Cu-Mn-O制备条件对其催化燃烧甲苯性能的影响

以甲苯催化燃烧为模型反应,考察了Cu-Mn-O催化剂共沉淀制备方法中沉淀剂、滴加方式和焙烧温度对其催化活性的影响.结果表明,以Na2CO3为沉淀剂、反滴(金属离子溶液滴加到碱液)、500℃焙烧所制得的催化剂具有较高的活性,其甲苯完全燃烧(甲苯转化率98%以上)温度为220℃.多晶粉末衍射(XRD)和比表面积(BET)表征发现,在Cu1.5Mn1.5O4晶相中掺杂少量的CuO晶相可以有效地提高催化剂活性,催化剂的比表面积(BET)越大,活性越高.     

M_xO_y/碳纳米管的低温选择性催化还原脱硝性能研究

采用等体积浸渍法制备了MxOy(M表示V、Mn、Cu、Fe)/碳纳米管(CNTs)4种催化剂,用BET法、透射电子显微镜(TEM)和傅立叶红外光谱(FTIR)进行结构表征,并对其低温选择性催化还原(SCR)NO性能进行了考察和对比。结果表明,在NO为1248mg/m3、NH3为707mg/m3、O2为5%(体积分数)、气体总流量为700mL/min、反应温度为353～513K的条件下,不同催化剂存在不同的最佳活性温度,V2O5/CNTs催化剂在473K的较低温度下NO转化率达到最大,为82.9%;各催化剂活性均随着O2含量的增加先升高后降低,且变化幅度相似;在20～160min时,各催化剂活性随着反应时间的变化基本保持不变;催化剂活性均随氨氮比(NH3/NO)的增大先升高后降低,最佳NH3/NO为1.0(体积比)。     

新型MnOx/CNTs催化剂低温选择性催化还原NO

采用等体积浸渍法制备了MnOx/CNTs催化剂,用于低温NH3选择性催化还原(SCR)NO的实验.使用BET,FT-IR,TEM和XRD对催化剂进行表征,结果表明:碳纳米管经混酸超声分散,增加了羧基活性基团,锰氧化物颗粒分布较均匀.在模拟烟气条件下,考察了催化剂的MnOx负载量、煅烧温度及质量和烟气流速比(W/F)对NO脱除率的影响.煅烧温度为773 K,MnOx负载量为10%时,NO脱除率达到98.56%;W/F为2～3 mg/(mL·min-1)时NO的脱除率更高.     

负载型Mn-Ce／TiO2催化剂的制备及其低温脱硝活性

以成型TiO2作为载体,通过浸渍法制备了Mn-Ce／TiO2低温SCR催化剂,并系统研究了制备方法、煅烧条件、活性组分担载量、Mn含量等参数对催化剂催化还原NO性能的影响。结果表明,煅烧温度的升高会促使活性组分结晶度的提高,从而引起催化活性的降低,在500℃和600℃下所得Mn-Ce／TiO2催化剂活性组分为无定型态,表现出较高的脱硝活性。活性组分担载量的增加有利于催化活性的提高。Mn含量对Mn-Ce／TiO2催化剂的活性有较大影响,当Mn／（Mn＋Ce）摩尔比为40％和85％时,催化剂活性最高。     

Ce掺杂改性对MnFe2O4低温选择性催化还原脱硝性能的影响研究

采用水热合成法制备了Ce掺杂MnFe2O4催化剂,用于低温选择性催化还原(SCR)脱硝.对催化剂晶型、脱硝性能和表面结构等进行分析,结果表明,Ce/(Fe+Mn)为0.5％(摩尔分数,下同)时催化剂表现出最优的SCR活性,80℃NO去除率可达100％;Ce/(Fe+Mn)分别为5.0％ 和10.0％ 时,催化剂80℃N...     

CeO_2-CoO/ACF低温SCR烟气脱氮性能的研究

活性炭纤维(ACF)经硝酸处理后采用浸渍法制备了CeO2-CoO/ACF复合催化剂,测试了其在以氨气为还原剂的低温SCR过程中的催化活性,同时研究了金属氧化物浸渍顺序及负载量、催化剂煅烧温度、空速比(SV)、NH3/NO(摩尔比)、O2含量等因素对NO转化效率的影响。研究发现,负载量为10%的CeO2-CoO/ACF复合催化剂经煅烧后在120~240℃时具有很高的催化活性,并且在NO初始浓度为1 000 mg/m3、空速比(SV)为6 000 h-1、NH3/NO为1.05、O2体积分数在3.0%时具有较高的NO转化效率。     

新型MnOx/CNTs催化剂低温选择性催化还原NO

采用等体积浸渍法制备了MnOx/CNTs催化剂,用于低温NH3选择性催化还原（SCR）NO的实验。使用BET,FT-IR,TEM和XRD对催化剂进行表征,结果表明：碳纳米管经混酸超声分散,增加了羧基活性基团,锰氧化物颗粒分布较均匀。在模拟烟气条件下,考察了催化剂的MnOx负载量、煅烧温度及质量和烟气流速比（W/F）对NO脱除率的影响。煅烧温度为773 K,MnOx负载量为10%时,NO脱除率达到98.56%;W/F为2-3 mg/（mL·min^-1）时NO的脱除率更高。     

