共查询到20条相似文献,搜索用时 448 毫秒
1.
Dielectric barrier discharge (DBD) and catalysis hybrid process was used to remove nitrogen oxides and particulate matters
from diesel engine exhaust. The DBD reactor converts a part of NO into NO2, and then the exhaust gas containing the mixture of NO and NO2 enters the catalytic reactor where both NO and NO2 are reduced to N2. The effect of energy density (power input divided by gas flow rate) and reaction temperature on the removal of nitrogen
oxides was investigated with a stationary diesel engine. The hybrid process was able to remove about 80% of the initial nitrogen
oxides at an energy density of 25 J/L and 150°C. The removal of particulate matters did not largely depend on the electrode
structure, but it was a strong function of the energy density. On the basis of 80% removal efficiency, the energy yield for
nitrogen oxides was 40 eV/molecule while that for particulate matters was 83 kJ/mg. The present study suggests that this kind
of hybrid process can be applied to simultaneous removal of nitrogen oxides and particulate matters from diesel engine exhausts. 相似文献
2.
Mukundan Devadas Oliver Kr?cher Alexander Wokaun 《Reaction Kinetics and Catalysis Letters》2005,86(2):347-354
Summary Fe-ZSM5 coated on a cordierite monolith was characterized and tested in the selective reduction of nitrogen oxides (NOx) with ammonia. More than 70 % of the NOxwere converted at T>350 °C if only NO was present in the feed. For equimolar amounts of NO and NO2in the feed, NOxconversions of over 90 % were reached for T = 200-450 °C. Hydrothermal ageing of Fe-ZSM5 resulted in a small loss in NOxconversion and enhanced N2O formation. 相似文献
3.
Doo-Seong Hwang Yun-Dong Choi Gyeong-Hwan Jeong Jei-Kwon Moon 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(3):2175-2180
Korea Atomic Energy Research Institute (KAERI) started a decommissioning program of a uranium conversion plant. The treatment of the sludge waste, which was generated during the operation of the plant, is one of the most important tasks in the decommissioning program of the plant. The major compounds of sludge waste are nitrate salts and uranium. The sludge waste is denitrated by thermal decomposition. The treatment of off-gas evolved from the thermal decomposition of nitrate salts in the sludge waste is investigated. The nitrate salts in the sludge were decomposed in two steps: the first decomposition is due to the ammonium nitrate, and the second is due to the sodium and calcium nitrate and calcium carbonate. The components of off-gas from the decomposition of ammonium nitrate at low temperature are NH3, N2O, NO2, and NO. In addition, the components from the decomposition of sodium and calcium nitrate at high temperature are NO2 and NO. Off-gas from the thermal decomposition is treated by the catalytic oxidation of ammonia and selective catalytic reduction (SCR). Ammonia is converted into nitrogen oxides through the oxidation catalyst and all nitrogen oxides are removed by SCR treatment besides nitrous oxide, which is greenhouse gas. An additional process is needed to remove nitrous oxide, and the feeding rate of ammonia in SCR should be controlled properly for evolved nitrogen oxides. 相似文献
4.
The photocatalytic methods for nitrogen oxides removal were recently very intense areas of scientific research. Photo-deNOx processes offer interesting ways for abatement of these harmful gases. This review describes several methods for removing NO by photocatalytic reactions. These methods can be classified into three major groups: photo selective catalytic reduction (photo-SCR), photo-oxidation and photo-decomposition. The application of photocatalysts and photo-processes for NOx abatement in real-scale cases are presented. The fast-growing development of these methods is revealed by the large number of issued patents in photo-deNOx applications. The mechanism of NO creation and the traditional methods (primary and secondary) of NOx removal are summarized and discussed. A cooperative system that combines the traditional (thermal) process and a photo-process is then proposed for improving NOx removal efficiency. 相似文献
5.
