• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.158.2-158.2
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• 2011

DME is acronym of dimethyl ether, which is spotlighted as an ideal fuel to produce hydrogen due to its high hydrogen/carbon ratio, high energy density and easiness to carry. In this research, we calculated thermodynamic hydrogen (or syngas) yield from DME autothermal reforming and compared to other fuels. The reforming efficiency was about 80% above $700^{\circ}C$. Lower OCR has higher reforming efficiency but, it requires additional heat supply since the reactions are endothermic. SCR has no significant effect on the reforming efficiency. The optimized condition is $700^{\circ}C$, SCR 1.5, OCR 0.45 without additional heat supply. Comparing to other commercial gaseous fuels (methane and propane), DME has higher selectivity of $H_2O$ and $CO_2$ than the others due to the oxygen atom in the molecule. To apply DME autothermal reforming to real system, a proper catalyst is required. Therefore, it is performed the experiment comparing various novel metal catalysts based on CGO. Experiments were performed at calculated condition. The composition of product was measured and reforming efficiency was calculated. The catalysts have similar efficiency at high temperature(${\sim}800^{\circ}C$) but, CGO-Ru has the highest efficiency at low temperature ($600^{\circ}C$).

• Journal of Hydrogen and New Energy
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• v.17 no.3
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• pp.241-247
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• 2006

The catalytic performances for CO preferential oxidation in hydrogen-rich fuels were investigated by varying the types of alumina supports, additives excluding platinum, and synthetic methods of impregnation and sol-gel synthesis. The reactions were conducted in the range of $25{\sim}300^{\circ}C$ over Pt, Co, and/or Na impregnated catalysts supported on commercial gamma-alumina, pseudoboehmite, or sol-gel derived xerogels. Catalytic activities were enhanced by cobalt addition due to strong Pt-Co interactions in the bimetallic phase. Additional sodium promoted not only the formation of the Pt-Co bimetallic interphase but also oxygen adsorption capability, giving rise to increase in the CO oxidation rate at lower temperatures. Moreover, chemical interaction between Pt and Co was considerably enhanced by sol-gel synthesis.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.406-409
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• 2012

Recently, enormous research efforts have been focused on the development of non-precious catalysts to replace Pt for electrocatalytic oxygen reduction reaction (ORR), and to reduce the cost of proton exchange membrane fuel cells (PEMFCs). In recent years, heteroatom (N, B, and P) doped carbon nanostructures have been received enormous importance as a non-precious electrode materials for oxygen reduction. Doping of foreign atom into carbon is able to modify electronic properties of carbon materials. In this study, nitrogen and boron doped carbon nanostructures were synthesized by using a facile and cost-effective thermal annealing route and prepared nanostructures were used as a non-precious electrocatalysts for the ORR in alkaline electrolyte. The nitrogen doped carbon nanocapsules (NCNCs) exhibited higher activity than that of a commercial Pt/C catalyst, excellent stability and resistance to methanol oxidation. The boron-doped carbon nanostructure (BC) prepared at $900^{\circ}C$ showed higher ORR activity than BCs prepared lower temperature (800, $700^{\circ}C$). The heteroatom doped carbon nanomaterials could be promising candidates as a metal-free catalysts for ORR in the PEMFCs.

• Journal of Electrochemical Science and Technology
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• v.15 no.3
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• pp.353-364
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• 2024

Through component regulation and morphological construction, it is of considerable significance to develop high-activity and high-stability electrocatalyst for hydrogen evolution in electrolytic water. In the hydrothermal process, Mo-doped nickel-based sulfide catalysts (Mo-NiS-Fx) with a variety of morphologies (prisms, rods, flakes, and cones) were created by adding NH₄F with varying masses. Among these, the flaky Mo-NiS-F1.2 exhibited exceptional performance towards electrochemical hydrogen evolution reaction, surpassing most similar catalysts with an overpotential of 79 mV at 10 mA cm^-2 and a Tafel slope of 49.8 mV dec^-1. Significantly, Mo-NiS-F1.2 maintained its high activity for hydrogen evolution over 60 h at a current density of 10 mA cm^-2, making it suitable for widespread commercial application. According to the experimental findings, an electrocatalyst with a high surface area and a porous structure is better suited to exposing more gas transfer routes and active sites, which would encourage the hydrogen evolution reaction. This study presents a straightforward procedure for creating electrocatalysts with a range of morphologies, which can serve as a model for the creation of catalysts for use in industrial manufacturing.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.11 s.254
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• pp.1123-1130
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• 2006

This study discusses about research efforts of hydrogen generation from hydrocarbon(e.g., diesel, gasoline, natural gas, and LPG), especially, butane reforming by using Autothermal Reforming Reaction (ATR) technology. Several catalysts were selected for butane ATR. Thermodynamic reactor conditions (temperature, $O_2$/C, S/C) are varied and reforming characteristics of 2 catalysts (Pt and Rh on ceramic supports) and 1 commercial catalyst (FCR-HC35) have been examined. To understand reaction behaviors in an ATR reactor comprehensively, temperature profiles of reactor were observed. By mass transfer limitation, fuel conversion decreases when GHSV increases. Significant temperature variation along the reactor was observed and it was mainly due reaction kinetics difference between exothermic oxidation and endothermic reforming reaction.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.63-66
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• 2007

