• Journal of Korean Society for Atmospheric Environment
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• v.15 no.4
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• pp.457-461
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• 1999

Recently, increasing usage of diesel vehicle, many countries try to reduce the pollutant materials by emission regulation standard. Particularly, in our country, the supplement ratio of diesel vehicle is high, and air pollution by particulate matter(PM) is very serious. So, in theoretical study wer analyzed the formation principle of gaseous emission and PM, the characteristics of CVS-75 mode. In experimental study, we tested exhaust gas reduction of emission and PM, the characteristics of CVS-75 mode. In experimental study, we tested exhaust gas reduction of disel oxidation catalyst(DOC) by CVS-75 mode in light duty diesel vehicle. In case of an automobiletest with the 2,956cc diesel engine which DOC was equipped, CVS-75 mode which is similar to driving conditions on the road was chosen as the restrictive mode of light duty diesel automobile in our country. According to the Pt, the reduction rate of exhaust emission was estimated with using 0.1% high sulfur fuel and 0.05% low sulfur fuel.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.3
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• pp.261-266
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• 1998

Recently, air pollution is increased according to increase of vehicle. So many countries are studying about DOC for diesel emission decrease. However, there are many difficulty in applying to DOC . In this study, SOx exhaust gas equipped with DOC was studied and we obtained several test results as following. First, in diesel oxidation catalyst, additives such as Pt is very effective for 503 and sulfate. Second, the oxidative activity for 502 has decreased to add such as Pt and the decrease of 502 is effect for the reduction of PM in high temperature . And finally, in high temperature, concentration of SOx is increased and temperature is affected by process from SOB to 503, whereas engine performance and fuel consumption are not affected by equipped DOC.

• Clean Technology
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• v.16 no.4
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• pp.265-271
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• 2010

The deactivated diesel oxidation catalyst(DOC) was remanufactured by ultrasonic wave treatment with various solutions, followed by active component re-impregnation. The catalytic performance and surface properties of remanufactured DOC were studied at various remanufacturing conditions. The proper ultrasonic-wave cleaning time at various solutions and optimal re-impregnation amounts of active component for the best catalytic performance were investigated. The catalytic performance tests on the conversions of CO and THC(total hydrocarbon) were also carried out at various temperatures by catalytic reaction test unit using bypass gas from the diesel engine dynamo system. It was found that the catalytic performance of DOC remanufactured with the high-temperature air washing, ultrasonic wave cleaning at acidic/basic solutions and active component re-impregnation method was recovered to 90% level of its activity compared to that of the fresh DOC, which was caused by removing the deactivating materials from the surface of the DOC through the analyses of catalyst performance test and their characterization by Optical microscope, EDX, ICP, TGA, and porosimeter.

• International Journal of Automotive Technology
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• v.7 no.5
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• pp.527-534
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• 2006

Modern passenger cars with diesel engines are equipped with DOC(diesel oxidation catalyst) for the purpose of reducing HC and CO in the exhaust stream. Cold start exhaust emissions pose troubles here as on gasoline engine vehicles. As a result, some of the diesel passenger cars roll off todays the assembly lines with WCC(warm-up catalytic converter). Oxidation characteristics of the particulates in WCC is analyzed in this study by EEPS(engine exhaust particulate size spectrometer). The maximum number of PM is found to come out of WCC in sizes near 10nm when an HSDI diesel engine is operated under the conditions of high speed and medium to heavy load. When the temperature of the WCC exceeds $300^{\circ}C$, the number of PM smaller than 30 nm in diameter sharply increases upon passing through the WCC. Total mass of emitted PM gets reduced downstream of the WCC under low speed and light load conditions due to adsorption of PM onto the catalyst. Under conditions of high speed and medium to heavy load, the relatively large PM shrink or break into fine particles during oxidation process within the WCC, which results in more mass fraction of fine particles downstream of the WCC.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.7
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• pp.15-23
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• 1999

In recent years, environmental damage to urban area becomes serious problem due to the exhaust emissions by increasing the number of vehicle . Especially, diesel particulate matters(DPM) are hazardous air pollutant s to human health and environment. The reduction technologies of exhaust emissions from diesel engines are improvement of engine combustion, fuel quality and development of diesel exhaust aftertreatment. In this study, a diesel oxidation catalyst(DOC) that is one of diesel exhaust aftertreatments was made for performance evaluation . It was tested for NA and turbocharged engine by D-13 mode that currently be used for regulation driving test mode in Korea Scanning mobility particle sizer (SMPS) was used for the analysis of the particle size distribution with and w/o DOC. As the results , for NA and tubochartged engine, CO, THC, DPM was respectively reduced 85.7, 40.7,3.3% and 79.1, 53.1, 11.6% by DOC. Test results of particle size distribution was showed that particle number is 107 ~108per ㎤ , 2 $\times$105 ~5$\times$105$\mu\textrm{g}$/㎥ for weight concentration and 100~200nm for particle mean size in diesel engine and there is no effect to reduce the particle concentration by the DOC.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.8
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• pp.34-42
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• 1999

