甘氨酸合钴溶液脱除NO

结合乙二胺合钴具高效脱NO的特性,选取与乙二胺合钴配位结构相似的氨羧化合物——甘氨酸,替代乙二胺作钴配合物配体进行脱NO研究,以期解决乙二胺易挥发、难运输等问题.实验表明：甘氨酸合钴的初始浓度对NO脱除影响显著,随浓度的增大NO脱除率提高;吸收剂的pH值和吸收反应温度也对NO脱除率影响显著,最佳pH值为中性至弱碱性,最佳反应温度50℃左右;同时脱硫脱氮时,尿素的加入因其可促进SO^2-₃的氧化,从而提高甘氨酸合钴同时脱硫脱氮能力.     

烟气处理时乙二胺合钴高效脱NO实验研究

烟气同时脱硫脱氮中NO脱除是关键问题,乙二胺合钴具有高效脱NO能力,但Co2(SO3)3沉淀的生成导致脱氮率迅速降低,本研究在乙二胺合钴中加入尿素,使吸收后SO2高效氧化生成易溶于水的Co2(SO4)3,避免降低脱NO活性组分乙二胺合钴的浓度,而保证高效同时脱硫脱氮。实验证明:尿素质量分数的大小对SO2氧化率影响很大;吸收液pH值增大,反应温度的升高及氧气体积分数的增大,都可提高SO2氧化率;在乙二胺合钴溶液中加入尿素,在保证SO2氧化率几乎达到100%的同时,也保证较长时间内NO脱除率在95%以上。     

NO与Co(NH_3)_6~(2+)气液反应动力学

用Co(NH3 ) 2 + 6的氨水溶液可同时实现NO的氧化和吸收过程 .NO与Co(NH3 ) 2 + 6气液反应动力学研究表明 ,NO与Co(NH3 ) 2 + 6的反应为瞬间反应 ,当Co(NH3 ) 2 + 6浓度低于 2 0mmol·L-1时过程为双膜控制 ,当Co(NH3 ) 2 + 6浓度大于 2 0mmol·L-1时过程逐渐变为气膜控制 .NO的吸收速度随温度的升高而降低 ,气相中氧的存在有利于NO的吸收 ,但当氧的含量高于 5 2 %后再继续增加氧的含量NO吸收速率提高不大 .经研究建立了有氧时NO与Co(NH3 ) 2 + 6气液反应动力学方程     

三乙烯四胺合钴溶液脱除烟气中NO的实验研究

采用三乙烯四胺合钴溶液作为吸收液,在填料塔内,对模拟烟气进行了湿法脱硝的实验研究.主要考察了不同吸收液的NO脱除能力,以及温度和氧体积分数对NO脱除效率的影响.研究结果表明:无氧条件下,三乙烯四胺合钴溶液脱除NO的能力比Fe2+-乙二胺四乙酸(EDTA)溶液脱除NO的能力强;气相中的氧体积分数对NO的脱除影响显著,气相...     

催化氧化-碱液吸收脱除硝酸工业NOx废气

碱液吸收脱除硝酸工业NOx废气中通常通过配气来提高脱除率,针对此方法导致的有效气损失及碱液消耗高的问题,提出了以改性活性炭(MAC)为催化荆的催化氧化-碱液吸收的处理工艺.探讨了相对湿度、氧化温度、氧化时间对NO催化氧化以及NOx氧化度对碱液吸收的影响.结果表明,相对湿度的增加强烈抑制了NO的转化;随着氧化温度从30℃升至90℃,干气条件下NO转化率由43%下降至19%,但湿气条件下NO氧化反应存在最佳反应温度为50～70℃.碱液吸收实验表明,氧化度为50%～60%时NOx脱除率最高,可达85%以上,催化氧化-碱液吸收的多级组合可实现硝酸工业废气中NOx的有效脱除.     

臭氧氧化—钙法吸收同时脱硫脱硝的试验研究

针对国内某石化企业CFB锅炉烟气特点,进行实验室烟气模拟,采用臭氧氧化—钙法吸收同时脱硫脱硝工艺进行小试研究.实验采用臭氧将NO氧化为NO2,再通入鼓泡反应器中与Ca（OH）2浆液发生吸收反应,达到同时脱硫脱硝的目的.实验结果表明：NOx脱除率与臭氧投加量成正比,当臭氧投加量为1.1时,NOx脱除率可达到90％以上;SO2初始浓度的变化对NOx脱除率影响不大;NO初始浓度和烟气含氧量对SO2脱除率影响效果均不显著;烟气含氧量的增大有利于NOx的脱除.     

