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1.
1IntroductionSpinelismorestablethanaluminainoxidation ,al kali,salt,fusedmetal,slagandcarbonatmosphere .Inrecentyears ,moreattentionhasbeengiventoit .Andithasbeenwidelyusedinthefieldofinsulated materials ,high performanceceramicsandrefractories .Concentratedalumina spinelslurrieswithgoodfluid ityarecrucialtopreparealumina spinelcastables .Whethertheconcentratedslurrycanbeobtainedornothastightrelationshiptoitsrheologicalbehavior .Ingener al ,therheologicalbehavioroftheslurryisaffectedbyanumber…  相似文献   

2.
A barium‐containing three‐way automotive emission catalyst was submitted to a NOx storage step in flowing lean gas mixture containing 340 ppm NO and 8 vol% O2 in helium. NOx release was carried out in the 250–550°C temperature range, either in pure helium or in the presence of a 10 vol% CO2 in helium mixture. It was shown that at 450–550°C all of the stored NOx on the barium trap can be released fastly in the CO2‐containing gas mixture or, after a longer time, in pure helium: these data show that NOx release can occur in the absence of a reducing agent. The NOx release was not complete at 350°C and did not occur at 250°C. The assisting effect of CO2 as regards to NOx release was interpreted in terms of the existence of the CO2,gas + *NO2,stored ⇌ *CO2,stored + NO2,gas equilibrium, suggesting the competitive storage of CO2 and NO2 for a unique type of barium storage sites (*). This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

3.
《分离科学与技术》2012,47(15):3113-3135
Abstract

Activated carbons with a wide range of burn‐off degrees obtained from Eucalyptus kraft lignin have been used to study the influence of the presence of water vapor on VOCs adsorption. The amount adsorbed and the rate of adsorption of both benzene and water vapor increase with activated carbon burn‐off as a consequence of an increase of micropore volume, broadening of micropore size distribution and increasing development of meso‐ and macroporosity. Similar results were found for MEK and methanol. Benzene is only partially desorbed at the adsorption temperature and an appreciable amount of it remains in the carbon, most likely in the narrow micropores. On the contrary, water vapor is completely desorbed at the adsorption temperature and its adsorption profile clearly exhibits two steps with different adsorption rates, associated to water molecules adsorbed on the active sites given rise to cluster formation and further migration and filling of the micropores. Adsorption with mixtures of VOC and water vapor has been carried out. The total amount adsorbed by the carbon, near the equilibrium point, is higher than in the case of the stream containing only the VOC. The adsorption rates for the mixtures streams are similar to that for the corresponding streams containing only the VOC in the case of carbons with a well developed porous structure. However, the presence of water vapor increases the rate of adsorption on the activated carbons with narrower microporosity. Saturation of the activated carbon with water vapor prior to the adsorption of a mixture containing benzene and water vapor has shown little effect on the amount of benzene adsorbed, suggesting that water and benzene molecules are adsorbed in different sites on the carbon surface.  相似文献   

4.
The emissions of benzo[a]pyrene at different temperatures and its concentration in the exhaust gases are measured in laboratory experiments on the carbonization (at temperatures up to 850°C) of coalpitch and petroleum-pitch binders and their mixtures with roasted petroleum and pitch coke. These pitch–coke mixtures are similar in composition to the anode mass used in aluminum production. The experiments confirm that the total benzo[a]pyrene emissions are much greater in the carbonization of petroleum pitch produced by cracking (T so = 100°C) than for electrode pitch (T so = 89°C) and other coal pitch. In most experiments, the benzo[a]pyrene emissions in the carbonization of pitch–coke mixtures is markedly less than for individual binder pitches. It is found that the benzo[a]pyrene emissions in the carbonization of a mixture based on pitch coke are much less than for a mixture based on petroleum coke in the high-temperature region that presents the greatest environmental hazard.  相似文献   

5.
The influence of zircon particle size and adding quan-tity on the properties of high alumian refractories have been researched,The phase composition and microstructure were analysed by SEM and X-ray diffraction,The research il-lustrated that high alumina refractories can be greatly im-proved by adding proper quantity of zircon micro powder to form dense corundum-mullite-zirconia matrix.  相似文献   

