CO2 Reforming with CH4 via Plasma Catalysis System

Reforming of CO2 and CH4 into syngas (mixture of H2/CO) can be an economical way to reduce anthropogenic emission of CO2 and CH4 and to generate alternative fuel. Up to date, catalysis and nonthermal plasma are two feasible techniques for CO2/CH4 reforming. However, both techniques face some obstacles which limit their applications. For catalysis, high energy consumption and catalyst deactivation are the major disadvantages while nonthermal plasma has the drawbacks of low selectivity and unwanted byproduct formation. To overcome the above obstacles, combining catalyst and nonthermal plasma as a hybrid system can induce synergistic effects to enhance syngas production rate and stability of the operating system. For the purpose of enhancing CO2 utilization efficiency, understanding the interactions between catalyst and nonthermal plasma is essential

Simultaneous removal of sulfur dioxide and nitric oxide from gas streams via combined plasma photolysis

The concept of applying Dielectric Barrier Discharge (DBD) and Combined Plasma Photolysis (CPP) to simultaneously remove SO\sb2 and NO from simulated flue gas streams has been evaluated with a laboratory-scale reactor. CPP relies on DBD to generate gas phase radicals which oxidize SO\sb2 and NO to form H\sb2SO\sb4 and HNO\sb3, respectively. UV irradiation is applied to photolyze O\sb3 to enhance OH generation. The resulting compounds can then be chemically neutralized with NH\sb3\sb{\rm (g)} and removed from the gas stream by an aerosol particle removal device. Experimental results indicate that the SO\sb2 and NO removal efficiencies with DBDs are sensitive to (H\sb20\sb{\rm (g)}), (O\sb2), (CO\sb2), and the temperature of the gas stream. When a sufficient voltage is applied to generate the plasma, both SO\sb2 and NO removal efficiencies increase with increasing (H\sb2O\sb{\rm (g)}). For the gas streams with same gas composition, SO\sb2 and NO removal efficiencies increases with increasing temperature as a result of higher reduced electric field (E/N). With sufficient (H\sb2O\sb{\rm (g)}), SO\sb2 removal efficiency increases with increasing (O\sb2) as a result of more OH radicals. In contrast, there is an optimal (O\sb2) which maximizes NO removal for a specific (H\sb2O\sb{\rm (g)}) in the gas stream. Electronegative gases like CO\sb2 tend to decrease both SO\sb2 and NO removal efficiencies. Injection of NH\sb3\sb{\rm (g)} into the gas stream significantly increases SO\sb2 removal efficiency due to the thermal reactions between SO\sb2 and NH\sb3\sb{\rm (g)}, while injection of NH\sb3\sb{\rm (g)} does not appreciably change NO removal efficiency with DBDs. Without NH\sb3\sb{\rm (g)} injection, 95% NO and 32% SO\sb2 are simultaneously removed with DBDs for the gas stream with composition of NO/SO\sb2/O\sb2/CO\sb2/H\sb2O\sb{\rm (g)}/N\sb2 = 0.025/0.1/6/12/15/66.875 % by volume at 160\sp\circC. SO\sb2 removal efficiency achieved by DBDs can be enhanced by UV irradiation. Conversely, UV irradiation decreases NO removal efficiency achieved by DBDs due to the regeneration of NO caused by the UV photolysis of NO\sb2 and HNO\sb3\sb{\rm (g)}.U of I OnlyETDs are only available to UIUC Users without author permissio

以介電質放電法去除502及NO之可行性研究

Concern over acid deposition has reulted in more stringent SO2 and NO emission standards as designated by the 1990 Clean Air Act Amendments. In view of the more stringent emission standards and the constraints of current air pollution control technology for removing SO2 and NO from gas streams, more effective air pollution control technologies should be searched. An innovative gas phase oxidation method using dielectric barrier discharges (DBDs ) has been developed to simultaneously remove SO2 and NO from gas streams. This process generates gas phase radicals such as OH, 1102, and 0. The radicals can then oxidize gaseous SO2 and NO to form particles consisting of I-12S04 and 11N03, respectively. The resulting compounds can then be chemically neutralized with NH3 and removed from the gas stream by othe conventional air pollution control devices. The effectiveness of DBDs to remove SO2 and NO from gas streams has been evaluated with a laboratory- scale reactor. Experimental results showed that about 35 % of SO2 can be removed from the gas stream at 160 ℃ with DBDs. This removal efficiency was achieved for a gas stream with an inlet SO2 concentration of 1000 ppmv, H20 concentration of 15 % by volume, CO2 concentration of 12 % by volume, O2 concentration of 6 % by volume with N2 as the carrier gas. The gas residence time is 5 sec and processing voltage is 25 kv (peak value). 99 % removal efficiency for NO was also achieved for the gas stream with an inlet NO concentration of 250 ppmv at the same operating conditions described above. These results indicated that DBDs have the potential to simultaneously remove SO2 and NO from gas streams generated by large scale sources of SO2 and NO, such as a coal-fired power plant. 大眾對酸性沉降之關切已導致世界各國對SO2及NO之排放，採取更嚴格之標準。鑑於目前各種控制方法之限制，有必要研究更有效之控制技術以因應未來之需要。本研究旨在探討利用介電質放電法以同時自氣流中去除SO2及NO之可行性。其過程是藉介電質放電產生OH、HO2及O等自由基利用氣態氧化原理將氣體中之SO2及NO氧化成硫酸與硝酸再移除之，亦可加入NH3中和後再去除。實驗結果顯示，氣流之溫度為160℃時，SO2之去除效率為35%，而NO之去除效率可達99%，此去除效率受使用電壓，氣流成份及溫度、氣體停留時間等操作參數之影響。此研究顯示，未來以介電質放電法同時去除氣流之SO2及NO甚具潛力