结构助剂SiO2、Al2O3对铁基催化剂浆态床F-T合成性能的影响

采用连续共沉淀与喷雾干燥成型技术相结合的方法制备了微球状Fe/Cu/K/SiO2和Fe/Cu/K/Al2O3催化剂，研究SiO2和Al2O3作为结构助剂对铁基催化剂吸附行为、炭化行为及F-T合成反应性能的影响。表征结果表明,与Al2O3相比较，SiO2抑制了H2的吸附，但促进了CO的吸附，有利于催化剂的炭化。催化剂在260℃、1.5MPa、H2/CO=0.67和2000h-1下的浆态床F-T合成反应评价表明，Fe/Cu/K/SiO2催化剂具有较高的F-T合成活性、高的水煤气变换反应（WGS）活性，且其烃产物选择性明显向高炭数方向偏移，而Fe/Cu/K/Al2O3催化剂则表现出较低的F-T合成活性、低的水煤气变换反应（WGS）活性和高的轻质烃选择性。但Fe/Cu/K/Al2O3催化剂比Fe/Cu/K/SiO2催化剂具有更好的运行稳定性。     

浆态床F-T合成Fe/Cu/K/SiO2催化剂中K助剂作用的研究

采用低温N2吸附、H2 TPR、CO2 TPD、MES、XRD,考察了K的加入顺序对两组微球状费托(F-T)合成Fe/Cu/K/SiO2催化剂的织构性质、还原行为、碳化行为、物相变化以及反应性能的影响。结果表明,K的加入顺序对催化剂的织构性质影响很小。先加Si后加K的催化剂具有较强的表面碱性,抑制催化剂在H2气氛下的初始还原,但促进了催化剂的碳化,且在浆态床F T反应中表现出良好的反应稳定性,较高的FTS反应活性,较低的甲烷选择性以及较高的重质烃和烯烃选择性,表现出良好的工业应用前景。     

浆态床F-T合成反应中反应参数对e/Cu/K/SiO2催化剂性能的影响

 用喷雾干燥法制备了微球状Fe/Cu/K/SiO2催化剂,并在不同的反应条件下对其在浆态床F-T合成反应中的催化性能进行了评价. 结果表明,反应温度和原料气H2/CO比的调变对催化剂运行稳定性的影响较大,反应初始阶段加入的液体石蜡介质对催化剂运行稳定性的影响不大. 原料气空速的增加可有效地提高反应的总烃时空产率,但同时CO转化率会明显降低,且重质烃选择性下降; 低H2/CO比的原料气有利于在保持合适的转化率的同时提高重质烃的选择性,并可明显提高总烃的时空产率; 提高系统压力可增大催化剂的催化活性,改善重质烃的选择性; 而提高反应温度尽管可明显提高催化剂活性,但同时也会促进WGS反应的发生,降低重质烃的选择性. 因此,浆态床F-T合成反应中操作参数的适当调变可使催化剂活性、产物烃分布和烃产率得到有效优化,最大限度地获得目的产物.     

Cu、K助剂对FeMn/SiO2催化费托合成的影响

研究了Cu、K助剂对共沉淀型FeMn/SiO2催化剂还原行为、吸附行为及费托(F-T)合成活性和选择性的影响. Cu助剂以与Fe、Mn、SiO2共沉淀的方式引入, 而K助剂是在喷雾干燥前均匀加入沉淀浆料引入的. 结果表明, Cu可明显提高催化剂的还原性能, K助剂能促进催化剂在CO中的还原但抑制在H2中的还原, 而同时加入Cu和K会进一步促进催化剂在H2或CO中的还原; Cu助剂能促进H2吸附而K助剂对H2吸附无明显影响; Cu在一定程度上提高了F-T合成活性, 缩短了反应诱导期, K明显促进了CO的转化而相对抑制了H2的转化, 并且延长了反应的诱导期, Cu与K协同作用不仅提高反应的转化率而且缩短了反应的诱导期; K使得烃产物平均分子量增加, Cu单独对烃产物分布影响不明显, 而与K共同作用会进一步增加烃产物的分子量.     

