铽改性铈锆固溶体

铽改性铈锆固溶体;Ce0.6Zr0.4-xTbxO2-y固溶体;三效催化剂;储氧材料;共沉淀法;溶胶-凝胶法     

稀土催化材料--铈锆固熔体的研究与应用

用助表面活性剂法制备一系列CexZr1-xO2固熔体, 对固熔体结构进行XRD表征(600和900 ℃焙烧), 研究了固熔体的结构、晶相,并进行储氧量、比表面积的测定和催化活性评价. 结果表明, 含铈锆固熔体的三效催化剂催化活性明显高于纯氧化铈的催化活性.     

溶胶-凝胶法合成稀土Z型铁氧体Ba3-xLaxCo2Fe24O41与表征

利用柠檬酸溶胶-凝胶法合成了掺杂镧的磁铅石型系列Z型铁氧体(Ba3-xLaxCo2Fe24O41,x=0.00～0.30).实验结果证明柠檬酸溶液的最佳溶胶化酸度为pH值在5.5～6.0之间;最佳合成条件烧结温度和时间分别为1250℃和5 h.红外光谱和热分析结果说明了随着镧掺杂量的增加,Z型铁氧体的合成温度也随之增加,且同时伴有失氧现象.     

掺杂对棒状纳米SrFe_(12)O_(19)形貌和性能的影响

以FeCl2为原料,利用化学沉淀法制备了针状纳米α-FeOOH中间体,并通过柠檬酸法在针状纳米α-FeOOH表面包裹锶的柠檬酸配合物,煅烧后形成的棒状纳米SrFe12O19并分别在共沉淀和溶胶-凝胶2个不同过程中对纳米SrFe12O19进行镧掺杂。采用XRD,TEM和振动样品磁强计(VSM)对SrFe12O19及掺杂锶铁氧体的结构、形貌及磁性能进行了表征。结果表明:沉淀法和柠檬酸法相结合后制得的针状前驱体于900℃煅烧后可制得平均直径为40nm,长径比为15～20的棒状纳米SrFe12O19。在沉淀过程中对前驱体进行掺杂后制得的SrLaxFe12-xO19较同温度时在溶胶-凝胶过程中进行掺杂制得样品的长径比有所增加,进而使得SrLaxFe12-xO19的各向异性变大,磁性能增加,且在沉淀过程中掺杂镧后,样品的矫顽力和饱和磁化强度达到最大值时,x值明显大于溶胶-凝胶过程中进行掺杂制得的棒状SrLaxFe12-xO19。利用共沉淀法掺杂后,当x=0.15时制备的样品的矫顽力最大为6179.1Oe,此时样品的饱和磁化强度和剩余磁化强度分别65.7和38.4emu·g-1。当x=0.2时制备的样品的饱和磁化强度达到最大值为67.3emu·g-1,样品的矫顽力为5852.7Oe。     

烟草模板制备掺杂过渡金属铈锆固溶体及其催化氧化CO性能研究

以烟梗丝、烟叶片和烟梗条等材料为模板掺杂过渡金属合成了一系列铈锆固溶体材料.对合成的材料进行了扫描电子显微镜(SEM)、N2吸附-脱附、程序升温还原(H2-TPR)、X-射线衍射法(XRD)、储氧量(OSC)、X-射线光电子能谱(XPS)等表征.对铈锆固溶体材料进行CO氧化活性评价,结果表明不同烟草模板制备的铈锆固溶体性能不同.以烟叶片为模板制备的掺铜铈锆固溶体具有极高的储氧量,高达2961μmol/g,但该材料催化氧化CO的活性并非最强.以烟梗丝为模板制备的掺铜铈锆固溶体在铈锆比为45∶45∶10时,对CO氧化有着很好的催化活性,起燃活性温度(T50)为91℃.     

从钯纳米溶胶出发制备Pd/Ce0.6Zr0.4-xYxO2纳米三效催化剂

从Pd纳米粒子溶胶出发,采用一步沉淀法和浸渍法分别制备了0.5%(质量分数)Pd/Ce0.6Zr0.4-x Y x O2(x=0,0.03,0.05,0.1)负载型三效催化剂,考察了贵金属纳米粒子的负载方法以及Y的掺杂量对三效催化活性和水热稳定性的影响。结果表明,和浸渍法制备的催化剂相比,采用一步沉淀法制备的催化剂具有更高的三效催化活性。对于一步沉淀法制备的催化剂,Y的掺杂量对新鲜样品的三效催化活性影响不大,然而,900℃水热老化后,Y的掺杂量为0.05的Pd/Ce0.6Zr0.35Y0.05O2催化剂表现出最佳的催化活性,且其三效窗口也最为稳定。以上研究结果表明,一步沉淀法是一种从贵金属纳米溶胶出发制备纳米三效催化剂的有效方法,且在铈锆储氧材料中掺杂适量的Y元素可以进一步提高催化剂的三效催化活性和水热稳定性。     