催化氧化耦合超重力技术脱除NO_x的研究

用Mn Fe Ox气相催化氧化NO,在旋转填充床中以Na OH溶液吸收脱除NO_x。考察模拟烟气中NO的转化率、进口体积分数、吸收液循环使用时间对NO_x脱除率影响,监测了吸收液循环使用时间420 min内的p H值及离子成分。结果表明,NO转化率55. 17%时,NO_x脱除率达93. 42%; NO进口体积分数提升,使NO_x的脱除率先上升后下降;Na OH吸收液循环使用420 min内,NO_x脱除率在90. 8%以上,反应产物为NO-2及少量NO-3,p H值12. 68。     

催化氧化耦合超重力技术脱除NO_x的研究

用Mn Fe Ox气相催化氧化NO,在旋转填充床中以Na OH溶液吸收脱除NO_x。考察模拟烟气中NO的转化率、进口体积分数、吸收液循环使用时间对NO_x脱除率影响,监测了吸收液循环使用时间420 min内的p H值及离子成分。结果表明,NO转化率55. 17%时,NO_x脱除率达93. 42%; NO进口体积分数提升,使NO_x的脱除率先上升后下降;Na OH吸收液循环使用420 min内,NO_x脱除率在90. 8%以上,反应产物为NO-2及少量NO-3,p H值12. 68。     

钴络合物液相络合NO的研究进展

介绍了钴络合物液相络合NO的研究情况,详细论述了其络合NO的反应机理、动力学、吸收液的再生和吸收过程的影响因素,同时详述了该类络合剂同时脱除SO2和NO的研究情况,并对今后该类络合剂单独脱氮和同时脱硫脱氮存在的主要问题和今后的发展方向提出了几点建议。     

垃圾焚烧烟气臭氧同时脱硝脱汞反应动力学研究

近年来,臭氧多种污染物一体化脱除技术在大气环境治理方面得到了广泛应用。臭氧作为一种强氧化剂,除了可将烟气中的NO深度氧化外,还可实现对微量重金属元素Hg的氧化脱除。通过建立臭氧与多种烟气污染物的反应动力学机理,采用Chemkin Pro软件,对某垃圾焚烧烟气臭氧同时脱硝脱汞过程进行反应动力学模拟。通过对NO、Hg与O_3反应的敏感度系数分析,得到O_3对NO和Hg氧化的关键基元反应,从而提出O_3和Hg的氧化反应路径;并进一步改变原烟气的初始参数,探究烟气温度、摩尔比和反应时间对NO和Hg脱除过程的影响。模拟结果表明,随着O_3/NO摩尔比增大,NO和Hg的氧化脱除效率增大。温度对于O_3深度氧化NO过程和Hg氧化脱除过程均有显著影响,温度过低,反应速率较慢,氧化过程延长;温度过高,反应速率加快,但由于中间产物的氧化分解,导致总体氧化脱除效率降低; NO深度氧化为N_2O_5的反应时间远大于初级氧化为NO_2的反应时间,深度氧化时间为5~8 s,最佳反应温度为60~80℃;垃圾焚烧过程产生的HCl气体对Hg氧化具有促进作用,Hg氧化为Hg~(2+)的反应时间在4~6 s,最佳反应温度在110℃左右,最终氧化产物为HgO和HgCl_2。     

NO与Co(NH3)2+6气液反应动力学

用Co(NH₃)²⁺₆的氨水溶液可同时实现NO的氧化和吸收过程.NO 与Co(NH₃)²⁺₆气液反应动力学研究表明,NO与Co(NH₃)²⁺₆的反应为瞬间反应,当Co(NH₃)²⁺₆浓度低于20mmol•L^-1时过程为双膜控制,当Co(NH₃)²⁺₆浓度大于20mmol•L^-1时过程逐渐变为气膜控制.NO的吸收速度随温度的升高而降低,气相中氧的存在有利于NO的吸收,但当氧的含量高于5.2%后再继续增加氧的含量NO吸收速率提高不大.经研究建立了有氧时NO 与Co(NH₃)²⁺₆气液反应动力学方程.     

