Nitrogen Oxides Ozonation as a Method for NOx Emission Abatement

Attempts to develop new technologies of reduction of NO_x emission are still carried out all around the world. However, most of them as literature survey suggests is focused on NO_x emission control from power plants and mobile vehicles. Fewer investigations are conducted on the NO_x emission abatement from the chemical industry. One of the relatively new approaches is the application of ozone injection into exhaust gas stream followed by an absorption process. Ozone is used to transform NO_x to higher nitrogen oxides that are more soluble in water, and therefore the higher yield of nitric acid is expected. The main objective of this article is to present results of our studies in which the effectiveness of the ozonation process, as well as the dependence of the conversion rate and the selectivities of NO ozonation into NO₂, N₂O₅ and HNO₃ on the residence time of reagents in the reactor space were studied. Results of laboratory investigations were confirmed during ozonation experiments with real exhaust gases from a nitric acid pilot plant in Fertilizers Research Institute in Pulawy, Poland.     

Synthesis of doped MnOx/diatomite composites for catalyzing ozone decomposition

The wide applications and unintended generation of ozone stimulate the exploration of catalysts for ozone decomposition. Herein, manganese oxides loaded on porous ceramic beads were prepared via a simple thermolysis method. Doping the composite with Ni, Fe, and Al could tune the oxygen vacancies in the manganese oxide, as evidenced by the X-ray photoelectron spectroscopy (XPS) analysis. The average valance of Mn could also be altered by the dopants. The catalytic properties of the composites doped with Fe, Ni, and Al have been significantly improved. And the Ni doped MnO_x with the highest density of oxygen vacancy exhibits the best catalytic activity. The prepared composite catalyst can easily be incorporated into filters for air circulation.     

Synthesis of MnOx/reduced graphene oxide nanocomposite as an anode electrode for lithium-ion batteries

We report the high performance of the manganese oxide/reduced graphene oxide (MnOx/rGO) nanocomposite as an anode electrode of a lithium-ion battery. The composite is synthesized by a low temperature (83 °C) chemical solution reaction, and shows relatively high specific capacities (660 mAh g⁻¹) after 50 cycles. For MnOx/rGO composites, the cycling stability is increased remarkably as compared to that seen with individual MnOx, and this is due to the synergistic effects of both the components in the composite. The rGO acts as a conductive buffer layer that suppresses the volume change of MnOx, and simultaneously promotes the conductivity of MnOx. The functional groups of graphene oxide facilitate MnOx formation at low temperature, and this retains the MnOx-graphene oxide connection, thus improving the capacity and cycling stability.     

烟气硫氧化物和氮氧化物控制技术小结

论述了烟气脱硫脱氮技术,并对这些技术的优缺点作了评述.     

用于氮氧化物处理的填料塔的设计

选用填料塔对草酸生产过程中产生的氮氧化物进行吸收处理。对填料塔本体进行了设计计算,结合已有的工程设计经验给出了确定填料塔本体尺寸的具体步骤,并讨论了设计应考虑的主要问题。所采用的工艺有效地降低了生产过程中氮氧化物的排放,降低了生产成本,减少了环境污染。     

Nitrogen Oxides Scrubbing with Alkaline Solutions

The absorption of NOx into sodium hydroxide solutions was studied in a small packed column. A simple mathematical model developed for this absorption was used for the determination of rate parameters relative to NOx species in such solutions. While hydrolysis is the main controlling step for NO₂, N₂O₄ and N₂O₃ species, nitrous acid HNO₂ plays an essential role for the NOx absorption in NaOH solutions. Our mechanistic and kinetic findings were validated as the model has worked with fair success in predicting both NOx removal efficiencies and liquid phase compositions.     