6.
研究了超声波对活性炭吸附/脱附Cr(Ⅵ)的影响,结果表明:有无超声波作用下,活性炭对Cr(Ⅵ)的吸附率均随pH值的升高而减小,相对于无超声作用体系,超声作用下的相平衡向吸附量减小的方向移动,且pH值越大,其减小的幅度越大;当Cr(Ⅵ)初始浓度由20 mg·L-1增至110 mg·L-1时,超声波作用下的Cr(Ⅵ)去除率由99.9%降至79.8%,平衡吸附量则由3.3 mg·g-1增至15.0 mg·g-1,与无超声波作用下的效果接近,但无超声波作用时的吸附率持续上升至平衡,而超声波作用下的吸附率先快速增加至近平衡,再出现小幅下降后又缓慢增至平衡。脱附实验发现,无论有无超声作用,活性炭表面Cr(Ⅵ)在蒸馏水中的脱附率均很小;添加NaOH可显著改善脱附效果,脱附率随NaOH用量的增加而增加,且超声场中NaOH对脱附的促进作用显著高于非超声场中的效果。  相似文献   

7.
Using magnesia and hercynite as materials, we researched the magnesia-hercynite brick in order to solve the problem of chrome-free brick used in the burning zone of cement rotary kiln. Effect of different firing temperature and different content of hercynite on properties of the brick were studied. The results show that the magnesiahercynite specimen fired at 1600℃ was densified and when the hercynite content is 7%, the cold crushing strength and the adhesive strength of rupture of the specimen have the highest value.  相似文献   

8.
《分离科学与技术》2012,47(9):1341-1344
The weight distribution coefficients (λM) of the most often occurring in zirconium salts ions (M(II), M(III) and M(IV)) have been determined in established earlier optimal conditions for separation of zirconium from hafnium by means of Diphonix® resin. Their values range from 21 (λZn(II)) to 1830 (λTi(IV)) and depend on the charge of M ion as well as on its radius. For ions of the highest λM (Ti(IV) and Fe(III)) their influence on hafnium – zirconium separation has been studied. Ti(IV) ions at concentration of 1% (in relation to Zr) has been found to noticeably affect separation of hafnium from zirconium by means of Diphonix® resin.  相似文献   

9.
《中国耐火材料》2000,9(2):23-28
Periclase-spinel-carbon brick was made from sintered spinel,fused magnesia and flake graphite as principal raw materials,the influence of Mg/Al(w/w) ratio and the addition of Al,Mg in the matrix of periclas-spinel-carbon brikc on the carbonization and thermal expansion coeffi-cient and the weight los of the brick after heating at 1500℃ in a flowing stream of dry N2for 1.5 h have been studied.The results show that to control Mg/Al(w/w) ration and to add both Al and Mg appropriately can obvi-ously improve the properties of the bricks.  相似文献   

10.
The catalytic activity of Pt catalyst loaded on -alumina was improved by Ba addition in simulated automotive exhaust gases. On the other hand, the result of Rh catalyst was the opposite. From the results of the partial reaction orders in C3H6–O2 reaction and TPR, it was concluded that the Ba addition to Pt catalyst suppressed the hydrocarbon chemisorption on the Pt catalyst and therefore allowed the catalytic reaction to proceed smoothly. On the other hand, Ba addition to Rh catalyst caused such a strong oxygen adsorption on Rh that rejected the hydrocarbon adsorption and suppressed the reaction.  相似文献   

11.
The focus of this study was the effect of spatial confinement on the development of nucleating agent-induced β phase polypropylene (PP) in the dynamically vulcanized thermoplastic elastomers (TPVs) based on dynamically vulcanized PP/ethylene-propylene-diene rubber (EPDM) blend. The melting behaviors, crystalline structures and the morphologies of the blends were studied by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and scanning electron microscopy (SEM). The results indicate that the EPDM phase undergoes a series of changes from the dispersed phase to a continuous one, and again to the dispersed phase with increased content of curing agent, and the PP component always shows itself in a continuous phase. In this process, with the content of the nucleating agent unchanged, the content of β phase PP in the blends initially increases a little and then decreases with increasing PF (Phenolic resin) content. We believe spatial confinement provides a good explanation for the development of β phase PP.  相似文献   

12.
Recently, inorganic–organic hybrid coatings produced by the sol–gel route have proven to be a potential protective treatment for wooden surfaces. In this study, the effect of curing process on simulated antisoiling properties of sol–gel coating was investigated. The sol–gel coating was spray-coated on pine sapwood and cured with different temperature and time combinations. The antisoiling properties were studied by measuring the water contact angle of the coating after different curing processes. In addition, abrasion resistance and contact angle of oleic acid were measured. An optical profilometer was used to investigate surface roughness of the coating. Sufficient hydro- and oleophobicity were obtained with all of the curing parameters. The comparison between curing parameters showed that lower temperature and 1–3 h curing time leads to significant improvement in the durability of the water and oil repellent properties of the coating.  相似文献   

