• Transactions of the Korean Society of Automotive Engineers
• /
• v.13 no.5
• /
• pp.181-187
• /
• 2005

The behavior of fox adsorption and desorption of the NOx storage catalyst supported on Ba additive were studied by the TPA/TPD experiments and reactivity tests. Applying the transient responses and NOx TPA/TPD test by CLD were effective methods to analyze the characteristics of the NOx storage catalyst. NOx variation of the NOx storage catalyst in the lean air/fuel conditions according to temperature was dominated by NOx adsorption and desorption rather than catalytic reduction. The presence of reductants in the lean mixture promoted the NOx desorption at the $500^{\circ}C$ higher temperature. The temperatures for maximum NOx conversion with CH4 and $C_3H_6$ as a rich spike reductant appear around $500^{\circ}C\;and\; 400^{\circ}C$ respectively.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.8
• /
• pp.789-798
• /
• 2011

We carry out an experimental investigation to analyze the basic performance of NO(nitric oxide) storage in a lean phase and also analyze the NO reduction achieved by the spraying of reducing agents in the rich phase of the exhaust gas in an LNT(Lean NOx Trap). This is an after-treatment system used to reduce the NOx emissions from a diesel engine. If the stored NO is reduced, we measure the outlet concentration downstream of the LNT. The test LNT material used in the experiments is commercial LNT. After being canned into stainless-steel(SUS304), it was built in a micro bench-flow reactor. Compositions of feed gases, three heated and three no heated gases were sprayed upstream of the LNT to analyze the characteristics. We use various temperatures and space velocities as response variables.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.12 no.5
• /
• pp.79-84
• /
• 2004

We evaluated the reduction performance of NOx storage catalyst and TWC for lean-burn natural gas engine by the model gas. The method of unsteady state reaction was used to compare with reduction performances of NOx storage catalyst and TWC. It was found that the effective parameter was rich spike duration, temperature of the model gas. In the presence of $CO_2$ and $H_2O$ in the reaction mixture was decreased the NOx reduction performance.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.15 no.3
• /
• pp.147-152
• /
• 2007

This study investigates the aging characteristics of NOx storage and reduction(NSR) catalyst on the emission conditions of lean burn natural gas vehicles. We designed various NSR catalysts using by the double-layer washcoat technology to increase of a surface area and a thermal durability performance of the catalysts. The experiments were conducted with 3 kinds of the NSR catalysts, which were manufactured using by a honeycomb cordierite substrate. It was found that Ba is weak in the thermal aging because it has lower melting temperature than that of precious metals (PMs). The suitable loading amount of Ba in this study should be about 42 g/L from the results of the NOx adsorption and the NOx reduction efficiency. The major reason in deactivation of the NSR catalyst is the decrease of the adsorption site owing to the agglomeration and sintering of Ba rather than PM aging by hydrothermal aging. It was confirmed by results of BET, SEM and TEM.

• Journal of the korean Society of Automotive Engineers
• /
• v.25 no.4
• /
• pp.52-55
• /
• 2003

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.9
• /
• pp.474-481
• /
• 2018

The policy-making and technological development of eco-friendly automobiles designed to increase their supply is ongoing, but the internal combustion engine still accounts for approximately 95% of automobiles in use. To meet the stricter emission regulations of internal combustion engines based on fossil fuels, the proportion of after-treatments for vehicles and (ocean going) vessels is increasing continuously. As diesel engines have high power and good fuel economy in addition to less CO2 emissions, their market share is increasing not only in commercial vehicles, but also in passenger cars. Because of the characteristics of the diesel combustion, however, NOx is generated in localized high-temperature combustion regions, and particulates are formed in the zones of diffusion combustion. LNT and urea-SCR catalysts have been developed for the after-treatment of exhaust gas to reduce NOx in diesel vehicles. This study examined the effect of a containing promoter on SCR catalysts to cope with the severe exhaust gas regulation. The de-NOx performance of the Mn-SCR catalyst was the best, and the de-NOx performance was improved as the ion exchange rate between Mn ion and Zeolyst was good and the activation energy was low. The de-NOx performance of the 7Cu-15Ba/78Zeoyst catalyst was 32% at $200^{\circ}C$ and 30% at $500^{\circ}C$, and showed the highest performance. The NOx storage material of BaO loaded as a promoter was well dispersed in the Cu-SCR catalyst and the additional de-NOx performance of BaO was affected by the reduction reaction of the Cu-SCR catalyst. Among the three catalysts, the 7Cu-15Ba/Zeolyst SCR catalyst was resistant to thermal degradation. The same type of CuO due to thermal degradation migrates and agglomerates because BaO reduces the agglomeration of the main catalyst CuO particles.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.34 no.7
• /
• pp.689-696
• /
• 2010

