• Clean Technology
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• v.26 no.3
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• pp.196-203
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• 2020

In this study, a Cu/hexaaluminate catalyst was prepared by a co-precipitation method, and then a binder was added to form a pellet. A catalyst in which Ni and Ru promoters were added to a Cu/hexaaluminate pellet catalyst was prepared. This study focused on examining the effect of the addition of Ni and Ru promoters on the properties of Cu/hexaaluminate catalysts and the decomposition reaction of ADN-based liquid monopropellants. Cu/hexaaluminate catalysts had few micropores and well-developed mesopores. When Ru was added as a promoter to the Cu/hexaaluminate pellet catalyst, the pore volume and pore size increased significantly. In the thermal decomposition reaction of ADN-based liquid monopropellant, the decomposition onset temperature was 170.2 ℃. Meanwhile, the decomposition onset temperature was significantly reduced to 93.5 ℃ when the Cu/hexaaluminate pellet catalyst was employed. When 1% or 3% of Ru were added as a promoter, the decomposition onset temperatures of ADN-based liquid monopropellant were lowered to 91.0 ℃ and 83.3 ℃, respectively. This means that the Ru promoter is effective in lowering the decomposition onset temperature of the ADN-based liquid monopropellant because the Ru metal has excellent activity in the decomposition reaction of ADN-based liquid monopropellant, simultaneously contributing to the increase of the pore volume and pore size. After the thermal treatment at 1,200 ℃ and decomposition of ADN-based liquid monopropellant were repeatedly performed, it was confirmed that the addition of Ru could enhance the heat resistance of the Cu/hexaaluminate pellet catalyst.

• Korean Chemical Engineering Research
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• v.59 no.2
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• pp.296-303
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• 2021

The objective of this study is to investigate the applicability of a Cu-supported honeycomb catalyst as a catalyst for decomposition of a low toxic liquid propellant based on ammonium dinitramide (ADN). A mixture of copper, lanthanum, and alumina was supported on the honeycomb support by wash coating to prepare a Cu-La-Al/honeycomb catalyst. We elucidated that the effect of metal loading on the physicochemical properties of Cu-La-Al/honeycomb catalyst and catalytic performance in decomposition of the ADN-based liquid propellant. As the number of wash coatings increased, the amount of active metal Cu was increased to 4.1 wt%. The BET surface area of the Cu-La-Al/honeycomb catalyst was in the range of 3.1~4.1 ㎡/g. The micropores were hardly present in Cu-La-Al/honeycomb catalysts, however, the mesopores and macropores were well developed. The Cu (2.7 wt%)-La-Al/honeycomb catalyst exhibited the highest activity in the decomposition of the ADN-based liquid propellant, which is attributed to the largest surface area, the largest pore volume, and the well-developed mesopores and macropores.

• Journal of Hydrogen and New Energy
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• v.27 no.3
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• pp.283-289
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• 2016

In this study, electrochemical characterizations of PdCu/C catalysts that are synthesized by modified polyol method are investigated. Most of all, amount of ethylene glycol (EG) that is used as main component for catalyst synthesis is mainly modulated to optimize synthetic condition of the PdCu/C catalyst, For evaluations about catalytic activity and performance of direct formic acid fuel cell (DFAFC), half cell and full cell tests are implemented. As a result, when amount of EG is 4M, catalytic activities of the PdCu/C catalyst such as peak current of formic acid oxidation and active surface area are best, while maximum power density of DFAFC using the optimized PdCu/C catalyst is better than that using commercial Pd/C (30 wt%) by 6%. Based on that, PdCu/C catalyst synthesized by modified polyol method plays a critical role in improving (i) catalytic activity for formic acid oxidation and (ii) DFAFC performance by employing as anodic catalyst.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.412-415
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• 2017

In this study, the decomposition performance of ammonia dinitramide (ADN) based liquid monopropellant was evaluated by using metal supported alumina bead catalyst. Alumina bead was calcined at $1200^{\circ}C$, and Pt and Cu were impregnated on alumina bead by excess water impregnation using a rotary evaporator. The decomposition temperature ($T_{dec}$) of ADN-based liquid monopropellant was measured in a home-made batch reactor. The decomposition temperature of Cu/$Al_2O_3$ catalyst was lower than that of Pt/$Al_2O_3$ catalyst, and $T_{dec}$ was about $130^{\circ}C$.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.511-521
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• 2000

