until the solution became transparent. Then, temperature was changed to 353K. After 96 h the solution became a white gel with a yellow liquid thin layer on the gel. Preparation of titania thin films was carried out as follows. We used gel samples before calcinations. Surfactant molecules in TiNWs can be removed by washing with alcohol. Standard Titania sample was prepared by mixing TiNWs with PEG(10%). Another samples were prepared by mixing TiNWs with both PEG(10%) and P-25(with various concentration). These samples were applied repetitivety to the conduction glass and distributed with a glass rod. Every time the sample was calcined at 723K for 30 min.
The photocurrent-voltage characteristics was measured using a potentiostat by irradiating with simulated solar light (bunko-keiki), i.e., AM1.5. IPCE (incident photon to conversion efficiency) was also measured. Titania particle P-25 was used as reference titania for comparison. We optimized the cell using various electrolyte. The conversion efficiency obtained by the six times repetitive coating resulted in over 8%. This data promise realization of highly efficiency dye-sensitized solar cells using TiNWs as semiconductor thin film through further improvement.

View full abstract

This study focused on polyalcohols as phase change material, which stores a large amount of latent heat at high temperature. D-Threitol, which is an isomer of meso-Erythritol, was studied to obtain its phase change characteristics by means of DSC analysis and a lab-scale heating and cooling apparatus. Usability of D-Threitol as phase change material was evaluated by comparison with other polyalocohols.
It was found that D-Threitol started to melt at around 90 degrees C with a relatively large latent heat of 225 kJ/kg. On the other hand, D-Threitol started solidification when the temperature was cooled between at 40 degrees C and 46 degrees C, indicated by a rapid rise to 89 degrees C in a lab-scale heating and cooling apparatus. It was then considered that D-Threitol was applicable as an environmental-friendly PCM for a hot water supply.

View full abstract

This study investigated a novel idea of combining a polyalcohol with an inorganic salt hydrate to prepare new PCMs suitable for domestic water heating. Specifically, the heat storage characteristics of a eutectic mixture of erythritol and MgCl₂ 6H₂O were evaluated. DSC analysis indicated that mixtures that contained less than 20wt% MgCl₂ 6H₂0 have melting points above 80°C and latent heat values greater than 120kJ/kg. Thermal cycling of erythritol-based PCMs in test tubes showed good stability in terms of nucleation temperature, melting point and latent heat of fusion after several heating-cooling cycles. The erythritol-based PCMs were found to undergo supercooling of about 50°C below the melting point, similar to erythritol. An evaluation of the specific heat, density and thermal conductivity of a mixture of erythritol and 10wt% MgCl₂ 6H₂O indicated that thermal properties of the mixture were potentially useful for domestic water heating. In a scale-up experiment, the solidification of a mixture of erythritol and 10wt% MgCl₂ 6H₂O was conducted using a visualization unit with a cooling vertical double-pipe. Analysis of the distribution of the salt hydrate component in the solid phase revealed the salt hydrate's possibility of accumulating at the bottom of the unit. This behavior was probably due to density differences between the mixtures' components. The effect of ultrasonic irradiation on the mixture's supercooling relaxation and component distribution was also investigated.

View full abstract

For effective utilization of thermal energy in sustainable development of society, chemical heat pump (CHP) systems are considered to be an effective system in the near future. The CHP can store thermal energy in the form of chemical energy, and release it at various temperature levels. Especially, we studied a calcium oxide/water CHP and a calcium sulfate/water CHP. Each of these CHPs has its merits and demerits, so the form of apparatus and system design suitable for the situation are very important. In this study, we calculated basic performances of the CHPs based on our previous theoretical and experimental data. Furthermore, we proposed thermal energy recycling utilization systems using CHPs from heat sources to heat applications in some case processes such as industrial drying process, engineering plant etc. As heat sources, unutilized energy such as waste heat from engineering plant and incinerator, surplus exhaust heat from a decentralized cogeneration system and renewable energy such as solar thermal, geothermal are considered. As heat applications, space heating/cooling, hot/cold water supply, drying, dehumidification, and ice production are considered. We calculated the total energy efficiencies and cost estimations of the proposed systems. As a result, it was found that the effective energy utilization system could be constructed by designing suitable CHP based systems using a calcium oxide/water CHP and a calcium sulfate/water CHP for sustainable society construction.