The effects of non-thermal plasma on selective catalytic reduction of NOx by C3H8 (C3H8-SCR) over Co/BEA catalyst were investigated over a wide range of reaction temperatures (473–773 K). The significant synergistic effect between non-thermal plasma and catalytic reduction by C3H8 was exhibited at low temperatures from 473 to 673 K. The synergetic effect diminished with increasing temperature. The NOx removal efficiency of non-thermal plasma facilitated C3H8-SCR hybrid system increased significantly with the increase in NO2/NO ratio from 0.13 to 1.06 when the specific input energy increased from 0 to 136 J L?1. The oxidation performance of NO to NO2 was significantly enhanced by C3H8 in the plasma reactor. Results of CO2/CO ratio and CO2 selectivity suggested that adding non-thermal plasma improved CO2 selectivity of C3H8-SCR. 200 ppm SO2 slightly inhibited NOx conversion of the non-thermal plasma facilitated C3H8-SCR hybrid system at below 673 K, whereas it exhibited no obvious effect at over 673 K. Non-thermal plasma was more selective toward NO oxidation than SO2 oxidation in the presence of C3H8. The non-thermal plasma facilitated C3H8-SCR hybrid system could be used stably in durability tests with several hundreds ppm of SO2. 相似文献
6.
B. S. Patil J. Rovira Palau V. Hessel Jürgen Lang Q. Wang 《Plasma Chemistry and Plasma Processing》2016,36(1):241-257
Nitrogen fixed in the form of nitrogen oxides is essential to produce fertilizers and many other chemical products, which is vital to sustain life. The performance of a milli-scale gliding arc reactor operated under atmospheric pressure has been studied for nitrogen oxides synthesis. In this work, the electrical and process parameters of the gliding arc reactor, such as frequency, pulse width, amplitude and feed ratio were investigated respectively. The experiments were performed at 1 L/min in a gliding arc discharge regime. The highest concentration of NOx was found to be ~1 % at energy consumption of 10 kWh/kg of NOx. Increase in frequency, pulse width and amplitude resulted in an increased specific energy input and NOx concentration. The feed ratio (N2/O2) affected the amount of NO and NO2 produced, which gives possibility to independently obtain the desired ratio of NO/NO2 by tuning the electrical and process parameters. 相似文献
7.
We investigated the effects of several process variables (initial concentrations of NO, NH3, and H2O and electron concentration) on NOx conversion by the pulsed corona discharge process (PCDP). In the PCDP, most of the NO is converted into NO2 and, later, into HNO3 which reacts with NH3 to form NH4NO3 particles. We solved the model equations of chemical species in the PCDP considering 23 chemical species and 54 chemical reactions. As the initial NO concentration increases or electron concentration decreases, it takes a longer reactor length to remove the NOx by the PCDP. As the initial H2O, it takes a shorter reactor length to remove the NOx. As the initial NO and H2O and electron concentration decreases, or as the initial NH3 concentration increases, it takes a longer reactor length to consume the NH3 by the particle formation reactions. The information on the effects of several process variables on the plasma chemistry in NOx conversion can be the basis guideline to develop a more efficient PCDP and this study can be extended to obtain the information on particle characteristics of ammonium salts. 相似文献
8.
M. Janda V. Martišovitš K. Hensel Z. Machala 《Plasma Chemistry and Plasma Processing》2016,36(3):767-781
Atmospheric pressure air plasma discharges generate potential antimicrobial agents, such as nitrogen oxides and ozone. Generation of nitrogen oxides was studied in a DC-driven self-pulsing (1–10 kHz) transient spark (TS) discharge. The precursors of NOx production and the TS characteristics were studied by nanosecond time-resolved optical diagnostics: a photomultiplier module and a spectrometer coupled with fast intensified camera. Thanks to the short (~10–100 ns) high current (>1 A) spark current pulses, highly reactive non-equilibrium plasma is generated. Ozone was not detectable in the TS, probably due to higher gas temperature after the short spark current pulses, but the NOx production rate of ~7 × 1016 molecules/J was achieved. The NO2/NO ratio decreased with increasing TS repetition frequency, which is related to the complex frequency-dependent discharge properties and thus changing NO2/NO generating mechanisms. Further optimization of NO2 and NO production to improve the biomedical and antimicrobial effects is possible by modifying the electric circuit generating the TS discharge. 相似文献
9.
