NO2促进碱液吸收NO的作用机理

在鼓泡床反应器中实验研究了碱液吸收NOx过程中NO2对NO吸收的促进作用,考察了NaOH浓度、NOx体积分数、NO/NO2体积比及反应温度(283~358 K)对NOx吸收效率的影响. 结果表明,在NOx≥600′10-6(j), NO/NO2≤2(j)的条件下,NO2有效促进了碱液对NO的吸收,且吸收NO的效率高于NO2. 反应体系气相与液相产物分析表明,吸收过程产生的暂态中间活性组分存在类催化作用,其反应机理为NO2与气相中H2O反应生成HONO(+M),其部分在液膜分解生成NO(aq)和×OH,生成的NO(aq)进入液相,×OH与气相中的NO反应,促进了NO的吸收.     

Thermal stability of NO 2 ⋅ and NO⋅ radicals formed in an Al23 catalyst during its preparation from a nitrate precursor

During the preparation of alumina as a catalyst support from aluminium nitrates by precipitation with a NH₄OH base, NO ₂ ^⋅ radicals have been formed in the catalyst after calcination under air in the solid at different temperatures. These radicals remained stable until a calcination temperature of 800°C. When the calcined catalyst was degassed under vacuum above 300 °C, the NO ₂ ^⋅ was reduced to give NO^⋅ and O^- species which were both tightly trapped in the solid. These latter species remained stable until vacuum treatment at 800 °C. This revised version was published online in July 2006 with corrections to the Cover Date.     

Crystallization and Porosity Evolution of AlOOH–Fe(NO3)3 Gels

Monolithic planar boehmite gels of thickness 0.15 mm seeded by Fe(NO₃)₃ were examined by quantitative DTA, dilatometry, SEM, surface area and pore size distribution and on-line optical transmittance from RT to 1270°C. Dispersed Fe³⁺ ions resulted in 5wt% Fe₂O₃, seeds in monolithic boehmite gels which affected the crystallization of corundum phase and the associated evolution of porosity (the change of inter-colloidal to inter-grain porosity) during heat treatment. Transformation of to -(Al, Fe)₂O₃ took place within individual grains of 100–120 nm size and was similar to unseeded boehmite gels except the a significantly higher frequency of homogeneous nucleation of corundum phase occurred. Gradual elimination of inter-grain pores during sintering was associated with the increase of light transmittance. Ceramics became transparent after sintering at temperatures over 1270°C.     

光催化氧化NO研究进展

烟气光催化脱硝技术是面向烟气净化过程的一种环境友好型处理工艺。开发高效稳定的光催化材料是光催化技术大规模应用的关键和基础。本文综述了光催化脱硝技术反应影响因素以及提高光催化脱硝效率的方法,并基于光催化脱硝技术研究的现状,对其研究方向提出建议。     

新型NO供体的合成研究及其体外NO释放性能

报道以阿司匹林、邻胺基苯甲酸和醋酸锰为原料合成含阿司匹林Mn2+配合物的中间体(1),以无水乙醇为溶剂,在35～45℃的条件下将(1)与NO反应成功合成了目标新型Mn-NO供体(2),并对目标化合物(2)的合成条件分别进行了探索性实验,确定了合成目标化合物(2)的优化条件.并通过元素分析、红外光谱、1HNMR、MS等手...     

NO reduction by C3H6 in excess oxygen over fresh and sulfated Pt‐ and Rh‐based catalysts

The selective catalytic reduction (SCR) of NO with C₃H₆ was studied over three noble‐metal‐based catalysts: 2% Pt/γ‐Al₂O₃, 2% Rh/γ‐Al₂O₃ and 1.5% Rh/TiO₂(4% WO₃). The SO₂ effect on the catalyst activity was examined using sulfated samples of the above catalysts and SO₂‐containing feeds. Temperature‐programmed desorption and oxidation studies were carried out to examine the adsorption characteristics of NO and C₃H₆, respectively, in the absence or the presence of SO₂. The adsorption data were linked to variations in the NO reduction rates over fresh and sulfated samples. Modification of the support surface as a result of the SO₂ presence affects the NO and propene sorption characteristics, the NO oxidation and the propene consumption rates. This revised version was published online in August 2006 with corrections to the Cover Date.     

