Hydrogenation of carbon monoxide over technetium catalysts

Supported Tc catalysts are active in CO hydrogenation, their activity depending on the nature of the support. The reaction proceeds predominantly toward methane formation. All catalysts studied yielded very little C₂ and C₃ hydrocarbons. The thermal desorption data indicate that the CO strongly bound to the substrate is responsible for CH₄ formation.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 7, pp. 1507–1511, July, 1992.     

Rhodium-technetium catalysts in the dehydrogenation of cyclohexane

The catalytic properties of a Rh-Tc/support (-Al₂O₃, SiO₂, or MgO) system in the dehydrogenation of cyclohexane have been investigated. A nonadditive increase in the catalytic activity of bimetallic catalysts in comparison with monometallic systems has been established. This effect depends on the ratio of the amounts of the supported metals and on the nature of the support. Diffuse reflectance spectra showed the presence of ionic forms of the metals in the bimetallic catalysts. Analysis of the catalytic and optical properties allowed one to draw the conclusion that the synergistic effect is explained by the formation of Rh_xTc_y clusters.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1563–1566, September, 1994.     

Synergistic effect for bimetallic Ru-Tc catalysts of cyclohexane dehydrogenation

Catalytic properties of the Ru-Tc/support (-Al₂O₃, Y₂O₃, and SiO₂) systems in the dehydrogenation of cyclohexane have been studied. The catalytic activity of the bimetallic catalysts depends on the nature of the support. A nonadditive increase in the catalytic activity of the bimetallic catalysts in comparison with monometallic samples was established. The value of the synergistic effect depends on the ratio between the amounts of the supported metals and the nature of the support. By using the diffuse reflectance spectra in UV- and visible regions and hydrogen chemisorption techniques, the modifying influence of the ionic metal species on the catalytic properties was shown.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1959–1963, August, 1996.     

Synergic effect of palladium-based bimetallic catalysts for the hydrogenation of nitroaromatics

Bimetallic catalysts, PdCl₂-MX_n and PdCl₂(PhCN)₂-Mx_n (MX_n=FeCl₃, Fe(acac)₃, Co(OAc)₂, CoCl₂, Co(acac)₂, NiCl₂, Ni(OAc)₂, RuCl₃, Cu(OAc)₂, CuCl₂), exhibit remarkable synergic effect which can obviously increase the activity of the monometallic Pd catalyst for the hydrogenation of nitroaromatics, whereas MX_n alone is not catalytically active under the same reaction conditions.     

Study of Supported Bimetallic Pd-Pt Catalysts. Characterization and Catalytic Activity for Toluene Hydrogenation

Bimetallic Pd-Pt catalysts were prepared either by a surface redox reaction (RC catalysts) or by coimpregnation (CI catalysts). RC bimetallic catalysts show a higher sulfur resistance in the course of toluene hydrogenation in the presence of thiophene compared to monometallic palladium and CI bimetallic catalysts. A characterization of the RC catalysts by IR and EXAFS allows to propose a structure of the Pd-Pt crystallites which would explain these results.     

Catalytic behavior of supported Pd catalysts in the selective hydrogenation of campholenic aldehyde to naturanol

Selective catalytic reduction of campholenic aldehyde to naturanol was investigated over Sn-and Fe-doped SiO₂, and Fe₂O₃-supported Pd catalysts. On Pd/SiO₂ and Pd-Sn/SiO₂ only saturated campholenic aldehyde is formed. Addition of Fe increases the C=O hydrogenation rate producing the corresponding unsaturated alcohol with a good selectivity. Also Fe₂O₃-supported catalysts were found to be more selective towards carbonyl hydrogenation. Addition of tin to Pd/Fe₂O₃ contributes to a further selectivity enhancement towards naturanol.     

CO2 Hydrogenation over Oxide‐Supported PtCo Catalysts: The Role of the Oxide Support in Determining the Product Selectivity

By simply changing the oxide support, the selectivity of a metal–oxide catalysts can be tuned. For the CO₂ hydrogenation over PtCo bimetallic catalysts supported on different reducible oxides (CeO₂, ZrO₂, and TiO₂), replacing a TiO₂ support by CeO₂ or ZrO₂ selectively strengthens the binding of C,O‐bound and O‐bound species at the PtCo–oxide interface, leading to a different product selectivity. These results reveal mechanistic insights into how the catalytic performance of metal–oxide catalysts can be fine‐tuned.     

Hydrogenation of ethyl acetate over supported rhenium catalysts

Re/Sibunite is a more active and selective catalyst for hydrogenation of ethyl acetate to ethanol under elevated temperatures and hydrogen pressures than Re/θ-Al₂O₃ and Re/γ-Al₂O₃. The activity of the catalyst is increased on replacing NH₄ReO₄ with HReO₄ and treatment of the support with a 13% solution of HNO₃. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1006–1008, May, 1999.     

Hydrogenation of acetylene into ethane–ethene mixtures over modified Pd–alumina catalysts

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Hydrogenation of cyclohexene on different types of catalysts

Hydrogenation of cyclohexene has been studied under pressure in a flow reactor on the following catalysts: Na- and H-forms of Y-type zeolites, erionite, magnesium and lanthanum oxides, palladium on silica and aluminum oxide. This reaction is accompanied by skeletal isomerization to give methylcyclopentane and methylcyclopentenes. The differences in activation energies for isomerization and hydrogenation reactions were estimated as 83–96 kJ/mole for NaY and Na,K-erionite, 33–50 kJ/mole for the H-forms of the zeolites, 33–37 kJ/mole on the Pd catalysts, and 25–33 kJ/mole on magnesium and lanthanum oxides. It is suggested that the cyclohexyl complex, formed as an intermediate during hydrogenation of cyclohexene on Na-forms of the zeolites, is neither a carbocation nor a radical.Deceased.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 117913. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 791–799, April, 1992.     

