Facile preparation and efficient MnxCoy porous nanosheets for the sustainable catalytic process of soot

The pursuit of high-performance is worth considerable effort in catalysis for energy efficiency and environmental sustainability. To develop redox catalysts with superior performance for soot combustion, a series of Mn_(x)Co_(y) oxides were synthesized using MgO template substitution.This method greatly improves the preparation and catalytic efficiency and is more in line with the current theme of green catalysts and sustainable development. The resulting Mn_(1)Co_(2.3) has a strong activation capability of gaseous oxygen due to a high concentration of Co^(3+) and Mn^(3+). The Mn doping enhanced the intrinsic activity by prompting oxygen vacancy formation and gaseous oxygen adsorption. The nanosheet morphology with abundant mesoporous significantly increased the solid–solid contact efficiency and improved the adsorption capability of gaseous reactants. The novel design of Mn_(1)Co_(2.3)oxide enhanced its catalytic performance through a synergistic effect of Mn doping and the porous nanosheet morphology, showing significant potential for the preparation of high-performance soot combustion catalysts.

Soot的Java程序控制流分析及图形化输出

Soot是一个Java编译优化框架,可以利用它实现Java字节码程序的数据流分析和控制流分析。在深入分析Soot控制流生成机制的基础上,详细叙述了利用Soot分析Java类的控制流并生成其控制流图的方法和过程,同时提出了将Soot生成的抽象的控制流图进行图形化输出的方法。

基于Soot控制流图的函数调用路径分析

每个应用系统中存在多条基于函数的调用路径,这些路径的准确提取对于程序的理解、测试和维护起着重要的作用。文章利用开源的Java程序编译优化框架-Soot,对java程序的数据流及控制流进行分析,提取函数间关联信息写入中间文件,并对文件中的数据进行了分析,阐述了程序函数调用路径生成的流程及Soot的优点。最后通过实验验证,相比其他程序调用分析软件,基于Soot调用路径分析的软件测试工具-JSFUNP,对程序调用路径的分析更加准确、高效。

SO_2与过渡金属离子在Soot上的非均相反应

应用FTIR-ATR研究了过渡金属离子与SO_2在Soot颗粒物表面的非均相反应,研究了在不同相对湿度(RH)环境且有Fe^(3+)和Mn2+存在条件下,SO_2在Soot颗粒表面发生的非均相反应过程。发现Fe^(3+)和Mn2+对于SO_2的非均相氧化反应有着显著的催化效应,并且随着RH的增加,硫酸盐的生成速率逐渐增大。该研究加深了对SO_2的迁移转化规律及其致霾效应的理解。

基于Soot的JAVA字节码优化及性能分析

Java语言至今已成为最受欢迎的编程语言之一,由于其平台无关性、执行的安全性以及垃圾收集等特性而得到广泛应用,受到众多的IT企业及开发者的支持。然而,与诸如C/C++这类语言比起来,Java语言的运行性能在很多情况下还有待提高,优化Java应用性能的课题就成为当前业界迫切需要解决的问题和研究的热点。本文从优化Java字节码的角度切入,介绍一款在其上进行优化和变换的框架,并展示相关应用的例子。

进气加湿与富氧对船用柴油机NOx-Soot排放的影响

通过一台满足TierⅡ排放标准的四冲程增压中冷船用柴油机,模拟研究了富氧燃烧结合进气加湿改善NOx-soot折衷关系的潜力,并探讨了实现TierⅢ排放标准的技术路线.本研究使用AVLFire软件建立仿真模型.结果表明:单独使用富氧燃烧时,缸内温度较高,燃烧持续期较短,soot排放减少,NOx排放恶化,而单独使用进气加湿时呈相反的趋势.当发动机运行在转速为1350 r/min、75%负荷工况下,进气氧体积分数为21%~23%、加湿率为0~100%时,可实现NOx-soot排放同时降低且低于原机.氧体积分数为21%和加湿率为100%匹配,可以实现TierⅢ排放法规.两种措施的优化组合可以获得NOx-soot排放的最佳优化区域.

