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车用三效催化转化器发展概况 总被引:2,自引:0,他引:2
从载体及三效催化剂角度论述了车用三效催化转化器的发展;指出了影响车用三效催化转化器性能的因素,这些因素的作用是协同的;为提高催化转化器的性能,必须采用系统的方法对其进行优化设计。 相似文献
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车用催化转化器的数值模拟与实验研究 总被引:1,自引:0,他引:1
采用数值模拟和实验相结合的方法比较了常规结构和一种特殊结构双载体三效催化转化器的性能。数值模拟的结果表明,安装环形片的催化转化器流动均匀性优于常规结构的催化转化器。实验结果表明,安装环形片可以提高催化器的转化效率。 相似文献
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本文介绍了摩托车排气净化催化转化器的研究情况 ,包括催化剂的研制及转化器的结构设计 ,经过实验室模拟尾气活性评价、转鼓台架检测、实车试验 ,证明所研制的催化转化器具有较好的催化活性和实用性。同时讨论了催化转化器与二冲程、四冲程摩托车匹配的问题。 相似文献
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摩托车污染控制催化转化器的试验研究 总被引:3,自引:0,他引:3
本文介绍摩托车排气净化催化转化器的研究情况,包括催化剂的研制及转化器的结构设计,经过实验室模拟尾气活性评价、转鼓台架检测、实车试验,证明所研制的催化转化器具有较好的催化活性实用性。同时讨论了催化转化器与二冲程、四种程摩托车匹配的问题。 相似文献
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A series of iron–manganese oxide catalysts supported on TiO2 and titanium nanotubes (TNTs) were studied for low temperature selective catalytic reduction (SCR) of NO with NH3 in the presence of SO2. The results showed that the specific surface area and the amount of Brønsted acid sites were highly correlated. The results also demonstrated that higher Mn4+/Mn3+ ratios and larger specific surface areas might be the main reasons for the excellent performance of MnFe-TNTs catalyst after SO2 poisoning. The SO2 poisoning effect could be minimized by reducing the GHSV, increasing the reaction temperature, or increasing the [NH3]/[NO] molar ratio. The results also indicated that the formation of ammonium sulfate had a stronger effect on the NO conversion efficiency as compared to the formation of metal sulfate. Thus operating the low temperature SCR at above 230 oC to avoid the formation of ammonium sulfate would be the priority choice when SO2 poisoning is a concerned issue.?Implications: Low-temperature selective catalytic reduction (SCR) has attracted increasing attention due to that it can reduce the energy consumption for the SCR process employed in industries such as steel plants and glass manufacturing plants. However, it also suffers from the sulfur dioxide (SO2) poisoning problem. This study investigates the possibility of using titania nanotubes (TNTs) as the support of Mn/Fe bimetal oxide catalysts for low-temperature SCR to reduce the SO2 poisoning. The results indicated that the MnFe-TNT catalyst can tolerate SO2 for a longer time as compared with the MnFe-TiO2 catalyst. 相似文献
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用于气态零价汞转化的催化剂研究 总被引:4,自引:0,他引:4
零价汞的高效去除是燃煤烟气汞污染控制过程中的关键环节。为了促进烟气中的零价汞转化为易于去除的氧化态汞,分别考察了在有HCl存在时,几种过渡金属氧化物(Cu、Fe、Mn、Co和Zr)对零价汞氧化的催化作用,以筛选出性能较好的催化组分;为提高催化剂的抗SO2性能,分别尝试了利用几种金属元素(Sr、Ce、W和Mo)对催化剂进行掺杂改性的方法。结果表明,锰氧化物的催化作用最好,其最佳使用温度在573 K左右;SO2对零价汞的催化氧化有明显抑制作用,在无SO2及1 400 mg/m3SO2时锰催化剂对零价汞催化氧化效率分别为93%和78%。而Mo改性的锰氧化物催化剂的抗硫性能大幅提高,在1 400 mg/m3SO2存在的情况下其对零价汞的催化氧化效率可达到90%以上,较其他改性元素高。 相似文献
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基于微生物酸性铁溶液烟气脱硫特性,实验构建了一套内循环气升式反应器.在反应器中,利用处于对数生长期的氧化亚铁硫杆菌(Thiobacillus ferrooxidans)酸性铁溶液进行了模拟烟道气SO2脱除实验研究.为寻求高脱硫率,实验研究了铁离子浓度、入口氧含量、细菌数和pH值的变化对脱硫率的影响.考察了反应液中Fe(Ⅱ)离子浓度的变化规律.实验表明,含T.f菌酸性铁溶液的脱硫效果较高;Fe离子浓度在7.67 g/L左右时脱硫率最佳;入口气中氧含量、反应液中细菌数和pH值越高,反应液的脱硫率也就越高.反应液中的Fe(Ⅱ)离子浓度是一先扬后抑的变化过程. 相似文献
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低温选择性催化还原(SCR)脱硝是国内外脱硝技术研发的热点,但目前主要集中在实验室小试范围,无法完全反映催化剂在实际烟气中的运行状况。在30 t/h循环流化床燃煤锅炉脱硫除尘装置后建设了2 000~5 000 m3/h的SCR脱硝中试装置,经系统研究发现,中试使用的蜂窝式催化剂对SO2和NO具有很强的吸附能力,且反应温度、喷氨速率和气体空速均会影响催化脱硝效率。为期5 d的连续运行实验结果表明,催化剂的脱硝效率一直稳定在30%~50%,并未发现明显的失活,这证明设计除雾除尘器、较大的混合器、混合器与反应器间较长的管路均有利于缓解催化剂因SO2、H2O和飞灰中的碱性金属导致的失活。 相似文献
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Fenton氧化法同时脱硫脱硝的实验研究 总被引:1,自引:0,他引:1
应用Fenton液相氧化吸收法进行同时脱硫脱硝实验。首先,利用单因素实验,分别考察了H2O2浓度、Fe2+投加量、初始pH值、UV照射和温度对脱硫脱硝的影响。结果表明,SO2和NO去除率随着H2O2浓度和Fe2+投加量的增大而提高;初始pH对SO2和NO的去除有较大影响;UV能促进SO2和NO的净化;温度对脱硫效率影响不大,但对NO的去除有显著作用,适当升温可以提高脱硝效率。随后,考察了SO2对NO去除率的影响。通过单独脱硝和同时脱硫脱硝的对比实验发现,SO2的加入对NO的去除有一定的促进作用,Fenton法可同时获得起始约80%的脱硝效率和98%以上的脱硫效率。 相似文献
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Chun W. Lee Ravi K. Srivastava S. Behrooz Ghorishi Thomas W. Hastings Frank M. Stevens 《Journal of the Air & Waste Management Association (1995)》2013,63(12):1560-1566
