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DEVELOPMENT OF LARGE VOLUME AIR PLASMA FOR PRACTICAL APPLICATION TO GAS CONTAMINANT REMOVAL

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Abstract
Non-thermal plasma catalyst systems have been used for environmental control, including abatement of VOC and NOx removal at atmospheric pressure because of their hazardous impact on the environment and human health. This dissertation investigates non-thermal corona plasma generated in a honeycomb monolith catalyst for VOC decomposition and rotational gliding arc plasma produced for NOx reduction from the diesel exhaust gas. The general aim of the research is developing non-thermal air plasma catalyst systems to improve the removal efficiency of VOC and NOx via investigating the effects of several input parameters, processes, and experimental conditions.
In the case of VOC decomposition, the effective removal of acetaldehyde by humidified air plasma was investigated with a high throughput of contaminated gas in a sandwiched honeycomb catalyst reactor at surrounding ambient temperature. Here, acetaldehyde at the level of a few ppm was successfully oxidized by the honeycomb plasma discharge despite the harsh condition of large water content in the feed gas. The conversion rate of acetaldehyde increased significantly with the presence of catalysts coating on the surface channels. The increased conversion rate was also obtained with a high specific energy input (SEI) and total flow rate. Interestingly, the conversion changed negligibly under the acetaldehyde concentration range from 5 to 20 ppm. However, the conversion rate decreased toward increased water amount in the feed gas. Notably, about 60% of acetaldehyde in the feed was oxidized under SEI of 40 J/L at water amounts ≤ 2.5%, approximately 0.5 g/kWh for acetaldehyde removal. Also, the plasma-catalyst reaction was superior to the thermal reactive catalyst for acetaldehyde removal in airborne pollutants. In comparison with other plasma-catalyst sources for acetaldehyde removal, the energy efficiency under the condition is comparable. Moreover, the honeycomb plasma discharge features high throughput, avoiding pressure drop, and straightforward reactor configuration, suggesting potential practical applications.
The removal of NOx over Ag/γ-Al2O3 catalyst coupled with gliding arc plasma at low temperatures is demonstrated. Specifically, n-heptane (the reducing agent) was pretreated by exposure to gliding arc plasma (the outlet gas temperature of 73.4 °C) before injecting into the simulated diesel exhaust gas and passing it through the catalyst zone. As a result of the plasma treatment, the feed gas consisted of oxygenated hydrocarbons (OHCs), which serve as reducing agents, instead of only n-heptane without plasma treatment. Consequently, the NOx removal efficiency increased substantially by approximately 10% at temperatures of [165-225 °C], owing to the presence of the OHCs. The dependence of the NOx removal efficiency on typical reducing agents was examined; these results agreed with our hypothesis that aldehyde derivatives were more effective than the parent compound (n-heptane) for NOx removal at low temperatures. However, enhancement of the NOx removal efficiency after plasma pretreatment was not observed at high plasma discharge power. This is because NOx is formed from the air and a significant amount of n-heptane is completely oxidized to CO2 when the gliding arc plasma is operated at high power. Besides, the plasma treatment of n-heptane did not improve the NOx removal under high operating temperature conditions at which the catalyst itself exhibits high catalytic activity. This led us to surmise that boosting the effectiveness of the OHCs generated during plasma pretreatment would require the ratio of the exhaust gas flow rate to the reducing agent flow rate to be high, which is challenging to realize in laboratory-scale experiments. This method would lower the energy consumption of the plasma stage.
Author(s)
마트야크보브 노시르
Issued Date
2022
Awarded Date
2022-08
Type
Dissertation
URI
https://dcoll.jejunu.ac.kr/common/orgView/000000010693
Alternative Author(s)
MATYAKUBOV NOSIR SHIHNAZAROVICH
Affiliation
제주대학교 대학원
Department
대학원 에너지응용시스템학부 에너지화학공학전공
Advisor
Mok, Young Sun
Table Of Contents
TABLE OF CONTENTS
ABSTRACT III
DECLARATION V
ACKNOWLEDGEMENTS VI
TABLE OF CONTENTS 1
LIST OF FIGURES 5
LIST OF TABLES 9
ABBREVIATIONS 10
CHAPTER 1 ‒ INTRODUCTION TO THE RESEARCH 13
1.1. Background 13
1.2. Plasma 15
1.3. The environmental problems 18
1.3.1. Climate change and the greenhouse effect 18
1.3.2. Acid rain 19
1.3.3. Ozone layer depletion and Ground-level ozone 19
1.4. Research purpose 19
1.5. Structure of the dissertation 20
CHAPTER 2 ‒ EXPERIMENTAL MATERIALS AND METHODS 22
2.1. Corona discharge plasma for acetaldehyde removal 22
2.1.1. Configuration of IPC reactor 22
2.1.2. Experimental setup 24
2.1.3. Term definition used for analyzing the result 26
2.2. Gliding arc plasma for NOx removal 27
2.2.1. Configuration of PPC reactor 27
2.2.2. Catalyst preparation 29
2.2.3. Experimental setup 29
2.2.4. Properties of gliding arc plasma discharge 31
2.2.5. Term definition used for analyzing the result 34
CHAPTER 3 ‒ EFFECTIVE PRACTICAL REMOVAL OF ACETALDEHYDE BY A SANDWICH-TYPE PLASMA-IN-HONEYCOMB REACTOR UNDER SURROUNDING AMBIENT CONDITIONS 36
3.1. Introduction 36
3.2. Experimental 36
3.3. Results and Discussion 36
3.3.1. Dependence of honeycomb discharge on acetaldehyde concentration and process time 36
3.3.2. A role of metal catalyst on the acetaldehyde removal process 40
3.3.3. Dependence of the acetaldehyde removal on the input parameters 45
3.3.4. Plasma chemistry of honeycomb discharge 51
3.3.5. Comparison of acetaldehyde removal by the honeycomb plasma with other processes 52
3.4. Summary 56
CHAPTER 4 ‒ ENHANCING THE SELECTIVE CATALYTIC REDUCTION OF NOX AT LOW TEMPERATURE BY PRETREATMENT OF HYDROCARBONS IN A GLIDING ARC PLASMA 57
4.1. Introduction 57
4.2. Experimental 58
4.3. Results and Discussion 58
4.3.1. Performance of NOx removal over Ag/γ-Al2O3 catalyst in the low-temperature range 58
4.3.2. Improvement of NOx removal by gliding arc plasma 62
4.3.3. Potential pretreatment of HC injection by plasma and future study 69
4.3.4. Analysis of optical emission spectra of the gliding arc plasma 70
4.4. Summary 72
CHAPTER 5 ‒ GENERAL CONCLUSION 73
BIBLIOGRAPHY 76
APPENDIX A: LIST OF PUBLICATIONS 92
APPENDIX B: LIST OF CONFERENCES 94
Degree
Doctor
Publisher
제주대학교 대학원
Appears in Collections:
Faculty of Applied Energy System > Energy and Chemical Engineering
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  • Embargo2022-08-18
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