• Korean Journal of Metals and Materials
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• v.46 no.12
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• pp.823-829
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• 2008

The solvent extraction process for the recovery of vanadium from leaching solution of SCR(selective catalytic reduction) spent catalyst was investigated by using Alamine336 as an extractant. The effects of experimental conditions, such as initial pH and concentration of sulfate ion, and ammonia concentration of stripping solution were studied. The extraction percentage of vanadium were increased with the increase of initial pH of leaching solution and decreased with the increase of sulfate ion. More than 99% of vanadium in leaching solution were extracted and stripped at the A/O ratio of 1.0 in 2 stages. On the basis of these results, an optimum solvent extraction process which vanadium was effectively recovered from SCR spent catalyst was proposed.

• Clean Technology
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• v.22 no.4
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• pp.211-224
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• 2016

Three way catalyst has been used extensively for the exhaust gas treatment for the internal combustion gasoline engine. While, numerous research efforts have been directed to develop various technologies for the abatement of exhaust gas from diesel engine. Diesel engine operating under lean condition produces large amount of NOx and the corresponding catalytic technology employing vanadium supported titania using ammonia has been commercialized for heavy duty vehicle. Recently, the Cu catalyst supported on zeolite has been investigated for NOx abatement using ammonia because of its critical importance for ultra low emission vehicle. The current review shows the recent trend in research and development for zeolite based copper catalysts, which are mainly used as catalysts for selective catalytic reduction using ammonia, are one of the aftertreatment technologies for effectively removing nitrogen oxides from diesel exhaust.

• Korean Journal of Metals and Materials
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• v.49 no.8
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• pp.596-600
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• 2011

Thermal degradation behavior of a $WO_3-TiO_2$ monolithic catalyst was investigated in terms of structural, morphological, and physico-chemical analyses. The catalyst with 4 wt.% $WO_3$ contents were prepared by a wet-impregnation method, and a durability test of the catalysts were performed in a temperature range between $400^{\circ}C$ and $800^{\circ}C$ for 3 h. An increase of thermal stress decreased the specific surface area, which was caused by grain growth and agglomeration of the catalyst particles. The phase transition from anatase to rutile occurred at around $800^{\circ}C$ and a decrease in the Brønsted acid sites was confirmed by structural analysis and physico-chemical analysis. A change in Brønsted acidity can affect to the catalytic efficiency; therefore, the thermal degradation behavior of the $WO_3-TiO_2$ catalyst could be explained by the transition to a stable rutile phase of $TiO_2$ and the decrease of specific surface area in the SCR catalyst.

• Korean Chemical Engineering Research
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• v.44 no.5
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• pp.540-546
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• 2006

Effects of organic and inorganic additives on the SNCR reaction of NOx were investigated in a pilot scale flow reactor with a variation of operating parameters. NOx reduction efficiency increased with the increase of a residence time and an initial NOx concentration. NOx reduction reaction by urea solution started to appear about 850 and then reached to maximum value around $970^{\circ}C$. NOx reduction efficiency also increased with the increase of NSR (Normalized Stoichiometric Ratio) up to 2.0. Addition of ethanol and phenol as an organic additives shifted the optimum temperature window to lower region with decreasing the maximum NOx reduction efficiency. This might be due to the side reaction of hydrocarbon in ethanol structure. NaOH addition widened the temperature window and enhanced the NOx reduction efficiency about 10％ due to the chain reaction of NaOH and the reduction of $N_2O$.

• Applied Chemistry for Engineering
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• v.19 no.5
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• pp.512-518
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• 2008

The present work studied the selective catalytic reduction (SCR) of NO to $N_2$ by $NH_3$ over $V/TiO_2$ focusing on NOx control for the stationary sources. The SCR process depends mainly on the catalyst performance. The reaction characteristics of SCR with $V/TiO_2$ catalysts were closely examined at low and high temperature. In addition, adsorption and desorption characteristics of the reactants on the catalyst surface were investigated with ammonia. Seven different $TiO_2$ supports containing the same loading of vanadia were packed in a fixed bed reactor respectively. The interaction between $TiO_2$ and vanadia would form various non-stoichiometric vanadium oxides, and showed different reaction activities. There were optimum calcination temperatures for each samples, indicating different reactivity. It was finally found from the $NH_3-TPD$ test that the SCR activity was nothing to do with $NH_3$ adsorption amount.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.6
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• pp.140-145
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• 2012