Abstract Selective catalytic reduction (SCR) technology increasingly is being applied for controlling emissions of nitrogen oxides (NOx) from coal-fired boilers. Some recent field and pilot studies suggest that the operation of SCR could affect the chemical form of mercury (Hg) in coal combustion flue gases. The speciation of Hg is an important factor influencing the control and environmental fate of Hg emissions from coal combustion. The vanadium and titanium oxides, used commonly in the vanadia-titania SCR catalyst for catalytic NOx reduction, promote the formation of oxidized mercury (Hg2+). The work reported in this paper focuses on the impact of SCR on elemental mercury (Hg0) oxidation. Bench-scale experiments were conducted to investigate Hg0 oxidation in the presence of simulated coal combustion flue gases and under SCR reaction conditions. Flue gas mixtures with different concentrations of hydrogen chloride (HCl) and sulfur dioxide (SO2) for simulating the combustion of bituminous coals and subbituminous coals were tested in these experiments. The effects of HCl and SO2 in the flue gases on Hg0 oxidation under SCR reaction conditions were studied. It was observed that HCl is the most critical flue gas component that causes conversion of Hg0 to Hg2+ under SCR reaction conditions. The importance of HCl for Hg0 oxidation found in the present study provides the scientific basis for the apparent coal-type dependence observed for Hg0 oxidation occurring across the SCR reactors in the field. 相似文献
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S. Matsuda M. Takeuchi T. Hishinuma F. Nakajima T. Narita Y. Watanabe 《Journal of the Air & Waste Management Association (1995)》2013,63(4):350-353
The body of Information presented in this paper is directed to those Individuals concerned with the removal of NOx in combustion flue gases. A catalytic process for the selective reduction of nitrogen oxides by ammonia has been investigated. Efforts were made toward the development of catalysts resistant to SOx poisoning. Nitrogen oxides were reduced over various metal oxide catalysts in the presence or absence of SOx(SO2 and SO3). Catalysts consisting of oxides of base metals (for example, Fe2O3) were easily poisoned by SO3, forming sulfates of the base metals. A series of catalysts which are not susceptible to the SOx poisoning has been developed. The catalysts possess a high activity and selectivity over a wide range of temperatures, 250—450°C. The catalysts were tested in a pilot plant which treated a flue gas containing 110-150 ppm NOx, 660-750 ppm SO2, and 40-90 ppm SO3. The pilot plant was operated at 350°C and at a space velocity of 10,000 h-1. The removal of nitrogen oxides was more than 90% for several months. A mechanism of the NO-NH3 reaction has also been investigated. It is found that NO reacts with NH3 at a 1:1 mole ratio in the presence of oxygen and the reaction is completely inhibited by the absence of oxygen. The experimental data show that the NO-NH3 reaction in the presence of oxygen is represented byNO + NH3 + 1/4 O2 = N2 + 3/2 H2O. 相似文献
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Zhen-Shu Liu Wen-Kai Li Ming-Jui Hung 《Journal of the Air & Waste Management Association (1995)》2014,64(9):1038-1044
Incineration flue gas contains polycyclic aromatic hydrocarbons (PAHs) and sulfur dioxide (SO2). The effects of SO2 concentration (0, 350, 750, and 1000 ppm), reaction temperature (160, 200, and 280 °C), and the type of activated carbon fibers (ACFs) on the removal of SO2 and PAHs by ACFs were examined in this study. A fluidized bed incinerator was used to simulate practical incineration flue gas. It was found that the presence of SO2 in the incineration flue gas could drastically decrease removal of PAHs because of competitive adsorption. The effect of rise in the reaction temperature from 160 to 280 °C on removal of PAHs was greater than that on SO2 removal at an SO2 concentration of 750 ppm. Among the three ACFs studied, ACF-B, with the highest microporous volume, highest O content, and the tightest structure, was the best adsorbent for removing SO2 and PAHs when these gases coexisted in the incineration flue gas.
ImplicationsSimultaneous adsorption of sulfur dioxide (SO2) and polycyclic aromatic hydrocarbons (PAHs) emitted from incineration flue gas onto activated carbon fibers (ACFs) meant to devise a new technique showed that the presence of SO2 in the incineration flue gas leads to a drastic decrease in removal of PAHs because of competitive adsorption. Reaction temperature had a greater influence on PAHs removal than on SO2 removal. ACF-B, with the highest microporous volume, highest O content, and tightest structure among the three studied ACFs, was found to be the best adsorbent for removing SO2 and PAHs. 相似文献