• 한국환경과학회지
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• 제26권1호
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• pp.67-78
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• 2017

Combustion of ethanol (EtOH) at low temperatures has been studied using titania- and silica-supported platinum nanocrystallites with different sizes in a wide range of 1~25 nm, to see if EtOH can be used as a clean, alternative fuel, i.e., one that does not emit sulfur oxides, fine particulates and nitrogen oxides, and if the combustion flue gas can be used for directly heating the interior of greenhouses. The results of $H_2-N_2O$ titration on the supported Pt catalysts with no calcination indicate a metal dispersion of $0.97{\pm}0.1$, corresponding to ca. 1.2 nm, while the calcination of 0.65% $Pt/SiO_2$ at 600 and $900^{\circ}C$ gives the respective sizes of 13.7 and 24.6 nm when using X-ray diffraction technique, as expected. A comparison of EtOH combustion using $Pt/TiO_2$ and $Pt/SiO_2$ catalysts with the same metal content, dispersion and nanoparticle size discloses that the former is better at all temperatures up to $200^{\circ}C$, suggesting that some acid sites can play a role for the combustion. There is a noticeable difference in the combustion characteristics of EtOH at $80{\sim}200^{\circ}C$ between samples of 0.65% $Pt/SiO_2$ consisting of different metal particle sizes; the catalyst with larger platinum nanoparticles shows higher intrinsic activity. Besides the formation of $CO_2$, low-temperature combustion of EtOH can lead to many other pathways that generate undesired byproducts, such as formaldehyde, acetaldehyde, acetic acid, diethyl ether, and ethylene, depending strongly on the catalyst and reaction conditions. A 0.65% $Pt/SiO_2$ catalyst with a Pt crystallite size of 24.6 nm shows stable performances in EtOH combustion at $120^{\circ}C$ even for 12 h, regardless of the space velocity allowed.

• International Journal of Aeronautical and Space Sciences
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• 제18권2호
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• pp.270-278
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• 2017

This paper describes development procedure and verification test results of a bi-propellant thruster using hydrogen peroxide and kerosene. The design thrust of the thruster is about 500 N and six swirl type coaxial injectors were used. The passage type manifolds were employed for the injector head to reduce the response time. The passage was designed to minimize stagnation points and recirculation region to ensure uniform flow distribution and sufficient cooling performance through flow analysis using Fluent. A catalytic igniter using hydrogen peroxide was installed at the center of the injector head. The propellant feeding and spray characteristics were confirmed by hydraulic tests. Combustion tests were performed on design and off-design points to analyze combustion characteristics under various mixture ratio conditions. The combustion test results show that combustion efficiency was over 95 % and chamber pressure fluctuation were less than 1.5 % under all test conditions.

• 한국군사과학기술학회지
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• 제13권6호
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• pp.1180-1187
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• 2010

In the last decade, hydrogen peroxide has received renewed interest as a green propellant which is non-toxic, environmentally clean and relatively easy to handle. This study was performed to acquire the design technique and combustion performance of a 200N bi-propellant engine using hydrogen peroxide and kerosene. The engine which used a catalytic ignition method was designed and cold flow tests were carried out to investigate atomization characteristics. Combustion tests including a pulse mode operation were performed to investigate the combustion performance on various O/F ratios. The results showed that the combustion efficiency and the repeatability of the engine performance were enough to use as an essential database for the development of a high performance engine.

• 항공우주시스템공학회지
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• 제11권2호
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• pp.9-15
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• 2017

제올라이트 촉매를 이용한 에탄올의 연소 성능 향상 가능성과 질소산화물 및 일산화탄소 배출 특성을 검증하기 위해 촉매 반응 생성물, 에탄올, 케로신을 연료로 사용하여 마이크로 가스터빈 엔진 구동실험을 수행하고 그 결과를 비교하였다. 촉매 반응 생성물의 추력은 케로신의 추력보다 낮았으나 에탄올을 사용했을 때에 비해 평균적으로 5% 정도 향상되었다. 촉매 반응 생성물의 질소산화물과 일산화탄소 배출량은 전반적으로 케로신에 비해 매우 낮게 측정되었다. 결론적으로 제올라이트 촉매를 이용하여 에탄올을 개질하는 경우, 에탄올의 친환경성을 유지하면서 엔진성능을 개선할 수 있는 가능성을 확인하였다.