View full abstract

A gas circular loop system of CaO/CO₂ chemical heat pump was proposed due to improve the thermal performance of the heat pump. The loop system consists of CaO packed reactor, a carbon dioxide storage reactor, heat exchanges and a high temperature pump. The carbon dioxide as working fluid is circulating in this loop. In the design of the loop system, the understanding thermal performance on the CaO packed reactor and choosing of optimum reactor operation condition are important. This study mainly deals with the CaO packed reactor. The carbonation rate of calcium oxide in the packed reactor was discussed as function of the initial reaction temperature and reaction pressure, experimentally. Then, an analytical model for thermal performance evaluation in the packed reactor was developed, and was validated by experimental results. The heat output performance of the loop system was evaluated using the analytical model. The numerical analysis indicated that the proposed system could realize an effective heat recovery and high heat output performance at a constant temperature.

View full abstract

Among the desiccant cooling process, two-rotor process consisting of a honeycomb rotor dehumidifier and a sensible heat exchanger is the mainstream of the cooling processes which are practically applied to supermarket, hospital and so on. Most of them are driven with a higher regeneration temperature around 100-140°C obtained from gas-engine heat pump or micro gas turbine generator. However, performance evaluation of the 2-rotor desiccant cooling regenerated by a low temperature heat around 50-80°C has not been carried out sufficiently considering the requirement of effective use of lower temperature waste heat. This study aims to clarify the influences of the operating condition, air conditions, and process configuration on the performance of the 2-rotor desiccant cooling.Effect of water spray evaporative cooling at the inlet of regeneration air stream on the process performance was also investigated. This evaporative cooling was expected to cause humidity increase in regeneration air reducing the dehumidifying performance of the honeycomb absorber, while the evaporative cooling plays an important role to produce lower temperature in supply air. Experimental results showed that the amount of dehumidified water at the process without water spray evaporative cooler was actually larger than that of process with water spray evaporative cooler. This behavior was due to increase of humidity or relative humidity in the regeneration air as expected. However, temperature of supply air produced by the process with evaporator was rather lower than that of the other, resulting higher COP value. It was concluded that the evaporative cooler effectively worked at higher regeneration temperature and lower ambient humidity.

View full abstract

A desiccant evaporative cooling consists of a honeycomb rotary dehumidifier, a sensitive heat exchanger and water spray evaporative cooler. Especially, solar assisted one is quite attractive considering various environmental problems caused by conventional electricity driven air conditioners. Unfortunately, the cooling performance is strongly influenced by solar irradiation and ambient air condition. This study aimed to clarify its actual performance and energy efficiency in Japanese summer condition. The process performance has been examined by means of temperature decrease between outside air and supply air, and COP_s (COP value basing on solar irradiation). Stable solar irradiation at a clear sky gave the desiccant cooling process a higher regeneration temperature and dehumidifying performance. Average temperature decrease and COP_s in this condition were 10 °C and 0.41, respectively. Unstable solar irradiation at somewhat cloudy made the regeneration air temperature lower resulting a poor dehumidifying performance. However, decreasing the cooling performance was comparatively small due to buffering effect by thermal storage in the circulating water. At higher humidity condition, the amount of dehumidified water became higher than that dehumidified at low humidity condition due to increasing relative humidity of outside air or effective adsorption capacity of the desiccant rotor. However, temperature decrease in this condition was just 6.9 °C. This behavior is mainly due to humidity increase and simultaneous temperature rise at the dehumidified air. In this situation, an effective evaporation in the following water spray evaporative cooler also does not occur. This study tries to make clear these complicated relationships between solar irradiation, process configuration and cooling performance.