MnOx/颗粒活性炭催化臭氧氧化技术降解硝基苯效能研究

通过半动态实验,对MnOx/GAC(颗粒活性炭)催化臭氧氧化技术氧化硝基苯的降解效能与动力学规律进行了初步研究.结果表明MnOx/GAC催化臭氧氧化过程对硝基苯具有较高的催化活性,在相同的反应条件下,MnOx/GAC催化臭氧氧化技术对硝基苯的降解效率是单独臭氧氧化的2.4倍.催化剂对硝基苯有一定的吸附作用.MnOx/GAC催化剂的存在提高了臭氧的利用率.MnOx/GAC催化臭氧氧化过程存在着催化剂最佳投量,硝基苯初始浓度与反应速率常数有良好的线性相关性,水质本底对MnOx/GAC催化臭氧氧化效率也有影响.     

MnOx/γ-A12O3催化加氢合成3,5-二甲氧基苯甲醛

将3,5-二羟基苯甲酸与硫酸二甲酯在碱性条件下反应生成3,5-二甲氧基苯甲酸甲酯,然后在高压下以MnOx/γ-Al2O3为催化剂催化加氢得到3,5-二甲氧基苯甲醛.总收率81.7%.催化剂采用共沉淀法制备,Mn载量wMn=15.3%.     

Ni/Pillared Clays as Catalysts for the Selective Catalytic Reduction of Nitrogen Oxides by Propene

Different and alternative methods for the preparation of Ni/pillared clays based on impregnation and encapsulation procedures are reported. Several nickel precursors and metal loadings are considered in order to evaluate their influence on the structural, textural and catalytic properties of the resulting solids. The behaviour of the optimum solids as catalysts has been proved in the selective catalytic reduction of nitrogen oxides with propene, and the relevance of the oxidant nature was checked by changing the composition of the oxidant mixture. Of all the factors studied, the nature of the nickel precursors appears as the most important one, owing to the formation of different active nickel species during the synthesis procedure.     

MnO_(x/γ)-Al_2O_3催化加氢合成3,5-二甲氧基苯甲醛

α将3,5-二羟基苯甲酸与硫酸二甲酯在碱性条件下反应生成3,5-二甲氧基苯甲酸甲酯,然后在高压下以MnOx/y-Al2O3为催化剂催化加氢得到3,5-二甲氧基苯甲醛。总收率81.7％。催化剂采用共沉淀法制备,Mn载量wMn=15.3％。     

无定形MnOx/SiO2催化剂的合成及低温催化氧化甲醛机理

甲醛因其污染范围广、持续时间长、危害性大等特性被视为室内有害物质的头号“杀手”。本文采用自组装法于SiO₂表面原位生长MnO_x（MnO_x/SiO₂催化剂）并用于低温催化氧化甲醛的研究,XRD、SEM-EDS、TEM和BET表征显示,MnO_x以无定形态均匀地分布在SiO₂载体表面,同时考察了MnO_x的负载量以及煅烧温度对甲醛催化活性的影响。实验结果表明,优选的质量分数13% MnO_x/SiO₂无定形催化剂具有较大的比表面积（高达164.85m²/g）和丰富的活性位点（Mn³⁺,75.6%）,而较大的比表面积有利于更多的甲醛分子吸附在催化剂表面并进行活化反应。对甲醛进行连续性动态检测,结果显示催化剂在连续催化6h后仍保持80%以上的去除效率,表明无定形催化剂具有良好的低温催化效果。随着温度的升高,催化甲醛过程中间产物（甲酸根）被进一步分解,有利于催化剂的再生使用,当温度达到90℃时,甲醛的去除效果可达90%。     

Capture of Nitrogen Oxides with a Fibre Chemisorbent

A system for cleaning nitrogen oxides from a gas-air mixture was proposed. The degree of sorption of nitrogen dioxide is determined by the rate of passage of the gas–air mixture through the filter and its concentration. Weakly basic VION AN-1 fibre treated with 3% sodium hydroxide solution was used as the chemisorbent. A hypothesis was advanced concerning the chemistry of capture of nitrogen dioxide by weakly basic VION AN-1 fibre treated with 3% sodium hydroxide solution.     