In late 1997, the portion of registered light-duty diesel vehicle was 25.3% and its emission rate was 17.1% in Korea. Especially, diesel particulate matters(DPM) and NOx are hazardous air pollutants to human health and environment in urban area. The reduction technologies of exhaust emissions from diesel engines are improvement of engine combustion, fuel quality and development of diesel exhaust after treatment , In this study , a light-duty diesel oxidation catalyst(DOC) that is one of the diesel exhaust after treatment was made for performance evaluation and the emission characteristics were tested on CVS-75 mode. And the analysis of the particle size distribution with scanning mobility particle 100, 67.6% and 66.7, 10.0% for Pt and Pt-V catalyst .And for Pt catalyst, the PM increased 7.8% because of increasing sulfate but Pt-V catalyst reduced the PM to 23.0% . Test results of particle size distribution showed that peak values of number and mass densities are respectively 100∼200nm their distribution trend independent of vehicle speed.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.37-38
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• 2012

Two catalyst systems with different content of precious metal coated on DOC are carefully tested in a diesel engine to investigate the emission characteristics of $NO_2$. Three types of experiment methods ($NO_2$ conversion test, ETC mode test, and BPT test) are applied to compare the performance of the two catalyst systems. All the experimental results consistently indicate that it is possible to satisfy $NO_x$ regulation by properly lowering the content of precious metal without the loss of PM removal performance.

• Journal of Power System Engineering
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• v.5 no.2
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• pp.13-21
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• 2001

Diesel emission control is being addressed worldwide to help preserve the global environment. This paper mainly deals with the effects of oxidation catalysts to reduce emissions from the automotive heavy-duty diesel engine. Two types of the oxidation catalyst with different kinds of precious material were used. An 11 litter displacement diesel engine with turbocharger was operated to evaluate DOC with various engine speed, load conditions under D-13 mode cycle. We could propose the detail emission data of an automotive heavy-duty diesel engine and the characteristics of the conversion efficiency of the DOC under the D-13 mode. It was found that the mean conversion efficiencies of CO and THC were 49.7% and 61% under the D-13 mode test, respectively.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.5
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• pp.529-537
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• 2000

Several Pt-based oxidation catalysts with different loading were prepared with various metal precursor solutions and characterized with H$_2$ chemisorption and TEM for Pt particle size. V was added to Pt-based catalyst for inhibiting SO$_2$oxidation reaction, as result, Pt-V/Ti-Si catalyst prepared by ERMS(Free Reduced Metal in Solution) method showed high enough activity and better inhibition on SO$_2$oxidation than Pt only catalyst. Optimum Pt particle size for diesel oxidation reaction turned out to be the size of around 20 nm. A prototype catalyst was prepared for light=duty diesel passenger car, and teated for the emission reduction performance with Korean regulation test mode(CVS-75 mode) on chassis dynamometer. The catalyst shows the performance reduction of 75~94% for CO, 53~67% for HC and 10~31% for PM. In the case of heavy-duty diesel catalyst, the domestic formal regulation teat mode D-13 was adopted for both Na engine and Turbo engine. The conversions of CO and THC are high enough(86% and 41%) while the reductions of NOx and PM are relatively low(3~11%).

• Journal of Mechanical Science and Technology
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• v.20 no.1
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• pp.1-12
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• 2006

This work reviews the effects of catalyst formulation and exhaust gas composition on soot oxidation in CDPF (Catalytic Diesel Particulate Filter). DOC's (Diesel Oxidation Catalysts) have been loaded with Pt catalyst (Pt/$Al_{2}O_3$) for reduction of HC and CO. Recent CDPF's are coated with the Pt catalyst as well as additives like Mo, V, Ce, Co, Fe, La, Au, or Zr for the promotion of soot oxidation. Alkali (K, Na, Cs, Li) doping of metal catalyst tends to increase the activity of the catalysts in soot combustion. Effects of coexistence components are very important in the catalytic reaction of the soot. The soot oxidation rate of a few catalysts are improved by water vapor and NOx in the ambient. There are only a few reports available on the mechanism of the PM (particulate matter) oxidation on the catalysts. The mechanism of PM oxidation in the catalytic systems that meet new emission regulations of diesel engines has yet to be investigated. Future research will focus on catalysts that can not only oxidize PM at low temperature, but also reduce NOx, continuously self-cleaning diesel particulate filters, and selective catalysts for NOx reduction.