纯碱液喷射吸收高浓度NO和NO2混合气体的研究

在喷射吸收器内用纯碱液吸收 NO_x 气体,从理论上和实验上研究了碱液浓度、NOx 浓度和组成、反应温度、液气比和气速等对吸收度的影响。结果表明,在碱度为40—60g/L,反应温度为40—50℃,液气比10—12L/Nm~3,NO_x 浓度在3%左右和 NO_x 氧化度在50%左右时可得到最佳的NO_x 吸收度。与同样条件下的填料塔相比较,可节省1—2只吸收器和数个氧化塔;NaNO_2的产量可提高20—30%,能耗降低10—30%。     

Imaging and chemical probing on the atomic scale: reconstruction and dynamics of the systems O2/Rh and NO2–H2/Pt

This paper presents two case studies of adsorbate-induced surface reconstruction, on the one hand, and dynamical reaction imaging along with local chemical probing, on the other hand. The first one deals with the oxygen-induced reshaping of 3D Rh crystals. Field ion microscopy (FIM) was applied to image in real-space the change from a nearly hemispherical shape in the absence of oxygen toward a polyhedral one in the presence of oxygen. Shape transformation occurs at temperatures of 380–550 K and is associated with the appearance of facets with {111} and {001} orientation. The only high-index planes present in the polyhedral form are of {137} symmetry. (1×2) and (1×3) missing-row reconstructions appear in the {113} and {011} planes. The polyhedral form has also been imaged under in situ conditions of the oxygen–hydrogen reaction on Rh at 505 K. The second case study deals with kinetic non-linearities occurring in the NO₂ reaction with hydrogen on the surface of a 3D Pt crystal reconstructed to a top- and edge-truncated pyramid. The reaction was found to ignite in the {012} corner planes of the crystal. One-dimensional wavefronts were subsequently observed to move along the 211 zone lines. These studies were performed by video-FIM and could be correlated with a local chemical analysis by time-of-flight mass spectrometry of ionised species. The mass spectrum provided information on water product (H₂O⁺ and H₃O⁺) and NO intermediate formation. Strong fluctuations in the NO ₂ ⁺ current indicated the occurrence of NO₂ surface diffusion. These species are most likely responsible for the field ion image formation.     

NO x Storage and High Temperature Soot Oxidation on Pt–Sr/ZrO2 Catalyst

NO _x storage–release and soot oxidation have been studied using strontium promoted zirconia with different surface areas. It was found that the amount of the adsorbed NO _x increases with the increase of the support surface and Sr concentration up to 20 wt% Sr. Introduction of platinum has no effect on the amount of NO _x stored, but improve soot oxidation due to recycling of NO to NO₂. A combination of oxidation catalyst with NO _x storage materials enables to lower the temperature of 20% soot conversion up to 100 °C in comparison with un-catalyzed soot oxidation.     

NO分解催化剂的研究进展

直接催化分解被公认是消除NO污染最有吸引力的方法。从贵金属、金属氧化物、复合氧化物和Cu-ZSM-5分子筛等方面综述了国内外有关NO催化分解的研究进展。指出了NO催化分解催化剂研究中存在的问题及其发展方向。     

催化氧化NO技术研究进展

简要阐述了NO催化氧化反应机理,重点介绍了活性炭催化剂、分子筛及其负载型催化剂、贵金属催化剂、过渡金属氧化物催化剂以及钙钛矿催化剂作为NO催化氧化催化剂的研究进展及其优缺点,评述了SCO催化剂的工业应用前景。     

LaCo1−x Pd x O3 Perovskite-Type Oxides: Synthesis, Characterization and Simultaneous Removal of NO x and Diesel Soot

A series of naometric perovskite catalysts LaCo_1?x Pd _x O₃ (x = 0, 0.01, 0.03) were prepared via a solution combustion synthesis route using metal nitrates as oxidizers and urea as fuel. It is essential to add a certain amount of ammonia aqueous solution to Pd²⁺ ions solution in the catalyst preparation process. Homogeneous nanoparticles LaCo_1?x Pd _x O₃ catalysts with the sizes in the range of 68–122 nm were obtained and characterized by using of XRD, BET, H₂-TPR, XPS, SEM and TEM. Pd was successfully introduced into the LaCoO₃ perovskite lattices. Further information was obtained by using XPS upon the LaCo_0.97Pd_0.03O₃ (with NH₄OH) sample after H₂-TPR. The results revealed that surface Pd was reduced to the metallic state at the end of the first step in the H₂-TPR experiment, and some surface Co could be reduced to metallic Co simultaneously. The catalytic properties were investigated for simultaneous NO _x -soot removal reaction. The performance of LaCo_1?x Pd _x O₃ catalysts were greatly improved by the partial substitution of Pd. The maximum NO conversion into N₂ and the ignition temperature of soot are 32.8% and 265 °C, respectively.     