View full abstract

A multi-pass honeycomb rotor adsorber has been proposed to achieve a low temperature heat driven desiccant cooling process. This multi-pass honeycomb rotor adsorber has a sandwich arrangement of honeycomb shaped adsorbent blocks and aluminum passages. In the regeneration step, hot water flows in the passages heating the honeycomb adsorbent. Simultaneously, outside air is co-currently supplied to the adsorbent layer to discharge the desorbed water vapor. On the other hand, adsorption heat caused in the adsorption step can be removed by cool air which is counter-currently passing through inside of the passages to keep the sufficient adsorption capacity / rate. The vaporization heat of water remaining in the passages also accelerates the cooling of the adsorbent rotor. Dehumidifying performance of the above mentioned adsorber has been investigated under various operating conditions, which are air velocity of each sector, rotation speed of adsorbent rotor, temperature of hot water and so on. At first, optimal rotation speed was found. It was confirmed that the adsorber could be regenerated by direct hot water heating and removal of adsorption heat generated in the adsorption step achieved the semi-isothermal dehumidification. It was also found that lower temperature heat around 50°C was still effective in regeneration of the adsorbent rotor although the same temperature air was needed to discharge the desorbed water vapor. At the moment, detailed investigations including the influence of heat transfer between honeycomb rotor and aluminum passage are being carried out to improve the dehumidifying performance.

View full abstract

Thermosensitive water vapor adsorbent for the desiccant air conditioning was developed by the immobilization of the thermosensitive gel onto the silica gel. The numerical study on heat and mass transfer (water vapor) in a thermosensitive adsorbent packed within a bed column was carried out. A part of dehumidified air was recycled through a heat exchanger into the packed bed column to increase the capacity of the adsorbent for water vapor. The effects of recycle ratio on both temperature rising within the packed bed column and efficiency of dehumidification were investigated numerically. It was confirmed that the rise of temperature within the packed bed column was reduced by introducing the recycle process, and the dehumidified effect increased with increasing the recycle ratio. The amount of water vapor adsorbed onto the thermosensitive adsorbent before breakthrough of humidity drastically increased with this recycle operation, resulting in an increase of dehumidified amount of air.

View full abstract

We have developed a thermosensitive adsorbent that shows hydrophilicity below its phase transition temperature and hydrophobicity above one. For this reason, the adsorption amount of water vapor changes drastically around the phase transition temperature. Using this thermosensitive adsorbent, new desiccant air-conditioning system is proposed. This system is expected to save the energy to regenerate and to make the regeneration temperature low in comparison with the conventional systems. This system, however, requires the limitation condition to keep the temperature of the adsorbent below the phase transition temperature during adsorption.The aim of this work is to embody the concept of this new system with fin-tube type heat exchanger that is adopted as the adsorbent unit. Possibility of designing the reactor structure to overcome the limitation condition described above is examined. The surface of the fin and the tube is coated with the thermosensitive adsorbent. Water is employed as the coolant. For the simulation analysis, three dimensional finite element method is used. The calculated results show that it is possible to design the configuration of the heat exchanger to eliminate the heat of adsorption and simultaneously to keep the temperature of the adsorbent below the phase transition temperature. Furthermore, it is confirmed that this system requires much smaller amount of energy for its regeneration than the conventional systems and makes use of the low level waste heat sources below 333K.

