• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.2
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• pp.78-83
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• 2011

Diesel engine has many advantages such as high thermal efficiency, low fuel consumption and low emission of CO2. However, the diesel engine faced with strengthened emission regulation about NOx and PM. To suppress NOx emission, after-treatment systems such as Lean NOx Trap (LNT), Selective Catalytic Reduction (SCR) are considered as a more practical strategy. This paper investigated the performance of Lean NOx trap of the 4 stroke diesel engine which had a LNT catalyst. Characteristic of exhaust emission at NEDC mode was analyzed. From this result, the effect of nozzle attaching degree, injection quantity and gas flow change on NOx conversion performance was clarified.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.4
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• pp.165-172
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• 2008

Urea-SCR, the selective catalytic reduction using urea as reducing agent, has been investigated for about 10 years in detail and today is a well established technique for deNOx of stationary diesel engines. In the case of the SCR-catalyst a non-uniform velocity and $NH_3$ profile will cause an inhomogeneous conversion of the reducing agent $NH_3$, resulting in a local breakthrough of $NH_3$ or increasing NOx emissions. Therefore, this work investigates the effect of flow and $NH_3$ non-uniformities on the deNOx performance and $NH_3$ slip in a Urea-SCR exhaust system. From the results of this study, it is found that flow and $NH_3$ distribution within SCR monolith is strongly related with deNOx performance of SCR catalyst. It is also found that multi-hole injector shows better $NH_3$ uniformity at the face of SCR monolith face than one hole injector.

• Environmental Engineering Research
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• v.20 no.4
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• pp.397-402
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• 2015

SCR has been popularly approved as one of the most effective means for NOx emission control in heavy-duty and medium-duty vehicles currently. However, high urea dosing would lead to ammonia slip. And $NH_3$ sensor for vehicle emission applications has not been popularly used in real applications. This paper presents experimental studies on the diesel engine urea-SCR system by using a double NOx sensor system that is arranged in the downstream of the SCR catalyst based on ammonia cross-sensitivity. It was shown that the NOx conversion efficiency rised as $NH_3/NOx$ increases and the ammonia slip started from the $NH_3/NOx$ equal to 1.4. The increase of temperature caused high improvement of the SCR reaction rate while the space velocity had no obvious change. The ammonia slip was in advance as catalyst temperature or space velocity increase and the ammonia storage reduced as catalyst temperature or space velocity increase. The NOx real-time conversion efficiency rised as the ammonia accumulative storage increase and reached the maximum value gradually.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.10
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• pp.1817-1824
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• 2000

This study is carried out to investigate the discharge characteristics of PCDD/Fs from municipal solid waste(MSW) incinerator, According to the results measured at several air pollution control devices(APCDs), the largest amount of polychlorinated dibenzo-p-dioxins/dibenzofurans(PCDD/Fs) are found at selective catalytic reduction (SCR) inlet. Therefore, it concludes that the electrostatic precipitator(EP) provides the appropriate condition for the formation of PCDD/Fs. The concentration of PCDD/Fs shows a large difference with the season. The concentration of PCDD/Fs in winter is higher than that of autumn, which suggests that the formation of PCDD/Fs is affected by the MSW components and the operation condition of municipal solid waste incinerator(MSWI).

• Journal of ILASS-Korea
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• v.21 no.2
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• pp.71-77
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• 2016

Air pollutants nitrogen oxides are inevitably generated in the combustion reaction. Its amount trend is steadily increasing because the rapid modern industrialization and population growth. For this reason, NOx is controlled to reducing the harmful components in the exhaust gas. So Marine Environment Protection Committee (MEPC) take effect 'Tier I', 'Tier II' of air pollution regulation in 2005 and 2011 respectively. According to NOx emissions are strictly regulated management of the vessel through them. In addition, since 2016 the regulation enter into force in the next step 'Tier III' was confirmed by MEPC 66th committee. It's 80% enhanced emissions limits than the 'Tier I' Alternatively these emission regulation, research is actively being carried out about exhaust gas after-treatment methods through the vessel application of Selective Catalytic Reduction(SCR). Therefore depending on the basic specification of cell density according to the Area velocity, Space velocity, Linear velocity is studied the effects of NOx removal efficiency

• Journal of the Korean Ceramic Society
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• v.26 no.1
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• pp.100-108
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• 1989