F和S共掺V_2O_5/TiO_2催化剂对NH_3-SCR活性的影响

在V_2O_5/TiO_2催化剂基础上进行非金属改性载体的研究。采用溶胶凝胶法、浸渍法制备了一种新的氟、硫共掺杂氧化钒/氧化钛催化剂,探讨了新型催化剂对低温SCR活性的影响。并通过比表面积测试(BET)、X射线衍射实验(XRD)、H2和NH3的化学吸附特性测试(H2-TPR、NH3-TPD)等技术对催化剂的理化性能进行表征。研究结果表明,氟、硫掺杂催化剂提高了低温SCR活性,拓宽了活性温度范围,在F与S摩尔比为x3时,获得了最佳的脱硝性能。     

Ce-Sn-W-O_x催化剂的配伍优化及脱硝影响因素

采用共混热解法制备系列Ce-Sn-W-Ox复合氧化物,用于NH3选择性催化还原NO。通过正交实验优化CeSn-W-Ox配方,采用环境扫描电镜(ESEM)、X-射线衍射仪(XRD)等表征分析催化剂的微观形貌和固相结构,确立Ce-Sn-WOx最佳配比及结构形貌。结果表明,以粒度为5~8 mm的堇青石瓷片担载分散Ce-Sn-W-Ox,进行NH3-SCR脱除NO,当Ce/Sn/W元素摩尔比为1∶0.8∶0.6时,Ce Sn0.8W0.6Ox/堇青石NH3-SCR脱除NO效果最好。当空速为7 200 h-1,催化剂在252~426℃内脱除NO效率均大于94%。重点考察了反应空速(GHSV)、水蒸气(H2O)、SO2等对Ce Sn0.8W0.6Ox/堇青石NH3-SCR脱除NO活性的影响。研究表明,空速低于10 000 h-1时,催化剂脱硝活性受空速影响小;单独通入5%H2O对催化剂脱硝活性基本没有影响;单独通入429 mg/m3SO2导致催化剂活性略有降低;同时通入429 mg/m3SO2和5%H2O,催化剂脱硝活性下降至85.33%,除去SO2和H2O后,催化剂活性又能明显回升。     

Fe添加对Mn/γ-Al2O3催化剂低温选择性催化还原NO的性能影响

为考察Fe添加量对锰基催化剂低温选择性催化还原(SCR)烟气中NO的性能,采用湿式浸渍法制备以γ-Al_2O_3为载体,以MnOx、FeOx为活性组分的系列催化剂,通过X射线衍射(XRD)、扫描电镜(SEM)、X射线光电子能谱(XPS)分析等手段对其进行表征。结果表明:Fe的引入对提高催化剂的SCR活性具有明显的促进作用。Fe添加量为0.04 mmol/g时制备的Mn(0.8)-Fe(0.04)/γ-Al_2O_3催化剂脱硝效率在150℃条件下即可以达到93.1%。Fe添加量为0.04mmol/g时催化剂中形成的球状结晶β-MnO_2分散最为均匀,最有利于催化反应的进行。比表面积不是影响催化剂SCR活性的决定性因素。Mn(0.8)-Fe(0.04)/γ-Al_2O_3催化剂孔径分布以2～50nm的中孔为主,活性组分也主要负载到较大的中孔中,有利于催化反应的进行。Fe的加入可以提高催化剂的抗硫性能。     

Optimization of Height of Release of Air Pollutants

A number of key projects in the Environmental Protection Agency (EPA) particulate R&;D program having applicability to industry are presented. For electrostatic precipitators (ESP) there is presented the result of work on large diameter discharge electrodes which provide a decrease in penetration of up to a factor of 4 when compared to conventional small diameter electrodes. Also discussed is the multistage ESP which provides a collection efficiency that would require a collecting plate area 4 or 5 times larger with conventional ESP technology. The E-SOX technology makes use of the multistage concept to free up space in the ESP for SO₂ removals of up to 90%. Electrostatically augmented fabric filtration provides a reduction in pressure drop of about 5 0% as compared to conventional fabric filtration. Wind tunnel modeling of windbreaks for material storage piles indicates a potential for providing engineering design data that would allow significant emission reduction caused by wind erosion     

Investigation of the characteristics of the reflectivity of clouds

This paper investigates some of the reflectivity characteristics that clouds (when modelled as solid bodies) must exhibit to be compatible with observations that the reflecting surface of a cloud (i) appears almost equally bright across its face, (ii) is brightest when the cloud is opposite to the Sun but decreases in brightness as the cloud moves to other positions and (iii) increases in brightness with increasing optical thickness of the cloud in the observer's line of sight. These observations, respectively, are shown to imply that the peak value of the bidirectional total reflectivity from a cloud surface (i) increases in inverse proportion to the cosine of the angle between the Sun and the normal to the cloud surface, as the incident angle increases, (ii) appears to be directed back in the direction of the incident radiation, and (iii) increases as optical thickness of the cloud in the observer's line of sight increases. The results could have application in many fields (e.g. modelling diffuse radiance distributions for cloudy skies).     