Investigation was carried out lean burn de-NOx properties of Pt-$TiO_2$ bifunctional catalyst by propylene in order to get the high de-NOx activity and the wide temperature window under coexistence of $SO_2$ and $H_2O$. Only noncatalyst and carrier catalyst themselves had NOx conversion activity at high temperature over $400^{\circ}C$. NOx conversion activity of catalysts exchanged copper ion resulted in Cu-$TiO_2$>Cu-ZSM-5>Cu-$Al_2O_3$>CU-YZ>Cu-AZ. Catalysts impregnated with platinum based on titania gave the results of high NOx conversion activity at low temperature. $250^{\circ}C$. Bifunctional catalysts based on Pt-$TiO_2$ showed high NOx conversion activity both at a low zone of $300^{\circ}C$ and a high zone of $500^{\circ}C$. Pt-$TiO_2$/$Al_2O_3$ catalyst gave the highest NOx conversion activity at a low temperature zone. and Pt-$TiO_2$/$Mn_2O_3$(21) catalyst gave the highest NOx conversion activity at a high temperature zone. Under the coexistence of $SO_2$ and $H_2O$. NOx conversion activities of 0.55wt%Pt-$TiO_2$/5wt%Cu-ZSM-5 catalyst was high both at a low and high temperature zone, and increased depending on oxygen concentration. 0.55wt%Pt-$TiO_2$/5wt%Cu-ZSM-5 catalyst showed the best correlation between de-NOx activities and the propyl ere conversion rates to CO on the log function.

• Applied Chemistry for Engineering
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• v.33 no.5
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• pp.466-470
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• 2022

The catalytic thermal oxidizer process has recently attracted considerable attention for the oxidation and decomposition of volatile organic compounds at low temperatures (< 450 ℃) with high efficiency (> 95%). Although many noble metal catalytic materials are well established, they are expensive and hazardous. Herein, highly active and low-cost Cu-Mn bimetallic catalysts were prepared using a simple and facile synthesis method involving the co-precipitation of Cu and Mn precursors. The synthesis of the catalyst was optimized by controlling the composition ratio of Cu and Mn. The optimized catalyst exhibited a large surface area of 230.8 m²/g with a mesoporous structure. To demonstrate the catalytic performance, the Cu-Mn catalyst was tested for the oxidation reaction of ethyl acetate, showing a high conversion efficiency of 100% at a low temperature of 250 ℃.

• Clean Technology
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• v.19 no.3
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• pp.287-294
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• 2013

The $NH_3$-selective catalytic reduction (SCR) reaction of NO with excess of oxygen were systematically investigated over Cu-zeolite and Fe-zeolite catalysts. Cu-zeolite and Fe-zeolite catatysts to adapt the SCR technology for mobile diesel engines were prepared by liquid ion exchange and incipient wetness impregnation of $NH_4$-BEA and $NH_4$-ZSM-5 zeolites. The catalysts were characterized by BET, XRD, FE-TEM (field emission transmission electron microscopy) and SEM/EDS. The SCR examinations performed under stationary conditions showed that the Cu-exchanged BEA catalyst revealed pronounced performance at low temperatures of $200{\sim}250^{\circ}C$. With respect to the Fe-zeolite catalyst, the Cu-zeolite catalyst showed a higher activity in the SCR reaction at low temperatures below $250^{\circ}C$. BEA zeolite based catalyst exhibited good activity in comparison with ZSM-5 zeolite based catalyst at low temperatures below $250^{\circ}C$.