The Because of its high thermal efficiency, the direct injection (DI) diesel engine has emerged as a promising potential candidate in the field of transportation. However, the amount of nitrogen oxides ($NO_x$) increases in the local high-temperature regions and that of particulate matter (PM) increases in the diffusion flame region during diesel combustion. In the de-$NO_x$ system the Lean $NO_x$ Trap (LNT) catalyst is used, which absorbs $NO_x$ under lean exhaust gas conditions and releases it in rich conditions. This technology can provide a high $NO_x$-conversion efficiency, but the right amount of reducing agent should be supplied to the catalytic converter at the right time. In this research, the emission characteristics of a diesel engine equipped with a micro-reformer that acts as a reductants-supplying equipment were investigated using an LNT system, and the effects of the exhaust-gas temperature were also studied.

• Proceedings of the KAIS Fall Conference
• /
• 2009.12a
• /
• pp.1050-1053
• /
• 2009

상용화 되고 있는 Pt/BaO/$Al_2O_3$촉매에 Iron을 첨가량에 따른 흡장량의 증가를 알아내기 위한 실험을 실행하였다. $SO_2$를 포함하고 있는 배기가스중의 NOx를 제거하기 위해 SOx 존재 하에서 Pt/Co/BaO/$Al_2O_3$촉매에 Iron량을 증감하여 흡장량을 비교분석하였으며, 10%에서 높은 흡장 면적을 나타내었다. XRD와 BET 결과 고온 소성시 흡장량 감도는 Pt의 열화 소결이 원인인 것으로 나타난다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.6
• /
• pp.167-175
• /
• 2018

Natural gas is a clean fuel that discharges almost no air-contaminating substances. This study examined the simultaneous reduction of $CH_4$ and NOx of NGOC/LNT catalysts for CNG buses related to the improvement of the $de-CH_4/NOx$ performance, focusing mainly on identifying the additive catalysts, loading of the washcoat, stirring time, and types of substrates. The 3wt. % Ni-loaded NGOC generally exhibited superior $CH_4$ reduction performance through $CH_4$ conversion, because Ni is an alkaline, toxic oxide, and exerts a reducing effect on $CH_4$. A excessively small loading resulted in insufficient adsorption capacity of harmful gases, whereasa too high loading of washcoat caused clogging of the substrate cells. In addition, with the economic feasibility of catalysts considered, the appropriate amount of catalyst washcoat loading was estimated to be 124g/L. The NOx conversion rate of the NGOC/LNT catalysts stirred from $200^{\circ}C$ to $550^{\circ}C$ for 5 hours showed 10-15% better performance than the NGOC/LNT catalysts mixed for 2 hours over the entire temperature range. The NGOC/LNT catalysts exhibitedapproximately 20% higher $de-CH_4$ performance on the ceramic substrates than on the metal substrates.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.15 no.5
• /
• pp.105-111
• /
• 2007

In this study, we investigated the conversion performance of de-NOx catalyst for lean-burn natural gas engine. As a de-NOx catalyst, NOx storage reduction catalyst was composed of Pt, Pd and Rh with washcoat including Ba and Ni, Ru-ZSM-5. Ni, Ru-ZSM-5, which was regarded as a NOx direct decomposition catalyst, was made up of ion exchanged ZSM-5 by 5wt.% Ni or Ru. The performance of de-NOx catalyst was evaluated by NOx storage capacity and catalytic reduction in air/fuel, $\lambda=1.6$. The catalytic reaction was also observed when the added fuel was supplied to fuel rich atmosphere by fuel spike period of 5 seconds. The NOx conversion of the catalysts with Ni-ZSM-5 or Ru-ZSM-5 was mainly caused by the effect of NOx adsorption of Ba rather than the catalytic reduction of Ni, Ru-ZSM-5. Ni, Ru-ZSM-5 catalysts can not use for the NSR catalyst because they have quick process in thermal deactivation.