Catalytic oxidation of soot particulates over MnO_x-CeO_2 oxides prepared by complexation-combustion method

MnOx-CeO2 oxides prepared by complexation-combustion method were used for soot oxidation. The highest conversion rate of soot was obtained on a MnOx-CeO2 oxide prepared under mild acid condition of pH = 4, where the oxidation temperature corresponding to maximum activity was decreased more than 150 ℃ compared with that of un-catalytic soot oxidation. The structure and property of the catalysts were investigated by X-ray powder diffraction （XRD） and temperature programmed reduction （TPR）. The results indicated that there were at least two kinds of Mn species present in MnOx-CeO2 catalysts, i.e. Mn ions within CeO2 lattice and high dispersion MnOx on the surface of CeO2. The presence of Mn ions in the CeO2 lattice improved the oxygen vacancy due to the charge difference, and the CeO2 considerably decreased the reduction temperature of MnOx. The capability to activate oxygen through the oxygen exchange between O2 in gas phase and lattice oxygen species in MnOx-CeO2 oxide contributed to the high catalytic activity for the reaction.

Catalytic combustion of diesel soot over K_2NiF_4-type oxides La_(2-x)K_xCuO_4

Nanostructure K2NiF4 type oxides La2-xKxCuO4 complex oxides were prepared using the Sol-Gel method, characterized by X-Ray Diffraction （XRD）, Fourier Transform Infrared （FT-IR）, and Scanning Electron Microscopy （SEM）. The catalytic activity for soot combustion was evaluated by the Temperature-Programmed Reaction （TPO） technique. The results demonstrated that the substitution quality of K^＋ for La^3＋ at the A-site would increase the catalytic activities of La2-xKxCuO4 for soot combustion greatly; the substitution quality affected the structure and catalytic activity obviously. The La1.8K0.2CuO4 complex oxides with tetrahedral structures had the best catalytic activity for soot combustion, and the ignition temperature of soot combustion was lowered from 490 to 320 ℃.

Macroporous perovskite-type complex oxide catalysts of La_(1-x)K_xCo_(1-y)Fe_yO_3 for diesel soot combustion

A facile procedure was carried out to prepare macroporous perovskite-type complex oxide catalysts of La1–xKxCo1–yFeyO3(x=0,0.1,y=0,0.1) by using the combined method of organic ligation and solution combustion.This method could ensure the formation of the desired macroporous structures and the desired crystal phases of the prepared catalysts.It was found that the macroporous catalysts showed higher catalytic activities for soot combustion than that of the corresponding nanometric samples,and the macroporous ...

Simultaneous catalytic removal of NOx and diesel soot particulate over perovskite-type oxides and supported Ag catalysts

A series of perovskite type oxides and supported Ag catalysts were prepared, and characterized by X ray diffraction (XRD) and X ray photoelectron spectroscopy (XPS). The catalytic activities of the catalysts as well as influencing factors on catalytic activity have been investigated for the simultaneous removal of NOx and diesel soot particulate. An increase in catalytic activity for the selective reduction of NOx was observed with Ag addition in these perovskite oxides, especially with 5% Ag loading. This catalyst could be a promising candidate of catalytic material for the simultaneous elimination of NOx and diesel soot.

Soot formation and oxidation during bio-oil gasification:experiments and modeling

A model is proposed to describe soot formation and oxidation during bio-oil gasification.It is based on the description of bio-oil heating,devolatilization,reforming of gases and conversion of both char and soot solids.Detailed chemistry (159 species and 773 reactions) is used in the gas phase.Soot production is described by a single reaction based on C2H2species concentration and three heterogeneous soot oxidation reactions.To support the validation of the model,three sets of experiments were carried out in a lab-scale Entrained Flow Reactor (EFR) equipped with soot quantification device.The temperature was varied from 1000 to 1400 C and three gaseous atmospheres were considered:default of steam,large excess of steam(H2O/C=8),and the presence of oxygen in the O/C range of 0.075–0.5.The model is shown to accurately describe the evolution of the concentration of the main gas species and to satisfactorily describe the soot concentration under the three atmospheres using a single set of identified kinetic parameters.Thanks to this model the contribution of different mechanisms involved in soot formation and oxidation in various situations can be assessed.

Novel Approach for Improved Tribological Behavior of Biodiesel Soot in Liquid Paraffin

To improve the tribological behavior of biodiesel soot(BDS) in liquid paraffin(LP), the order of biodiesel soot was increased through thermally oxidized treatment at 500 ℃, and the oil solubility was then improved through a modification using oleylamine(OLA). The BDS and thermally oxidized oleylamine-modified BDS(T-BDS-OLA)were characterized through various methods including the use of TG, FETEM, Raman spectroscopy, FTIR, and a zeta potentiometer. The tribological properties and mechanisms of the BDS before and after the thermally oxidized treatment modification were investigated using a ball-on-disc reciprocating tribometer, FESEM, 3 D laser-scanning microscopy, and Raman spectroscopy. The results showed that T-BDS-OLA has a higher degree of order than the BDS, with an onion-like microstructure. BDS and T-BDS-OLA can both improve the antifriction and antiwear properties of LP at a soot content of 0.1%-0.4%, while T-BDS-OLA in LP shows better antifriction and antiwear properties than BDS. The tribological mechanisms can be attributed to both types of soot acting as spacing and roll bearing between the friction surfaces. In addition, the exfoliated graphitic sheets from T-BDS-OLA can form a carbon lubrication layer providing easy sliding.

