• Journal of Microbiology and Biotechnology
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• v.2 no.4
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• pp.248-254
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• 1992

The initial growth of Clostridium acetobutylicum was not inhibited by 1 atm of H$_2$ while H$_2$ reduced glucose consumption in a solventogenic culture of a phosphate limited 2-stage chemostat. Under 1 atm of H$_2$, a solventogenic culture consumed hydrogen, but an acidogenic culture produced hydrogen. H$_2$ consumption by the solventogenic culture was enhanced by the addition of 5 mM neutral red, an artificial electron carrier with a redox potential of -325 mV. Hydrogenase activity, measured in both directions of production and consumption, showed that activity coupled with methyl viologen is higher in an acidogenic culture than in a solventogenic culture, and that the two cultures have similar activities for methylene blue reduction. The solventogenic culture showed a higher activity coupled with neutral red than the acidogenic culture. From these results, it is hypothesized that hydrogen producing hydrogenase activity is high during the acidogenic phase, and decreases as solventogenesis starts, and that the solventogenic culture produces a second hydrogenase which uses an electron carrier other than ferredoxin. This hypothesis was supported by the fact that enzyme activities involved in electron flow can be coupled to neutral red, indepedent of ferredoxin, and that neutral red addition to the fermentation system increased butanol yield, with a decrease in production of less reduced fermentation products, and $H^2$.

• New & Renewable Energy
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• v.5 no.2
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• pp.9-14
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• 2009

Automobile Shredder Residue (ASR) is very appropriate in a gasification melting system. Gasification melting system, because of high reaction temperature over than $1,350^{\circ}C$, can reduce harmful materials. To use the gasification processes for hydrogen production, the high concentration of CO in syngas must be converted into hydrogen gas by using water gas shift reaction. In this study, the characteristics of shift reaction of the high temperature catalyst (KATALCO 71-5M) and the low temperature catalyst (KATALCO 83-3X) in the fixed - bed reactor has been determined by using simulation gas which is equal with the syngas composition of gasification melting process. The carbon monoxide composition has been decreased as the WGS reaction temperature has increased. And the occurrence quantity of the hydrogen and the carbon dioxide increased. When using the high temperature catalyst, the carbon monoxide conversion ratio ($1-CO_{out}/CO_{in}$) rose up to 95.8 from 55.6. Compared with average conversion ratio from the identical synthesis gas composition, the low temperature catalyst was better than the high temperature catalyst.

• Korean Chemical Engineering Research
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• v.43 no.6
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• pp.668-674
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• 2005

It is reported that a method for the hydrogen production from the propane decomposition using carbon black as a catalyst is more effective than from the methane decomposition. Since the by-products like CO and $CO_2$ are not produced by the direct decomposition of propane, it is considered as an environmentally sustainable process. In this study, hydrogen was produced by the direct decomposition of propane using either commercial activated carbon or carbon black at atmospheric pressure in the temperature range of $500-1,000^{\circ}C$. Resulting products in our experiment were not only hydrogen but also several by-products such as methane, ethylene, ethane, and propylene. Hydrogen yield increased as temperature increased because the amount of those by-products produced in the experiment was inversely proportional to temperature. The achieved hydrogen yield at $750^{\circ}C$ with commercial DCC N330 catalyst was 22.47％ in this study.

• Korean Chemical Engineering Research
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• v.59 no.4
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• pp.503-507
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• 2021

Sodium borohydride, NaBH₄, has many advantages as hydrogen source for portable proton exchange membrane fuel cells (PEMFC). When PEMFC is used outdoors as a transport type, it is economical to hydrolyze NaBH₄ using fresh water instead of distilled water. Therefore, in this study, hydrogen was generated using fresh water instead of distilled water during the NaBH₄ hydrolysis process. The properties of NaBH₄ hydrolysis were studied using an activated carbon-supported Co-P-B/C catalyst. Fresh water did not generate tetrahydrate during the NaBH₄ hydrolysis process, and distilled water produced tetrahydrate by-products, which consumed a lot of water during the hydrolysis process, indicating that at the end of the reaction at a high concentration of 25% or more of NaBH₄, dry by-products and unreacted NaBH₄ remained. As a result, when fresh water was used, the hydrogen yield and hydrogen generation rate were higher than that of distilled water at a high concentration of 25% or more of NaBH₄, indicating that it is suitable for use in transport-type fuel cells such as unmanned aerial vehicles.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.4
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• pp.268-273
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• 2014

Experiments on carbonization were conducted using fish offal generated from fish market for the purpose of resource recycling. Elemental composition of fish offal and effect of carbonation temperature on the overall yield were investigated. Carbon and hydrogen contents of fish offal were 51.1% and 7.6%, respectively in view of elemental composition. Particularly, nitrogen and sulfur contents were as high as 9.8% and 1.0%, respectively. These values suggests that odor problem of fish offal can be serious. Comparing elemental composition of fish offal with other waste materials, it is thought that carbon and hydrogen contents are considerably high. These implies that thermal disposal will be the best option for final disposal method of fish offal. As a results of carbonization experiments on Mackerel, Hairtail, Croaker and mixed sample of Mackerel, Hairtail and Croaker, carbonization patterns were quite similar irrespective of fish species. Carbonization yield was varied significantly depending on carbonization temperature at the carbonization time of 5 minutes and 10 minutes. When the carbonization time was maintained longer than 30 minutes, yield variation depending on time variation at each temperature was insignificant. Thus, it can be concluded that effect of carbonization time on overall yield was minor when the carbonization time was maintained longer than 30 minutes. Primary vaporization in carbonization conducted at the temperature of $400^{\circ}C$ was minor. Thus, difference of yield between temperature of $500^{\circ}C$ and $400^{\circ}C$ was appeared greatly. It can be concluded that yield difference depending on carbonization temperature can be neglected if the carbonizing temperature exceed $600^{\circ}C$ and carbonizing time exceed 10 minutes at the same time.

