共查询到20条相似文献,搜索用时 865 毫秒
1.
Meijuan Lu Rong Huang Peitao Wang Limin Chen Junliang Wu Mingli Fu William Wen Bichun Huang Daiqi Ye 《Plasma Chemistry and Plasma Processing》2014,34(5):1141-1156
MnxOy/SBA-15 catalysts were prepared via the impregnation method and utilized for toluene removal in dielectric barrier discharge plasma at atmospheric pressure and room temperature. The catalysts were characterized by X-ray diffraction, N2 adsorption–desorption, Raman spectroscopy, X-ray photoelectron spectroscopy, H2 temperature-programmed reduction, and O2 temperature-programmed desorption methods. The characterization results indicated that manganese loading did not influence the 2D-hexagonal mesoporous structure of SBA-15. The catalyst had various oxidation states of manganese (Mn2+, Mn3+, and Mn4+), with Mn3+ being the dominant oxidation state. Toluene removal was investigated in the environment of pure N2 and 80 % N2 + 20 % O2 plasma, showing that the toluene removal efficiency and CO2 selectivity were noticeably increased by MnxOy/SBA-15, especially in the presence of 5 % Mn/SBA-15. This activity was closely related to the high dispersion of 5 % Mn on SBA-15 and the lowest reduction temperature exhibited by this catalyst. Mn loading increased the yield of CO2 in the N2 plasma and promoted the deep oxidation of toluene. During toluene oxidation, oxygen exchange might follow a pathway, wherein bulk oxygen was released from the MnxOy/SBA-15 surface; gas-phase O2 subsequently filled up the vacancies created on the oxide. Each of the manganese oxidation states played an important role; Mn2O3 was considered as a bridge for oxygen exchange between the gas phase and the catalyst, and Mn3O4 mediated transfer of oxygen between the catalyst and toluene. 相似文献
2.
Tao Wang Bao-Min Sun Hai-Ping Xiao Dong Wang Xiang-yu Zhu Ya-feng Zhong 《Plasma Chemistry and Plasma Processing》2013,33(4):681-690
The present work investigates experimentally the effect of H2O vapor on the removal of NO at elevated temperatures. Breakdown voltage, discharge characteristics and NO removal efficiency were studied under various conditions of water vapor content. The experimental results indicate H2O can greatly enhance the NO removal efficiency from a NO/O2/N2/C2H4/H2O system, but the breakdown voltage increases as the relative humidity of the gas increases. Moreover, the effect of temperature on NO removal at a relative gas humidity of 30 % was analyzed. With an increase in temperature, E/N increased, producing more active species and energetic electrons; electron detachment also became significant at high temperature and the rates of major reactions were promoted, intensifying the conversion of NO. 相似文献
3.
Honghong Yi Xi Yang Xiaolong Tang Shunzheng Zhao Yonghai Huang Xiaoxu Cui Tiecheng Feng Yueqiang Ma 《Plasma Chemistry and Plasma Processing》2018,38(2):331-345
Degradation of adsorbed toluene over 13X zeolite, 5A molecular sieve and Al2O3 by non-thermal plasma was investigated. Different discharge modes, including closed and ventilated discharge were compared. The carbon balance and COx yield of 13X zeolite were increased by 17.6 and 19.4% by ventilated discharge, respectively, compared with closed discharge. But for 5A molecular sieve and Al2O3, the carbon balance and COx yield by closed discharge were greater than those by ventilated discharge. It meant that the closed discharge was more suitable for low-concentration of VOC and the residence time of reactants would be prolonged. Removal of high-concentration VOC by ventilated discharge was more appropriate because of more reactive oxygen species generated. Furthermore, the effect of discharge background gas was studied. Removal of adsorbed toluene over Co/13X by oxygen and air with different flow rate as background gas were compared. The removal efficiency was reduced as flow rate of background gas increased. The oxygen-discharge was more efficiency for toluene oxidation and inhibited the generation of nitrogen oxides. 相似文献
4.