View full abstract

We have developed a new hydrogen production process "HyPr-RING" where high pressure steam thermochemically decomposes organic materials such as coal with a calcium-based CO₂ sorbent. In this study, the comparison of behavior of trace elements between in a batch and in a continuous reactor was studied. In the experiment with a small batch reactor, a mixture of pulverized Taiheiyo-coal and water with Ca(OH)₂ was charged into a micro reactor. The reactor was put into a fluidized sand bath and rapidly heated to a subcritical condition. In the experiment with a continuous reactor, Taiheiyo-coal was charged into the fixed bed reactor. After the pressure in the reactor system was increased, the reactor was heated to a high temperature by using an electric furnace, and high temperature steam was continuously injected into the reactor below. In both experiments, the residual solid and liquid collected were analyzed with ICP-AES. Consequently, in the batch experiment conversions of most of metals into liquid were increased with reaction temperature, while in the continuous experiment they were hardly increased with temperature. In both experiments, conversions of most of metals into liquid occurred during pyrolysis and gasification in the initial stage. As the result obtained at 973 K, 19.8 MPa and 10 minutes in the batch experiment, Al, Fe and Mo were almost in the solid, while Mg, Ti, Cu, Zn and Pb were recovered in the liquid. However, it seems that Cu, Zn and Pb were partially in gas phase during reaction because they are easier to be volatilized. As the result obtained at 973 K, 6.0 MPa and 160 minutes in the continuous experiment, most of metals were only in the solid, while Zn was detected in the liquid. These experimental results almost corresponded with results of thermodynamic equilibrium calculation.

View full abstract

Coal-integrated gasification/gas turbine (CIG/GT) based power plants are well known to achieve the advantage of higher electric efficiency and lower costs than direct combustion based power plants. Since the gasification is an endothermic, thermochemical conversion process, it requires heat to proceed. In general, this heat is furnished by internal combustion taking place in the gasifier by virtue of oxygen-blown or air-blown gasification. However, the direct combustion of the solid fuel is realized to be inefficient with respect to large amount of exergy destruction posed during the combustion, especially at relatively low temperature like gasification temperature. This causes the overall performance deterioration of the CIG/GT system. Therefore, a decrease in the exergy destruction during the combustion can contribute to improvement on the overall system efficiency. In this paper, an innovative concept of energy-recuperative gasification was proposed and incorporated in the CIG/GT system. The idea is to make use of the waste heat from the gas turbine exhaust as the reaction heat for the gasification instead of the internal combustion. This type of energy recuperation is also called thermochemical recuperation. In addition, the proposed CIG/GT incorporates other effective energy recuperation, including heat and steam recuperation, in order to maximize the generation efficiency. The feasibility of the concept implementation and the system improvement were preliminarily examined and discussed.

View full abstract

Low rank coals are deposited abundantly in several regions throughout the world and they will continue to be significant resources for both energy and chemicals. However, they have not been utilized to the same extent as higher rank coals because of their high water contents (40-70wt%) and low calorific values. Developments of dewatering and upgrading processes are necessary to utilize the coals on a large scale. Hydrothermal treatment has generally been conducted by adding extra water to the coal prior to treatment, leading to a decrease in the efficiency of the process. In this study hydrothermal treatment of a brown coal was performed by utilizing the water inherent in coal. An Australian brown coal, Loy Yang, was solely loaded in an autoclave and treated at 200∼350°C for 30 and 180 min. Measured temperature vs. pressure relationship closely followed the vapor pressure curve during treatment of the coal, revealing that hydrothermal conditions are maintained throughout the experiments with only the inherent water. The water content of the treated coals decreased with increasing temperature. The oxygen content of the treated coal decreased above 250°C, which successfully increased the calorific value of the treated coal. FTIR analysis revealed that the carboxyl groups were selectively decomposed through these treatments.

