• Bulletin of the Korean Chemical Society
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• v.15 no.2
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• pp.132-138
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• 1994

Bis(diethylamino)aluminum hydride was utilized in a systematic study of the approximate rates and stoichiometry of the reaction of excess reagent with 55 selected organic compounds containing representative functional groups under standardized conditions (THF, $0^{\circ}C$, reagent to compound=4 : 1) in order to define the characteristics of the reagent for selective reductions. The reducing action of BEAH was also compared with that of the parent aluminum hydride. The reducing action of the reagent is quite similar to that of aluminum hydride, but the reducing power is much weaker. Aldehydes and ketones were readily reduced in 1-3 h to the corresponding alcohols. However, unexpectedly, a ready involvement of the double bond in cinnamaldehyde was realized to afford hydrocinnamyl alcohol. The introduction of diethylamino group to the parent aluminum hydride appears not to be appreciably influential in stereoselectivity on the reduction of cyclic ketones. Both p-benzoquinone and anthraquinone utilized 2 equiv of hydride readily without evolution of hydrogen, proceeded cleanly to the 1,4-reduction products. Carboxylic acids and acid chlorides underwent reduction to alcohols slowly, whereas cyclic anhydrides utilized only 2 equiv of hydride slowly to the corresponding hydroxylacids. Especially, benzoic acid with a limiting amount of hydride was reduced to benzaldehyde in a yield of 80%. Esters and lactones were also readily reduced to alcohols. Epoxides examined all reacted slowly to give the ring-opened products. Primary and tertiary amides utilized 1 equiv of hydride fast and further hydride utilization was quite slow. The examination for possibility of achieving a partial reduction to aldehydes was also performed. Among them, benzamide and N,N-dimethylbenzamide gave ca, 90% yields of benzaldehyde. Both the nitriles examined were also slowly reduced to the amines. Unexpectedly, both aliphatic and aromatic nitro compounds proved to be relatively reactive to the reagent. On the other hand, azo- and azoxybenzenes were quite inert to BEAH. Cyclohexanone oxime liberated 1 equiv of hydrogen and utilized 1 equiv of hydride for reduction, corresponding to N-hydroxycyclohexylamine. Pyridine ring compounds were also slowly attacked. Disulfides were readily reduced with hydrogen evolution to the thiols, and dimethyl sulfoxide and diphenyl sulfone were also rapidly reduced to the sulfides.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.3
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• pp.245-255
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• 2009

Effect of CO$_2$ concentration on reduction reactivity of oxygen carrier particles for chemical-looping combustor were investigated. Four particles, NiO/bentonite, OCN601-650, OCN702-1100, OCN702-1250, were used as oxygen carrier particles and two kinds of gases (CH$_4$, 5%, N$_2$ balance and CH$_4$ 5%, CO$_2$ balance) were used as reactants for reduction. For all oxygen carrier particles, higher maximum conversion, reduction rate, oxygen transfer capacity, and oxygen transfer rate were achieved when we used N$_2$ balance gas. OCN601-650 particle showed higher oxygen transfer rate for all gases than other particles, and therefore we selected OCN601-650 particle as the best candidate. For all particles, lower carbon depositions were observed when we used CO$_2$ balance gas.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.6
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• pp.549-555
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• 2019

Electrocatalysis of oxygen reduction reaction (ORR) using Pt nanoparticles or bimetal on carabon was studied. Currently, the best catalyst is platinum, which is a limited resource and expensive to commercialize. In this paper, we investigated the cheaper and more active electrocatalysts by making Pt nanoparticles and adding 3D transition metal such as copper. Electrocatalysts were obtained by chemical reduction based on ethylene glycol solutions. Elemental analysis and particle size were confirmed by XRD and TEM. The electrochemical surface area (ECSA) and activity of the catalyst were determined by electrochemical techniques such as cyclic voltammetry and linear sweep voltammetry method. The commercialized Pt support on carbon (Pt/C, JM), synthesis Pt/C and synthesis Pt3Cu1 alloy nanoparticles supported on carbon were compared. We confirmed that the synthesized Pt3-Cu1/C has high electrochemical performance than commercial Pt/C. It is expected to develop an electrocatalyst with high activity at low price by increasing the oxygen reduction reaction rate of the fuel cell.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.4
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• pp.284-292
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• 2022