Aluminum hydroxides were prepared by the alkoxide hydrolysis method using Al-isopropoxide as a starting material and NH4OH as a catalytic agent. When Al-isopropoxide was hydrolyzed in a H2O-NH3 system, only Al(OH)3 was obtained over all pH values. However, AlOOH was formed besides Al(OH)3 when Al-isopropoxide was hydrolyzed in a H2O-NH3-isopropyl alcohol system. The AlOOH/Al(OH)3 ratio was increased as the isopropyl alcohol content was increased. The hydroxides, Al(OH)3 and AlOOH, obtained in this study and the commerical products, $\alpha$-Al2O3 and AlOOH were subjected to the carbothermal reduction and nitridation reaction to product AlN powder, using carbon black as a reducing agent under N2 atmosphere at various temperatures. AlN was synthesized from the obtained Al(OH)3 and the commercial AlOOH at 145$0^{\circ}C$, however, synthesized from the obtained AlOOH and the commercial alpha-alumina at 135$0^{\circ}C$. The temperature difference is assumed to be attributed to the reactivity of those powders. AlN powder prepared from the Al-isopropoxide was observed to have the narrower particle size distribution than that prepared from the commercial $\alpha$-Al2O3 or AlOOH.

• Journal of Electrochemical Science and Technology
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• v.7 no.1
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• pp.76-81
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• 2016

An anatase TiO₂ nanotube array (NTA) was fabricated by anodization and successive heat treatments. When the anatase TiO₂ NTA was cathodically polarized, its color changed to blue, and it could be used as an electrochemically active anode for an oxygen evolution reaction (OER) in alkaline water electrolysis. The structure of the blue anatase TiO₂ NTA was controlled by the anodization conditions and its catalytic activity increased with an increase of the surface area. The activity of the blue anatase TiO₂ NTA gradually reduced with the continued OER because of the partial oxidation of Ti³⁺ to Ti⁴⁺. However, an intermittent cathodic regeneration process could significantly slow its reduction rate. The blue anatase TiO₂ NTA could be an alternative anode for alkaline water electrolysis.

• Journal of Power System Engineering
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• v.17 no.1
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• pp.27-35
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• 2013

SCR (Selective Catalytic Reduction) on DPF (Diesel Particulate Filter) is a multi-functional after-treatment device which integrates soot filtration and DeNOx function into a single can. Because of its advantage in package and cost, the SCR on DPF is considered as a potential candidate for future application. It inherently employes wall flow type monolithic reactor so ash included in exhaust gas may deposit inside the inlet channel of this device. This study is intended to identify the impact of ash deposit on SCR reaction under wall flow type monolithic reactor. Simulation approach is used so relevant species transport equations for wall flow type monolith is derived. These equations can be solved together with momentum conservation equations and give solution for conversion performance. Both ash deposit and clean catalyst case are simulated and comparison of these two cases gives an insight for the impact of ash deposit on conversion performance. Ash deposit can be classified as ash layer and ash plug. and impact of ash deposit is described along with different morphology of ash deposit.

• Applied Chemistry for Engineering
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• v.7 no.1
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• pp.171-176
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• 1996

The easily biodegradable nonionic surfactant of glucamide(N-alkyl-N-acyl glucamine) was synthesized by the two-step reaction. The first step was the amination between alkylamine and glucose in methanol. Then, alkyl glucamines were obtained by reduction using Ni catalyst under the high pressure with 86~93% of reaction yield. The second step was the synthesis of glucamide from alkyl glucamine and fatty acid methyl ester in methanol under the alkali catalytic condition while refluxing the solvent. The reaction yield of this step was 84~95% except the benzyl glucamine, which the reaction yield was 50~70%. The molecular structure of four kinds of alkyl glucamine and 16 kinds of glucamide with different alkyl and acyl groups was studied by IR, MS and NMR.

• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2385-2390
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• 2011

Preparation of ammonium dihydrogenphosphate supported on alumina ($NH_4H_2PO_4/Al_2O_3$) and its primary application as a solid acid supported heterogeneous catalyst to the synthesis of 1,2,4,5-tetrasubstituted imidazoles by a one-pot, four-component condensation of benzil, aromatic aldehydes, primary amines, and ammonium acetate under thermal solvent-free conditions were described. The results showed that the novel catalyst has high activity and the desired products were obtained in high yields. Furthermore, the products could be separated simply from the catalyst, and the catalyst could be recycled and reused with only slight reduction in its catalytic activity. Characterization of the catalyst was performed by FT-IR spectroscopy, the $N_2$ adsorption/desorption analysis (BET), thermal analysis (TG/DTG), and X-ray diffraction (XRD) techniques.