Morphological and semi-quantitative characteristics of diesel soot agglomerates emitted from commercial vehicles and a dynamometer

Diesel soot aggregates emitted from a model dynamometer and 11 on-road vehicles were segregated by a micro-orifice uniform deposit impactor （MOUDI）. The elemental contents and morphological parameters of the aggregates were then examined by scanning electron microscopy coupled with an energy dispersive spectrometer （SEM-EDS）, and combined with a fractional Brownian motion （fBm） processor. Two mode-size distributions of aggregates collected from diesel vehicles were confirmed. Mean mass concentration of 339 mg/m3 （dC/dlogdp） existed in the dominant mode （180-320 nm）. A relatively high proportion of these aggregates appeared in PM 1, accentuating the relevance regarding adverse health effects. Furthermore, the fBm processor directly parameterized the SEM images of fractal like aggregates and successfully quantified surface texture to extract Hurst coefficients （H） of the aggregates. For aggregates from vehicles equipped with a universal cylinder number, the H value was independent of engine operational conditions. A small H value existed in emitted aggregates from vehicles with a large number of cylinders. This study found that aggregate fractal dimension related to H was in the range of 1.641-1.775, which is in agreement with values reported by previous TEM-based experiments. According to EDS analysis, carbon content ranged in a high level of 30%-50% by weight for diesel soot aggregates. The presence of Na and Mg elements in these sampled aggregates indicated the likelihood that some engine enhancers composed of biofuel or surfactants were commonly used in on-road vehicles in Taiwan. In particular, the morphological H combined with carbon content detection can be useful for characterizing chain-like or cluster diesel soot aggregates in the atmosphere.

Catalytic combustion study of soot on Ce_(0.7)Zr_(0.3)O_2 solid solution

The Ce0.7Zr0.3O2 solid solution and CeO2 were prepared using the sol-gel method. The phase structure, crystallite sizes and the reducibility of the catalysts were characterized by XRD and H2-TPR techniques. XRD results indicated that Zr^4＋ had replaced part of Ce^4＋ to form a fluorite-like solid solution, which was favorable to obtain ultrafine nanoparticles. The ratio of main HE consumption for Ce0.7Zr0.3O2：CeO2 was 4.4：1.0, implying that the solid solution could improve the reducibility compared to the single CeO2. The Ce0.7Zr0.3O2 solid solution catalyst showed a sharp combustion peak at 397 ℃, which was 200 ℃ lower than that of the single soot. The good catalytic activity of the Ce0.7Zr0.3O2 was attributed to the formation of nano-CeO2-based solid solution, which enhanced the reducibility and then improved the combustion activity. As Ce0.7Zr0.3O2 could be easily reduced to Ce0.7Zr0.3O2-x meanwhile, after oxygenation, the Ce0.7Zr0.3O2.x was recovered to Ce0.7Zr0.3O2 completely. A catalytic combustion reaction mechanism was proposed： the Ce0.7Zr0.3O2 was reduced to Ce0.7Zr0.3O2-x by the reaction with carbon and then it was recovered to Ce0.7Zr0.3O2-x by the interaction with O2.

Numerical study on soot removal in partial oxidation of methane to syngas reactors

The serious carbon deposition existing in catalytic partial oxidation of methane(CPOM) to syngas process is one of the key problems that impede its industrialization. In this study, 3-dimensional unsteady numerical simulations of the soot formation and oxidation in oxidation section in a heat coupling reactor were carried out by computational fluid dynamics(CFD) approach incorporating the Moss-Brookes model for soot formation. The model has been validated and proven to be in good agreement with experiment results. Effects of nozzle type,nozzle convergence angle, channel spacing, number of channels, radius/height ratio, oxygen/carbon ratio, preheat temperature and additional introduction of steam on the soot formation were simulated. Results show that the soot formation in oxidation section of the heat coupling reactor depends on both nozzle structures and operation conditions, and the soot concentration can be greatly reduced by optimization with the maximum mass fraction of soot inside the oxidation reactor from 2.28% to 0.0501%, and so that the soot mass fraction at the exit reduces from0.74% to 0.03%.

