溶胶凝胶法制备中孔分布集中的氧化铝催化材料

报道一种新的中孔氧化铝催化材料的制备方法.通过该方法可以以无机盐和SB粉为原料经过沉淀、解胶的过程首先制得稳定的铝溶胶,然后经过干燥、焙烧得到中孔氧化铝催化材料.用BET,TEM,DTA和XRD等方法对该中孔氧化铝催化材料的基本物理化学性质进行了表征.实验结果表明在不使用模板剂的前提下,通过本文报道的方法能够制得比表面积较大、中孔分布集中的氧化铝材料,并且其孔径分布主要集中在4nm左右.实验结果表明以SB粉为原料制备得到的氧化铝材料具有较好的热稳定性.     

高温高表面氧化铝新材料的制备化学研究

随着催化工业的发展,迫切需要在高温下既能保持较大比表面积,又具有良好的热稳定性的新型活性氧化铝。这种氧化铝作为一种载体,可直接应用于催化燃烧和汽车尾气净化等领域。目前,工业生产用的氧化铝经高温煅烧后,微孔易烧结并向稳定相态α相转变,造成其比表面积迅速下降。为了解决这一问题,近年来国外已进行了许多这方面的研究［1-5］,它们绝大多数采用以镧浸渍对氧化铝表面进行改性的表面保护方法,但我国在这方面却发展缓慢。我们曾报导过硅的添加对氧化铝表面性质的影响,本文以未加镧的氧化铝为空白实验,采用溶胶─凝胶法（体相与表面同时保护法）来制备样品,系统研究了不同含量镧的添加对氧化铝热稳定性的影响。     

氧化铝柱层状类钙钛矿型铌酸盐KSr2Nb3O10的制备与表征

采用分步交换法,制备了氧化铝柱层状类钙钛矿型新铌酸盐KSr2Nb3O10。采用X射线衍射、扫描电镜对该化合物的结构与形貌进行了表征,并测定了其比表面积。结果表明,该化合物具有较高的热稳定性和较大的比表面积。     

介孔氧化铝的制备及应用

本文介绍了介孔氧化铝(MA)的各种制备方法,概括了MA制备的分析表征方法,如TEM、SAED、XRD、LAXRD、气体吸附-脱附、DT-TGA等。通过平均孔径、比表面积、MA形貌等因素,讨论和总结了制备方法、铝源、模板剂、反应物配比、pH值和后处理方法等对MA制备和热稳定性的影响,综述了近年来MA的研究和应用进展,并对今后的研究方向进行了展望。     

胶溶法制备铈锆镧共改性氧化铝及催化性能

γ-Al2O3是机动车尾气净化催化剂的常用载体,其高温热稳定性、比表面积、孔容、孔径及表面酸性等对催化活性有很大影响.近年来,大量研究结果表明,铈、锆、镧和钡等元素的添加可以提高氧化铝的高温热稳定性和催化活性[1～3],然而这些研究大多致力于单组分或者双组分改性氧化铝,制备方法以浸渍法和溶胶-凝胶法为主.胶溶法制备三组分共同改性氧化铝的研究很少.本文利用胶溶法制备了系列铈、锆、镧改性氧化铝,讨论了三组分共同添加对氧化铝载体的性质以及催化剂活性的影响.     

高温高表面氧化铝新材料的制备化学研究——La、Ba共添加对氧化铝热稳定性的影响

本文用镧、钢共同添加并使用溶胶－凝胶法制得改性氧化铝,详细研究了在保持La含量为5．2 wt%时,Ba添加量的改变对氧化铝热稳定性的影响,实验结果表明镧,钡元素的共添加能大大增加氧化铝的热稳定性,从而使氧化铝在高温下保持高比表面积,体相中同时添加5．2wt%La和2wt?以及5．2wt%La和7wt?能使氧化铝保持较好的热稳定性,样品经1100℃煅烧20h后,比表面分别达100．8m^2.g^-1和92．3m^2.g^-1.通过对添加物与氧化铝保持高温高表面能力的内在联系的探讨,得出Ba、La元素的添加提高氧化铝热稳定性的原因主要表现在两方面,一是抑制氧化铝的微孔烧结速度,二是阻止了氧化铝向α相的转变。     

蜂窝状堇青石载体Al2O3涂层的原位合成

 采用改进的原位合成法（原位－浸涂法）在蜂窝状堇青石载体表面制备了多孔氧化铝涂层．着重研究了制备条件对涂层负载、晶相及其孔结构性质的影响，并与其他方法制备的涂层进行了比较．结果表明，采用多次原位合成法制备能提高氧化铝涂层的牢固度，但每次负载量偏低；原位－浸涂法适宜的制备参数为：水解温度83℃，水／异丙醇铝摩尔比60，pH值3．5～4．0，焙烧温度500℃．原位－浸涂法有利于制备Al2O3涂层，具有较好的牢固度，而且涂层的孔径分布窄，具有较大的比表面积、比孔体积和平均孔径．     