• Clean Technology
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• v.29 no.4
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• pp.321-326
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• 2023

Recently, there has been a growing interest in clean hydrogen energy that does not emit carbon dioxide during combustion due to the increasing focus on carbon neutral. Research related to hydrogen production continues, and in this study, we applied waste-derived synthesis gas to the water-gas shift reaction to simultaneously treat waste and produce high-purity hydrogen. To enhance catalytic activity in the high-temperature water-gas shift (HT-WGS) reaction, magnesium was used as a support material alongside cerium. Cu-CeO₂-MgO catalysts were synthesized, with copper acting as the active component for the HT-WGS reaction. A study on the catalytic activity based on the preparation method was conducted, and the Cu-CeO₂-MgO catalyst prepared by impregnation method exhibited the highest activity in the HT-WGS reaction. The observed superior performance of the Cu-CeO₂-MgO catalyst prepared through the impregnation method can be attributed to its significantly higher oxygen storage capacity and amount of active Cu species.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.112-118
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• 2018

In order to meet the strict emission regulations for internal combustion engines based on fossil fuel, the proportion of after-treatments for vehicles and vessels is gradually increasing. Diesel engines have high power, good fuel economy, and lower $CO_2$ emissions, and their market shares are increasing in commercial vehicles and passenger cars. However, NOx is generated in the localized high-temperature combustion regions, and particulate matter is formed in the zones of diffusion combustion. LNT and urea-SCR catalysts have been developed for after-treatment of the exhaust gas to reduce NOx in diesel vehicles. This study aims to improve the NOx reduction performance of Cu SCR catalyst, which is widely used in light, medium, and heavy-duty diesel engines. The de-NOx performance of $5Cu-2ZrO_2$/93Zeolyst(Si/Al=13.7) SCR catalyst was about 5-50% higher than that of $5Cu-2ZrO_2$/93Zeolite(Si/Al=2.9) at catalyst temperatures of $300^{\circ}C$ or higher. The zeolite had lower metal dispersion than zeolyst, and the reaction rate of the catalyst decreased as the average particle size increased. The $10Cu-2ZrO_2$/88Zeolyst catalyst loaded with 10wt% Cu had the highest NOx conversion rate of 40% at $200^{\circ}C$ and about 65% at $350^{\circ}C$. The ion exchange rate of Cu ions increased with that of Al, the crystalline compound of zeolite, and the de-NOx performance was improved by 20-40% compared to other catalysts.

• Korean Chemical Engineering Research
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• v.45 no.6
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• pp.566-572
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• 2007

Two hybrid catalysts for the direct synthesis of DME were prepared and the catalytic activity of these catalysts were investigated. The hybrid catalyst for the direct synthesis of DME was composed as the catalytic active components of methanol synthesis and dehydration. The methanol synthesis catalyst was formed from the precursor contained Cu and Zn, the methanol dehydration catalyst was used ${\gamma}-Al_2O_3$. As PM-CZ+D and CP-CZA/D, Two hybrid catalysts were prepared by physical mixing method (PM-CZ+D) and precipitation method (CP-CZA/D), respectively. PM-CZ+D was prepared by physically mixing methanol synthesis catalyst and methanol dehydration catalyst, CP-CZA/D was prepared by depositing Cu-Zn or Cu-Zn-Al components on ${\gamma}-Al_2O_3$. The crystallinity and the surface morphology of synthesized catalyst were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM) to investigate the physical property of prepared catalyst. And BET surface area by $N_2$ adsorption and the surface area of Cu by $N_2O$ chemisorption were investigated about the hybrid catalysts. In addition, catalytic activity of these hybrid catalysts was examined with varying reaction conditions. At that time, the reaction temperature of $250{\sim}290^{\circ}C$, the reaction pressure of 50~70 atm, the $[H_2]/[CO]$ mole ratio of 0.5~2.0 and the space velocity of $1,500{\sim}6,000h^{-1}$ were investigated the catalytic activity. From these results, it was confirmed that the reactivity of CP-CZA/D was higher than that of PM-CZ+D. When the conditions of reaction temperature, pressure, $[H_2]/[CO]$ ratio and space velocity were $260^{\circ}C$, 50 atm and 1.0, $3,000h^{-1}$ respectively, CO conversion using CP-CZA/D hybrid catalyst was 72% and the CO conversion of CP-CZA/D was more than 20% compared with the CO conversion of PM-CZ+D. It was known that Cu surface area of CP-CZA/D hybrid catalyst was higher than that of hybrid PM-CZ+D catalyst using $N_2O$ chemisorption. It was assumed that the catalytic activity was improved because Cu particle of hybrid catalyst prepared by precipitation method was well dispersed.