• 동력기계공학회지
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• 제17권1호
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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.

• 한국자동차공학회논문집
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• 제16권5호
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• pp.68-76
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• 2008

Diesel $NO_x$ reduction by $NH_3$-SCR in conjunction with the effective oxidation precatalyst was analytically investigated. Physicochemical processes in regard to $NH_3$-SCR $NO_x$ reduction and catalytic NO-$NO_2$ conversion are formulated with detailed descriptions on the commanding reactions. A unified model is correctly validated with experimental data in terms of extents of $NO_x$ reduction by SCR and NO-$NO_2$ conversion by DOC. The present deterministic model based on the rate expressions of Langmuir-Hinshelwood reaction scheme finds a conversion extent directly. A series of numerical experiments concomitant with parametric analysis of the $NO_x$ reduction was conducted. $NO_x$ reduction is promoted in proportion to DOC volume ar lower temperatures and an opposite holds at lower space velocity and intermediate temperatures. $NO_x$ conversion is weakly correlated to the space velocity and the DOC volume at higher exhaust temperature. In DOC-SCR system, the $NO_x$ reduction efficiency depends on the $NH_3/NO_x$ ratio.

• Bulletin of the Korean Chemical Society
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• 제35권2호
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• pp.525-530
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• 2014

Titanium dioxide nanotube supported ZSM-5 zeolite composite catalyst was fabricated by decorating ZSM-5 zeolite on the hydrothermally synthesized titanium dioxide via hydrothermal process and subsequent annealing. The catalyst was characterized by X-ray powder diffraction (XRD), Transmission electron microscopy (TEM) and Nitrogen adsorption-desorption (BET). The surface acidity of the catalyst was measured by means of Fourier transform infrared (FT-IR) spectrum of pyridine adsorption. And the catalytic activity for ethanol dehydration to ethylene was evaluated in a continuous flow fixed-bed reactor. Attributed to the increase of the effective surface acid sites caused by titanium dioxide nanotube as electron acceptor, titanium dioxide nanotube supported ZSM-5 zeolite composite catalyst exhibits strongly enhanced activity for ethanol dehydration to ethylene.

• Korean Journal of Chemical Engineering
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• 제35권11호
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• pp.2157-2163
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• 2018

Catalytic reactors have been essential for chemical engineering process, and different designs of reactors in multi-scales have been previously studied. Computational fluid dynamics (CFD) utilized in reactor designs have been gaining interest due to its cost-effective advantage in designing the actual reactors before its construction. In this work, butadiene synthesis via oxidative dehydrogenation (ODH) of n-butene using tubular reactor was used as a case study in the CFD model. The effects of coolant and reactor diameter were investigated in assessing the reactor performance. Based on the results of the CFD model, the conversion and selectivity were 86.5% and 59.5% respectively in a fixed bed reactor under adiabatic condition. When coolants were used in a tubular reactor, reactor temperature profiles showed that solar salt had lower temperature gradients inside the reactor than the cooling water. Furthermore, higher conversion (90.9%) and selectivity (90.5%) were observed for solar salt as compared to the cooling water (88.4% for conversion and 86.3% for selectivity). Meanwhile, reducing the reactor diameter resulted in smaller temperature gradients with higher conversion and selectivity.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제33회 KOSCO SYMPOSIUM 논문집
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• pp.20-26
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• 2006

본 연구는 Fuel-NOx 제어를 위한 암모니아 중 질소성분의 전환반응에 대한 실험 결과이다. 특히 열분해가스 촉매연소에서 NOx 생성을 줄이기 위한 제어 조건을 제시하였으며, Fuel-NOx 반응 메카니즘 연구의 기초자료를 제시하였다.

• Bulletin of the Korean Chemical Society
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• 제33권2호
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• pp.524-528
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• 2012

A kind of nanosized sulfated zirconia was prepared by a hydrothermal method, and full characterized by XRD, TEM, BET, TGA, and FTIR. Its catalytic activity was evaluated in the esterification reactions, including the testing of the catalytic reusability and the optimization of reaction conditions. The obtained catalyst was revealed to be highly efficient solid catalyst for the esterification of acetic acid with n-butanol, presenting the advantages of high conversion and selectivity, easy recovery, and steady reusability.

• Bulletin of the Korean Chemical Society
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• 제33권8호
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• pp.2748-2752
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• 2012

Cr(III) and Co(III) complexes with acetylacetonate were anchored onto a mesoporous MCM-41 through Schiff condensation. The materials were characterized by XRD, FT-IR, BET, CHN and ICP techniques. Elemental analysis of samples revealed that one C=N bond was formed through Schiff condensation on MCM-41 surface. The catalysts were tested for the alcohol oxidations using t-butyl hydroperoxide (TBHP) and $H_2O_2$ as oxidant. The catalytic experiments were carried out at both room temperature and reflux condition. Various solvents such as dichloromethane, acetonitrile and water were examined in the oxidation of alcohols. Among the different solvents, catalytic activity is found more in acetonitrile. Further, the catalysts were recycled three times in the oxidation of alcohols and no major change in the conversion and selectivity is observed, which shows that the immobilized metal-acetylacetonate complexes are stable under the present reaction conditions.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.403.2-403.2
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• 2016

Porous materials play a significant role in energy storage and conversion applications such as catalyst support for polymer electrolyte membrane fuel cell. In particular, hierarchical porous materials with both micropores (poresize, ${\delta}$ < 2 nm) and regularly arranged mesopores (2 nm < ${\delta}$ < 50 nm) are known to greatly enhance the efficiency of catalytic reactions by providing enormous surface area as well as fast mass transport channels for both reactants and products from/to active sites. Although it is generally agreed that the microscopic structure of the porous materials directly affects the performance of these catalytic reactions, neither detailed mechanisms nor fundamental understanding are available at hand. In this study, we propose an atomistic model of hierarchical nanostructured porous carbons (HNPCs) in molecular dynamics simulations. By performing a systematic study, we found that structural features of the HNPC can be independently altered by tuning specific synthesis parameters, while remaining other structures unchanged. In addition, we show some structure-property relations including mechanical and gas transport properties.

• Environmental Engineering Research
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• 제13권4호
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• pp.192-196
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• 2008

The generation of high purity hydrogen from reformed hydrocarbon fuels, or syngas, is essential for efficient operation of the fuel cell (PEMFC, Polymer Electrolyte Membrane Fuel Cell). Usually, major components of reformed gas are $H_2$, CO, $CO_2$ and $H_2O$. Especially a major component, CO poisons the electrode of fuel cells. The water gas shifter (WGS) that shifts CO to $CO_2$ and simultaneously produces $H_2$, was developed to a two stage catalytic conversion process involving a high temperature shifter (HTS) and a low temperature shifter (LTS). Also, experiments were carried out to reduce the carbon monoxide up to $3{\sim}4%$ in the HTS and lower than 5,000 ppm via the LTS.

• 한국자동차공학회논문집
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• 제10권5호
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• pp.1-8
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• 2002

For gasoline engines, a three-way catalytic converter that has the maximum efficiency at stoichiometric air/fuel ratio is used to clean up the exhaust gas. So a precise air/fuel ratio control is necessary to maximize the catalytic conversion efficiency, For a transient condition, a fred-forward air/fuel ratio control method that estimates the air mass inducted into a cylinder is being used. In this study, a fuel injection map that makes an accurate air/fuel ratio control possible was constructed for the very same transient condition. For the same condition above, intake air model and fuel model were refined so that fuel injection values based on air mass through a throttle valve and intake manifold pressure are equal to the map values.