• Applied Chemistry for Engineering
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• v.25 no.2
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• pp.227-232
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• 2014

Depolymerization of sodium alginate (SA) was carried out by electron beam irradiation in a hydrogen peroxide atmosphere. E-beam with 1.0 and 2.5 MeV of accelerating voltages were employed in this experiment. For control of molecular weight and the radiation yield of scission ($G_s$), the irradiation dosage of e-beam was managed in a range from 2.5 to 20 kGy while the quantity of hydrogen peroxide was adjusted in a range of 0 to 4.5%. The chemical structure of the depolymerized sodium alginate (DSA) was analyzed to have scission of 1,4-glycoside bond mainly and a few fragmentary formate end groups which may be produced by the cleavage between C2 and C3 in repeating unit of alginate. It turned out to have simple chemical structures at the DSA end groups, produced by e-beam irradiation, similar with those in the polymer SA structure. As a result, the molecular weight of SA decreased as the energy and dosage of applied e-beam increased, and the radiation yield of scission showed the best result at 2w/v% in SA concentration. The highest radiation yield of scission ($7.919{\times}10^4mol/J$) was confirmed when an irradiation dosage of 20 kGy (2 MeV) and 1.5% hydrogen peroxide were used in 2% SA aqueous solution.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.1
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• pp.47-60
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• 2021

Hydrogen is a next-generation energy source, and according to the roadmap for activating the hydrogen economy, it is expected that industries to stably produce, store, and transport of hydrogen as well as the supply of hydrogen fuel cell vehicles will be made rapidly. Accordingly, safety measures for accidents of hydrogen vehicles in confined spaces such as tunnels are required. In this study, as part of a study to ensure the safety of hydrogen fuel cell vehicles in road tunnels, a basic investigation and research on the risk of fire and explosion due to gas leakage and hydrogen tank rupture among various hazards caused by hydrogen fuel cell vehicle accidents in tunnels was conducted. The following results were obtained. In the event of hydrogen fuel cell vehicle accidents, the gas release rate depends on the orifice diameter of TPRD, and when the gas is ignited, the maximum heat release rate reaches 3.22~51.36 MW (orifice diameter: 1~4 mm) depending on the orifice diameter but the duration times are short. Therefore, it was analyzed that there was little increase in risk due to fire. As the overpressure of the gas explosion was calculated by the equivalent TNT method, in the case of yield of VCE of 0.2 is applied, the safety threshold distance is analyzed to be about 35 m, and number of the equivalent fatalities are conservatively predicted to reach tens of people.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.3
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• pp.333-339
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• 2011

In the present work, it was attempted to produce $H_2$ from food waste by the two-stage fermentation system. Food waste was acidified to lactate by using indigenous lactic acid bacteria under mesophilic condition, and the lactate fermentation effluent (LFE) was subsequently converted to $H_2$ by photo-fermentation. $Rhodobacter$ $sphaeroides$ KD131 was used as the photo-fermenting bacteria. The optimal conditions for lactate fermentation were found to be pH of 5.5 and substrate concentration of 30 g Carbo. COD/L, under which yielded 1.6 mol lactate/mol glucose. By filtering the LFE and adding trace metal, $H_2$ production increased by more than three times compared to using raw LFE, and finally reached the $H_2$ yield of 3.6 mol $H_2$/mol lactate. Via the developed two-stage fermentation system $H_2$ yield of 5.8 mol $H_2$/mol glucose was achieved from food waste, whose value was the highest that ever recorded.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.6
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• pp.587-594
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• 2010

Hydrogen is an alternative fuel for the future energy which can reduce pollutants and greenhouse gases. Synthesis gas has played an important role of synthesizing the valuable chemical compounds, for example methanol, DME and GTL chemicals. Renewable biomass feedstocks can be potentially used for fuel and chemicals. Current thermal processing techniques such as fast pyrolysis, slow pyrolysis, and gasification tend to generate products with a large slate of compounds. Lignocellulose feedstocks such as forest residues are promising for the production of bio-oil and synthesis gas. Pyrolysis and gasification was investigated using thermogravimetric analyzer (TGA) and bubbling fluidized bed gasification reactor to utilize forest woody biomass. Most of the materials decomposed between $320^{\circ}C$ and $380^{\circ}C$ at heating rates of $5{\sim}20^{\circ}C$/min in thermogravimetric analysis. Bubbling fluidized bed reactor was used to study gasification characteristics, and the effects of reaction temperature, residence time and feedstocks on gas yields and selectivities were investigated. With increasing temperature from $750^{\circ}C$ to $850^{\circ}C$, the yield of char decreased, whereas the yield of gas increased. The gaseous products consisted of mostly CO, $CO_2$, $H_2$ and a small fraction of $C_1-C_4$ hydrocarbons.

• Journal of the Korean Chemical Society
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• v.9 no.2
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• pp.106-109
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• 1965

The effects of methyl borate, iodine and potassium iodide on the Co-60 gamma radiolysis of methanol have been reinvestigated at room temperature, utilizing an experimental technique based on gas chromatographic determinations of the gaseous products of the radiolysis. The presence of methyl borate reduces the yield for ethylene glycol to some extent, with slight reductions of the yields for hydrogen and formaldehyde. The presence of iodine causes appreciable reduction of the yields for hydrogen, formaldehyde and ethylene glycol, with a slight reduction of the yield for methane. The presence of potassium iodide reduces the yields for hydrogen and ethylene glycol but increases that for formaldehyde. A mechanism of the radiolysis reaction is discussed, on the basis of the observed data.