13.
The effect of press direction on the thermal expansion,slag resistance,etc.of periclase-spinel-carbon brick has been studied in this article.The results show that the therma‘ expansion rate in the direction parallel to the press axis is larger than that in the direction perpendicular to the press axis and the slag resistance in the direction parallel to the press axis is much better than that in the perpendicular direction.The directional distribution of graphite in the specimen is observed with the microscope.  相似文献   

14.
The enzyme amylase is one of the hydrolyzing enzymes used in detergent formulation in order to remove soil based on polysaccharides. The effectiveness of the enzyme depends on its compatibility with other ingredients of the formulation. Among the studied additives, comprising anionic surfactants sodium dodecyl hydrogen sulfate (SDS) and dioctyl sodium sulfosuccinate, the cationic surfactant cetyl trimethyl ammonium bromide (CTAB), nonionic surfactants polyoxyethylene sorbitan monooleate and polyoxyethylene octyl phenyl ether, carboxy methyl cellulose and sodium sulfate, only the anionic surfactant SDS and cationic surfactant CTAB showed catalytic enhancement of α-amylase. The kinetic parameters, K m and k cat, showed an increase in catalytic activity in the micellar pseudophase. The decrease in optimum temperature from 55 to 30 °C and the shift in optimum pH from 5.5 to 7 on the addition of SDS and CTAB for the hydrolysis of starch are very favorable to enhance the washing characteristics.  相似文献   

15.
《中国橡胶》2015,(8):13-15
<正>In 2014,the major economic indicators of rubber industry only realized slight growth.Although the export increased,the tire export,infl uenced by the"Double Anti"of the U.S.on Chinese semi-steel tire,remained in doubt;the realized profi t growth of the industry continued to slide,the inventory increased,and the economic situation was not optimistic.  相似文献   

16.
1IntroductionCorundum-mullite materials have been recognizedand adopted as important refractories because of theirexcellent properties,such as high refractoriness,highresistance to creep,good mechanical and chemical sta-bility at high temperatures,high th…  相似文献   

17.
In this paper,both oxidation and corrosion resistance of low-carbon magnesia-carbon materials containing 4.0wt% graphite with metallic Al and Mg-Al alloy powders as antioxidants were investigated.Meanwhile,the microstructures of samples corroded by slag were observed with optical microscope as well.The test results revealed the properties of oxidation and corrosion resistance of low-carbon magnesia-carbon materials could be improved obviously by adding metal Al powder and Mg-Al alloy powder.The rule of improving oxidation resistance was illegibility when metal Al powder and Mg-Al alloy powder were added together.It was harmful to corrosion resistance by mixed adding metal Al powder and Mg-Al alloy powder into the materials,at the same time,the corrosion resistance would decreased with the increasing of Mg-Al alloy content.The corrosion resistance of samples with 0.5wt% or 3.0wt% Mg-Al alloy was better. The oxidation resistance and corrosion resistance of materials with metal Al or Mg-Al alloy respectively were better than that with mixed metal Al and Mg-Al alloy. As a result, Mg-Al alloy was more suitable for low-carbon composite materials than metal Al as additives.  相似文献   

18.
Pentanal is also called N-pentanal.It isan important intermediate for organicsynthesis.Pentanal can be processedinto pentanol through hydrogenation andpentanol can be processed into pentanoicacid through oxidization.45% pentanol  相似文献   

19.
The synthesis of hybrid polypyrrole–montmorillonite (Ppy–MMT) nanocomposites and their effects on the improvement of the protection efficiency of the epoxy coatings on aluminum corrosion were studied. In order to understand the effect of MMT and Ppy on the corrosion inhibition performance of the epoxy coatings in 3.5% NaCl solution, the epoxy (E), epoxy blend with MMT (EM) and polypyrrole (EP) coatings were investigated by electrochemical impedance spectroscopy (EIS). It was shown that EM and EP systems could not provide a good corrosion protection for long-time applications. The results showed that the incorporation of Ppy–MMT nanocomposites inside the epoxy notably increases the resistance of the coating in comparison to the other coatings for long-time period. These phenomena can be attributed to specific morphology of the nanocomposite. The structure and morphology of nanocomposites were studied by FT-IR and XRD techniques, as well as, scanning electron microscopy (SEM).  相似文献   

20.
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