Reaction Mechanism of Ethoxyethane and Ethylene Oxide in the Cold Plasma Environment
| Autor: | Wei-Tung Liao, 廖渭銅 |
|---|---|
| Rok vydání: | 2000 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 89 A radio frequency plasma system was used to decompose the ethoxyethane and ethylene oxide contained gases. The decomposition fraction of EOE and EO, and the profile of final products in the effluent of reactor were investigated under various operational parameters, including input power wattage, equivalence ratios, feeding concentration of EOE or EO and total gas flow rate. In the case for decomposition of EOE, the dominant factors controlling the creation of glow discharge are also discussed. The results showed that, at lower input power wattages, the creation of glow discharge is strongly dependent on the plasma production index. When input power wattages are smaller than 30W, the minimum values of PPI ranged between 18.2 and 19.0. In addition, due to the importance of the high-energy electrons in the RF plasma system, the EO decomposition fraction in plasma reaction increased with decreasing operational pressure, while that in thermal reaction, reported by previous investigations, increased with increasing operational pressure. However, owing to the electrophilic characteristic of oxygen atom in the EO molecule, causing the effect of electron attachment, in conditions of higher EO feeding concentration, the pressure dependence became the same for both plasma- and thermal- reaction. Under the conditions of EOE/Ar and EO/Ar plasma systems, the main products are CO, CH4, C2H6 and C2H2, while the main products of EOE/O2/Ar and EO/O2/Ar plasma systems are CO2 and H2O at a higher O2/EOE and O2/EO ratios, respectively. In H2/EO/Ar plasma system, increasing the inlet H2/EO ratio will reduce the concentration of CO and promote the formation of hydrocarbons in the effluent. Furthermore, an innovative method was used to carry out the simulation of ethylene oxide oxidation in an RF plasma reactor. The mechanism involves participation of 36 species in 140 elementary reactions. The object of this work is to simulate the stable species mole fraction profiles measured in flowing plasma system at constant temperature and pressure. Sensitivity analysis was also performed for the identification of the rank order of significance of reaction in the mechanism in model''s predictions. The results showed that the decomposition reactions for EO were changing with varying O2/EO ratio in the complex plasma system. The most important reaction at O2/EO ratio of zero is the electron dissociation reaction of EO, C2H4O + e- ® CH3CHO + e-。Howerer the most significant reaction at O2/EO ratio of 5.0 is the formation reaction of HO2, which forms OH radicals in advance, then enhances the decomposition of C2 H4O by the reaction, C2H4O + OH = C2H3O + H2O。 To conclude the results for the decomposition of EOE or EO in RF plasma system, both are easily decomposed in the plasma environment. The decomposition fraction could reach nearly 100% under most operational conditions. Therefore, the RF plasma system is a highly potential tactic to treat the flue gas from the operation room or sterilization room in the hospital, which use the EOE as the anesthetic and the EO as the sterilizer. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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