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1.
Four monolithic catalysts with low concentration of noble metal were prepared by the immersion method [ Pt/La- Al2O3, Pt/La-Al2O3 + Pt/OSM (2 : 1 ), Pt/La-Al2O3 + Pt/OSM ( 1 : 1 ) Pt/La-Al2O3 + Pt/OSM ( 1 : 2) ], and measurements of their activity were carded out in a conventional fixed-bed flow reactor. The results show that the oxygen storage material (OSM) that is added can promote the activity of the prepared catalysts and can decrease the complete conversion temperature of cooking fume. When the ratio between La-Al2O3 and OSM is 1 : 1, the catalyst has the highest activity, and the complete conversion temperature of cooking fume is 270℃ ; the catalyst thus prepared can be applied in a wide range of gas hourly space velocity (GHSV) [from 10000 to 60000 h^-1]. The catalyst obtained shows great potential for practical application.  相似文献   

2.
PAH emission from the powered engines fueled by a 95 leadfree gasoline (95-LFG), a 92 leadfree gasoline (92-LFG) and a Premium leaded gasoline (PLG) with two gasoline additives (SA and SB) were collected using a PAH sampling system with a particulate interception device. Twenty one PAHs were analyzed primarily by an GC/MS, while eight metal elements were determined mainly by an ICP-AES. This investigation showed that the gasoline additives contain more amounts of carcinogenic PAHs than gasolines do. Blending these additives do raise the PAH content in the gasolines, simultaneously, will emit more amount of PAHs from the tailpipe of engine exhaust. It is suggested that before a gasoline additive is commercialized, an assessment on its PAH emission should be evaluated to make sure that the additive will not emit more PAHs and cause adverse effect on public health.  相似文献   

3.
Probabilistic Nonroad Mobile Source Emission Factors   总被引:1,自引:0,他引:1  
Quantitative methods for characterizing both variability and uncertainty are applied to case studies of nitrogen oxides (NOx) and total hydrocarbon air pollutant emission factors for construction, farm and industrial engines. A database was developed and statistical methods were used to identify statistically significant categories, including gasoline engines, two-stroke diesel engines, and four-stroke diesel engines. Emissions were not found to be statistically significantly different for older versus newer nonroad diesel engines nor when comparing naturally aspirated and turbocharged engines. Interengine variability in emissions was quantified using Weibull, gamma, and lognormal distributions. Bootstrap simulation was used to characterize confidence intervals for the mean. The 95% confidence intervals for the mean emission factors were as small as ?10 to +11% and as large as ?48 to +49%, with an average range of ?26 to +27%. Asymmetry in the confidence intervals is attributable to small sample sizes and skewness in the data. Estimates of uncertainty convey information regarding the quality of the emission factors and serve as a basis for calculation of uncertainty in emission inventories.  相似文献   

4.
Manabu Oku  李鑫 《世界钢铁》2011,11(5):10-16
为了减轻空气污染和缓解全球变暖,各个国家均出台了尾气排放标准,且限制标准越来越严格。在此背景下,多种技术已被应用以满足相关要求,如提高燃油燃烧率、催化效率,降低排气管热容量等。而这一系列措施均会导致汽车尾气的最高温度上升。近些年,汽车排气系统零件主要用铁素体不锈钢制作,因为铁素体不锈钢的热膨胀系数小,耐循环氧化和耐高温疲劳性能均优于奥氏体不锈钢。介绍了日新制钢新研发的汽车排气系统用耐热不锈钢,以及该钢种的研发现状和发展趋势。Nb、Mo、Cu在700℃时的固溶强化和析出强化对提高铁素体不锈钢的高温强度非常有效,而添加Nb、Mo、W主要是在900℃时起到固溶强化作用。Cr,Si和Mn可降低铁素体不锈钢(含14%Cr)在大气中950℃保温200h的氧化程度。特别是添加0.8%及以上的Mn可有效提高氧化皮的附着力。事实证明,日新制钢开发的NSSHR-1(14Cr-1Mn-0.9Si-Nb)和NSSHR-2(10Cr-0.9Si-Nb-Ti)铁素体不锈钢与441和439不锈钢相比,具有更高的耐热性和成形性。  相似文献   

5.
NiO-Ce0.5Zr0.5O2catalysts were prepared by citrate method and used for hydrogen production from steam reforming of ethanol (SRE). The effect of nickel content and space velocity on the catalytic performance was investigated. The prepared catalysts were character-ized with XRD and thermal analysis techniques. 20%NiO-Ce0.5Zr0.5O2 catalyst was very active and selective for hydrogen production via SRE, in which ethanol conversion of 100% could be obtained with feed component of 20% (H2O+EtOH) and 80% N2, water/ethanol of 3/1 in molar ratio at 350 ℃. Also, the catalyst showed good stability for anti-sintering and carbon-resistance. The XRD illuminated that both NiO and Ce0.5Zr0.5O2 crystal sizes were very small in NiO-Ce0.5Zr0.5O2 catalyst, and Ce0.5Zr0.5O2 solid solution was formed.  相似文献   

