Hydrogen formation from glucose was examined using a batch reactor in high temperature high pressure water at 300°C. Homogenous catalysts (H2SO4 and NaOH) were not effective for H2 formation from glucose at this condition. Heterogeneous catalysts: Ag2O, CuO, Cr2O3, Fe2O3, MgO, MnO2, MoO3, NiO, rutile TiO2, and ZnO, were applied and then it was found that MnO2 and ZnO effectively promoted H2 formation. In order to enhance H2 yield, glucose in high pressure high temperature water was partially oxidized in the presence of ZnO. As a result, 25 % H2 (glucose mole basis) was obtained. In this reaction, by-production of methane was not observed. The enhancement of H2 yield was not observed when ZnO was located at gas phase. It suggested that a precursor of H2 formed in the aqueous phase.
By partial oxidation of glucose with ZnO in high pressure high temperature water at 300°C, glucose was converted into H2 with relatively high yield and without CH4 formation. In order to understand the reaction mechanism and the optimum condition of the process, we performed glucose partial oxidation at 200-300°C to analyse an intermediate of H2, without ZnO, which probably promotes the intermediate into H2. As a result, we detected a high yield of HCOOH. The formation of HCOOH was sensitive to reaction temperature and the yield was the highest at 200°C among the experimental conditions. It was confirmed that the role of ZnO was a promoter of HCOOH decomposition into H2 and CO2 through HCOOH conversion experiments with and without ZnO at 200-300°C. The conversion of HCOOH with ZnO was within a few minutes at 300°C. Through the study, we suggested that two-stage reaction is effective for H2 formation from glucose partial oxidation: the partial oxidation of glucose is conducted at 200°C and the conversion of HCOOH is achieved over 300°C. To confirm the idea, the two-stage reaction was performed: the partial oxidation of glucose was conducted at 200°C with ZnO followed to increase temperature up to 300°C for promotion of H2 formation. The H2 yield was less amount than expected. This was probably due that ZnO prohibited the formation of HCOOH on glucose partial oxidation at 200°C.
In this research, the model to quantify various environmental and social benefits comprehensively expected by governmental countermeasures execution was developed as a reasonable method of policy decision making on domestic livestock manure oversupply problem. The developed model was applied to Maebashi city, Gunma Prefecture as a case study. The model consists of "Sub-model for Agricultural Material Flow Analysis" considering Life Cycle Assessment and "Sub-Model for Characterization of Environmental and Social Benefits". The output of this model showed the cost-benefit ratio of proposed countermeasures. As the items of benefits, these 8 categories were chosen by panel method: water pollution, soil pollution, air pollution, global warming, acidification, protection of exhaustible resource, food self-sufficiency ratio and energy self-sufficiency ratio. As a result, "Compost use promotion" plan and "Feed production support" plan showed a large cost-benefit ratio in some categories (not all). However, both measures had upper limits of possible budget distribution by model constraints. Therefore, it was suggested that the combination of countermeasures would be necessary in terms of both reasonable budget distribution and diversity of expected benefits. The result would contribute to the construction of the reasonable decision making method.
Poultry manure can be completely gasified in supercritical water. In this paper, the behavior of the seven inorganic elements, N, Ca, K, P, S, Cl and Si in layer poutlry manure during supercritical water gasification has been studied to analyze the potential of the by-products of poultry manure gasification for recycling. The inorganic elements in the starting poultry manure, and in the solid and liquid phases after reaction, were quantitatively analyzed. Furthermore, the experimental data were confirmed with thermodynamic equilibrium calculations using computer software. Following gasification the elements N, K and Cl partitioned almost completely into the liquid phase, Ca, P and Si partitioned almost completely into the solid phase, and S partitioned between both phases.
This paper describes the results of life cycle environmental analysis of hydrogen energy systems. It is proposed that hydrogen can be produced from coke oven gas (COG), and then stored and distributed to consumption sites in the form of organic hydride (methylcyclohexane/toluene). In this study, such a hydrogen energy system is analyzed in terms of primary energy requirement and CO2 emission, with a special attention to the hydrogen distribution using organic hydride. The results show that energy requirement and CO2 emission at consumption sites (i.e. dehydrogenation reaction of methylcyclohexane, refining of hydrogen) account for a large percentage of the whole system. From the results, it is understood that this is a special characteristics of the organic hydrides option. It also implies that primary energy requirement for the organic hydride option is almost equivalent to the liquid hydrogen option, but it is lager than the compressed hydrogen option. Furthermore, improvement analysis is carried out focusing on the characteristics of organic hydride. The results reveal that CO2 emission from the whole system are considerably reduced if waste heat from fuel cells at consumption sites can be used as energy source for dehydrogenation reaction of methylcyclohexane.
