可控条件对钾铈镧氧化物催化氧化碳烟颗粒的影响

采用柠檬酸络合燃烧法制备得到钾铈镧复合氧化物催化剂,利用程序升温反应(TPR),研究了各反应条件对催化剂活性的影响,考察并确定了催化氧化碳烟颗粒过程中各反应条件的最优水平,并对各反应条件在催化剂活性中的贡献大小进行了分析和讨论.结果表明,尾气中O2体积分数的升高,剂碳比的增大,都有利于碳烟颗粒的催化氧化.在碳烟氧化过程...     

Research on K-V-rare Earth Metal Catalysts for Diesel Soot Oxidation

Five types of KNO₃-NH₄VO₃-rare earth metal nitrate (K-V-rare earth metal) catalysts supported on a-porous alumina ceramic substrates were prepared by a coating method. All the catalysts were characterized by X-ray diffraction and thermogravimetry/differential scanning calorimetry. Catalytic activities were evaluated by a soot oxidation reaction using a temperature-programmed reaction system. The experimental results show that the addition of rare earth metal compound could obviously improve the catalytic activities of the K-V-based catalysts. The proper ratio of K-V-rare earth metal catalysts can not only lower the soot onset ignition temperature, but also quicken the soot oxidation rate. The crystalline phases formed by K, V, and rare earth metal are stable.     

K2Ti2O5对汽车尾气中碳烟的催化氧化性能研究

通过溶胶凝胶法制备了K2Ti2O5催化剂,并利用XRD,SEM,BET等方法进行了表征。利用程序升温反应对K2Ti2O5的碳烟催化氧化性能进行了研究。结果表明,K2Ti2O5具有一定的碳烟催化氧化活性。同时,一定量的NOx有助于K2Ti2O5的催化氧化活性,说明K2Ti2O5是一种潜在的可同时去除NOx和碳烟的新型催化剂。由于K2Ti2O5对碳烟具有较高的催化氧化活性、较好的抗水性和低廉的价格,因此是一种具有较好发展前景的汽车尾气净化催化剂。     

Alkali-silica reactivity of different aggregates from mineral and textural characteristics

To identify the aggregates causing the alkali-silica reaction, and the reactivity of rocks in different parts of China, the mineral and texture characteristics of some typical coarse ag gregates and the alkali reactivity of these aggregates were systematically investigated. On one hand, petrographic examination of aggregates, combined with X-ray diffraction analysis, chemical analysis, scanning electron microscopy, was conducted for analyzing their mineralogy and texture. It was found that not only mineral characteristics, but also their interior structure would affect their potential alkali-silica reactivity. Furthermore, the alkali-silica reactivity of aggregates is due to their mineral compositions, such as containing different alkali-reactive minerals, while, different stuctures of those aggregates with similar minerals affect their reactivity to some extent. There are some amount of micro-aperture and cracks across the quartz in the aggregate, which may become the natural accesses for Na^＋, K^＋, and OH^- ions to intrude in the mortar or concrete during the process of alkali-silica reaction. Alkali-silica reactivity of the aggregates was detected by the accelerated mortar bars test. It was revealed that all the aggregates tested were alkali-silica reactive and the results were also in accordance with their mineral and structure analysis.     

K-Ba-Sm柴油车尾气碳烟氧化催化剂的制备与表征

采用KNO3、Ba(NO3)2、Sm(NO3)3.6H2O 3种化合物为原料,以多孔氧化铝为载体,运用涂抹法制备了用于催化柴油机尾气碳烟氧化的催化剂。用TPR对催化剂的活性进行了测量,并采用SEM和XRD对其结构进行了表征。实验结果表明,K-Ba-Sm催化剂的催化性能良好,最终能将陶瓷基片上的碳烟在低于450℃条件下完全催化氧化掉。其中以n(K)∶n(Ba)∶n(Sm)=1∶0.1∶0.1组成的催化剂效果最好,其起燃点为325℃。保持K、Ba的含量不变,随着Sm(NO3)3.6H2O物质的量的增大,其催化活性有些减弱,碳烟起燃温度升高。另外,K、Ba、Sm组成的催化剂有吸收空气中CO2的现象。     