NO与Co(NH3)2+6气液反应动力学

用Co(NH₃)²⁺₆的氨水溶液可同时实现NO的氧化和吸收过程.NO 与Co(NH₃)²⁺₆气液反应动力学研究表明，NO与Co(NH₃)²⁺₆的反应为瞬间反应，当Co(NH₃)²⁺₆浓度低于20mmol•L^-1时过程为双膜控制，当Co(NH₃)²⁺₆浓度大于20mmol•L^-1时过程逐渐变为气膜控制.NO的吸收速度随温度的升高而降低，气相中氧的存在有利于NO的吸收，但当氧的含量高于5.2%后再继续增加氧的含量NO吸收速率提高不大.经研究建立了有氧时NO 与Co(NH₃)²⁺₆气液反应动力学方程.     

Reaction of nitric oxide and nitric oxide + carbon monoxide with amorphous Fe-Co-B alloy powders

The activity of amorphous Fe---Co---B alloy powder was investigated for the decomposition and the reduction of nitrogen monoxide. The transient response technique and a fixed bed reactor were applied to study the interactions of the Fe---Co---B alloy with two gas mixtures: NO + Ar at 353 and 573 K and NO + CO + Ar at 333–573 K. Moessbauer spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to study the state of the initial sample and the samples utilized in both gas mixtures. It is shown that the amorphous Fe---Co---B alloy powder has an activity for the direct decomposition of nitric oxide to nitrous oxide and nitrogen at a high gas space velocity (26 000 h⁻¹). Oxygen from the decomposed nitric oxide poisons the surface for the formation of nitrogen. In the presence of carbon monoxide (a NO + CO + Ar gas mixture) nitric oxide is reduced to nitrous oxide at 333–353 K and fully reduced to nitrogen at 373–573 K. The quantities of the carbon dioxide formed are not equal to the values expected from the stoichiometry of the NO + CO reaction. Probably, the interaction of carbon monoxide with the adsorbed oxygen (left on the surface by the decomposed nitric oxide) enhances the rate of nitric oxide decomposition to nitrous oxide and nitrogen. The rate limiting steps for both reactions of nitric oxide decomposition, as indicated by the transient response data, change with increasing temperature. The data from the Moessbauer spectroscopy and the X-ray photoelectron spectroscopy (XPS) studies have shown that the amorphous Fe---Co---B alloy powder undergoes phase changes under the conditions of both, the NO + Ar and the NO + CO + Ar gas mixtures. Boron migrates to the surface of globules and serves the accumulation of oxygen by the formation of B₂O₃ (or B(OH)₃).     

Characterization and catalytic properties of perovskites with nominal compositions La1-xSrxAl1-2yCuyRuyO3

Nine different metal oxide catalysts were prepared by impregnating alumina washcoats with water solutions containing La³⁺, Sr²⁺, Cu²⁺ and Ru³⁺ ions and calcining them at 900°C. The produced samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) studies combined with energy-dispersive spectroscopy (EDS) analysis, X-ray powder diffraction and specific surface area measurements. A perovskite phase of the nominal composition La_1-xSr_xAl_1-2yCu_yRu_yO₃ was found in all samples, in increasing amount in the samples with increasing contents of strontium and ruthenium. The catalysts were evaluated with respect to light-off temperatures and redox characteristics using two gas mixtures, one containing NO/CO/C₃H₆/O₂/N₂ and the other NO/CO/N₂. The light-off temperatures for nitric oxide reduction decreased from 534 to 333°C for the catalysts without and with strontium and ruthenium, respectively. In the presence of oxygen the conversion of nitric oxide declined rapidly under oxidative conditions whereas in absence of oxygen this decline was less pronounced and found to be linear over the entire redox interval studied. These studies suggest that the perovskite phase takes an active part in the conversion of nitric oxide and carbon monoxide to nitrogen and carbon dioxide.     