View full abstract

We have presented a new coal solvent extraction method that enhances the extraction yield dramatically by using a flowing stream of a solvent at high temperature. The extract yield reached 65 to 80% for bituminous coals using tetralin as a solvent under 10 MPa at 350°C, and the extract was separated into about 25 to 40% of soluble fraction at room temperature (soluble) and about 40% of solid fraction (deposit) which precipitated from the extract at room temperature. It was found that the soluble and the deposit were almost free from inorganic materials. To utilize these clean carbonaceous materials for specific purposes, their fractionation and more detailed characterization are essential. Then the deposit, which is soluble at 350°C but insoluble in tetralin at 25°C (Frac.+25-350), was further extracted at several different temperatures below 350°C. It was found that five extraction steps could fractionate the coal into 8 fractions. Ultimate analysis and molecular mass measurement showed that the fractions obtained at lower temperature consisted of smaller molecular mass compounds which were existent in the parent coal and have larger atomic H/C ratio. Furthermore, the fractionation behaviors are discussed in terms of the solution theory by using solubility parameters. From a practical viewpoint, the melting and plastic behavior of Frac.+25-150 (softening temperature: 270°C) was very close to that of a naphthalene-based pitch (softening temperature: 223°C) which was synthesized for producing high performance carbon materials. This result suggested a possibility of utilizing the fraction as a feedstock of high performance carbon materials.

View full abstract

Bench scale pulverized coal combustor with oxygen has been designed. Experiment is conducted in a down-fired, cylindrical and vertical furnace. An Indonesian sub-bituminous coal is used for combustion experiment. In burner design, the strong swirl burner could not realize flame stabilization, because coal particles with carrier flow were cut off the flow passage into the furnace by untidiness flow. On the other hand, weak swirl burner experiment was able to obtain good mixing flow pattern and flame stabilization. High combustion efficiency at 99.7 % has been achieved, and it depends on the oxygen ratio and primary and secondary oxygen flow ratio (R_f). The NO_x concentration is raged from 1650 to 1800 ppm on the complete combustion region, and conversion ratio of fuel nitrogen to NO_x (CR_NOx) is increased significantly as the oxygen ratio increased. Decrease in weight fractions of Na, Mg, K and Ca that have lower boiling points in ash is confirmed, since the very high temperature flame vaporized these matters.

View full abstract

Some trace metal compounds in the fuel tend to be enriched in the fine particulates. The fine particulates with the size of less than 1 m as well as hot metallic vapor with alkali metal compounds cause erosive and corrosive effects to blades of a gas turbine. Therefore, it is necessary to understand behaviors and mechanisms of fine particulates formation with alkali metal compounds during coal combustion. Combustion tests were conducted, using an electrically heated drop tube furnace to burn two types of coal with different Na and K concentrations. The burning particles were collected by a Low Pressure Impactor (LPI). As a result, the enrichment mechanism of Na was elucidated by the size distribution of Na concentration in the fine particulates collected in each stage of the LPI. For the fine particulates, the enrichment phenomena were controlled by an internal reaction of Na compounds vapor with fine ash particulates or nucleation, which depended on the coal type. For the relatively coarse particulates, on the other hand, the gas film diffusion controlled the enrichment of Na compounds into the ash particles with the chemical reactions of Na compounds vapor with the those ash particles.

View full abstract

The purpose of this study is to clarify the relationship among the reactivity of coal char, the carbonaceous structural change, and the ash behavior. The steam gasification of various coal char was carried out in a fixed-bed reactor. After the gasification, the reacted char was analyzed by LRS (Laser Raman Spectroscope), and SEM/EDX (Scanning Electron Microscope, Energy Dispersive X-ray Spectroscopy). In order to evaluate the progress of carbonaceous graphitization, we observed I_D/I_V ratio that was one of the Raman parameters. As a result, graphitization of coal char was equally observed under every condition as the increasing of conversion rate. So we estimated that the progress of graphitization would be caused with following reason. Disordered carbon structure, whose reactivity was higher, had been gasified alternatively, consequently the ratio of carbon that had graphitic structure increased relatively.Then in order to clarify the ash behavior affecting the char reactivity, characterizations of each char was carried out using SEM/EDX. From the results of observing SEM image and EDX-mapping, we found the different behavior of elements and novel parallel analysis between EDX-mapping and LRS-mapping was very effective for the comprehensive evaluation of ash behavior and carbonaceous structure. As the gasification reaction, the reactivity of char was partially decreased, because the surface of carbon had been covered with certain elements such as Si, and reaction gas could not contact with the carbon.

View full abstract