SO2-4对铁基催化剂上费托合成反应的影响

以FeCuK/SiO2为母体催化剂,用不同浓度的NH4HSO4水溶液进行等体积浸渍,制备了不同SO2-4含量的费托合成(FTS)铁基催化剂.采用原子发射光谱、低温N2吸附、 X射线光电子能谱、程序升温还原和穆斯堡尔谱等技术对催化剂进行了表征,并在H2/CO摩尔比0.67,WHSV=2 000 h-1,压力1.5 MPa和温度250 ℃条件下进行了浆态床FTS反应.结果表明,少量SO2-4能促进催化剂在H2中的还原;在合成气还原过程中,少量SO2-4对催化剂的碳化程度影响不大,但大量SO2-4严重抑制催化剂的碳化.在约500 h的运行实验中,各催化剂样品表现出的催化活性有所差异,但均呈现较好的稳定性.SO2-4可抑制水煤气变换反应活性,且随着SO2-4含量的增加,抑制作用愈加明显;同时,催化剂上浸渍少量SO2-4可有效抑制CH4的生成,提高低碳烯烃的选择性.     

SO4^2-对铁基催化剂上费托合成反应的影响

以FeCuK/SiO2为母体催化剂,用不同浓度的NH4HSO4水溶液进行等体积浸渍,制备了不同SO42-含量的费托合成(FTS)铁基催化剂.采用原子发射光谱、低温N2吸附、X射线光电子能谱、程序升温还原和穆斯堡尔谱等技术对催化剂进行了表征,并在H2/CO摩尔比0.67,WHSV=2 000 h-1,压力1.5 MPa和温度250℃条件下进行了浆态床FTS反应.结果表明,少量SO42-能促进催化剂在H2中的还原;在合成气还原过程中,少量SO42-对催化剂的碳化程度影响不大,但大量SO42-严重抑制催化剂的碳化.在约500 h的运行实验中,各催化剂样品表现出的催化活性有所差异,但均呈现较好的稳定性.SO42-可抑制水煤气变换反应活性,且随着SO42-含量的增加,抑制作用愈加明显;同时,催化剂上浸渍少量SO42-可有效抑制CH4的生成,提高低碳烯烃的选择性.     

Fe改性工业Cu/Zn/Al催化剂上甲醇水蒸气重整反应制氢的研究

在Fe改性工业Cu/Zn/Al催化剂上进行了甲醇水蒸气重整反应的研究.在常压下考察了Fe含量的变化、反应温度、进料空速对反应的影响规律.反应结果表明,Fe的存在可以促进水煤气变换反应,显著降低产物中的CO含量,从而证明了在Cu/Zn/Al催化剂上甲醇水蒸气重整反应和水煤气变换反应同时发生.     

K_2O助剂对合成碳酸二甲酯用Cu-Ni/MoO_3-SiO_2催化剂吸附和反应性能的影响

用等体积浸渍法制备了MoO3 SiO2 (MoSiO)表面复合氧化物负载的Cu Ni K2 O催化剂。利用IR ,TPR ,TPD以及微反技术研究了K2 O助剂对CO2 和CH3OH在Cu Ni MoSiO催化剂表面上吸附和合成DMC(碳酸二甲酯 )反应性能的影响。结果表明 :K2 O助剂的加入 ,使CO2 在催化剂表面吸附强度增加 ,当K2 O含量达Cu Ni总量的 15 %时 ,CO2 在催化剂表面上吸附后生成K2 CO3;CH3OH在催化剂表面上的解离吸附态 (CH3O- H )的吸附强度减弱 ;CO2 和CH3OH在Cu Ni K2 O MoSiO催化剂表面反应主要产物为DMC ,H2 O ,CO和CH2 O。随着K2 O助剂的加入 ,反应转化率在 10 %之前增加 ,之后下降 ,DMC选择性稍有提高。副产物 (CO和CH2 O)的选择性下降。根据实验结果探讨了K2 O对催化剂表面活性中心的电荷分布的影响。     