制备方法对Pd催化剂上丙烯选择性还原NO反应性能的影响

 采用三种不同方法制备了氧化铝负载的Pd催化剂．比表面积测定\r\n结果表明,与浸渍法相比,溶胶－凝胶加浸渍法和溶胶－凝胶法制备的\r\nPd／Al2O3样品具有较大的比表面积,但抗烧结性能不佳．其中采用溶\r\n胶－凝胶法制备的样品中,由于Pd分散于体相中,表面的活性位相对较\r\n少,造成催化剂在NO选择性还原反应中的活性较差;而将Pd浸渍于溶胶\r\n－凝胶法制得的Al2O3载体上所获得的催化剂比表面积较大,活性较好\r\n．添加CeO2的样品活性总体上比Pd／Al2O3样品高．其中采用溶胶－凝\r\n胶法制备的样品比表面积不大,并且XRD数据表明Al2O3和CeO2是高度分\r\n散并均匀地搀杂在一起的,不象在浸渍法制备的样品中那样以大晶粒的\r\n形式存在,因而CeO2的助剂作用没有充分体现出来,催化剂的活性比浸\r\n渍法制备的样品差一些．     

蜂窝状堇青石载体A12O3涂层的原位合成

采用改进的原位合成法(原位-浸涂法)在蜂窝状堇青石载体表面制备了多孔氧化铝涂层．着重研究了制备条件对涂层负载、晶相及其孔结构性质的影响，并与其他方法制备的涂层进行了比较．结果表明，采用多次原位合成法制备能提高氧化铝涂层的牢固度，但每次负载量偏低；原位-浸涂法适宜的制备参数为：水解温度83℃，水／异丙醇铝摩尔比60，pH值3．5～4．0，焙烧温度500℃．原位-浸涂法有利于制备A12O3涂层，具有较好的牢固度，而且涂层的孔径分布窄，具有较大的比表面积、比孔体积和平均孔径．     

胶凝对氧化钡改性的氧化铝热稳定性的作用(英)

比较了γＡｌ２Ｏ３ 和胶凝预处理的拟薄水铝石经Ｂａ 改性前后在１ １５０ ℃高温下的热稳定性．ＢＥＴ表面积、孔径分布和ＸＲＤ 表征结果表明, 胶凝处理降低了氧化铝的孔径并加速了高温烧结．Ｂａ 的引入抑制了上述两种氧化铝向α相的转变,同时与ＢａＯ发生高温固相反应形成钡的六铝酸盐,但拟薄水铝石的胶凝处理削弱了Ｂａ 的高温稳定作用． 结果显示, γＡｌ２Ｏ３ 经Ｂａ 的改性不但抑制了αＡｌ２Ｏ３ 的生成,而且还抑制了γＡｌ２Ｏ３ 的烧结．     

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.     

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。     

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.     

Acid hydrolysis of carboxymethylcellulose of low degree of substitution

Cotton cellulose was swollen in a sodium hydroxide solution and carboxymethylated by a two-bath method for different periods of time for each process. The kinetics of acid hydrolysis and the crystallinity of the swollen and carboxymethylated samples were measured. The proportion of broken bonds, rate constants for hydrolysis, and permeability of cellulose to hydrolyzing agents were calculated. The susceptibility of glycosidic linkages to acid hydrolysis was improved by carboxymethylation more than by swelling in alkali. The increased accessibility of carboxymethylcellulose to acid was regarded as a consequence of increased intra-and intercrystalline swelling and of the glycosidic bonds' weakness caused by the electron-attracting carboxymethyl group on the C-6 position.     

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.     

Estimation of Kinetic Parameters of Thermal Oxidation of Ilmenite

The aim of the presented work was the investigation of thermal oxidation of ilmenite in static air atmosphere. The investigations were carried out by use of a derivatograph (MOM, Hungary). The changes of crystallographic structure of investigated samples were identified by X-ray diffractometry on Philips PW-1710 diffractometer. In temperature above 500°C appears structure of hematite Fe₂O₃. On the basis of the thermogravimetric measurements, the contracting area and contracting volume models were found as the best fitting experimental data. This revised version was published online in August 2006 with corrections to the Cover Date.     

Mechanism of action of base-catalyzed oxygenation of phenol derivatives

Cyclopropyl derivative of 2,6-di-tert-butylphenol is synthesized as a probe to investigate the mechanism of base-catalyzed autooxidation of phenol derivatives. Our study indicates that one electron reduction of molecular oxygen from phenolate gives phenoxyl radical 3, a key intermediate of autooxidation. The coupling of phenoxyl radical and superoxide radical gives peroxylate anion 4 and produces the final epoxy alcohol adduct 6.     

氯氧化镁生成热的研究

用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。     

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.