不同铝源与铈锆复合的性能及机制

制备了CZ及CZ/AL,CZ/AS与CZ/AM(铈锆固溶体与氧化铝的复合氧化物),通过X射线衍射(XRD)、比表面(BET)、储放氧(OSC)和透射电镜(TEM)等手段对样品的晶相结构、比表面、储氧性能及微观结构等进行表征。结果表明:CZ/AL及CZ/AS都可形成单一稳定的立方晶型结构,氧化铝的掺杂可提高铈锆固溶体的比表面及耐高温稳定性,其中CZ/AS的比表面最高,CZ/AL储氧性能最大。此外,其复合机理表明,Al2O3与铈锆固溶体在纳米级别上的化学复合与纯粹的机械混合相比,前者具有更加稳定的晶型结构、更大的比表面和更好的储氧性能。     

钾元素掺杂对铈锆固溶体中氧物种的影响

采用溶胶-凝胶法制备了一系列不同摩尔比K+掺杂的铈锆固溶体xK-Ce0.7Zr0.3O2(x=0.05,0.10,0.15,0.20,0.25,0.30,0.35,0.40),对其催化碳烟颗粒物(PM)燃烧的活性进行了评价,并采用XRD,H2-TPR,O2-TPD,XPS测试方法对催化剂样品进行了表征。结果表明:K+掺杂后均形成了具有立方面心萤石结构的K-Ce-Zr-O固溶体催化剂。K+掺杂量的改变导致铈锆固溶体产生不同程度的晶格畸变及表面活性氧的含量改变;掺杂K+有利于晶格氧的流动性和铈锆固溶体的释放氧能力的增强,促进催化活性的提高。当0.10≤x≤0.40时,催化剂具有较好的催化性能。     

铈锆复合氧化物氧非化学计量值的测定

1引言采用氨水共沉淀法制备出CexZr1-xO2-δ复合氧化物。用氧化还原返滴定法测定样品氧非化学计量值,并采用热重法进行方法比对实验以考察方法的可行性。结果表明,本方法可得到准确CexZr1-xO2-δ的氧非化学计量值δ的测定值,并分别对不同原子比的CexZr1-xO2-δ复合氧化物样品的     

溶胶-凝胶法合成纳米铬酸锶镧的工艺研究

以硝酸镧、硝酸铬、硝酸锶为原料，乙二醇为分散剂，柠檬酸为胶溶剂，用溶胶-凝胶法合成纳米级的铬酸锶镧粉体。利用TG，DSC，XRD分析研究了粉料的晶化过程。利用HREM分析了煅烧温度、含锶量对粉料粒径的影响。研究表明，获得纳米晶的最佳烧结温度在800℃。随着锶掺杂量的增加，粉料的粒径逐渐变小。     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Synthesis of phenolic components of Grains of Paradise

Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。     

Study of hydration of two cements of different strengths

Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, M_o, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700^oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date.     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

恶臭嗅辨实验室建设探讨

针对恶臭测试的环境影响问题,提出了解决的实例方案,并对方案的要点及优缺点进行讨论,此方案在实际操作中具有较好的效果。     

Investigation of Kinetics of Solid-Phase Synthesis of Lithium Orthosilicate

The kinetics of the interaction between lithium carbonate and silica with various degrees of dispersion was investigated by TG and DTA methods. It was found that the utilization of pyrogenic silica with a specific surface area of about 300 m²g^-1 instead of aerosil with one of 175 m²g^-1 leads to an increase of the reaction rate between lithium carbonate and silica, which depends on the formation and growth of lithium orthosilicate crystals in the first stage, and is conditioned by the diffusion of lithium and oxygen ions through the lithium orthosilicate layer formed at temperatures above 800 K. This supposition is supported by the kinetic analysis results obtained with the use of the different models. The optimal regime of heating is recommended. This revised version was published online in July 2006 with corrections to the Cover Date.     

小环化合物中饱和碳质子化学位移的计算

小环化合物由于其张力、构型、构象和各向异性效应等原因,环碳上质子化学位移缺乏规律性,难以预测,对此作者曾提出一种近似算法。本文根据303种小环化合物中饱和碳质子的化学位移实验数据,将适于计算这类质子化学位移的公式表述为:     

解决能源问题的新途径--光解水制氢的研究

面对日益枯竭的能源危机,氢能是一种洁净、最有前景的替代能源。目前在各种制氢的方法中光催化分解水制氢的研究最多,光解水过程中催化剂最关键,本文对利用太阳能光解水的途径、提高光催化反应效率以及光催化剂的开发研究进行了综述。