硫代硫酸铵预硫化的Mo/Al2O3催化剂加氢脱硫反应性能研究

研究了新型固体硫化剂硫代硫酸铵对加氢脱硫催化剂的预硫化。采用浸渍法将硫代硫酸铵负载在Mo/Al₂O₃模型催化剂上制备出预硫化的催化剂。通过X射线衍射、还原气氛的热重质谱联用和光电子能谱等表征手段研究了预硫化催化剂的物相、活化以及反应后催化剂的表面成分。结果表明,硫代硫酸铵中不同价态的硫在催化剂活化过程中起到不同作用,S^2-硫化活性金属,S⁶⁺修饰载体,减少载体与活性金属的相互作用,促进硫化。不同S/Mo摩尔比的预硫化催化剂经原位氢气活化用于噻吩加氢脱硫反应,S/Mo摩尔比为3的预硫化催化剂显示出最好的加氢脱硫活性,预硫化催化剂比Mo/Al₂O₃催化剂的脱硫活性提高17%。     

反应气氛中二氧化硫存在下La_(0.8)K_(0.2)Mn_(0.95)Cu_(0.05)O_3催化剂对碳烟的氧化

利用La0.8K0.2Mn0.95Cu0.05O3氧化模拟碳烟,考察预硫化处理及程序升温氧化中SO2对催化剂性能的影响。采用H2-TPR,FTIR和XPS等方法对催化剂性能进行了表征。XPS表明催化剂在0.02%SO2气氛中400℃下进行4 h的预硫化后OI(O2-)转化为OII(O-),催化剂活性增加;TPO反应中低浓度SO2(0.01%)促进了催化剂的活性,可能是较高温度下高活性K的存在,有效阻止了硫酸盐的生成及积累,对O-的消耗减少。催化剂在0.02%SO2气氛中300℃下预硫化超过1 h以后活性明显降低,预硫化1.5 h后催化剂表面的O2-几乎消耗完全,O-大大减少,二者都转化为O(O2-);可能是较低温度下硫酸盐逐渐积累,加快了O2-的消耗,导致可用的氧源枯竭,催化剂活性降低。     

碳化铁催化剂的制备及其对CO加氢的催化活性

 以Fe2O3为原料,采用两种预处理方法制备了碳化铁催化剂. 结果表明,直接在CO气氛下进行碳化处理,或者以H2预还原后再用CO进行碳化处理均可以制备出碳化铁催化剂. 碳化温度是制备过程中的关键因素. 对于Fe2O3样品,较适宜的碳化温度是350 ℃,而对于添加了K助剂的样品,只有经H2预还原处理后再于350 ℃用CO碳化处理4 h才能将样品完全转化为Fe5C2. 在CO加氢的评价实验中,碳化铁催化剂表现出很高的催化活性,生成的烃类产物中主要是饱和烷 烃,未检测到乙烯的生成. 而在K改性的催化剂上反应产物中烯烃的含量明显提高.     

FeS阳极过程电化学研究

采用高温合成法由光谱纯的Fe和S制备FeS,并应用电位扫描和电位阶跃法研究FeS在0.5mol·L-1H2SO4+0.5mol·L-1K2SO4溶液中的阳极电化学行为.考察酸度对FeS阳极极化的影响,测定阳极过程的传递系数β、交换电流I0和Fe2+在FeS中的固相扩散系数DFe以及不同电极电位下阳极电化学反应活化能ΔEa.     

CoMo型耐硫变换催化剂不同硫化剂的器外预硫化研究

从多种硫化剂中筛选出(NH_4)_2S和Na_2S,分别采用不同的预硫化技术对工业级CoMo型耐硫变换催化剂进行器外预硫化,采用XRD、XPS和HRTEM等表征手段对催化剂的晶相结构、表面特性和微观形貌进行表征。(NH_4)_2S和Na2S作为预硫化剂对催化剂的晶相结构没有明显影响;用(NH_4)_2S进行预硫化时活性组分发生部分O-S交换,而用Na_2S进行预硫化时活性组分仍保持为氧化态,两种预硫化型催化剂在反应器内随着反应温度升高,硫化深度为S-Na_2SS-(NH_4)_2S常规器内预硫化;器内预硫化和(NH_4)_2S作为预硫化剂MoS_2片层结构堆叠层数集中在2-3层,而用Na_2S进行预硫化时MoS_2片层堆叠层数明显变多,集中在3-5层。采用微型固定床评价装置,选择285、350、450℃三个反应温度,催化剂的活性顺序为SNa_2SS-(NH_4)_2S常规器内预硫化。     

氧化钼在CH4/H2气氛中还原碳化机理研究

采用TG-DTA技术研究了MoO3在CH4/H2气氛中的还原碳化行为,考察了程序升温速率和还原碳化终点温度对氧化钼还原碳化行为的影响,并探索适宜的还原碳化条件。结果表明,在1℃/min的程序升温条件下,MoO3在CH4/H2气氛中经三段失重过程被还原碳化为Mo2C,相应的反应历程为MoO3→MoO2→MoOxCy→Mo2C,适宜的还原碳化终点温度为675℃;程序升温速率升至2℃/min以上时,MoO3在CH4/H2气氛中的反应历程为MoO3→MoO2→Mo＋MoOxCy→Mo2C,且随程序升温速率的增大,第二段失重过程中金属Mo的生成量增大,还原碳化反应的始、终点温度升高。提高还原碳化终点温度,MoO3在CH4/H2气氛中的还原碳化反应规律相同,但过高的还原碳化温度会引起有机烃类分解生炭反应的发生,沉积在催化剂的表面,导致制备的碳化钼催化剂表面积炭增多,比表面积降低,从而引起催化活性的下降。     