D. S. Krivoruchenko A. V. Kucherov N. S. Telegina D. A. Bokarev P. Selvam A. Yu. Stakheev 《Russian Chemical Bulletin》2014,63(2):389-395
The catalytic properties of the Mn-Fe-Beta system with Mn contents in the range 0.1–16 wt.% were studied in the selective catalytic reduction (SCR) of NO x with ammonia. The catalyst structure was investigated using IR spectra of adsorbed NO, temperature-programmed reduction with hydrogen (H2-TPR), X-ray diffraction analysis, and ESR. The use of manganese as a promoter substantially increases the activity of iron-containing catalysts in the SCR of NO x with ammonia. At low contents (<2 wt.%), Mn exists in the cation form and the catalytic activity of the Mn-Fe-Beta system does not increase. At a higher content of Mn, clusters MnO x begin to form, which are highly active in the oxidation of NO to NO2 and the low-temperature catalytic activity of the Mn-Fe-Beta system increases. The observed increase in the low-temperature catalytic activity in the process of SCR of NO x with ammonia is related to a change in the reaction route. The MnO x clusters favor the oxidation of NO and the iron cations facilitate the reaction of “fast” SCR. 相似文献
10.
Andrzej G. Chmielewski Yongxia Sun Janusz Licki Andrzej Pawelec Sylwia Witman Zbigniew Zimek 《Radiation Physics and Chemistry》2012,81(8):1036-1039
High concentration of NOx removal from simulated off-gases was investigated using electron beam (EB) technology. Simulated off-gases were prepared by combusting Polish light oil or nature gas with addition of NO from a NO gas cylinder. Irradiation was carried out under a ILU-6 accelerator. It was found that removal efficiency of NOx was influenced by inlet concentration of NO, temperature, SO2 concentration, absorbed dose and irradiation dose rate. Methods of enhancing NOx removal efficiency with additives using EB were also discussed. 相似文献
11.
Nitrogen oxides are nowadays a subject of global concern. Several types of nitrogen oxides exist in the environment: N2O, NO, NO2, N2O3, N2O4, N2O5. The abbreviation NO
x
usually relates to nitric oxide NO, nitrogen dioxide NO2, and nitrous oxide N2O. The first two are harmful pollutants for both environment and human health, whereas the third is one of the greenhouse
gases. Implementation of stringent NO
x
emission regulations requires the development of new NO
x
removal technologies from exhaust gases. One of many proposals for NO
x
emission reduction is the application of an oxidizing agent which would transform NO
x
to higher nitrogen oxides with higher solubility in water. The main objective of the paper was to present the rate constant
of nitric oxide oxidation, determined in our studies. 相似文献
12.
D. E. Doronkin L. V. Piryutko E. V. Starokon’ G. I. Panov A. Yu. Stakheev 《Kinetics and Catalysis》2012,53(6):747-752
The catalytic properties of Fe-ZSM-5 zeolites with different iron contents have been investigated in the selective catalytic reduction (SCR) of NO x with ammonia. The observed catalytic properties the zeolites are correlated with the concentration of the iron-containing sites that are stabilized in the zeolite and effect N2O decomposition (??-sites). The catalysts activated at a high temperature to increase the ??-site concentration (by a factor of 5?C10) are more active in NO x SCR with ammonia than the unactivated samples. However, the difference between the activities of the activated and unactivated catalysts is well below the difference between the ??-site concentrations in these catalysts. The nonlinear relationship between these parameters is evidence that the ??-sites in Fe-ZSM-5 is not the only factor determining the activity of Fe-ZSM-5 in NO x SCR with ammonia. The activated catalysts show a low activity in nonselective ammonia oxidation and, accordingly, a high selectivity in the target process at high temperatures. 相似文献
13.