催化光度法测定水中痕量NO2^—和NO3^—

研究了催化光度法测定水中亚硝酸盐氮和硝酸盐氮，在一定条件下，亚硝酸根可以催化甲基红与溴酸钾反应，使甲基红溶液颜色消退，ｌｇ（Ａ０／Ａ）与ＮＯ２＾－量成正比，据此测定ＮＯ２＾－－Ｎ。硝本盐用海绵状镉还原后测定总量，差减法求出ＮＯ３＾－－Ｎ。     

Promotional Effects of H2O Treatment on NO x Storage Over Fresh and Thermally Aged Pt–BaO/Al2O3 Lean NO x Trap Catalysts

A simple liquid water treatment applied to fresh and thermally aged Pt(2 wt%)–BaO(20 wt%)/Al₂O₃ lean NO _x trap catalysts at room temperature induces morphological and structural changes in the barium species as followed by XRD and TEM analysis. During the water treatment, liquid water sufficient to fill the catalyst pore volume is brought into contact with the samples. It was found that irrespective of the original barium chemical state (highly dispersed BaO or crystalline BaAl₂O₄), exposing the sample to this liquid water treatment promotes the formation of BaCO₃ crystallites (about 15–25 nm of its size) without changing the Pt particle size. Such transformations of the barium species are found to significantly promote NO _x uptake from 250 to 450 °C. The increase in the NO _x uptake for the water-treated samples can be attributed to an enhanced Pt–Ba interaction through the redistribution of barium species. These results provide useful information for the regeneration of aged lean NO _x trap catalysts since water is plentiful in the exhaust of diesel or lean-burn engines.     

NO调节剂精氨酸氨基多糖问世

江苏南通双林生物制品有限公司利用丰富的甲壳素资源及自身的技术优势,研制开发出一种新刑NO调节剂精氨酸氨基多糖。该产品具有氨基多糖、精氨酸双重功效和明显的调节NO分泌和传递作用,广泛应用于生物医药、保健品等领域,可有效预防心血管疾病和自身免疫性疾病。     

MnFeOx催化剂低温催化氧化NO

采用有机溶剂法制备非负载型MnFeOx催化剂,用于低温选择性催化氧化NO.研究了催化剂前驱体、Mn7+:Mn2+摩尔比、制备方法等对低温催化氧化NO的影响.实验结果表明,Mn(CH3COO)2作为催化剂前驱体较其它三种物质更有利于提高NO的转化率;Mn7+∶Mn2+=2∶1时低温脱硝性能较优;与共沉淀法比较,有机溶剂法制备的MnFeOx催化剂低温催化氧化活性较好,NO的转化率达到83％.结合扫描电子显微镜(SEM)、X射线衍射仪(XRD)、比表面积测定仪(BET)、X射线光电子能谱仪(XPS)、H2程序升温还原(H2-TPR)表征手段分析,Mn和Fe元素在Mn(CH3 COO)2作为前驱体的催化剂表面上分散均匀,催化剂脱硝性能提高;随着Mn7+∶Mn2+摩尔比增加,催化剂内部发生团聚,比表面积和平均孔径逐渐减小,不利于低温选择性催化氧化反应;同时,NO的催化活性受结晶度的影响,有机溶剂法制备的MnFeOx催化剂结晶度低,具有较多氧空穴,有利于低温脱硝.     

污泥热解炭脱除NO特性

以废水污泥热解产生的污泥热解炭为原料,通过酸洗、活化、负载Fe、H_2还原等方式考察不同污泥热解炭样品对脱硝性能的影响。结果表明,污泥原样中的Fe_2P、FeS等低价态的铁具有良好的脱硝性能,450~500℃时最大脱硝效率达到81%。经过HNO_3酸洗和KOH活化后的污泥热解炭,因为去除了Fe_2P、FeS等低价态的铁,脱硝效率大幅下降,在450~500℃的最大效率分别仅为30%和53%。而热解污泥负载样中的Fe主要以Fe_2O_3形式存在,其最大脱硝效率在450~500℃时只有50%。经过H_2还原后,负载样中的Fe_2O_3被还原为Fe_2P、FeS等低价态的铁,其最大脱硝效率在450~500℃时上升至94%。