6.
烧结合金广泛地用于制作汽车发动机阀座圈(VSI)。就增高耐热与耐磨耗性能而言,在合金化设计上,烧结合金远比常规的锻钢与铸造合金灵活。特别足,一些高钻烧结材料由于耐磨耗与耐热性高而广泛用作排气阀座圈材料。鉴于近来将发动机的A/F比(空气/燃料比)调整到比常规的贫化(即空气/燃料比增高),排气阀座圈的工作环境趋于严酷。这种A/F比贫化的趋向旨在减少排出的废气和减低燃料消耗。另一方面。也需要不断地减少使用像钴之类环境负荷高的材料。同时,钴昂贵,减低钴含母有利于节省这些材料。这篇论文详细报道了无钴、无铅及有利于环境的排气阀座矧的开发与使用。  相似文献   

7.
There are at least three obvious trends in the developments of automotive market in China : the evolution of emission standards from Euro Ⅱ to Euro Ⅲ, the demand of lean-burn gasoline engine and the time of diesel vehicles. The latest application and advances of exhaust catalysts by Chinese researchers, using some high effcient,economical and durable methods to meet these changes in emission regulations laws and engine technologies, were described. Rare earth oxides, such as lanthana, ceria-based solid solutions and perovskite-type oxides, are widely used as excellent promoters for thermal stability,oxygen storage capacity and oxidation/reduction activity in these catalysts. Four phases in the development of the auto exhaust catalyst industry in China since the mid 1970s were reviewed. It is argued that China will become the center of global auto exhaust catalysts industry in the next decades with its economic, technical and environmental incentives,which greatly depends on the research and development of rare earth.  相似文献   

8.
Exhaust emission regulations of the automotive are enforced in each country to prevent air pollution and global warming,and the restriction standard tends to become severer.Various techniques such as the combustion improvement of gasoline,upgrades of the catalyst,and the thermal capacity decreases in the exhaust lines are adopted to suit the regulations,and these lead to an increase of the maximum temperature of the exhaust gas. Recently,ferritic stainless steels are mainly used to parts of exhaust lines,as their thermal expansion coefficient is small,and the cyclic oxidation resistance and the thermal fatigue property are better than austenitic stainless steels. This paper presents newly developed heat-resistant stainless steels from Nisshin Steel for exhaust lines usage,and describes the currents of the steel development that could be envisaged in the future.With regard to improving the high-temperature strength of ferritic stainless steels,the addition of Nb,Mo and Cu is effective in solution hardening and precipitation hardening at 700℃,while the addition of Nb,Mo and W is effective in mainly solution hardening at 900℃.The addition of Cr,Si and Mn suppress the breakaway oxidation in air at 950℃up to 200 h of ferritic stainless steels containing 14%Cr.Especially,the addition of 0.8%or higher Mn would effectively improve the adherence of oxide scale.It is confirmed that ferritic stainless steels,NSSHR-1(14Cr-lMn-0.9Si-Nb) and NSSHR-2(10Cr-0.9Si-Nb-Ti ),is having a superior heat resistance,formability and cost performance compared to conventional Type441 and Type439 respectively.  相似文献   

9.
Oncostatin M (OSM) is a member of the interleukin-6 (IL-6) family of cytokines that share the gp130 receptor subunit. Of these family members, leukemia inhibitory factor (LIF) is most closely related to OSM, and various overlapping biologic activities have been described between human LIF and OSM (hLIF and hOSM). Two types of functional hOSM receptors are known: the type I OSM receptor is identical to the LIF receptor that consists of gp130 and the LIF receptor beta subunit (LIFRbeta), and the type II OSM receptor consists of gp130 and the OSM receptor beta subunit (OSMRbeta). It is thus conceivable that common biologic activities between hLIF and hOSM are mediated by the shared type I receptor and OSM-specific activities are mediated by the type II receptor. However, in contrast to the human receptors, recent studies have demonstrated that mouse OSM (mOSM) does not activate the type I receptor and exhibits unique biologic activity. To elucidate the molecular structure of the functional mOSM receptor, we cloned a cDNA encoding mOSMRbeta, which is 55.5% identical to the hOSMRbeta at the amino acid level. mOSM-responsive cell lines express high-affinity mOSM receptors, as well as mOSMRbeta, whereas embryonic stem cells, which are responsive to LIF but not to mOSM, do not express mOSMRbeta. mOSMRbeta alone binds mOSM with low affinity (kd = 13.0 nmol/L) and forms a high-affinity receptor (kd = 606 pmol/L) with gp130. Ba/F3 transfectants expressing both mOSMRbeta and gp130 proliferated in response to mOSM, but failed to respond to LIF and human OSM. Thus, the cloned mOSMRbeta constitutes an essential and species-specific receptor component of the functional mOSM receptor. Reminiscent of the colocalization of the mOSM and mLIF genes, the mOSMRbeta gene was found to be located in the vicinity of the LIFRbeta locus in the proximal end of chromosome 15.  相似文献   

