酸化觸媒에 의한 大型디젤엔진의 排出가스 淨化 特性 = Characteristics of Exhaust Emission Reduction of Heavy Duty Diesel Engine by Oxidation Catalyst

다국어 초록 (Multilingual Abstract)

The most desirable diesel oxidation catalyst (DOC) should have the properties of oxidizing CO, HC and SOF effectively at low exhaust gas temperature while minimizing the formation of sulfate at high exhaust gas temperature.
Precious metals such as platinum and palladium have been knowm to be sufficiently active for oxidizing CO, HC and SOF and also to have high activity for the oxidation of sulfur dioxide(SO_(2)) to sulfur trioxide(SO_(3)). There is a need to develop a highly selective catalyst which can promote the oxidation of CO, HC and SOF efficiently, but, on the other hand, suppress the oxidation of SO_(2). One approach to solve this problem is to load a base metal such as vanadium in Pt-based catalyst to suppress sulfate formation.
In this study, a Pt-V catalyst was prepared by impregnating platinum and vanadium onto a Ti-Si wash coated ceramic monolith substrate. The conversion retes of CO, HC and SO_(2) were investigated using a prepared Pt-V catalyst in a laboratory reactor by changing the formulations and reaction temperatures.
In addition, a prepared Pt-V catalytic converter was installed on a heavy duty diesel engine and the characteristics of the emission reduction were tested using a engine dynamometer at various operating conditions.
The emission reduction performance of Pt-V catalyst was also compared with that of a commercialized Pt catalyst currently being used in some of the heavy duty diesel engines in advanced countries.
The experimental results showed that vanadium was found to be a highly selective catalyst which does not significantly increase CO, HC light-off temperature and while simultaneously inhibiging the formation of sulface.
The effects of Pt-V and Pt catalysts on regulated and unregulated heavy duty diesel emissions were investigated using a 0.05 weight% sulfur content fuel with an engine dynamometer.
Experiments for gaseous emissions (CO, HC and aldehyde) as well as particulate emissions (TPM, SOF and sulface) have been conducted at several operating conditions such as T-7 mode, D-13 mode and S-13 mode before and after installing the Pt-V and Pt catalysts in the exhaust system.
The emission reduction performance of Pt catalyst with respect to CO, HC, SOF, PAHs and aldehyde was found to be a little higher than that of Pt-V catalyst, but the Pt catalyst showed innate disadvantage of causing an increase of TPM due to the sulfate formation via high SO_(2) conversion at high exhaust temperature, especially above 450℃.
In D-13 mode, Pt catalyst showed a conversion efficiency of 78% for CO, 35% for HC and 23% for TPM. On the other hand, Pt-V catalyst showed a conversion efficiency of 65% for CO, for 27% for HC and 7.8% for TPM. This result shows that the gas phase reduction with Pt catalyst was better than that of Pt-V catalyst, but the particulate reduction was reversed. However, the conversion efficiency of NO_(x) was low in both catalysts. The S-13 mode, representing the Seoul city bus driving pattern, showed almost similar results as the D-13 mode.
Only 1~3% of sulfur in the diesel fuel was converted to sulfur in TPM for the engine without catalyst, but almost 100% of sulfur conversion was achieved for the engine with Pt catalyst at maximum loading condition. In the case of Pt-V catalyst, there was no big difference in conversion with the base engine even at maximum loading condition.

목차 (Table of Contents)