Henrieta Nichipor Elena Dashouk Svetlana Yacko Yongxia Sun Andrzej G. Chmielewski Zbigniew Zimek Sylwester BuŁka 《Radiation Physics and Chemistry》2012,81(5):572-579
Computer simulations of benzene and toluene decomposition in air (79% N2+21% O2) and in flue gas (87% N2+10% O2+3% H2O+160 ppm SO2+80 ppm NO) under electron beam (EB) irradiation were carried out using computer code KINETIC and GEAR method. 285 reactions involving 73 species and 294 reactions involving 78 species were considered for simulation of benzene and toluene decomposition, respectively. Calculation results of benzene and toluene decomposition in air under electron beam agree well with the published experimental results. OH radicals play a main role in benzene or toluene decomposition. 相似文献
5.
Shui-E Yin Bao-Min Sun Xu-Dong Gao Hai-Ping Xiao 《Plasma Chemistry and Plasma Processing》2009,29(6):421-431
The effect of O2 and H2O vapor on the Nitric oxide (NO) removal rate, the NO2 generation rate and the discharge characteristics were investigated using the dielectric barrier discharge (DBD) reactor
at 1 atm pressure and at room temperature (20°). The results showed that the O2 present in the flue gas always hampered the removal of NO and the generation of N2O, but that the O2 could enhance the generation of NO2 in the NO/N2/O2 mixtures. Furthermore, with the increase of oxygen, the average discharge current gradually decreases in the reactor. The
H2O present in N2/NO hindered the removal of NO and the generation of NO2 but had no impact on the average discharge current in the reactor in the NO/N2/H2O mixtures in which the HNO2 and HNO3 was detected. The energy efficiency of the DBD used to remove the NO from the flue gas was also estimated. 相似文献
6.
Xiao-bin Liao Yu-fang Guo Jian-hua He Wei-jian Ou Dai-qi Ye 《Plasma Chemistry and Plasma Processing》2010,30(6):841-853
A method based on high performance liquid chromatography (HPLC), has been developed to measure hydroxyl radical (·OH) in plasma reactors. The determination was performed indirectly by detecting the products of the reaction of ·OH with salicylic acid (SAL). The applicability, and effect of time, specific input energy (SIE), relative humidity (RH),
catalyst were investigated. It was found that 3 h was the optimal trapping time; concentration of ·OH was (5.9–23.6) × 1013 radicals/cm3 at SIE range. The highest ·OH yield and toluene removal efficiency (η) were achieved with a RH of 20%. With MnO
x
, η was two times that without catalyst, while ·OH yield in gas stream was one-sixth that without catalyst. However, if summed with ·OH adsorbed on catalyst surface, the total ·OH yield was the same as without catalyst. Experiments performed with/without toluene allowed to determine the role of ·OH on decomposition of toluene in air plasma. 相似文献
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8.
Wang Xueqian Xu Ke Ma Yixing Ning Ping Cheng Chen Wang Langlang Cheng Jinhuan 《Plasma Chemistry and Plasma Processing》2016,36(6):1545-1558
The removal of hydrogen sulfide and dust simultaneously by the DC corona discharge plasma with a wire-cylinder reactor was studied at atmospheric pressure and room temperature. The outlet gases were analyzed by Fourier Transform Infrared. Chemical compositions of the dust collected from ground electrode were analyzed by X-ray fluorescence. The results showed that the DC corona discharge is effective in removing H2S and dust simultaneously. The best H2S conversion was gained with the 2 cm discharge gap. The lower inlet H2S concentration, the higher conversion efficiency was gained at any specific input energy (SIE), while the energy yield was on the contrary. The removal efficiency of H2S decreased gradually as oxygen concentration increased, which means that the H2S decomposition mainly depends on direct electron collisions or short-living species, such as·O, ·OH radicals in the non-thermal plasma. At the initial stage, the conversion efficiency of H2S increased with the increasing of relative humidity, but later decreased while the relative humidity keep increasing with the same SIE. Existing of dust can not only reduce the energy consumption of H2S conversion and improve the removal efficiency, but also inhibit the yield of SO2 for it can further react with some compounds in the dust. With the discharge gap of 2 cm, inlet H2S concentration of 2400 ppm, O2 Of 0.5 %, relative humidity of 41 %, dust content of 4000 ± 5 % mg/m3 and SIE of 600 J/L, the H2S conversion reached 98.8 %, and the dust removal efficiency was close to 100 %. 相似文献
9.