SINGLE Mo_(n)Fe_(4-n)S_(4) (n=0, 1, 2) CUBANE-LIKE CLUSTERS: PREPARATION FROM COMBI-NATION OF DINUCLEAR COMPLEXES AND THE STRUCTUREOF [Mo_(2)Fe_(2)S_(4)(C_(4)H_(8)dtc)_(6)]·3.5C_(2)H_(2)Cl_(4)

Three types of unit combinations, FeS2Fe + FeS2Fe, FeS2Fe + MoS2Fe and MoS2Mo + MoS2Mo, lead to Fe4S4, MoFe3S4 and Mo2Fe2S4 cubane-like clusters, respectively. A new doubly bridged single cubane cluster [Mo2Fe2S4(C4H8dtc)6]·3.5C2H2Cl4 has been obtained and its structure is discussed.     

CO_2加氢活性与担载铁催化剂表面Fe-O键强度的关系

采用浸渍 -还原法 ,制备了 Al2 O3、 Ti O2 、 Zr O2 担载铁催化剂 ,并在温度 6 2 3K、压力 1.5 MPa、空速80 0～ 10 0 0 h- 1、原料气组成 CO2 /H2 为 1∶ 2等实验条件下 ,考察了不同还原温度的催化剂在 CO2 加氢制低碳(C2 ～ C5 )烃中的反应活性 .结果表明 ,以 CO2 转化率计 ,各催化剂均存在最佳还原温度 (Fe/Al2 O3:873K;Fe/Ti O2 :773K;Fe/Zr O2 :72 3K) .将此温度与催化剂表面 Fe- O键强度相关联 ,发现在相同条件下 ,与载体 M-O键长有关的 Fe- O键越强 ,催化剂越容易被还原 ,最佳还原温度越低 ,反应活性越好 .     

硫代硫酸铵预硫化的MoO3／Al2O3催化剂的活化和加氢脱硫活性

以硫代硫酸铵为硫化剂对MoO3/Al2O3催化剂进行预硫化,考察了制备方法和活化条件对预硫化催化剂噻吩加氢脱硫活性的影响. 结果表明,硫代硫酸铵预硫化的催化剂活化后,加氢脱硫活性好,噻吩的转化率达到99%以上,而二甲基二硫硫化的MoO3/Al2O3催化剂在相同条件下,噻吩转化率只有92%. 合适的活化温度为200～300 ℃, 活化压力增加有利于预硫化催化剂的还原硫化和加氢脱硫活性的提高. 硫代硫酸铵预硫化催化剂的高脱硫活性主要归因于多层的Ⅱ型MoS2活性相的形成,其次是硫化程度的提高. 硫代硫酸铵预硫化催化剂经过氢气活化和补充硫化两个阶段,其硫化程度高于传统方法硫化的催化剂.     

Pt(111) 表面上表层 Fe (FeO) 结构和次表层 Fe 结构的可控转变

 利用扫描隧道显微镜 (STM) 和 X 射线光电子能谱 (XPS) 对 Pt(111) 表面制备的 Fe 单层薄膜及其在不同环境气氛条件下的多种结构进行了研究. 在温度为 487 K 的 Pt(111) 表面制备出了完整的 Fe 单层薄膜Fe/Pt(111). 对 Fe/Pt(111) 依次升高温度进行超高真空退火, STM 和 XPS 结果表明退火温度高于 800 K 时, 表面 Fe 原子扩散到次表层区域, 形成次表层 Fe 结构Pt/Fe/Pt(111). Pt/Fe/Pt(111) 在 O2 氧化气氛中经 850 K 退火可转变成表面 FeO 薄膜FeO/Pt(111). FeO/Pt(111) 结构在温和的 H2 还原气氛中 (600 K) 转变成表面 Fe 结构, 进一步的还原处理 (800 K) 则可以重新生成 Pt/Fe/Pt(111). 控制样品的环境气氛在 O2 和 H2 之间切换, 使得表面 Fe (FeO) 和次表面 Fe 可以重复地转变. 本研究实现了多种 Fe-Pt 表面结构的可控制备, 可为合理地设计高效、价廉的催化剂提供借鉴.     

利用手持技术改进测定乙醇分子结构实验

利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。     

光谱仪测试范围的扩展

由于石化行业的生产需要，其材质的使用具有多样性和广泛性，经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识，根据光谱仪的测试能力及标样的采集，实现了一个或几个元素测量范围的扩展，并对其测量的影响因素进行了研究。     

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.     

Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin

The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989.     

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.

     

物质分配系数的测定实验改进

实验教学目的是从解决实际问题出发,以实验技术训练和实验设计思想培养为目标。介绍了将单一的物质分配系数测定实验改进为综合实验,提高了实验效果及实验资源利用率。     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988.     

Calculation of enthalpies of hydrogenation of hydrocarbons

Sets of hydrogen molecule equivalents have been developed which permit the calculation of hydrogenation of different types of carbon-carbon bonds from ab initio total energies (3-21G and 6-31G* basis sets, and, to a more limited extent, for MP2/6-31G* data) of reactants and products. The calculated enthalpies of hydrogenation are in good agreement with experiment for unstrained molecules, with average errors on the order of 2 kcal/mol. The 6-31G* equivalents allow the enthalpies for strained molecules to be calculated accurately, but the 3-21G equivalents do not. The equivalents for both basis sets have been tested by calculating the enthalpies of hydrogenation of carbon-carbon bonds in nitrogen- and oxygen-containing organic molecules, free radicals, and classical carbocations. The results are in good agreement with experiment in most cases.