• 목차 = ⅰ
• 표목차 = ⅴ
• 그림목차 = ⅶ
• ABSTRACT = ⅹ
• Ⅰ. 서론 = 1
• 1.1 연구배경 = 1
• 1.2 연구목적 = 4
• Ⅱ. 이론적 고찰 = 6
• 2.1 디젤엔진의 오염물질 배출특성 및 저감기술 = 6
• 2.1.1 일산화탄소 및 탄화수소 = 6
• 2.1.2 질소산화물 및 입자상물질 = 8
• 2.2 디젤산화촉매에 의한 배출가스 정화 = 11
• 2.2.1 가솔린엔진의 산화촉매와 디젤엔진의 산화촉매 = 11
• 2.2.2 DOC의 반응 메카니즘 = 13
• 2.2.3 DOC의 성능에 미치는 영향인자 = 13
• 1) 촉매 및 조촉매 = 13
• 2) 담체 (Wash Coat) = 17
• 3) 연료중 황함유량 = 18
• 4) 배기 온도 = 20
• 5) 배기 유속 = 20
• Ⅲ. 실험장치 및 실험방법 = 21
• 3.1 DOC의 Reactor실험 = 21
• 3.1.1 촉매의 제조 = 21
• 1) 지지체(Substrate) = 21
• 2) 담체 = 21
• 3) 촉매용액 조제 = 22
• 4) 촉매용액의 함침 = 22
• 5) Pt-V 촉매의조성 = 23
• 3.1.2 실험장치 = 23
• 3.2 DOC의 Engine Bench 실험 = 25
• 3.2.1 실험용 엔진 = 25
• 3.2.2 연료 및 윤활유 = 25
• 1) 연료 = 25
• 2) 윤활유 = 25
• 3.2.3 실차 실험용 촉매장치 = 27
• 1) 촉매처리 = 27
• 2) 촉매의 Canning = 27
• 3) 촉매의 Aging = 28
• 3.2.4 배출가스 측정 = 28
• 1) 배출가스 측정장치 및 측정방법 = 28
• 2) 배출가스 측정을 위한 엔진 운전모드 = 30
• 3.2.5 미규제물질 분석 = 32
• 1) SOF측정 = 33
• 2) Sulfate (SO_(4)^(2-)) 분석 = 33
• 3) PAHs 분석 = 34
• 4) Aldehyde 분석 = 35
• Ⅳ. 결과 및 고찰 = 38
• 4.1 대형 디젤엔진의 배출가스 특성 = 38
• 4.1.1 디젤엔진의 운전조건에 따른 오염물질 배출특성 = 38
• 4.1.2 디젤입자상물질의 조성 = 42
• 4.1.3 디젤입자상물질의 입경분포 = 42
• 4.1.4 디젤입자상물질의 형태학적 관찰 = 49
• 4.1.5 디젤입자상물질의 연소특성 = 53
• 4.2 경유중 황함유량과 디젤 입자상물질 = 55
• 4.2.1 경유중 황이 디젤엔진의 입자상물질에 미치는 영향 = 55
• 1) 개요 = 55
• 2) 경유중 황함유량과 디젤엔진의 입자상물질 = 56
• 3) 경유중 황함유량과 촉매장착 디젤엔진의 입자상물질 = 59
• 4.2.2 디젤 입자상물질중 Sulfate가 SOF에 미치는 영향 = 68
• 1) 개요 = 68
• 2) 용매 추출시 Sulfate에 결합된 수분의 세척효과 = 68
• 3) 황산 및 결합수에 의한 포집효율의 증대 및 Scrubbing 효과 = 70
• 4) SOF의 탄화수소 조성 = 71
• 4.3 디젤산화촉매의 배출가스 정화특성 = 72
• 4.3.1 DOC의 Reactor실험에 의한 성능평가 = 72
• 1) 촉매 및 조촉매의 영향 = 72
• 2) 담체의 영향 = 77
• 3) 공간속도의 영향 = 81
• 4.3.2 엔전운전조건(T-7모드)에 따른 DOC의 배출가스 정화 특성 = 83
• 1) 운전조건의 설정 = 83
• 2) 가스상물질의 정화 특성 = 86
• 3) 입자상물질의 정화 특성 = 89
• 4) 미규제 유해물질의 정화 = 94
• 4.3.3 복합운전모드(composite driving cycle)에 의한 DOC의 배출가스 정화 특성 = 99
• 1) 복합운전 모드의 특성 = 99
• 2) 규제물질의 정화 = 102
• 3) 미규제 유해물질의 정화 = 109
• Ⅴ. 결론 = 113
• 참고문헌 = 116
• 부록 = 125
• 부록 A 경유중 황과 디젤엔진의 입자상물질의 상관 측정방법 = 125
• 부록 B 디젤 입자상물질 중 Sulfate와 SOF의 상관 측정방법 = 127
• 부록 C SOF의 탄화수소 조성분석 Gas chromatogram = 132
• 부록 D PAHs 농도의 문헌적 비교검토 = 135
• 부록 E D-13모드 및 S-13모드에 의한 배출가스 측정데이타 = 137