The effectiveness of applying dielectric barrier discharges (DBDs) to remove p-xylene from gas streams was experimentally investigated in this study. Parameters investigated include applied voltage, gas flow rate, gas temperature and gas composition. Experimental results indicate that as high as 100% p-xylene removal efficiency is achieved for the gas stream containing low p-xylene concentration of 26 ppmv. Removal efficiency of p-xylene achieved with DBDs increases with increasing applied voltage. However, energy consumption is also increased with increasing applied voltage. The best energy efficiency of 7.1 g/kWh is achieved for the gas streams containing 500 ppmv p-xylene, 5% O2, 1.6% H2O(g), and balanced N2 at the applied voltage of 18 kV. Product analysis indicates that around 70 or 95% of the carbons in p-xylene molecules are transformed into carbon dioxide for the gas streams without or with water vapor, respectively. 相似文献
10.
Treatment of H2S and NH3 using the non-thermal plasma (NTP) methods was investigated. Two NTP systems were used in this study, one consisting of a multi-cell plate-to-wire reactor (PTW), and the other consisting of an ozonization chamber and the multi-cell PTW reactor. Each cell of the PTW reactor had a sheet of copper foil embedded in dielectric layers as its high voltage electrode and a wired rack as its gounded electrode. Use of the wired rack type electrode allowed large flow throughput, and promoted intense local electric fields. The experiments showed that under constant energy input, the decomposition efficiency of H2S or NH3 decreased with increasing initial concentration of the gas, and increased with increasing injected ozone and relative humidity. Injection of NH3 into H2S stream did not improve the H2S decomposition efficiency but was necessary for removal of sulfite-containing compounds in the discharge air. 相似文献
11.
Removal of SO2 from Gas Streams by Oxidation using Plasma-Generated Hydroxyl Radicals 总被引:1,自引:0,他引:1
Mindong Bai Zhitao Zhang Mindi Bai Chengwu Yi Xiyao Bai 《Plasma Chemistry and Plasma Processing》2006,26(2):177-186
The key problem for the removal of SO2 by electrical discharge methods is how to obtain the hydroxyl radicals at high concentration and large production rates. With the micro-gap discharge method, O2 and H2O in simulated gas streams (N2/O2/H2O/SO2) are ionized into a large number of OH. radicals to oxidize SO2 into SO3 which reacts with H2O forming H2SO4 droplets at 120 °C in the absence of any catalyst or absorbent. The droplets are captured with an electrostatic precipitator. As a result, conversion of SO2 to primarily H2SO4 is limited by the generation of OH. radicals. By increasing the reduced field and concentrations of O2 and H2O, the amount of OH. radicals increase resulting in more removal of SO2 from gas streams. The removal efficiency of SO2 reaches 100% when the residence time is only 0.74 s. Therefore, a new gas-phase oxidation method for removal of SO2 without NH3 additive is found. 相似文献
12.
N. Blin-Simiand F. Jorand L. Magne S. Pasquiers C. Postel J.-R. Vacher 《Plasma Chemistry and Plasma Processing》2008,28(4):429-466
Toluene removal is investigated in filamentary plasmas produced in N2 and in N2/O2 mixtures by a pulse high voltage energised DBD. Influence of the oxygen percentage (lower than 10%) and of the temperature
(lower than 350°C) is examined. Toluene is removed in N2 through collisions with electrons and nitrogen excited states. The removal efficiency is a few higher in N2/O2. It increases when the temperature increases for N2 and N2/O2. Both H- and O-atoms play an important role in toluene removal because H can readily recombine with O to form OH, which is
much more reactive with toluene than O. H follows from dissociation of toluene and of hydrogenated by-products by electron
collisions. Detection of cyanhidric acid, acetylene, formaldehyde, and methyl nitrate strengthens that dissociation processes,
to produce H and CH3, must be taken into account in kinetic analysis. Formation and treatment of deposits are also analysed. 相似文献
13.