V. I. Zheivot T. A. Nikoro V. N. Krivoruchko L. I. Panina L. G. Pinaeva L. A. Isupova 《Journal of Analytical Chemistry》2007,62(12):1170-1175
Peculiarities of the determination of nitrogen oxides and ammonia in the reaction products of ammonia oxidation are studied by gas chromatography. Particular attention was paid to the sampling problem. It is shown that in the course of the transportation of samples containing nitrogen(II) oxide and oxygen, the oxidation of nitrogen(II) oxide to nitrogen(IV) oxide takes place in the vapor phase. The conditions were found for suppressing or even eliminating the gas-phase reaction of NO oxidation to NO2. A procedure for the gas-chromatographic analysis of the reaction products in the catalytic oxidation of ammonia is proposed using several samples and packed columns, including the determination of NO with respect to NO2 formed in the gas-phase oxidation of NO. 相似文献
14.
Attempts to develop new technologies of NO
x
(NO + NO2) emission reduction are still carried out all around the world. One of the relatively new approaches is the application of
ozone injection into the exhaust gas stream followed by the absorption process. Ozone is used to transform NO
x
to higher nitrogen oxides which yield nitric acid with better effectiveness. The main objective of this paper was to study
the influence of mole ratio (MR) O3/NO used in the ozonation process of NO
x
on the effectiveness of NO
x
oxidation to higher oxides. The ozonation process was carried out in a flow reactor for concentrations of nitric oxide in
the range of 1.5 × 10−5−7.7 × 10−5 mol dm−3 and varying O3/NO mole ratios. Measurements were conducted with the use of a FTIR spectrometer. The results obtained prove that for MR higher
than 1, the oxidation effectiveness of nitric oxides generally reaches 95 %, whereas for MR higher than 2, oxidation of NO
x
to higher nitrogen oxides is completed. 相似文献
15.
臭氧氧化结合湿法喷淋对玻璃窑炉烟气同时脱硫脱硝实验研究 总被引:2,自引:0,他引:2
采用臭氧氧化结合湿法喷淋对模拟玻璃窑炉烟气开展了同时脱硫脱硝实验研究.采用不同溶液(NaOH、Na2S)进行了喷淋实验.结果表明,保证溶液pH值在10以上,NaOH浓度对NOx脱除效率无影响,SO2的存在促进了NOx吸收.当O3/NO物质的量比为1.6、溶液NaOH浓度为0.5%时,NOx脱除效率可达70%,SO2脱除效率在99%以上.往喷淋液中添加Na2S,NOx脱除效率随Na2S浓度增加而提高,SO2的存在对NOx脱除效率无影响.当O3/NO物质的量比为1.2、溶液中NaOH浓度为0.5%、添加剂Na2S浓度为0.6%时,NOx脱除效率可达70%,SO2脱除效率在95%以上.60 min长时间运行实验证明,模拟烟气中的NOx经碱液和添加剂吸收后主要以NO-2的形式存在于喷淋液中,且NOx脱除效率不随溶液pH值的变化而变化. 相似文献
16.
《中国化学快报》2021,32(10):2963-2974
The simultaneous removal of SO2, NOx and Hg0 from industrial exhaust flue gas has drawn worldwide attention in recent years. A particularly attractive technique is selective catalytic reduction, which effectively removes SO2, NOx and Hg0 at low temperatures. This paper first reviews the simultaneous removal of SO2, NOx and Hg0 by unsupported and supported catalysts. It then describes and compares the research progress of various carriers, eg., carbon-based materials, metal oxides, silica, molecular sieves, metal-organic frameworks, and pillared interlayered clays, in the simultaneous removal of SO2, NOx and Hg0. The effects of flue-gas components (such as O2, NH3, HCl, H2O, SO2, NO, and Hg0) on the removal of SO2, NOx, and Hg0 are discussed comprehensively and systematically. After summarizing the pollutant-removal mechanism, the review discusses future developments in the simultaneous removal of SO2, NOx and Hg0 by catalysts. 相似文献
17.
