Liquid phase hydrogenation of naphthalene in the presence of CO over supported Ni catalyst

The liquid phase hydrogenation of naphthalene was performed in the presence of CO over a commercial Ni/SiO₂-Al₂O₃ catalyst. Naphthalene was hydrogenated even in the presence of CO at elevated temperatures, accompanying the hydrogenation of CO. Two activation energy values were obtained for the naphthalene hydrogenation depending on the reaction temperature. FT-IR measurement of the adsorbed CO was also carried out. Hydrogenation of the adsorbed CO created sites active for naphthalene hydrogenation.     

Ni/Mo/N催化剂合成及其在噻吩存在体系下苯加氢反应中的应用(英文)

Ni/Mo/N间隙型催化剂具有高的加氢活性及良好耐硫性, 可应用于煤液化油加氢精制高性能喷气燃料. N原子由于只占据晶格间隙位置, 在进入Ni/Mo过程中会因不占据晶格中的特定晶位, 容易从金属晶格溢出导致无法形成稳定的Ni/Mo/N间隙型催化剂. 为此, 本文利用前驱体晶型控制的方式来实现Ni/Mo/N催化剂合成. 采用络合物分解一步法, 考察了不同结晶过程和老化时间对合成的Ni/Mo/N催化剂用于苯加氢反应活性影响, 并采用X射线衍射、X射线光电子能谱和透射电镜-能量色散X射线光谱对催化剂结构组成进行表征. XRD分析结果显示, 钼酸铵[(NH4)6Mo7O24·4H2O]、乙酸镍[Ni(CH3COO)2·4H2O]和六亚甲基四胺(HMT)添加顺序、结晶过程和老化时间直接影响催化剂组成, 并决定Ni/Mo/N晶相的形成. 结晶过程慢速搅拌速度和短老化时间有利于合成含Ni2Mo3N, Mo2C和Ni晶相的高活性Ni/Mo/N间隙型催化剂, 使苯加氢制环己烷模型反应苯的最大转化率达93%, 环己烷选择性为100%. 含0.01 wt%噻吩的存在使苯转化率由72%降至50%, XPS分析结果表明, 催化剂表面形成的MoS2是催化剂活性降低的重要因素.     

用ETV-ICP-MS研究Cr、Ni、Zr、Nb、Yb在石墨炉中的蒸发/原子化机理

本文以电热蒸发电感耦合等离子体质谱（ETV-ICP-MS）为手段,探讨了Cr、Ni、Zr、Nb和Yb在石墨炉中的蒸发/原子化机理;比较了不同化学改进剂存在条件下,Cr、Ni、Zr、Nb和Yb的蒸发行为和在石墨炉原子吸收（GFAAS）中的原子化行为;考察了石墨炉温度和ICP功率等实验参数对上述元素发射强度及轮廓的影响.结果表明,Pd和Mg化合物的存在对Cr、Ni、Zr、Nb和Yb的蒸发/原子化行为没有明显的化学改进作用;然而,以聚四氟乙烯（PTFE）为化学改进剂时,可显著改善Cr、Ni、Zr、Nb和Yb的蒸发行为,避免难熔碳化物的形成,降低待测物的蒸发温度;对Cr和Ni的GFAAS信号强度略有增强;但是,由于Yb、Nb和Zr氟化物的离解键能很高,难以离解/原子化,PTFE的存在反而降低了Yb、Nb和Zr在GFAAS中的信号强度.     

Ionic hydrogenation in the presence of surface-active substances

Conclusions Surface-active substances can be efficient catalysts of the ionic hydrogenation reaction.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimichekaya, No. 4, pp. 941–942, April, 1984.     

Selective hydrogenation of acrylonitrile over a supported Ni catalyst

Acrylonitrile can be selectively hydrogenated into propionitrile at about 400 K over a ceramic-supported Ni catalyst. At low surface coverages, the observed rates of hydrogenation are proportional to the first powers of the partial pressures of both acrylonitrile and dihydrogen, in agreement with Langmuir-Hinshelwood kinetics.

---

400 . , , -.

     

Isoprene hydrogenation in the presence of cobalt pohosphine complexes

The influence of the type of phosphine on the yield of methylbutenes in isoprene hydrogenation with complex cobalt catalysts has been studied. The complex H₃Co[P(n-C₄H₉)₃]₃ has been identified by the NMR method in the catalytic system Co(C₅H₇O₂)₂+P(n-C₄H₉)₃+Al(C₂H₅)₃. A mechanism of isoprene hydrogenation is suggested.

---

. Co(C₅H₇O₂)₂+P(n-C₄H₉)₃+Al(C₂H₅)₃ H₃Co[P(n-C₄H₉)₃]₃. .