碳烟氧化催化剂La(Nd)PbK的催化活性及抗硫性能

采用涂抹法制备负载在α-Al2O3陶瓷基片上的碳烟氧化催化剂,用程序升温反应装置(TPR)研究了不同组分催化剂的催化活性,并考察其吸水性和抗硫性能。结果表明:当n(Pb)∶n(K)=1∶2时催化剂起燃温度仅为308℃,最高的峰值氧化温度405℃,在448℃左右,催化剂作用下,碳烟完全氧化。当n(Nd)∶n(Pb)∶n(K)=1∶1∶10和n(La)∶n(Pb)∶n(K)=1∶1∶10时催化剂的起燃温度分别为308℃和313℃;峰值氧化温度分别在403℃和410℃。催化剂经硫化后,n(Nd)∶n(Pb)∶n(K)=2∶1∶10和n(La)∶n(Pb)∶n(K)=1∶1∶2时催化剂的起燃温度分别为352℃和357℃。表明稀土金属La、Nd的加入提高了催化剂的催化活性、吸水性及抗硫中毒性。     

Kinetics of Internal Oxidation of Cu-Al Alloy Plate

The kinetics of internal oxidation of dilute Cu-Al alloys, containing up to 2.214% molar fraction Al, was investigated over the temperature range of 1023K to 1273K, and the depth of internal oxidation was measured by microscopies. A modified rate equation was derived to describe the kinetics of internal oxidation of Cu- Al alloy plate. Based on the derived equation, the permeability of oxygen in solid copper was obtained from the internal oxidation measurements. The experimental results show that the depth of the internal oxidation is a parabolic function of time, there is no evidence for preferential diffusion along grain boundaries and an outer layer of pure copper was formed on the external surface of samples.     

缸内燃油喷射发动机碳烟生成机理特征分析

为精确计算压燃式缸内燃油喷射发动机中的碳烟生成,提出了新的计算模型. 不同的燃烧室区域应用不同的计算模型,当区域温度T<1 500 K,只计算气体状态下生成的碳烟前驱物PAHs;当区域温度T≥1 500 K,碳烟前驱物PAHs和源项均进行计算。计算前驱物PAHs利用修改的F-M模型,碳烟源项的生成包括碳烟的起始、生长、氧化以及聚合。同时认为温度和过量空气系数是影响碳烟生成的最主要因素,即在温度T>1 500 K,过量空气系数Ф<0.6才能产生碳烟. 新的计算模型移植在KIVA-3V源代码中,计算了直喷式发动机在不同喷射时间、不同轨压下的碳烟瞬态值,并用试验验证了该模型. 给计算直喷式柴油机生成的碳烟提供了新的方法.     

碳烟在钛酸钾上的催化氧化性能及动力学研究

采用溶胶-凝胶法合成了K2Ti4O9,K2Ti6O13和K2Ti2O5钛酸钾型催化剂。利用X射线衍射(XRD)、智能重量分析仪(IGA)等手段进行了表征,同时采用固定床对钛酸钾催化脱除柴油机尾气中碳烟颗粒的性能进行了测试,并对钛酸钾催化氧化碳烟的动力学进行了研究。结果表明,钛酸钾与传统催化剂相比具有更高的碳烟颗粒氧化性...     

汽车尾气中碳烟在钛酸钾上的催化氧化性能及动力学研究

采用溶胶-凝胶法合成了K₂ T_i4O₉ , K2 Ti₆O₁₃ 和K₂ Ti₂O₅ 钛酸钾型催化剂。利用X 射线衍射 (XRD)、智能重量分析仪(IGA)等手段进行了表征, 同时采用固定床对钛酸钾催化脱除柴油机尾气中碳烟颗粒的性能进行了测试, 并对钛酸钾催化氧化碳烟的动力学进行了研究。结果表明, 钛酸钾与传统催化剂相比具有更高的碳烟颗粒氧化性能, 在松散接触下依然能保持良好的活性, 且钾钛物质的量比为1 ∶1 的钛酸钾催化剂的脱除碳烟颗粒的效果最好。钛酸钾作用下碳烟的氧化为一级动力学反应, 且所建立的碳烟燃烧动力学方程与实验数据拟合较好。     

Optical investigation on polyoxymethylene dimethyl ethers spray flame at different oxygen levels in a constant volume vessel