10.
The neuropoietic cytokines of the interleukin-6 family are a group of structurally and functionally related polypeptides. We studied the effect of the multifunctional neuropoietic cytokines, including oncostatin M (OSM), leukemia inhibitory factor (LIF) and interleukin-6 (IL-6), on anaplastic glioma cell lines. Growth and morphology of the glioma cell lines were affected differently. While IL-6 and LIF exerted no or only small minor morphological changes and growth retardation, OSM induced a marked change in morphology and a strong suppression of growth. OSM treated cells were characterized by enlargement and the formation of multiple, thin processes thus resembling mature cultured astrocytes. The growth inhibitory effects were dose dependent with a maximum exerted by addition of 50 ng/ml OSM. The inhibition of DNA synthesis by OSM could be abolished by antibodies blocking either the activity of OSM or the OSM-receptor component, gp130.  相似文献   

11.
孙宇  张增胜  范建伟 《中国冶金》2015,25(12):59-63
研究以堇青石蜂窝陶瓷为载体,过渡金属元素为活性成分,利用纳米组装和灌注的方法将金属盐注入介孔分子筛的孔道中制备了一种在低温状态下具有高效脱硝性能的复合催化剂,且命名为GJ- HC- 4型催化剂,高效反应温度区间为200~300℃。针对不锈钢混酸酸洗NOx废气低温、低尘、高氧化度、高浓度的特点,选用GJ- HC- 4型低温催化剂,采用“喷淋吸收+预热+换热+加热+SCR反应+换热”的工艺。在现场设定反应温度为260℃的条件下,连续运行脱硝效率均高于95%,烟囱出口NOx浓度均低于150mg/m3。与V2O5/TiO2系催化剂相比较,GJ- HC- 4型催化剂在保证处理效率的前提下,具有非常优越的节能环保效应。  相似文献   

12.
13.
NiO-Ce0.5Zr0.5O2 catalysts were prepared by citrate method and used for hydrogen production from steam reforming of ethanol (SRE). The effect of nickel content and space velocity on the catalytic performance was investigated. The prepared catalysts were characterized with XRD and thermal analysis techniques. 20%NiO-Ce0.5Zr0.5O2catalyst was very active and selective for hydrogen production via SRE, in which ethanol conversion of 100% could be obtained with feed component of 20% (H2O+EtOH) and 80% N2, water/ethanol of 3/1 in molar ratio at 350 ℃. Also, the catalyst showed good stability for anti-sintering and carbon-resistance. The XRD illuminated that both NiO and Ce0.5Zr0.5O2 crystal sizes were very small in NiO-Ce0.5Zr0.5O2 catalyst, and Ce0.5Zr0.5O2 solid solution was formed.  相似文献   

14.
Three experiments were conducted to investigate the role of object representations in object substitution masking (OSM). OSM occurs when a very sparse mask is presented simultaneously with a target stimulus and the target offsets first, leaving the mask to linger in the display for some time. Results confirm earlier claims that there is an isolatable object-level component to OSM and indicate that a target can be protected from OSM if, prior to offsetting, it can be represented as a distinct object from the mask. When the mask was presented as sliding past the target (Experiment 1), as jiggling independently of the target (Experiment 2), or in a different color from the target (Experiment 3), OSM was reduced or eliminated. This suggests that OSM reflects basic updating processes that allow the perception of continuity of object identity over change. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   

