• 한국연소학회지
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• 제5권1호
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• pp.1-6
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• 2000

Surface reaction occurs at a certain surface temperature when a catalyst is heated up in a reactive mixture. If homogeneous ignition does not occur, a steady state is observed because the heat produced by the surface reaction is balanced with the heat loss caused by convection, conduction and radiation. The present paper treats the effects of pressure on the surface temperature at the steady state. Hydrogen and oxygen are used as reactants and nitrogen as an inert gas. A spherical platinum catalyst of 1.5 mm in diameter is sustained in the chamber with two wires of 0.1 mm in diameter. As results, there exists a maximum steady temperature at a certain relative hydrogen concentration which increases with total pressure. At the steady state, it can be approximated that the heat release is estimated by the mass transfer considering the effect of natural convection. The experimental results are explained qualitatively by the approximation.

• 한국산학기술학회논문지
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• 제19권9호
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• pp.474-481
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• 2018

친환경자동차의 보급 확대를 위한 정책수립과 기술개발이 지속적으로 이루어지고 있는 실정이나 아직까지도 내연기관이 차지하는 비중은 약 95% 차지하고 있다. 화석연료를 기반으로 하는 내연기관의 엄격한 배기가스규제를 충족시키기 위해 자동차와 선박용 후처리장치의 비중이 점차로 증가하고 있다. 디젤엔진은 이산화탄소 배출량이 적고 강력한 파워와 연료의 경제성을 가지고 있으며, 상용차뿐만 아니라 승용차에서도 시장의 수요가 증가하고 있다. 디젤 연료 특성으로 인하여 질소산화물은 국부적인 고온연소 영역에서 생성되며, 입자상물질은 확산연소 영역에서 생성된다. 희박한 LNT(질소산화물 흡장촉매)와 urea-SCR(선택적인촉매환원장치)는 디젤엔진에서 질소산화물을 저감시키기 위한 후처리장치로 개발되어져왔다. 이 연구는 가혹해지고 있는 배기가스 규제 대응을 위해 선택적인촉매환원장치의 촉매에 포함됨 조촉매의 영향을 파악하는 것이다. 망간-선택적인촉매환원장치의 질소산화물 저감 성능이 가장 우수하였으며, 망간 이온과 Zeolyst의 Al과의 이온교환이 잘 되었고, 활성화 에너지가 낮아 반응 속도가 빨라짐에 따라 질소산화물 저감 성능이 향상되었다. 7Cu-15Ba/78Zeolyst SCR 촉매의 질소산화물 저감 성능은 200도에서 32%, 500도에서 30%를 나타내며 가장 높은 성능을 나타내었고, 조촉매로 첨가된 산화바륨의 질소산화물의 흡장 물질이 Cu-SCR 촉매에 잘 분산되어 있고 Cu-SCR 촉매의 환원 반응과 더불어 산화바륨의 추가적인 질소산화물 저감 성능이 영향을 끼쳤기 때문이다. 7Cu-15Ba/Zeolyst SCR 촉매는 3종 촉매 중 열적 열화에서 내구성이 강하였다. 열적 열화에 따른 동종 성분 산화구리가 이동하여 응집되는데, 산화바륨이 주촉매 산화구리 입자의 응집을 감소시켰기 때문이다.

• 한국가스학회지
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• 제20권6호
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• pp.23-30
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• 2016

천연가스를 이용한 기존 엔진들은 효율이 우수한 희박연소를 구현하였지만 배기가스의 정화성능이 점차 강화되는 배기규제에 대응하기 위해, 이론공연비 연소 방식으로 관심이 옮겨지고 있다. 이론공연비 연소 방식은 유해 배출가스의 정화효율이 높은 삼원촉매를 사용할 수 있는 장점이 있지만, 높은 연소열 발생에 따른 열 내구성 문제와 연비가 해결과제로 남아 있다. 천연가스에 수소를 혼합한 수소-천연가스 혼합연료(HCNG))는 수소의 빠른 연소속도에 의한 영향으로 연소속도가 증가하고, 희박한계가 증가하여 배기가스재순환(Exhaust gas recirculation; EGR) 률의 공급을 증가할 수 있다. EGR률 상승은 연소온도를 낮추게 되어 엔진 열 내구성에 긍정적인 영향을 줄 수 있고, 압축비를 더욱 증가 시킬 수 있어서 효율적인 연소조건을 형성하도록 도움을 줄 수 있다. 본 연구에서는 기존 대형 가스엔진을 이용하여 개발한 이론공연비 연소 방식의 HCNG 엔진의 배출가스 저감을 최소화하기 위해, 삼원촉매를 개발 및 적용하여 배기가스 특성을 평가하고 분석하고자 하였다. 현재 상용화된 시내버스용 삼원촉매와 HCNG용으로 개발 중인 시제 삼원촉매를 각각 설치하여 정상상태 운전조건 및 과도운전조건에서 실험을 진행하고 모드실험 결과를 비교하였다.

• 한국수소및신에너지학회논문집
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• 제19권1호
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• pp.1-9
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• 2008

Human has faced in lack of fossil fuel and environmental crisis because of high population growth and development of industry. Hydrogen, unlimited amount and clean resource from water electrolysis, is remarkably known as the solution of recent energy crisis. One of the special characteristics of hydrogen is that a little amount of catalytic such as platinum and palladium makes nonflammable combustion, in other words catalyst combustion. Catalytic combustion fueled by hydrogen is environmentally friendly. This paper considers some comparisons of characteristic of catalytic combustion between a single layer of platinum catalyst, double layer of platinum and nickel catalysts and mixture of platinum and nickel catalysts. Some experiments of temperature distribution at different positions and characteristic of combustion in low temperature region were done in order to find an applicable possibility as a house-cooking burner.