Estimation of uncertainty of sampling for analysis of pesticide residues

Abstract

A computer model was used to take random samples from primary sample populations obtained from field trials to simulate the uncertainty of sampling for residue analysis of plant commodities and soil. The results indicate about 40%, 30% and 20% relative uncertainty when random samples of size 5, 10 and 25 are taken respectively, from a single lot. Therefore the sample size should be the same for establishing and enforcing legal limits.     

扬中生态环境建设的思考与实践

结合扬中生态环境的基本情况和存在的不足，进行了具体分析，对扬中未来生态建设的发展方向提出了建议及实施措施。     

实验室质量管理体系内部审核的实施

在实施ISO／IEC17025：1999标准《检测和校准实验室能力的通用要求》过程中，通过实验室质量管理体系内部审核的实践与系统分析，识别出内部审核实施阶段的关键环节，提出召开首次会议、收集审核证据、确定审核发现和召开末次会议的技术方法，对提高内部审核的质量和有效性、获得可靠的审核结论具有重要意义。     

次氯酸钠发生器的研制

介绍了电解法生产次氯酸钠的原理 ,并在原有生产工艺的基础上进行了重新设计和对设备的重新选择、改造 ,得出了各个工艺参数的最佳值 ,生产出高品质的次氯酸钠     

An application of the theory of kinematics of mixing to the study of tropospheric dispersion

The most common technique used for numerical simulations of tracer mixing is that of the numerical solution of the advection–diffusion equation with the unresolved fluxes parameterized using the similarity theory. Despite correct predictions of the overall directions of transport, models based on a numerical solution of the advection–diffusion equation lack sufficient accuracy to correctly reproduce the coupling of mixing with small scale processes which are sensitive to the microstructure of the tracer distribution. The objective of this paper is to revisit the basic formalism employed in numerical models used to investigate atmospheric tracers. The main mathematical method proposed here is the theory of kinematics of mixing which could be applied effectively for simulations of atmospheric transport processes. At the beginning of the paper, we introduce simple mathematical transformations in order to demonstrate how complex topological structures are created by mixing processes. These idealistic flow systems are essential to explain transport properties of much more complex three-dimensional geophysical flows. An example of the application of the kinematics of mixing to the analysis of tracer transport on a planetary scale is presented in the following sections. The complex filamentary structures simulated in the numerical experiment are evaluated using some commonly applied statistical measures in order to compare the results with the data published in the literature. The results of the experiment are also analysed with the help of simple conceptual models of fluid filaments. The microstructure of the tracer distribution introduced in the paper is essential to increase our understanding of atmospheric transport and to develop more realistic parameterizations of small-scale mixing. The presented results could also be used to improve calculations of the coupling between microphysical processes and tracer mixing.     

Impact of overexploitation of shellfish: northeastern coast of India

India has a very extensive coastline of about 7515 km, rich in diverse living resources. These resources continue to deteriorate with rampant harvesting or are altered for other uses such as aquaculture and fisheries. The present paper deals with degrading coastal habitats in northeastern India, and projects the intensity of the stress arising from the collection of tiger prawn seeds (Penaeus monodon) for aquacultural farms and molluskan shells for poultry feed and edible lime. Indiscriminate exploitation of these resources leads to a heavy reduction of the species concerned and other associated marine communities. The magnitude of such destruction has been quantified. The impacts of biodiversity loss and their after-effects on the ecobalance of this coastal system have become a matter of great concern to ecologists to maintain security and sustainability. The authors propose a public awareness program on themes relating to the importance of biodiversity for human livelihoods.     

Comparison of methods for evaluation of activity of photocatalytic films

Objective

This work aims to investigate the correlation between the photocatalytic activity determined by methylene blue bleaching (DIN 52980), stearic acid degradation, and degradation of acetone in gas phase.

Method

The photocatalytic TiO₂ coatings included in this investigation ranged from thin commercially available coatings (Activ^TM and BioClean^TM) and ready to use suspensions (Nano-X PK1245) to lab-produced PVD and sol?Cgel coatings. XRD analysis of the photocatalytic coatings showed that all the coatings consisted of nanocrystalline anatase, although the thickness and porosity varied considerably.

Results

The study showed that the reproducibility of the activity measurements was good. However, more importantly, the investigation showed that there is a good correlation between the activities determined by the different methods even though the characteristics of the photocatalytic coatings and the organic probe molecules varied considerably.

Conclusion

The overall findings of this work suggest that there is a good correlation between the investigated methods. These results are promising for the future work concerning standardization of methods for determination of the activity of photocatalytic films.