• Advances in Energy Research
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• v.2 no.1
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• pp.33-45
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• 2014

Photocatalytic hydrogen generation by water splitting ($H_2O_{(1)}{\rightarrow}H_2_{(g)}+1/2O_2_{(g)}$) has been studied on photocatalysts based on Zn, Cd, Fe and Cu, synthesized by coprecipitation. Iron and copper nanoparticles were incorporated as cocatalysts to enhance the photocatalytic activity of the ZnCd solid solution. The effect of the different synthesis parameters (temperature, elemental atomic ratios, amount of Cu and Fe incorporated in the catalyst and calcination temperature) on the photocatalytic production of hydrogen has been studied in order to determine the best experimental synthesis conditions. The catalysts have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and BET. The experiments of photocatalytic water splitting were performed in aqueous solution of the photocatalysts previously dispersed in a soft ultrasound bath. The photocatalysts were irradiated under different lights ranging from 220 to 700 nm. The photocatalytic activity was found to be clearly dependent on the specific area of the photocatalyst.

• Applied Chemistry for Engineering
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• v.19 no.2
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• pp.157-160
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• 2008

The generation of high-purity hydrogen from hydrocarbon fuels is essential for efficient operation of fuel cell. In general, most feasible strategies to generate hydrogen from hydrocarbon fuels consist of a reforming step to generate a mixture of $H_2$, CO, $CO_2$ and $H_2O$ (steam) followed by water gas shift (WGS) and CO clean-up steps. The WGS reaction that shifts CO to $CO_2$ and simultaneously produces another mole of $H_2$ was carried out in a two-stage catalytic conversion process involving a high temperature shift (HTS) and a low temperature shift (LTS). In a typical operation, gas emerges from the reformer is taken through a high temperature shift catalyst to reduce the CO concentration to about 3~5%. The HTS reactor was designed and tested in this study to produce hydrogen-rich gas with CO to a range of 2~4%. The iron based catalysts (G-3C) was used for the HTS to convert the most of CO in the effluent from the partial oxidation (POX) to $H_2$ and $CO_2$ at a relatively high rate. Parametric screening studies were carried out for variations of the following variables: reaction temperature, steam flow rate, components ratio ($H_2/CO$), and reforming gas flow rate.

• Nuclear Engineering and Technology
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• v.53 no.8
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• pp.2753-2760
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• 2021

This paper proposes using sodium-cooled fast reactor technologies for use in hydrogen vapor methane (SMR) modification. Using three independent energy rings in the Russian BN-600 fast reactor, steam is generated in one of the steam-generating cycles with a pressure of 13.1 MPa and a temperature of 505 ℃. The reactor's second energy cycles can increase the gas-steam mixture's temperature to the required amount for efficient correction. The 620 ton/hr 540 ℃ steam generated in this cycle is sufficient to supply a high-temperature synthesis current source (700 ℃), which raises the steam-gas mixture's temperature in the reactor. The proposed technology provides a high rate of hydrogen production (approximately 144.5 ton/hr of standard H₂), also up to 25% of the original natural gas, in line with existing SMR technology for preparing and heating steam and gas mixtures will be saved. Also, exergy analysis results show that the plant's efficiency reaches 78.5% using HTR heat for combined hydrogen and power generation.

• KSBB Journal
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• v.20 no.6
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• pp.413-417
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• 2005

The purple sulfur phototrophic bacterium, Thiocapsa roseopersicina NCIB 8347 has been studied on hydrogen production and cell growth under different culture conditions, such as light source, light intensity, and growth temperature. T. roseopersicina showed maximum cell growth of 1.38 and 1.42 g-DCW/L under 7.5-10 klux of halogen and fluorescent light, respectively, and produced maximum amount of hydrogen with values of 0.90 and 0.48 $mL-H_2/mg$-DCW under the irradiation of 10 klux of halogen and fluorescent light, respectively. The optimum growth temperature for hydrogen production was $26^{\circ}C$, and hydrogen production rate was lowered over $30^{\circ}C$. When T. roseopersicina was grown photoheterotrophically under irradiation of 8-9 klux of halogen lamp, the generation time was 4.2 hr. The strains started producing hydrgen from the middle of the logarithmic growth phase and continued until succinate concentration leveled out.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.4
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• pp.372-378
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• 2005

Ni/YSZ ($Y_2O_3$-stabilized $ZrO_2$) composite powder for a cathode material in high temperature electrolysis(HTE) was synthesized by a mechanical alloying method with Ni and YSZ powder. Microstructure of the composite and cell thickness for HTE reaction has been analyzed with various techniques of XRD, SEM to investigate effects of fabrication conditions. Employing the composite material, furthermore, the unit cell for HTE has been studied to evolve hydrogen from water. XRD patterns showed that the composites after wet mechanical alloying were composed of respective nano-sized crystalline Ni and YSZ. While ethanol as additive for mechanical alloying increased to $20\;{\mu}m$ of average particle size of the composites, alpha-terpineol effectively decreased to sub-micro size of that. This study has been found out the evolution of hydrogen by HTE reaction employing the fabricated cathode material, showing 1.4 ml/min of $H_2$ generation rate as increasing $20\;{\mu}m$ of cathode thickness.