化工行业氮氧化物控制技术

化工行业氮氧化物最大来源是高温燃烧系统。燃料性质、空气-燃料比、空气过量程度,以及火焰温度是影响氮氧化物生成量的关键因素。控制氮氧化物的方法有两类:一是燃烧过程中控制,通过改善燃烧参数以避免氮氧化物的生成;另一种是燃烧后控制,就是设法把已经生成的氮氧化物从废气中除去。概述了这些控制方法的原理、特点和影响因素。     

Preparation and characterization of Ag/MnOx/perovskite catalysts for CO oxidation

The spray decomposition method with lanthanum nitrate, manganese nitrate, silver nitrate and citric acid was used to synthesize Ag- and Mn-incorporated perovskites. The resulting samples were characterized by X-ray diffraction, BET adsorption measurement, X-ray photoelectron spectroscopy, and temperature-programmed oxygen desorption (O₂-TPD) measurement. The obtained composite Ag/MnO_x/perovskites catalysts exhibit higher activity by a few orders of magnitude at 338 K than that of LaMnO₃. From the O₂-TPD measurement, the high activity of the Ag/MnO_x/perovskites may result from the increase of weak oxygen adsorption below 373 K. This revised version was published online in July 2006 with corrections to the Cover Date.     

加压条件下氮氧化物的水吸收研究

为寻求高效控制氮氧化物的方法,在实验室用模拟氮氧化物废气对其进行加压吸收.结果表明,在低压时(0～0.4 MPa),水对氮氧化物吸收效率随着氮氧化物进口浓度的增大而减小,而在高压时(0.4～0.8 MPa),吸收效率随着氮氧化物进口浓度的增大而增大.同一进口浓度下的吸收效率随系统压力的增大而增大,0.8 MPa下的吸收效率是常压吸收效率的6倍多,但高于0.6 MPa后吸收效率增大趋势变小.因此,加压吸收是控制氮氧化物的一种很好的方法,0.4～0.6 MPa吸收氮氧化物比较适宜.回收的硝酸的价值可以弥补气体压缩的运行成本.     

化石燃料燃烧过程中氮氧化物排放量的评估

介绍了计算化石燃料燃烧过程中NOx排放量的3种估算方法,分别是<"八五"环境统计手册>、(1996年修订版)和Kato N排放因子计算法.通过举例对3种估算方法进行了比较,并指出了各自的使用条件,各企业可根据具体情况分别选用.     

稀燃汽车尾气NO_x催化净化技术

稀燃汽车尾气中NOx如何高效消除是环境催化领域亟需解决的问题。从稀燃汽车面临的挑战出发,重点概述了稀燃汽车尾气NOx的催化净化技术,包括催化分解、选择性催化还原、NOx存储还原,并讨论了该领域存在的问题以及研究方向。     

Polymerized Organic-Inorganic Synthesis of Mixed Oxides

A new and simple chemical route has been used to synthesize mixed-oxide powders. The method uses long-chain polymers, such as poly(vinyl alcohol) and poly(ethylene glycol). The chemistry of the precursor solution differs from other solution-polymerization techniques. The stabilization of the cations in the precursor is established not only through the chemical binding of cations with the functional groups, but also, in major part, through the physical entrapment of the metal ions in the network of the dried polymer carrier. Pure, single-phase calcium aluminate, yttrium aluminate, and yttrium phosphate powders have been produced, while maintaining a 4:1 ratio of positively charged valences of the cations (Me ^{n +}) to negatively charged hydroxyl (-OH⁻) groups. The ceramic yield of the new method (the ratio of the weight of the ceramic powders to the weight of the organics that are used in the preparation) is ∼2.     

氧化铝陶瓷料浆添加剂合成及性能研究

以对氨基苯磺酸、苯酚、甲醛为主要原料,合成了氨基磺酸系减水剂,研究了氨基磺酸系减水剂的合成工艺路线及原料配比、原料浓度、反应pH值、反应温度等因素对减水效果的影响,验证了优化工艺条件下聚合产物的重复性及扩大性,并用红外光谱对聚合产物的结构进行了分析与表征。优化的反应条件为:n(对氨基苯磺酸)∶n(苯酚)∶n(甲醛)=1∶2∶6、反应初始pH值为8、氨基苯磺酸的浓度为0.4 mol/L、反应温度为90~95℃时。