• 한국수소및신에너지학회논문집
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• 제25권2호
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• pp.122-130
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• 2014

Attrition characteristics of WGS catalysts for pre-combustion $ CO_2$ capture were investigated to check attrition loss of those catalysts, to check change of particle size distribution during attrition tests, and to determine solid circulation direction of WGS catalysts in a SEWGS system. The cumulative attrition losses of two catalysts increased with increasing time. However, attrition loss under humidified condition was lower than that under non-humidified condition case for long-term attrition tests. Between two catalysts, attrition loss of PC-29 catalyst was higher than that of commercial catalyst for long-term attrition tests. However, the commercial catalyst generated much more fines than PC-29 catalyst during attrition. Therefore, we conclude that the PC-29 catalyst is more suitable for fluidized bed operation if we take into account the separation efficiency of cyclone. Based on the results from the tests for the effect of humidity on the attrition loss, we selected solid circulation direction from SEWGS reactor to regeneration reactor because the SEWGS reactor contains more water vapor than regeneration reactor.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2000년도 제20회 KOSCO SYMPOSIUM 논문집
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• pp.152-161
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• 2000

The catalytically stabilized combustion of $CH_4$-air mixture on platinum catalyst was investigated numerically using a 2-D boundary layer model with detailed heterogeneous and homogeneous chemistries. The actual surface site density of monolith coated with platinum was decided by the comparison with experimental data. The comparisons were made between results for cases where only heterogeneous chemistry was allowed and both heterogeneous and homogeneous chemistries were allowed. It was found that the homogeneous reaction in the monolith had little effect on the change of temperature profile, methane conversion rate and light off location. The contributions of each reactions related with CO formation were discussed on the surface. The effects of operation conditions such as equivalence ratio, temperature, velocity and pressure at the entrance were studied. In thermal combustor, CO and NOx was produced less than 1 ppm at the exit and the production of $N_{2}O$ was more dominant than that of NO.

• 한국응용과학기술학회지
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• 제24권1호
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• pp.67-73
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• 2007

Methane combustion over perovskite catalysts was investigated. For the preparation of catalysts, Co, Mn, Fe, and Ni were used as B-site components of the perovskite catalysts $(ABO_3)$ and La was used as A-site component. The effect of calcination temperature on methane combustion and perovskite structure was also investigated. The structure of perovskites, surface area, and adsorbed oxygen species were tested with XRD, BET apparatus, and $O_2-TPD$, respectively. The formation of perovskite structure was affected by the calcination temperature. The catalyst desorbing oxygen at a lower temperature showed better activity for the methane combustion, therefore, the oxygen species desorbing at lower temperatures is responsible for the methane combustion.

• 대한환경공학회지
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• 제28권3호
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• pp.249-256
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• 2006

함침법과 침적침전법으로 Cu-Mn 산화물 촉매를 제조하여 톨루엔 촉매 분해 반응을 조사하였다. 구리와 망간이 혼합됨으로 촉매활성을 증진 시킬 수 있음을 확인할 수 있었다. 또한 같은 화학적 조성으로 제조된 함침법보다 침적침전법에 의해 제조된 Cu-Mn 산화물 촉매에서 톨루엔 분해 반응 활성이 더 높았다. 침적침전법에 의해 제조된 촉매는 10일간의 장기 분석과 수분 첨가에 의한 톨루엔 분해 효율에 변화가 없었다. 촉매 특성 분석 결과에 기초하여 보면, 침적침전법은 촉매의 표면에 균일한 분산과 작은 크기의 입자를 제공하며 환원 능력을 증진시키는 것으로 판단된다. 따라서 침적침전법은 촉매의 성능을 향상 시키고 촉매의 안정성을 중진 시키는 것으로 생각 된다. 또한 Cu-Mn 산화물 촉매에서 톨루엔 분해 반응은 산화환원 반응에 의존하며 $Cu_{1.5}Mn_{1.5}O_4$ 스피넬 구조가 주요한 촉매 활성점으로 작용하는 것으로 추측된다.

• 융복합기술연구소 논문집
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• 제9권1호
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• pp.7-12
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• 2019

The aim of this study is to improve the durability performance of catalysts for a catalytic combustor and to obtain operating conditions for stable combustion of the catalytic combustor. It was attempted to improve the durability of the catalysts by adding a promoter in order to reduce the cost of replacing Pt catalyst while maintaining stability. The main catalyst used in the study was Pt and the promoters were Ni and La. Pure Pt3/γ-Al₂O₃ catalyst without promoter was promoted to fast sintering states under harsh conditions and catalytic combustion was turned off, whereas the catalysts added La, Ni as promoter were showed relatively slow sintering states. It can be concluded that the promoter La, Ni effectively contributes to the improvement of the durability of the Pt catalyst, and it is possible to get longer durability and more stable duration than the conventional catalytic combustor.

• 한국대기환경학회지
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• 제11권2호
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• pp.131-136
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• 1995

The experiment for decomposing CFF-113 by a honeycomb catalyst was carried out in this study. Benzene and water were used as decomposing agents. The reaction of decomposition was from 600 .deg.C to 900.deg.C. Benzene was injected at 900.deg.C and then the catalyst was heated to 1100.deg.C by the heat of combustion of it. The electric power of the reactor was turned off when the combustion was started. The reaction temperature, however, was main trained and the decomposition of CFC-113 continued at that time. It was found that the highest decomposition efficiency was 80% at the ratio of benzene/CFC-113 of 20/1 in this experiment.