The Role of Diesel Soot in the Tribological Behavior of 150SN Base Oil

The diesel soot was collected from diesel engine exhaust pipe. The morphology and structure of the collected diesel soot was characterized by HRTEM, XRD and XPS and its tribological behavior was investigated by a SRV IV oscillating reciprocating friction and wear tester. Test results showed that the tribological behavior of diesel soot was largely influenced by the test load. Under a low load, the diesel soot could reduce the wear volume of the disc. While under a high load, the diesel soot could reduce the friction coefficient of base oil. Based on the characterization of the worn scars by the SEM technique, the 3D surface profiler and the Raman spectroscopy, it was assumed that the core-shell structure of diesel soot with several graphitic layers played important roles. On one hand, its spherical and special structure could make it roll between friction pairs to reduce wear under a low load. On the other hand, its outer-shell graphite layers could be peeled off to form lubrication film to reduce friction under a high load and shear force.

Catalytic Combustion of Diesel Soot over K_2NiF_4-type Oxides La_(2-x)K_xCuO_4

The K2NiF4 type oxides, La2-x KxCuO4 complex oxides with nanometric size were prepared by sol-gel method. The characters of these samples were analyzed by H2-TPR, XRD, FT-IR and SEM. The catalytic activity for soot combustion was evaluated by temperature-programmed reaction （TPO） technique. The results demonstrate that the substitution of K^＋ for La^3＋ at A-site will increase the catalytic activities of La2-xKxCuO4 to soot combustion greatly, and the substitution quantity affects the structure and catalytic activity obviously. The La1.8 K0.2 CuO4 complex oxides with tetrahedral structure has the best catalytic activity for soot removal reaction, the ignition temperature of soot combustion is decreased from 490 to 320℃.

Reconstruction model for temperature and concentration profiles of soot and metal-oxide nanoparticles in a nanofluid fuel flame by using a CCD camera

This paper presents a numerical study on the simultaneous reconstruction of temperature and volume fraction fields of soot and metal-oxide nanoparticles in an axisymmetric nanofluid fuel sooting flame based on the radiative energy images captured by a charge-coupled device（CCD） camera. The least squares QR decomposition method was introduced to deal with the reconstruction inverse problem. The effects of ray numbers and measurement errors on the reconstruction accuracy were investigated. It was found that the reconstruction accuracies for volume fraction fields of soot and metaloxide nanoparticles were easily affected by the measurement errors for radiation intensity, whereas only the metal-oxide volume fraction field reconstruction was more sensitive to the measurement error for the volume fraction ratio of metaloxide nanoparticles to soot. The results show that the temperature, soot volume fraction, and metal-oxide nanoparticles volume fraction fields can be simultaneously and accurately retrieved for exact and noisy data using a single CCD camera.

Effect of Diesel Soot on the Distribution,Composition and Mechanical Properties of ZDDP Tribofilm

To investigate the effect of diesel soot on the distribution,composition and mechanical properties of ZDDP tribofilm,a HFRR tribometer was applied to study the tribological performance.Worn surfaces lubricated with ZDDP and soot were analyzed by laser microscopy,SEM/EDS,Raman spectroscopy,XPS,and a nano-indentation equipment.Results show that soot scrapes off the ZDDP tribofilm and can be embedded into the worn surface,leading to the reduction of film thickness and non-uniform distribution of tribofim.The phosphate structure in ZDDP tribofilm changes from short chain pyrophosphate to long chain metaphosphate due to the increased contact stress caused by the soot abrasive wear,which can promote the cross-linking of ZDDP.The hardness(H)and elastic modulus(E)of the worn surfaces increase,while the ratio of hardness to elastic modulus,H/E,decreases,which indicates that the reduction of wear resistance is caused by the soot.

Simulation and Experimental Study on the Effect of Dispersants on Soot Aggregation

Diesel engine technology innovation causes excessive soot accumulated in engine oil.Due to its detrimental effect on lubricant and diesel engine,improving the dispersibility of engine oil to restrain soot aggregation efficiently is the key technique for formulations.In this study,the aggregation of soot and interaction between dispersant and soot were investigated by molecular dynamic simulation.It was found that the molecular interaction between the dispersant and the soot aggregation system had a significant influence on disrupting the soot aggregation.Bis-PIBSI was more beneficial to having more interaction sites with soot molecules,while the mono-PIBSI with a high proportion of polar groups had stronger interaction with soot molecules.According to the simulation result,suggestions for use of additives were proposed.Carbon black dispersancy test was exploited to verify the dispersion effect of different dispersants on carbon black.The results indicate that mono-PIBSI and bis-PIBSI added at suitable mixture ratio to lubricant could perform good dispersion ability.