• 자원리싸이클링
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• 제29권6호
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• pp.114-124
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• 2020

시멘트 산업에서 질소산화물 배출은 중요한 문제로 인식되고 있으며 이를 저감하는 기술은 공정변경, 단계적 연소, 저 NOx 버너, SNCR, SCR로 나눌 수 있다. 이중 시멘트 산업에서 가장 많이 사용되고 있는 SNCR 운영만으로는 향후 강화될 배출허용기준을 만족시키기 어려울 것이 예상되며 SCR 등의 추가적인 장비 개선 및 기술 확보가 필요한 상황이다. 이에 따라 최근에는 국외를 중심으로 SNCR 및 SCR 동시 적용 기술, 분진 및 탈질 필터 기술과 NO 산화를 이용한 제거기술 등을 개발하고 있다.

• Journal of Mechanical Science and Technology
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• 제20권1호
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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.

• 융복합기술연구소 논문집
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• 제10권1호
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• pp.19-24
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• 2020

The purpose of the study is to investigate the thermal durability characteristics of the Pt catalyst and additives used in a catalytic combustor. The catalyst used in the experiment was based on Pt (3 wt%), and a total of 12 types were prepared using a combination of additives (Ni, La, Ce, Fe, and Co). From the results, In the fresh state, the two types of combination catalysts with the highest C₃H₈ conversion were Pt_Ce (79.9%) at 500℃, and in the three types of combination catalysts, Pt_La_Ni (93.4%) at 500℃ had the best performance. Among aged catalysts at 850℃ and 8 hours, Pt-La-Ni and Pt-Ni-Ce catalysts showed the highest C₃H₈ conversion of about 71% at 500℃.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2001년도 제22회 KOSCI SYMPOSIUM 논문집
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• pp.99-105
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• 2001

For the design of selective catalytic reactors of NOx by $NH_3$, engineering approach can be performed to determine the reactor shape, mixing device and $NH_3$ injection system. This study shows the optimization of guide vanes to improve the flow pattern near the catalyst layer of SCR in a untility boiler. By varying their spacings and shapes, flow performance of guide vanes was analyzed to achieve an uniform velocity distribution which increases the NOx convesion efficiency, and a flow direction normal to the layer which minimises the erosion by the dust in the flue gas. Including these results, experimental and numerical studies for the SCR design were discussed.

• 동력기계공학회지
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• 제3권2호
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• pp.20-25
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• 1999

Experiments were carried out to investigate the characteristics of formaldehyde emission from the small gasoline engine and its reduction technologies. Catalytic converters used are Pt/Rh, Pd/Rh, Pd/Pt, $62cell/cm^2$ monolith type. The measurement of formaldehyde was conducted by using the method of DNPH-GC. From the experimental results, formaldehyde emission increased in a lean mixture due to incomplete combustion of the hydrocarbons. The order of catalytic activity of formaldehyde oxidation was Pt/Rh > Pd/Rh > Pd/Pt. As the distance from the exhaust manifold to the inlet of the catalyst became far, in spite of lower catalyst temperature, formaldehyde concentration decreased because of the adsorption of formaldehyde.

• 한국수소및신에너지학회논문집
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• 제15권3호
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• pp.244-249
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• 2004

Pd catalyst have been used in hydrogenation, oxidation, and low temperature combustion reaction. Recently, it has been candidated as a possible reagents in the partial oxidation of methanol reformers of the fuel cell. Pd catalysts, even though it is very precious and expensive, catalytic functioning is good, but it still need to be improved in the matter of durability and low catalytic activity after calcination. In this study, we synthesize the improved Pd catalyst and study their chemical functioning.