Hyun-Ha Kim Masami Sugasawa Hiroshi Hirata Yoshiyuki Teramoto Katsunori Kosuge Nobuaki Negishi Atsushi Ogata 《Plasma Chemistry and Plasma Processing》2013,33(6):1083-1098
This paper presents a new type of ozone-assisted catalysis for toluene decomposition. The different catalytic activities of ZSM-5 and Ag/ZSM-5 were incorporated into a layered catalyst with a tandem configuration. Instead of increasing the amount of metal catalyst, the layered catalyst was formed, which had an equal amount of bare ZSM-5 and Ag/ZSM-5 and could achieve both high toluene conversion and CO2 selectivity concurrently. The properties of each catalyst were evaluated with respect to toluene conversion, formation of intermediates, CO2 selectivity and ozone demand factor. The bare ZSM-5 exhibited higher toluene conversion than the Ag/ZSM-5, while its activity toward deep oxidation was limited. However, the Ag/ZSM-5 was found to be effective for the deep oxidation of reaction intermediates (HCOOH and CO). Separate oxidation tests with HCOOH and CO revealed that the ZSM-5-supported Ag nanoparticles could oxidize the HCOOH and CO in the absence of ozone, which was not possible with the bare ZSM-5. Plausible pathways for the oxidation of toluene with O3 over ZSM-5 and Ag/ZSM-5 were proposed based on the experimental evidence. 相似文献
14.
Decomposition of Toluene in a Plasma Catalysis System with NiO, MnO2, CeO2, Fe2O3, and CuO Catalysts
Junliang Wu Yixia Huang Qibin Xia Zhong Li 《Plasma Chemistry and Plasma Processing》2013,33(6):1073-1082
The performance of NiO, MnO2, CeO2, Fe2O3, and CuO catalysts on alumina in removing toluene from a gas stream was studied in a plasma catalysis system. The NiO catalyst performed better than the other catalysts, generating more toluene-destroying oxygen species by decomposing ozone. The optimum nickel loading in the NiO/γ-Al2O3 catalyst was approximately 5 wt%, close to the monolayer dispersion threshold of NiO on γ-Al2O3. The presence of water vapor had a negative effect on catalytic performance due to its quenching of high speed electrons and its competition with toluene for adsorption sites. Water vapor also reduced the outlet ozone concentration by inhibiting the production of key intermediate in the ozone formation process. 相似文献
15.
Influence of Support Type and Metal Loading in Methane Decomposition over Iron Catalyst for Hydrogen Production 下载免费PDF全文
Ahmed A. Ibrahim Ahmed S. Al‐Fatesh Wasim U. Khan Mostafa A. Soliman Raja L. AL Otaibi Anis H. Fakeeha 《中国化学会会志》2015,62(7):592-599
Natural gas resources, stimulate the method of catalytic methane decomposition. Hydrogen is a superb energy carrier and integral component of the present energy systems, while carbon nanotubes exhibit remarkable chemical and physical properties. The reaction was run at 700 °C in a fixed bed reactor. Catalyst calcination and reduction were done at 500 °C. MgO, TiO2 and Al2O3 supported catalysts were prepared using a co‐precipitation method. Catalysts of different iron loadings were characterized with BET, TGA, XRD, H2‐TPR and TEM. The catalyst characterization revealed the formation of multi‐walled nanotubes. Alternatively, time on stream tests of supported catalyst at 700 °C revealed the relative profiles of methane conversions increased as the %Fe loading was increased. Higher %Fe loadings decreased surface area of the catalyst. Iron catalyst supported with Al2O3 exhibited somewhat higher catalytic activity compared with MgO and TiO2 supported catalysts when above 35% Fe loading was used. CH4 conversion of 69% was obtained utilizing 60% Fe/Al2O3 catalyst. Alternatively, Fe/MgO catalysts gave the highest initial conversions when iron loading below 30% was employed. Indeed, catalysts with 15% Fe/MgO gave 63% conversion and good stability for 1 h time on stream. Inappropriateness of Fe/TiO2 catalysts in the catalytic methane decomposition was observed. 相似文献
16.