Effect of the oxidation of activated carbon by hydrogen peroxide on its catalytic activity in the regeneration of Co(II)TETA

Cobalt(II) triethylenetetramine (Co(II)TETA) formed by soluble cobalt(II) salt combining with triethylenetetramine will be used as a wet denitration technique since it can interact with nitric oxide to accomplish quick absorption of NO from gas phase. However, the oxygen in the flue gas will oxidize Co(II)TETA to Co(III) TETA, resulting in the reduction of denitrification efficiency. Activated carbon has been used to promote the regeneration of Co(II)TETA due to its unique surface characteristics. Hydrogen peroxide solution is utilized as a modifier in the carbon modification to improve the catalytic performance of activated carbon. The experiments demonstrate that the best regeneration efficiency of Co(II)TETA is gained by the modified carbon impregnated in 0.05 mol L⁻¹ H₂O₂ solution at 70°C for 12 h with a solid/liquid ratio of 1/50 (g/mL) followed being activated at 400°C for 2 h in N₂. After being treated with hydrogen oxide solution, the surface area and acidity of the carbon is increased. Continuous experiments reveal that the NO removal efficiency gained by modified activated carbon is about 8.36% higher than that gained by the original carbon.     

Selective Catalytic Reduction of NO by C3H6 over Co/Al2O3 Catalyst with Extremely Low Cobalt Loading

In order to reveal the optimum Co loading, the selective catalytic reduction of NO with C₃H₆ over Co/Al₂O₃ catalyst was studied in a systematic fashion by varying the amount of cobalt oxide. It was found that upon loading a small amount of cobalt oxide (namely 0.5 wt% on a Co metal basis), the combination between Co(II) acetate salt and a high-purity alumina provided an active catalyst in the presence of excess oxygen and water. TPR measurement showed the presence of Co species other than CoAl₂O₄ spinel in the most excellent performance catalyst, from which the active sites should be produced.     

Additional effects of cobalt precursor and zirconia support modifications for the design of efficient VOC oxidation catalysts

The influence of the ZrO₂ support modification by Y₂O₃ and the presence of ethylenediamine (“en”) during the preparation of Co/ZrO₂ were studied and compared with a reference catalyst conventionally prepared by impregnation of ZrO₂ with an aqueous solution of Co(NO₃)₂. The effect of the en/Co molar ratio (x = 1–3) was studied. Activation of cobalt species was followed by differential thermal and thermogravimetric analyses (DTA/TG) analyses and by specific surface area measurements which evidence the complete cobalt precursor decomposition at 450 °C, whatever the support composition and the en/Co molar ratio. The addition of an aqueous solution of ethylenediamine to a cobalt nitrate solution led to a strong increase in the catalytic activity of the activated solids for the toluene deep oxidation as compared to the reference catalyst. The best catalytic results were explained in terms of cobalt oxides dispersion (X-ray diffraction (XRD)) and also in terms of Co-support interaction (H₂-temperature-programmed reduction (TPR)). The generated cobalt species were reducible at much lower temperatures and were more active in the toluene total oxidation. Finally, an efficient catalyst was produced combining the modifications of the support by yttrium oxide and of the precursor (use of ethylenediamine).     

Designing a structured catalyst for selective reduction of O<Subscript>2</Subscript> by hydrogen in the presence of NO

The influence of the promoter (Pd) modifying additives of oxides of rare-earth (La₂O₃, CeO₂) and transition (NiO, CuO) metal oxides on the catalytic activity of Co₃O₄/cordierite in reactions of O₂ and NO reduction by hydrogen was studied. Introducing Pd and rare-earth metal oxides into the composition of cobalt oxide catalyst results in an increase in its activity in H₂ + 1/2O₂ → H₂O, H₂ + NO → 1/2N₂ + H₂O reactions and an increase in selectivity upon oxygen reduction by hydrogen in the presence of nitric oxide, due possibly to a decrease in the strength of oxygen bounds with the surface and the formation of low-temperature forms of oxygen, which is not typical of unpromoted cobalt oxide catalyst. A structured Pd-Co₃O₄-La₂O₃/cordierite catalyst was developed that surpasses the commercial granulated silver-manganese catalyst used in industry to purify the technological gases used in the production of hydroxylamine sulfate of oxygen impurities with reference to activity and selectivity (in the process of oxygen reduction in the presence of nitric oxide), and to thermal stability.