In this paper, high-speed imaging and spectrometry diagnostics were used to study the spray flame structures and emission spectra of polyoxymethylene dimethyl ethers(PODE) in an optical constant volume vessel. The effects of oxygen volume fraction(15% to 80%) on some typical combustion characteristics such as spatially integrated natural intensity, flame propagation speed, lift-off length and the distribution of flame emission spectra were investigated. The results show that the PODE spray flame mainly exhibits blue chemiluminescence, which is different from the diesel yellow diffusion flame dominated by soot radiation. As the oxygen concentration increases, the flame natural luminosity and propagation speed increases, the position of lift-off region and flame tip move towards the injector nozzle, and the flame width becomes narrower. According to the spectral results, the blue chemiluminescence generated by carbon monoxide oxidation dominates the PODE flame luminescence,suggesting that no soot is formed. The increase in oxygen concentration leads to enlarged intensity and gradient of PODE flame radiation. In summary, the combination of PODE and oxygen-enriched combustion shows no soot formation and promotes the oxidation of carbon monoxide and unburned hydrocarbon. This study can provide more insights into PODE spray combustion,and offer guidelines for achieving efficient and clean combustion.     

Influence of hydrogen-enriched atmosphere under coke oven gas injection on reduction swelling behaviors of oxidized pellet

It is of great importance to elucidate reduction swelling behaviors and reaction mechanism of oxidized pellet in hydrogen-enriched atmosphere under coke oven gas injection. In this work, the effects of hydrogen concentration in N_2-CO-H_2 atmosphere with unchanged CO content on reduction swelling behaviors of oxidized pellet at 1173 K were studied, to clarify the mechanism of hydrogen-enriched reduction and exclude the influences of CO. Then, the reduction swelling behaviors of oxidized pellet at 1173 K in actual atmosphere under coke oven gas(COG) injection, got from the simulation results of multi-fluid blast furnace model, were investigated. The results show that with the concentration of hydrogen increasing in N_2-CO-H_2 gas from 2% to 18%, the reduction swelling index of pellet decreases from 10.12% to 5.57% while the reduction ratio of pellet increases obviously from 39.85% to 69.58%. In addition, with COG injection rate increasing from 0 to 152.34 m~3/t, the reduction swelling index of pellet decreases slightly from 10.71% to 9.54% while the reduction ratio of pellet is increased from 31.57% to 36.39%. The microstructures of pellet are transformed from the platy structure to the flocculent structure.     

Microstructural Characteristics Analysis of PCE Copolymer from Methyl Allyl Polyethylene Glycol and Methacrylic Acid based on Determination of Monomer Reactivity Ratios

The reactivity ratio of monomer and the microstructure of copolymer as polycarboxylate ether (PCE) superplasticizer were investigated.Polycarboxylate ethers (PCEs) were synthesized from methyl allyl polyethylene glycol (MAPEG,M_w=2 400 g/mol) and methacrylic acid (MAA) via aqueous free radical copolymerization in low conversion (P20%).Gel permeation chromatography (GPC) and high performance liquid chromatography (HPLC) were used to track the residual concentration of the reactants and the amount of copolymer formed during the copolymerization.The reactivity ratios of monomers,MAPEG and MAA,were determined as r_(1(MAPEG))=0.0489 and r_(2(MAA))=1.6173,respectively,by employing the K-T and YBR methods.According to the obtained monomer reactivity results,the sequence distribution of the copolymer,the number average length of MAA in the polymerisate were found to decline with the decrease of the mole fraction of MAA in the polymerization system.As a result,the distribution of chain segments becomes narrower and the copolymer structure becomes more uniform.Therefore,uniform polymers could be obtained by slowly adding MAA monomer during copolymerization process.     

Determination of stacking fault energies in a high-Nb TiAl alloy at 298 K and 1273 K

The stacking fault energies of Ti-46A1-8.5Nb-0.2W alloy at 298 K and 1273 K were determined. The principle for the determination of the stacking fault energies is based on the fact that the stacking fault energy and the elastic interaction energy acting on the dissociated partial dislocations are equal. After the compress deformations with the strain of 0.2% at 298 K and 1273 K, and water quench to maintain the dislocation structures deformed at 1273 K, the dissociation distances between two partial dislocations were determined by weak beam transmission electron microscopy (WBTEM) technique. Based on these dissociation distances and the corresponding calculation method, the stacking fault energies were determined to be 77-81 mJ/m^2 at 298 K and to be 57-60mJ/m^2 at 1273 K respectively.     