Eui-Chan Jeon Ki-Joon Kim Jo-Chun Kim Ki-Hyung Kim Sang-Gwi Chung Young Sunwoo Young-Kwon Park 《Research on Chemical Intermediates》2008,34(8-9):863-870
Noble (Pt, Pd) and transition metals (Mn, Cu) were employed as coupling catalysts to evaluate the toluene (1500 ppm C of initial concentration) removal efficiencies in the electron beam (EB)-catalyst coupling system. The toluene removal efficiency was 60.1% in the EB-only system at a dose of 8.7 kGy. In the presence of the metal catalysts (Pt, Pd, Cu and Mn), the removal efficiency was enhanced by 37, 33, 6 and 22%, respectively, compared to that of EB-only treatment. It was found that the selectivity to CO2 with Pt and Pd coupling were relatively higher than those of Cu and Mn. Especially the CO2 selectivity of EB-Pt coupling was significantly high at a relatively low absorbed dose. The removal efficiencies were compared for loading of catalyst and there was no significant difference among 0.1, 0.5 and 1.0 wt%. 相似文献
17.
Hongbo Zhang Kan Li Tonghua Sun Jingping Jia Xueli Yang Yafei Shen Jun Wang Ziyang Lou 《Research on Chemical Intermediates》2013,39(3):1021-1035
As a kind of volatile organic compound, styrene is a typical industrial pollutant with high toxicity and odorous smell. In this study, the removal of malodorous styrene simulation waste gas was carried out in a self-made wire-tube dielectric barrier discharge reactor. The decomposition efficiency of the reaction was investigated under different applied voltages and flow rates. The results showed that nearly 99.6 % of styrene could be removed with a concentration of 3,600 mg/m3 and the applied voltage of 10.8 kV. However, the selectivity of CO2 and CO showed that the mineralization efficiency of styrene was less than 25 %. The by-products of the reaction, including O3, NO x and other intermediates, were also detected and analyzed under different applied voltages. The relationships between the applied voltage and the quantity of final product (CO2) and by-products (intermediate organics, NO x , O3) were investigated. The reaction mechanism was also described according to the bond energy and the intermediates that formed. 相似文献
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19.
Yao Shi Zhenhua Shao Tianyu Shou Rubin Tian Jianqing Jiang Yi He 《Plasma Chemistry and Plasma Processing》2016,36(6):1501-1515
Ultraviolet (UV) light with a wavelength of 254 nm was applied to a double dielectric barrier discharge (DDBD) system to decompose of gaseous xylene. The results show that a significantly synergistic effect can be achieved with the introduction of UV light into the DDBD system. When UV light is applied, the system show a 21.8 % increase in its removal efficiency for xylene at 35 kV with an ozone concentration close to 971 ppmv. The CO x (x = CO2 and CO) selectivity of outlet gas rises from 6.54 to 76.2 %. The optimal synergetic effect between UV light and DDBD can be obtained at a peak voltage of 30 kV. The system is robust for humidity, which only slightly reduces the xylene removal efficiency at a high peak voltage (30–35 kV). With the increase of gas flow rate, the removal efficiency for xylene decreases due to a reduced residence time. In addition, the products of xylene degradation were also analyzed. The major products of the degradation were found to be CO2 and H2O while byproducts such as O3 and HCOOH were observed as well. 相似文献
20.
J. H. Yan Zh. Bo X. D. Li Ch. M. Du K. F. Cen B. G. Chéron 《Plasma Chemistry and Plasma Processing》2007,27(2):115-126
The mechanism of hexane decomposition under gliding arc gas discharge conditions is studied from both qualitative and quantitative
analyses of its products for various hexane initial concentrations and different background atmospheres : nitrogen, argon,
air (O2 21% N2 79% vol.) and N2–O2 mixtures. The decomposition rate, which decreases with increasing hexane initial concentration, can reach 94% when the carrier
gas is air. Due to the electron energy consumed by the dissociation of nitrogen, the decomposition rate of hexane in nitrogen
is lower than in argon. The radical channel plays a predominant role in the hexane decomposition process. With increasing
oxygen concentration in the carrier gas, the hexane decomposition rate increases and promotes the conversion of CO– CO2, but it also leads to the formation of NO2. 相似文献