Recently, various after-treatment systems, such as LP-EGR(Low Pressure-Exhaust Gas Recirculation), SCR(Selective Catalytic Reduction) and LNT(Lean NOx Trap), were developed to obey the stringent emission regulations of diesel engine. There are many researches on LP-EGR system because it has advantages of NOx reduction and low fuel consumption. But, condensation water is generated in internal of intercooler tube and it contains various types of anion that cause the corrosion of aluminium tube. In this study, it is examined that the condensation water effects on corrosion of aluminium tube. And method for improvement of corrosion characteristics is investigated using the dipping and electrochemical test.

• Journal of Power System Engineering
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• v.20 no.1
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• pp.18-23
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• 2016

As diesel engines have high power and good fuel economy on top of less $CO_2$ emissions, their market shares are increasing not only in commercial vehicles but also in passenger cars. LNT, urea-SCR and combination of them have been developed for after-treatment of the exhaust gas to reduce NOx on diesel vehicles. The aim of this study is to investigate the $NH_3$ generation characteristics of LNT catalyst downstream. It was found from the experiments of the LNT catalyst that $H_2$ was useful as a reductant in SCR catalyst because it can enhance the de-NOx performance and improve $NH_3$ selectivity. The $NH_3$ generation of the LNT, when hydrothermally aged at $900^{\circ}C$ for 18 hr, increased to about 90ppm at $300^{\circ}C$ due to Pt sintering and Ba agglomeration. LNT catalyst was most sulfur poisoning at $500^{\circ}C$. The $NH_3$ slip increased due to the reduction of residence time according to SV increase.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.12
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• pp.952-960
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• 2009

Selective Catalytic Reduction (SCR) system is a high-effective NOx reduction technology in diesel engines. As the emission standard of diesel engines is more stringent, vehicle manufactures makes efforts on emission technologies. This paper discusses the performance of Urea-SCR system according to the engine operating conditions in a passenger diesel engine. Engine test results in this paper show that it is important to consider the catalyst temperature and space velocity to obtain high NOx conversion efficiency. In condition of high catalyst temperature, over 90% NOx conversion efficiency is indicated. However, when catalyst temperature is low, NOx conversion efficiency was decreased. Also, it was shown that space velocity mainly effects on the DeNOx performance under 220 degree celsius of SCR catalyst temperature. As the urea injection pressure was decreased, NOx conversion efficiency was declined. It is concerned about urea droplet atomization. This work shown in this paper can lead to improved overall NOx conversion efficiency.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.6
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• pp.19-25
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• 2008

Selective Catalytic Reduction is effective in the reduction of NOx emission. This research focused to evaluate the performance of a urea-SCR system and was conducted in two procedures. One is SCR reactor test using model gas in order to provide an optimal injection condition itself. In this step, some parametric study on emission temperature, space velocity, aspect ratio and the formation of urea spray were made by using flow visualization and Computation Fluid Dynamics techniques. The basic simulation results contributed in determining the layout for an actual engine test. The other is an engine performance and emission test. The urea injector was placed at the opposite direction of exhaust gases emitted into an exhaust duct and an optimal amount of a reducing agent is estimated accurately under different engine loads and speeds. Furthermore, the variation of NOx emission and applied amount of urea was investigated in terms of modes under the condition of with and without SCR, and other emissions such as PM, CO and NMHC were evaluated quantitatively as well. This research may provide fundamental data for the practical use of urea-SCR in future.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.6
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• pp.28-35
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• 2012

This study is on SCR reactor, NOx reduction system in Marine that has been an issue nowadays. Especially design data was obtained by numerical on flow uniformity that is one of the design factor in SCR reactor. Also pressure drop on catalyst size inserted into SCR reactor was compared by experiment and numerical analysis. S/W, numerical analysis used for this study was confirmed that the result of numerical analysis used STAR-CCM+, common use CFD code, pressure drop on catalyst is not big different from the result of numerical analysis. In addition, degree of uniformity of liquid on SCR reactor was over 0.9. Whereas it was assured that degree of uniformity of liquid was changed depends on the shape of pipe at the entrance of SCR.