     

Asymmetric hydrogenation in the presence of bicyclic chiral phosphines

Both enantiomers of trans-2,3-diphenylphosphinomethyl-norbornene-(5), prepared by two independent synthetic routes, were used as ligands in the asymmetric hydrogenation of -acetamidocinnamic acid in the presence of rhodium(I). Small variations in the ligand structure have a remarkable influence on the activity of the catalytic system.

---

-2,3----(5), , - (I). .

     

Exchange of molecular deuterium with dimethylformamide in the presence of a complex hydrogenation catalyst

Russian Chemical Bulletin -     

Synthesis of Ag/ZnO mixture for powdered contact materials

The processes of a ultrafine Ag/ZnO mixture produced by coprecipitation from salt solutions were investigated. The coprecipitation in AgNO₃-ZnNO₃-Na₂CO₃ system was analyzed in the presence of surfactants, considering the pH value and a solution composition contribution. The optimal coprecipitation conditions were Na₂CO₃ precipitating agent excess of ～20%, providing a pH value of ～10, with subsequent thermal decomposition of the mixture at about 700 K. A thermal analysis of the precursor mixtures were carried out. The phase composition, dispersity and morphology of the precipitates were determined before and after a thermal treatment. The size decrease of the precipitated particles, as well as dispersity and distribution uniformity increase of the oxide inclusions in the target composite matrix is due to the presence of surfactants in solutions.     

Pd/C-catalyzed chemoselective hydrogenation in the presence of diphenylsulfide

[Structure: see text] A Pd/C-catalyzed chemoselective hydrogenation using diphenylsulfide as a catalyst poison has been developed. This methodology selectively hydrogenates olefin and acetylene functionalities without hydrogenolysis of aromatic carbonyls and halogens, benzyl esters, and N-Cbz protective groups.     

Oxidation of 4-aminotoluene by ozone-air mixture in the presence of a stop-reagent

A study of the liquid-phase oxidation of 4-aminotoluene by ozone to 4-amino benzaldehyde in the presence of a manganese/bromide catalyst demonstrated that introduction of potassium bromide into the oxidizing system makes it possible to obtain 4-aminobenzaldehyde in the form of 4-(acetylamino)benzylidene diacetate (84.5%) as the main product. A reaction scheme accounting for the results obtained was suggested.     

Catalytic hydrogenation of a binary substrate mixture with pseudo-zero reaction order: Dependence of the overall rate on mixture composition

An abnormal dependence of overall hydrogenation rate on the composition of a cyclopentadiene-isoprene mixture for the case of pseudo-zero reaction order has been interpreted in terms of a model accounting for the inhomogeneity of active sites.

---

, , .

     

Acetophenone hydrogenation over a Pd catalyst in the presence of H2O and CO2

The addition of carbon dioxide and water enhances acetophenone hydrogenation activity over an activated carbon-supported palladium catalyst, and 1-phenylethanol can be easily recovered without distillation and neutralization. Two liquid phases (water and acetophenone) are indispensable for enhancement of the hydrogenation rate.     

Curing and thermal behaviour of epoxy resin in the presence of a mixture of imide-amines

The curing behaviour of diglycidyl ether of bisphenol-A (DGEBA) was investigated by the dynamic differential scanning calorimetry using varying molar ratios of aromatic imide-amines and 4,4′-diaminodiphenylsulfone (DDS). The imide-amines were prepared by reacting 1 mole of naphthalene 1,4,5,8-tetracarboxylic dianhydride (N) and 4,4′-oxodiphthalic anhydride (O) with 2.5 moles of 4,4′-diaminodiphenyl ether (E) or 4,4′-diaminodiphenyl methane (M) or 4,4′-diaminodiphenylsulfone (S) and designated as NE/OE or NM/OM or NS/OS. The mixture of the imide-amines and DDS at ratio of 0:1, 0.25:0.75, 0.5:0.5, 0.75:0.25 and 1:0 were used to investigate the curing behaviour of DGEBA. A single exotherm was observed on curing with mixture of imide-amines and DDS. This clearly shows that the two amines act as co-curing agents. Curing temperatures were higher with imide-amines having sulfone linkage irrespective of anhydride. Curing of DGEBA with mixture of imide-amines and or DDS resulted in a decrease in characteristic curing temperatures. The thermal stability of the isothermally cured resins was also evaluated using dynamic thermogravimetry in a nitrogen atmosphere. The char yield was higher in case of resins cured imide-amines based on N and E. The activation energy of decomposition and integral procedural decomposition temperature were also calculated from the TG data.     

Aniline hydrogenation in the presence of alumina-supported rhodium under hydrogen pressure

Aniline hydrogenation over 5% Rh/Al₂O₃ in water and an universal queous buffer has been studied at temperatures of 323–363 K and pressures of 2.02–10.10 MPa.

---

5% Rh/Al₂O₃ 323–363 K 0,5–10,10 .