助剂Li对CO2气氛下Fe-Li/AC催化剂上乙苯脱氢反应性能的影响

对 CO2 气氛下 Fe-Li/AC 催化剂上的乙苯脱氢反应性能进行了详细研究. N2 吸附-脱附、CO2 程序升温脱附和 X 射线衍射表征结果表明, 助剂 Li 不仅增加了催化剂比表面积和活性组分分散性, 而且增强了催化剂碱性和 CO2 吸附能力, 从而提高了 Fe/AC 对乙苯脱氢的催化性能. 助剂 Li 能显著提高 Fe/AC 催化剂的乙苯脱氢活性和 CO2 的促进作用, 抑制催化剂的失活. 在 Fe(3.0)-Li(0.6)/AC 催化剂(Fe 和 Li 的负载量分别为 3.0 和 0.6 mmol/g)上, 550 ℃、接触时间为 3.57 (g·h)/mol 和 CO2/乙苯摩尔比为 20 的条件下, 苯乙烯收率可达 62.9%, 选择性为 96.2%. CO2 气氛下的苯乙烯收率显著高于 N2 气氛下的, 归因于 CO2 能保持催化剂表面铁物种的高价态, 并通过逆水煤气变换反应在线除去脱氢反应生成的氢.     

助剂对低温水煤气变换反应Au/αFe2O3催化剂性能的影响

采用共沉淀法制备了系列Au/αFe2O3 MOxM=Zr、Al、Mg、Ca、Ba)催化剂，通过N2物理吸附、XRD、H2-TPR和CO2-TPD-MS等手段对催化剂的物化性质进行表征，考察了富氢下低温水煤气变换（WGS）反应中助剂对Au/αFe2O3催化剂性能的影响。结果表明，助剂ZrO2能有效提高Au/α Fe2O3催化剂在富氢气氛下低温WGS反应活性和稳定性，反应温度150℃时CO转化率可达88.45%，且催化剂具有较高的稳定性。研究发现，添加ZrO2助剂能抑制载体晶粒的生长，降低载体晶粒度，提高催化剂的比表面积，改善催化剂的还原性能和表面酸碱度，从而提高催化剂的催化活性和稳定性。     

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。     

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.     

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.

     

化学计量中不确定度评定研究进展

测量不确定度是表征合理地赋予被测量之值的分散性的参数。本文针对化学计量不确定度评定基础模型仅适用于线性模型、概率分布为正态分布或缩放位移t分布等局限,介绍了近年来不确定度评定的研究热点:蒙特卡罗方法(Monte Carlo Method,MCM),不确定度评定的来源、评定概念、评估方法及其发展过程,扩大了测量不确定度评定与表示的适用范围。     

微量钙的测定方法研究进展

介绍了1995-2006年期间测定微量和痕量钙的方法,如电感耦合等离子体-原子发射光谱法、原子吸收光谱法以及离子色谱法等的工作原理和特点,并说明了其测定微量钙的应用领域。并对微量钙的测定技术进行了展望(引用文献55篇)。     

Stages of thermal decomposition of sodium oxo-salts of sulphur

Thermal behaviour of sodium oxo-salts of sulphur: Na₂SO₄, Na₂S₂O₇, Na₂S₂O₆, Na₂SO₃, Na₂S₂O₅, Na₂S₂O₄, Na₂S₂O₃, Na₂S₃O₆ and of sulphides Na₂S and Na₂S₂ was studied on heating up to 1000°C. The experiments were performed with anhydrous compounds obtained from commercial products by recrystallisation and dehydration. The stage mechanisms of decomposition of anionic sub-lattices of the salts have been proposed basing on the Górski’s morphological classification of simple species. The thermal stability and the stage decomposition mechanisms were correlated with the structure and the potential chemical properties of the salt anions. The thermal decomposition processes were studied by means of thermal analysis, and the decomposition products were identified by means of X-ray phase analysis.