• Bulletin of the Korean Chemical Society
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• v.32 no.12
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• pp.4392-4396
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• 2011

Porous silicon with a complex network of nanopores is utilized for photoelectrochemical energy conversion. A novel electroless Pt deposition onto porous silicon is investigated in the context of photoelectrochemical hydrogen generation. The electroless Pt deposition is shown to improve the characteristics of the PS photoelectrode toward photoelectrochemical $H^+$ reduction, though excessive Pt deposition leads to decrease of photocurrent. Furthermore, it is found that a thin layer (< 10 ${\mu}m$) of porous silicon can serve as anti-reflection layer for the underlying Si substrate, improving photocurrent by reducing photon reflection at the Si/liquid interface. However, as the thickness of the porous silicon increases, the surface recombination on the dramatically increased interface area of the porous silicon begins to dominate, diminishing the photocurrent.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.1
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• pp.135-144
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• 2021

In this study, we investigated the characteristics of the process of hydrogen production using boil-of gas (BOG) generated from an LNG-fueled ship and the application of hydrogen fuel cell systems as auxiliary engines. In this study, the BOG steam reformer process was designed using the UniSim R410 program, and the reformer outlet temperature, pressure, and the fraction and consumption of the product according to the steam/carbon ratio (SCR) were calculated. According to the study, the conversion rate of methane was 100 % when the temperature of the reformer was 890 ℃, and maximum hydrogen production was observed. In addition, the lower the pressure, the higher is the reaction activity. However, higher temperatures have led to a decrease in hydrogen production owing to the preponderance of adverse reactions and increased amounts of water and carbon dioxide. As SCR increased, hydrogen production increased, but the required energy consumption also increased proportionally. Although the hydrogen fraction was the highest when the SCR was 1.8, it was confirmed that the optimal operation range was for SCR to operate at 3 to prevent cocking. In addition, the lower the pressure, the higher is the amount of carbon dioxide generated. Furthermore, 42.5 % of the LNG cold energy based on carbon dioxide generation was required for cooling and liquefaction.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.1
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• pp.39-46
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• 2014

Our lab designs a heat exchangers for hydrogen gas. Coolant is water, thus it is very difficult to determine heat transfer parameters in this gas-liquid system. Repeated experiments gives overdesign value 6.06%, overall heat transfer coefficient 36.32 ($kcal/m^2-hr-^{\circ}C$) for Hydrogen. Theoretically determined overall heat transfer coefficient is 38.44 ($kcal/m^2-hr-^{\circ}C$). Our lab simulated this system and overdesign 30.4% shows good match with this experiment by HTRI. These parameters are in same range with literature.

• Membrane Journal
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• v.32 no.5
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• pp.283-291
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• 2022

Hydrogen energy has received much attention as a solution to the supply of renewable energy and to respond to climate change. Hydrogen is the most suitable candidate of storing unused electric power in a large-capacity long cycle. Among the technologies for producing hydrogen, water electrolysis is known as an eco-friendly hydrogen production technology that produces hydrogen without carbon dioxide generation by water splitting reaction. Membranes in water electrolysis system physically separate the anode and the cathode, but also prevent mixing of generated hydrogen and oxygen gases and facilitate ion transfer to complete circuit. In particular, the key to next-generation anion exchange membrane that can compensate for the shortcomings of conventional water electrolysis technologies is to develop high performance anion exchange membrane. Many studies are conducted to have high ion conductivity and excellent durability in an alkaline environment simultaneously, and various materials are being searched. In this review, we will discuss the research trends and points to move forward by looking at the research on anion exchange membranes based on commercial polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) block copolymers.

• Journal of the Korean Wood Science and Technology
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• v.28 no.4
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• pp.17-24
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• 2000

The peroxidase activity was localized cytochemically to get an insight into its precise function in lignin biosynthesis. In this work, cerium chloride ($CeCl_3$) was used as a trapping agent for hydrogen peroxide ($H_2O_2$) generated from peroxidase. Seasonal variation of peroxidase activities in cambial region of Populus, Pinus, and Ginkgo was investigated at subcellular levels. Under transmission electron microscopy, electron dense deposits of cerium perhydroxide formed by reaction with $H_2O_2$ were observed in cambium and its immediate derivatives. The staining with $CeCl_3$ in cambium varied with growth seasons. The strongest $H_2O_2$ accumulation, regardless of tree species, appeared in May. Staining pattern of $CeCl_3$ in the cambium of poplar indicated that the production of peroxidase started in March before the opening of buds and reached the highest in May and then declined in August. Ginkgo and Pinus showed relatively late generation of $H_2O_2$ production when compared with Populus. Although Ginkgo and Pinus are classified into gymnosperms, however, the generation of peroxidase production and its duration was different from each other. Little staining appeared in all the tree samples collected in September before falling the leaves.