Spectrophotometric Determination of Ammonia and Nitrogen Oxides in the Reaction Products of Ammonia Oxidation 总被引:1,自引:0,他引:1
E. F. Sutormina 《Journal of Analytical Chemistry》2004,59(4):331-334
A spectrophotometric procedure is developed for the simultaneous determination of ammonia, NO, and NO2 in the reaction products of the catalytic oxidation of ammonia under industrial conditions. Samples are taken from the reactor, and the analysis is made at 250°C. A multiple linear regression is used for the calibration. The relative standard deviation of the determination of ammonia and nitrogen oxides is no higher than 6%. 相似文献
18.
采用原位红外光谱研究了在具有短程有序Ce-O-Ti结构的非晶Ce-Ti氧化物上NH3选择性催化还原(SCR) NOx反应. 在反应条件下,催化剂表面主要被NH3吸附物种覆盖,而检测不到NOx吸附物种. 经测定,NO的反应级数为0.5-0.6,表明Langmuir-Hinshelwood机理和Eley-Rideal机理同时存在. 可能的机理是NH3吸附物种和弱吸附的NOx反应,生成NHyNO3 (y = 0-4)活性中间物种,并通过GAUSSIAN计算和原位红外结果证实了它们的存在. Ce-O-Ti结构中Ce与Ti之间表现出原子尺度的相互作用,所以在SCR反应的活性温度窗口下,催化剂的氧化还原活性提高. 相似文献
19.
Lander Hollevoet Dr. Fatme Jardali Dr. Yury Gorbanev Dr. James Creel Prof. Annemie Bogaerts Prof. Johan A. Martens 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(52):24033-24037
Ammonia is an industrial large-volume chemical, with its main application in fertilizer production. It also attracts increasing attention as a green-energy vector. Over the past century, ammonia production has been dominated by the Haber–Bosch process, in which a mixture of nitrogen and hydrogen gas is converted to ammonia at high temperatures and pressures. Haber–Bosch processes with natural gas as the source of hydrogen are responsible for a significant share of the global CO2 emissions. Processes involving plasma are currently being investigated as an alternative for decentralized ammonia production powered by renewable energy sources. In this work, we present the PNOCRA process (plasma nitrogen oxidation and catalytic reduction to ammonia), combining plasma-assisted nitrogen oxidation and lean NOx trap technology, adopted from diesel-engine exhaust gas aftertreatment technology. PNOCRA achieves an energy requirement of 4.6 MJ mol−1 NH3, which is more than four times less than the state-of-the-art plasma-enabled ammonia synthesis from N2 and H2 with reasonable yield (>1 %). 相似文献
20.
Ye Liu Ping Ning Kai Li Lihong Tang Jiming Hao Xin Song Guijian Zhang Chi Wang 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(3):490-499
A series of modified porous activated carbon (AC) catalysts prepared by impregnation were investigated for the low-temperature (≤250°C) selective catalytic reduction (SCR) of NO x with NH3 with simultaneous removal of SO2. The effects of various preparation conditions and reaction conditions on NO and SO2 conversions were observed, such as support type, active components, copper loading, calcination temperature and presence of H2O and O2. The modified AC catalysts were characterized by BET, XRD, TG and TPX methods. The activity test results showed that the optimal catalyst is 15% Cu/WCSAC which can provide 52% NO conversion and 68% SO2 conversion simultaneously at 175°C with a space velocity of 30000 h?1, and the optimal calcination temperature was 500°C. The presence of H2O could inhibit NO conversion and promote the SO2 conversion. The effect of O2 (0–5%) was evaluated, and the NO and SO2 conversions were best when the concentration of O2 was 3%. Research demonstrated that Cu/WCSAC catalyst was a kind of potential catalysts due to the amorphous phase, high specific areas and high active ability. 相似文献