不同前驱体制备的Al/K碳烟燃烧催化剂的催化性能

以Al(NO3)3(或Al2O3)和KNO3(或KOH)为原料,采用直接涂抹法,制取不同比例的Al/K碳烟催化剂。通过程序升温氧化(TPO)研究了焙烧温度、老化时间对催化剂催化活性的影响,同时用XRD对催化剂的成分进行分析。结果表明,Al/K摩尔比为3∶1、1∶1和3∶1的Al2O3/KNO3,Al(NO3)3/KNO3和Al2O3/KOH催化活性都较高。但是,高温焙烧或老化时,由于降低催化剂的比表面积导致催化剂催化活性明显降低;Al2O3/KOH经过焙烧形成K2Al2O4,故表现出较好的催化活性,但是吸水能力较强。     

催化裂化柴油超声氧化脱硫工艺研究

采用超声氧化法脱除柴油中硫化物,降低了柴油的硫含量。实验考察了氧化温度、氧化时间、氧化剂体积分数、催化剂体积分数等条件对柴油脱硫效果的影响。结果表明,选用甲酸与硫酸混合物作为催化剂,催化剂体积分数为2%(催化剂中甲酸与硫酸体积比为3∶2)、氧化剂体积分数为9%、反应温度为70 ℃、反应时间为60min时,采用超声氧化法脱除重油催化裂化柴油中的硫化物,再经N,N-二甲基甲酰胺(DMF)萃取氧化,柴油脱硫率达到83%,十六烷值有所升高,提高了柴油的质量。     

厂拌热再生过程中旧矿料颗粒的迁移行为

为提高热再生混合料的均匀性与生产质量,设计一种以回收沥青路面材料(reclaimded asphalt pavement, RAP)模拟制备、利用磁铁分离新旧矿料及迁移程度测试为关键步骤的室内试验,并通过该试验分析了RAP掺量、拌和时间及沥青用量对不同规格旧矿料颗粒迁移程度的影响。试验结果表明:热再生沥青混合料中旧矿料颗粒不能全部脱离原矿料,其迁移程度约为55%~75%;RAP掺量对迁移程度影响不大,随着拌和时间和沥青用量的增加,迁移程度不断增大;适当延长拌和时间,掺加新沥青或再生剂以及增加沥青用量可以促进旧矿料有效迁移,提高热再生沥青混合料的均匀性。     

3,4,5—三甲氧基苯甲酸的合成

以对羟基苯甲醛为原料,以溴代,甲氧基化,甲基化,氧化四步合成了３,４,５－三甲氧基苯甲酸。其中溴代一步采用氯气和溴素混合物为溴化剂,甲氧基化一步用甲醇及ＤＭＦ混合物代替ＤＭＦ为溶剂,从而为节约生产成本创造了条件。３,４,５－三甲氧基基苯 总收率为７７．１％。     

利用茶渣制备茶黄素工艺的研究

以茶渣为原料进行化学氧化制备茶黄素的工艺研究．着重研究氧化剂K3Fe（CN）6／NaHC03、FeCl3、Fe2（SO4）3、Fe（NO3）3的氧化效果．结果表明,茶渣浸提液在以上4种氧化剂作用下均可氧化形成茶黄素,而碱性氧化剂K3Fe（CN）6／NaHCO3的氧化效果最好,当质量浓度为40mg／mL、添加量为3％、20℃下反应20min时,茶黄素生成量最高为0．23％．     

Kinetic equation for internal oxidation of Cu-Al alloy cylinders

The kinetics of internal oxidation of Cu-A1 alloy cylinders, containing up to 2.214mol% A1, were investigated in the temperature range of 1023 K to 1273 K, and the depth of internal oxidation was measured in the microscopy. A kinetic equation was derived to describe the internal oxidation of Cu-A1 alloy cylinders. For the internal oxidation of Cu-Al alloys employed in the synthesis of alumina dispersion strengthened copper, the kinetic equation can be simplified. The derived equation was checked experimentally by means of oxidation depth measurements and the results show that the derived equation is exact enough to describe the kinetics of internal oxidation of Cu-Al alloy cylinders. Based on this equation and the oxidation depth measurements, the permeability of oxygen in solid copper was obtained. Investigation also shows that there is no evidence for preferential diffusion along grain boundaries in the process of internal oxidation.