Reformers which produce hydrogen from natural gas are essential for the operation of residential PEM fuel cells. For this purpose, steam-methane reforming reactions with Ni catalysts is primarily utilized. Commercial Ni catalysts are generally made to have porous pellet shapes in which Ni catalyst particles are uniformly dispersed over Alumina support structures. This study numerically investigates the reduction of catalyst effectiveness due to the mass transport resistances posed by porous structures of spherical catalyst pellets. The multi-component diffusion through porous media and the accurate kinetics of reforming reaction is fully considered in the numerical model. The preliminary results on the variation of the effectiveness factor according to different operation conditions are presented, which is planned to be used to develop correlations in future studies.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.6
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• pp.649-656
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• 2010

Boron-doped $TiO_2$ photocatalysts were synthesized by a modified sol-gel method and their photocatalytic activities were performed and compared with those of pure synthetic and commercial $TiO_2$ catalysts under UV or visible light conditions. Pure $TiO_2$ itself exhibited very negligible photocatalytic performance under visible light conditions in the aspects of toluene decomposition reactions, although significant decomposition potential was observed as expected with UV light conditions. However, boron doping over $TiO_2$ significantly improved photocatalytic activity particularly under visible conditions, where over 95% degradation of toluene was achieved with 1wt% $B-TiO_2$ within 2 hrs. All the decomposition reactions seemed to follow pseudo first-order kinetics. The effects of boron-doping and its characteristics are further discussed through the kinetic studies and comparison of results.

• Bulletin of the Korean Chemical Society
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• v.30 no.12
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• pp.2899-2904
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• 2009

Esterification is an important class of reactions in the preparation of perfumery and flavor chemicals, wherein homogeneous, solid acidic, and superacidic catalysts are normally used. Now, an efficient and selective protocol for protection of various functionalized alcohols employing carboxylic acids as protecting agents is realized through the catalytic mediation of simple heteropolyoxometallates. In this methodology, water is the only by-product and notably the aspect of effluent treatments does not arise. The advantages include the operational simplicity, recycle ability of the catalyst and mild reaction conditions. The present catalytic system may be a potential candidate not only for laboratory practice but also for commercial applications and offers an environmentally safer alternative to the existing processes.

• Bulletin of the Korean Chemical Society
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• v.28 no.7
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• pp.1119-1126
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• 2007

Hydrogen gas and carbon nanotubes along with nanocarbon were produced from commercial natural gas using fixed bed catalyst reactor system. The maximum amount of carbon (491 g/g of catalyst) formation was achieved on 25% Ni, 3% Cu supported catalyst without formation of CO/CO2. Pure carbon nanotubes with length of 308 nm having balloon and horn type shapes were also formed at 673 K. Three sets of catalysts were prepared by varying the concentration of Ni in the first set, Cu concentration in the second set and doping with K in the third set to investigate the effect on stabilization of the catalyst and production of carbon nanotubes and hydrogen by copper and potassium doping. Particle size analysis revealed that most of the catalyst particles are in the range of 20-35 nm. All the catalysts were characterized using powder XRD, SEM/EDX, TPR, CHN, BET and CO-chemisorption. These studies indicate that surface geometry is modified electronically with the formation of different Ni, Cu and K phases, consequently, increasing the surface reactivity of the catalyst and in turn the Carbon nanotubes/H2 production. The addition of Cu and K enhances the catalyst dispersion with the increase in Ni loadings and maximum dispersion is achieved on 25% Ni: 3% Cu/Al catalyst. Clearly, the effect of particle size coupled with specific surface geometry on the production of hydrogen gas and carbon nanotubes prevails. Addition of K increases the catalyst stability with decrease in carbon formation, due to its interaction with Cu and Ni, masking Ni and Ni:Cu active sites.

• Applied Chemistry for Engineering
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• v.28 no.2
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• pp.221-229
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• 2017

In this study, a wet impregnation method was applied to catalysts based on the active metal Pt in order to confirm the oxidation characteristics of various commercial alumina supports at room temperature. The catalysts were characterized using XPS, CO-chemisorption, and BET. Various $Pt/Al_2O_3$ catalysts controlled the oxygen species of Pt by the electronegativity of electrons and charges when the catalyst was prepared according to the heat treatment conditions. The reason that the dispersion degree decreases with increasing Pt loading seems to be attributed to HT (Huttig Temperature) of Pt. In addition, the minimum hydrogen concentration that can be controlled at room temperature can control hydrogen from metallic Pt up to 1.0 vol% at over 70.09% in the catalyst.