The bench-scale production of hydrocarbon liquid fuel was successful from woody biomass via gasification. The production capacity of the biomass-to-liquid (BTL) plant used in this study was 1.9 L of hydrocarbon liquid from 13 kg of woody biomass per day. The BTL process involved the following steps: gasification of the woody biomass, wet and dry gas cleaning, gas compression, the removal of carbon dioxide, and the Fischer-Tropsch (FT) synthesis reaction. In the gasification step, oxygen-enriched air gasification was carried out using a downdraft fixed-bed gasifier. By increasing the oxygen content, which acts as a gasifying agent, from 21.0 to 31.5 vol%, the conversion to gas on a carbon basis increased from 91.9 to 96.3 C-mol%, while the concentrations of CO and H2 increased from 22.8 to 30.1 vol% and from 16.8 to 23.7 vol%, respectively. The product gas obtained with an oxygen content of 27.6 vol% was subsequently converted to a liquid fuel through the gas cleaning and FT synthesis reaction steps. The concentrations of H2S and COS produced in the gasification step decreased to less than 5 ppb through the scrubber and desulfurization tower for the wet and dry gas cleaning, respectively. The concentration of the syngas (CO + H2) increased from 48.1 to 56.0 vol%, while that of CO2 decreased from 12.1 to 0.6 vol% after the cleaned gas was passed through a carbon dioxide removal tower. Subsequently, the cleaned gas was compressed up to 12.6 MPa using compressors to obtain a feed gas for the FT synthesis reaction, and its composition was as follows: 30.8 vol% of CO, 25.2 vol% of H2, 0.9 vol% of CO2, 2.5 vol% of CH4, 40.6 vol% of N2, <5 ppb of H2S, and <5 ppb of COS. In the FT synthesis step, the hydrocarbon fuel was synthesized in a slurry bed reactor using hexadecane as the solvent and Co/SiO2 catalyst. The selectivity to hydrocarbon with a carbon chain length of more than 5 carbon atoms as a liquid fuel, i.e., a C5+ selectivity of 73.0% was obtained along with a chain growth probability of 0.85 under the following conditions: 3 MPa, 280 to 310°C, and when the ratio of catalyst weight to feed gas rate (W/F) was 86.9 g h/mol.
Ethylene is one of the most important intermediates in the industry, being expected to increase in the future despite a predicted shortage of petroleum. In previous papers, we showed that lipids in dead grape leaf (DGL) were attractive substances for biological ethylene production. Furthermore, we reported that 22 kinds of microorganisms including Bacillus mycoides KIOSB43 or the compounds containing ferrous ion such as FeSO4, FeCl2 and Fe(OOCCH3)2 related to ethylene production from DGL lipids. In order to establish a new technique for sustainable ethylene production independing on petroleum, we investigated the efficient procedure for producing ethylene from DGL. When mono- and di-saccharides were added to DGL, it was decomposed. Then, the treatments of B. mycoides after FeSO4 treatment produced large amounts of ethylene from the decomposed DGL as compared with those of B. mycoides before FeSO4 treatment. This procedure seems to be useful for producing bio-ethylene. Further experiments are needed to establish more efficient methods for the bio-ethylene production by improving the treatment of ferrous ion and by strengthening the activity of ethylene-producing microorganisms.
Utilization of biomass is discussed from the point of gasification, mechanical and electric power generation. The situation of biomass utilization varies greatly depending upon the socio-economic conditions as well as availability of the technologies. Thus the present conditions in the Philippines, Thailand and Myanmar appear to be very different reflecting the levels of economic growth of their own countries. In any case, the utilization of biomass with more efficient energy system is going to be even more important in the future because of the increased concerns of fuel price as well as global environment. International horizontal division of work and public private partnership, in cooperation with academic institutions, NPOs and agencies concerned, will be necessary for the implementation of the site specific technologies meeting the regional needs in the individual countries.