15.
Both Doppler supraorbital examination (OSM) and oculoplethysmography (OPG) were administered to 101 patients (202 arteries) to document the presence or absence of hemodynamically significant lesions of the internal carotid artery prior to angiography. There was no significant difference between the OSM and OPG with respect to diagnostic sensitivity or specificity, incidence of false-negative or false-positive results, and overall diagnostic accuracy. The diagnostic accuracy for the OSM and the OPG were 94.2% and 91.6%, respectively. In 171/202 (84.6%) arteries, the OSM and OPG were in diagnostic agreement, and the overall diagnostic accuracy of the combined tests was 97%. However, when the OSM and OPG did not agree (31/202 arteries, 15.4%), the diagnostic accuracy of neither the OSM nor the OPG was acceptable. Although the best diagnostic accuracy was obtained using two means of noninvasive cerebrovascular testing, in those instances where only one test may be available, the OPG would appear to be the test of choice. In those laboratories in which high diagnostic accuracy is obtained with the OSM, the addition of OPG testing will increase the overall diagnostic accuracy to a very high level. The presence of a midcervical bruit was found to have a very poor correlation with the incidence of hemodynamically significant stenoses of the internal carotid artery. Although both the OSM and OPG have minimal value in patients with symptomatic cerebrovascular disease, these tests play a very important role in screening patients for asymptomatic carotid stenosis or atypical cerebrovascular symptoms.  相似文献   

16.
Pd@Zr/Ce O2 core-shell catalyst prepared by hydrothermal method was applied in CO oxidation reaction, exhibiting high CO oxidation activity at low temperature.XRD(X-ray diffraction) analysis demonstrated that the remarkable enhancement of catalytic performance was found to depend on the presence of more oxygen vacancies in the core-shell structure, which contributed higher content of and ready release of active oxygen species at low temperature, confirmed by H2-TPR(temperature programed reduction) results.Interestingly, introducing a small amount of zirconium(0.5 wt.%) exhibited a significant improvement of catalytic activity because the introduction of Zr further improved the amount of crystal defects and promoted the migration of oxygen species.  相似文献   

17.
18.
The effects of Ce-ZrOx, Ce-LaOx, Ce-SmOx and Ce-GdOx additions to Rh/Al2O3 catalysts on methane autothermal re-forming were investigated. Activity tests showed that the addition of Ce-ZrOx could significantly reduce the concentration of CO in reformats. When Ce/Zr atomic ratio was 1:1, C%.5Zr0.5O2 solid solution with high thermal stability was obtained, which could effec- tively improve the catalytic performance effectively. The additives of alkaline-earth metals (Mg, K and Ca) on the catalytic properties were also studied. The results of experiments showed that the addition of MgO to Rh/Ce0.5Zr0.5O2/Al2O3 improved the stable per- formance and the carbon resistance of the catalyst. The optimized catalyst was 0.1%Rh/2.0%MgO/40%Ce0.5Zr0.5O2/Al2O3, which showed a highly stable performance for methane autothermal reforming.  相似文献   

19.
Nowadays,air pollution has become a prominent environmental problem and has attracted much attention.With the increase of vehicle retention quantity,the exhaust emissions have become the main sources of air pollution.To reduce pollution and hazards,vehicle exhaust emission regulations are becoming stricter and stricter,which puts forward higher requirements for purification of vehicle exhausts.At present,rare earths have been widely applied in vehicle exhaust purification because of their good catalytic performance,which is attributed to their unique 4 f electron layer structure occupied without full electrons,excellent oxygen storage/release capacity and redox ability.In this paper,the current status of rare earth catalysts and application of rare earth in different fuel vehicle exhaust catalysts,including three-way catalysts(TWCs) for gasoline vehicles,diesel exhaust catalysts for different pollutants(particulate matter(PM),NO_x,CO and HC) and catalysts for new energy vehicles with different fuels,are summarized in detail.Meanwhile,the corresponding mechanisms and the role of rare earth in vehicle exhaust catalysts are also simultaneously described.Furthermore,the challenges and development directions of rare earth catalysts for the purification of vehicle exhausts are also proposed.  相似文献   

20.
Oncostatin M (OSM) is a member of a family of cytokines that includes ciliary neurotrophic factor, interleukin-6, interleukin-11, cardiotrophin-1, and leukemia inhibitory factor (LIF). The receptors for these cytokines consist of a common signaling subunit, gp130, to which other subunits are added to modify ligand specificity. We report here the isolation and characterization of a cDNA encoding a subunit of the mouse OSM receptor. In NIH 3T3 cells (which endogenously express gp130, LIF receptor beta [LIFRbeta], and the protein product, c12, of the cDNA described here), mouse LIF, human LIF, and human OSM signaled through receptors containing the LIFRbeta and gp130 but not through the mouse OSM receptor. Mouse OSM, however, signaled only through a c12-gp130 complex; it did not use the LIF receptor. Binding studies demonstrated that mouse OSM associated directly with either the c12 protein or gp130. These data highlight the species-specific differences in receptor utilization and signal transduction between mouse and human OSM. In mouse cells, only mouse OSM is capable of activating the mouse OSM receptor; human OSM instead activates the LIF receptor. Therefore, these data suggest that all previous studies with human OSM in mouse systems did not elucidate the biology of OSM but, rather, reflected the biological actions of LIF.  相似文献   

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