Hydrogen is promising a candidate for energy supporting the carbon neutrality policy for greenhouse gas reduction, which is being promoted in several countries, including Korea. Although challenging efforts-such as lowering the costs of green hydrogen production and fuel cells-remain, hydrogen fuel cell electric vehicles (FCEVs) are expected to play a significant role in the energy transition from fossil fuels to renewable energy. In line with this objective, the hydrogen FCEV working group in the International Organization for Standardization (ISO) compiled and revised international standards related to hydrogen refueling stations as of 2019. A well-established hydrogen quality management system based on the standard documents will increase the reliability of hydrogen charging stations and accelerate the use of FCEVs. In this study, among the published ISO standards and other references, the main requirements for managing charging stations and developing related techniques were summarized and explained. To respond preemptively to the growing FCEV market, a continuous hydrogen quality monitoring method suitable for use at hydrogen charging stations was proposed.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.5
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• pp.453-458
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• 2017

A study on the modeling of the methane Chemical Looping Reforming system was carried out. It is aimed to predict the temperature and concentration behavior of the product through modeling of oxygen carrier fixed bed reactors composed of multiple stacks. In order to design the reaction system, first of all, the flow rate of the hydrogen to be produced was calculated. The flow rate ratio of the oxidation/reduction reactor was calculated considering the heat of reaction between adjacent reactors. Finally, in this paper, kinetic model including empirical coefficients was suggested.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1122-1123
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• 2006

Mn-Fe oxide and Mn-Fe oxide/$ZrO_2$(50wt%/50wt%) were prepared by ball milling method. XRD data of the prepared samples revealed that hematite and ferrite phase coexisted. Water splitting at 1273K, after thermal reduction at 1573K, was performed 4 times for the samples. Hydrogen production amount was analyzed by GC with TCD detector. Water splitting capacity of Mn-Fe oxide was improved by ball milling with $ZrO_2$.

• Transactions of the Korean hydrogen and new energy society
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• v.11 no.4
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• pp.179-188
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• 2000

The anodic reaction of hydrogen/oxygen gas mixture at platinum or palladium electrode interfacing with a solid polymer electrolyte was investigated using AC impedance method. The impedance spectrum of the electrode reactions of the mixture depends on the gas composition, electrode roughness, the mode of electrochemical operation and the cell potential. For electrolysis mode of operation, the spectrum taken for the reaction on a rough platinum electrode for the gas mixture revealed clearly that the local anodic reduction of oxygen gas takes place concurrently with the anodic oxidation of hydrogen gas.

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.5
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• pp.410-416
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• 2021

The initial electrochemical performance of ceramic fuel cell with thin-film electrolyte was evaluated in terms of peak power density ratio, open circuit voltage ratio, and activation/ohmic resistance ratios at 500℃. Hydrogen and air were used as anode fuel and cathode fuel, respectively. The peak power density ratio reduced as ~17% for 40 minutes, which rapidly decreased in the early stage of the performance evaluation but gradually decreased. The open circuit voltage ratio decreased with respect time; however, its time behavior was remarkably different with the reduction behavior of the peak power density ratio. The activation resistance ratio increased as ~15% for 40 minutes, which was almost similar with the time behavior of the peak power density ratio.

• Journal of Energy Engineering
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• v.13 no.1
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• pp.1-11
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• 2004

Gasification is the essential technology that can meet the interim hydrogen demand of large quantity before entering the hydrogen economy. Although the hydrogen production that is based upon the pure renewable energy like wind and solar power will eventually prevail, the interim mass production of hydrogen for the next ten to twenty years will come from the technologies that can demonstrate the economic feasibility in production cost with a high potential in minimizing CO$_2$ generation and in improving plant efficiency. Particularly, feedstock such as natural gas, coal, petroleum residual oil, wastes, and biomass appears to be utilized in Korea as hydrogen source, at least during the short and medium period of time, owing to the advantage in production cost. Because one of the main reasons behind the recent hydrogen issue is the reduction requirement of CO$_2$ that would be controlled according to the climate change protocol, hydrogen production technologies must be developed to yield the minimal CO$_2$ generation.

• Korean Chemical Engineering Research
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• v.43 no.3
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• pp.344-351
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• 2005

Hydrogen energy will be considered one of the most important energy carries for the future not only as raw material of petroleum chemical industry but also as the fuel of the fuel cell. The hydrogen production based upon the water electrolysis system combined renewable energy or atomic power energy is being watched as long-term hydrogen sources. Hydrogen from fossil fuel, especially natural gas steam reforming, is the economical mass production method at this time. But the cost of $CO_2$ reduction is added in the economic analysis of hydrogen production processes. Therefore many different results are suggested from these analyses about old processes, and modified schemes are studying for the efficient development. In this review, status for the technology of hydrogen production from natural gas are summarized.