ZrO2—SiO2负载Cu—Ni催化剂的CO2加氢反应性能

采用表面反应改性法,制备了ZrO2-SiO2（ZrSiO)表面复合物载体,用等体积浸渍法制备了ZrSiO担载的Cu-Ni双金属催化剂,借助BET、TPR、IR和微反等技术,研究了ZrSiO及其负载的Ni、Cu双金属催化剂的表面构造,化学吸附及催化CO2加氢的反应性能,结果表明,ZrSiO表面主要是价联型结构,ZrO2引入SiO2表面,可以有效地促进CuO和NiO的还原,在ZrSiO负载的Cu-Ni催化剂表面的Cu或Ni位,CO2发生化学 吸附形成线、剪式、卧式吸附态,在该催化剂上CO2的加氢反应产物主要是CH3OH3、CH4、CO和H2O生成CH3OH的选择性与催化剂组成及反应条件密切相关,在适当的条件,CH3OH的选择性大于90％。     

Hydrogenation on palladium-containing granulated catalysts 3. Synthesis of aminobenzimidazoles by catalytic hydrogenation of dinitroanilines

Efficient hydrogenation of o-aminonitrobenzenes on palladium-containing granulated carbon catalysts in carboxylic acid solutions was accompanied by cyclization into aminobenzimidazoles. A simple hydrogenation reactor with a fixed gauze holding a reusable granulated catalyst was designed. Acylated and sulfonylated 4(7)-aminobenzimidazoles were obtained. In terms of electronic and geometrical parameters, they are close analogs of biologically active imidazo[1,5,4-e,f ][1,5]benzodiazepines. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1171–1181, June, 2007.     

Activity and Selectivity in CO Hydrogenation with Silica-supported Ru-Co Bimetallic Cluster-derived Catalysts

The catalytic performance of bimetallic Ru-Co catalysts prepared from a series of H3Ru3Co(CO)12. RuCo2(CO)11 and HRuCo3(CO)12 in CO hydrogenation was investigated, and it was found that the Ru-Co bimetallic carbonyl cluster-derived catalysts showed a high activity for products, particularly higher oxygenates, compared with the catalysts prepared from impregnation or co-impregnation of monometallic clusters such as [HRu3(CO)11] and Co4(CO)12. The selectivity for oxygenates in CO hydrogenation highly increased with the molar ratio of Co/Ru in the Ru-Co bimetallic cluster to CO/H2 in feed gas. Raising reaction temperature led to an intensive increase of CO conversion and a considerable decrease of selectivity for oxygenates. In situ FT-IR studies revealed that the band at 1584 cm-1 on Ru-Co bimetallic cluster-derived catalysts at 453 K under syngas (CO/H2 = 0. 5) has a good linear relationship to rates of oxygenate formation, which is likely associated with an intermediate to produce oxygenates in CO hydro     

Polymer-supported palladium and platinum species as hydrogenation catalysts

The synthesis of new hydrogel copolymers and their use for anchoring Pd and Pt species is described. The supported catalysts are effective for the reduction of alkenes, dienes, alkynes, and nitroaromatics under mild conditions. The catalysts have been characterized by chemical analysis, particle size measurement, IR, TGA, and x-ray photoelectron spectra. Relative reactivities and the effects of substrate structure, solvents, catalyst loading, particle size of the catalysts, and partial pressure of hydrogen have been determined. The kinetics of hydrogenation have been analyzed using concepts useful under slurry reaction conditions. The recycling efficiencies of the catalysts and product analysis to establish selectivities have been assessed. © 1992 John Wiley & Sons, Inc.     

Nickel Reinforced Catalysts Over a Heat-Exchanging Surface for Benzene Hydrogenation

X-ray technique, mercury porosimetry and electron microscopy were used to study the regularities of formation of porous metallic nickel-aluminium supports reinforced with a steel grid and distributed over a heat-exchanging surface, and of nickel catalysts supported on them. Such catalysts are active in gas phase benzene hydrogenation and also possess high heat conductivity.     

Hydrogenation of nitroarenes on silica-supported copper catalyst

A 9% Cu/SiO₂ catalyst prepared by the deposition– precipitation technique was active in the hydrogenation of substituted nitrobenzenes at 170 °C and 13 atm H₂ in a batch reactor. Nitro groups were selectively reduced to NH₂ groups except for the case of 5-bromo-1,3-dinitrobenzene. The selectivity of the overall process is somewhat suppressed by inevitable formation of azo compounds and traces of tars due to the reactions of the obtained amines with nitroso intermediates.     

聚钛氨烷—铂—锰双金属络合物催化的苯酚选择性氢化反应的研究

制备了二氧化硅负载的聚钛氨烷－铂－锰双金属络合物。结果表明，该催化剂在常温常压下对苯酚具有较高的催化氢化活性和选择性，在双金属络合物中，缺电子的锰离子作为Ｌｅｗｉｓ酸吸附点对环己酮分子中的羰基具有很强的吸附能力，可明显抑制环己酮在铀金属表面的吸附和进一步氢化，环己酮在终产物中的含量可达４９．２％，研究了Ｎ／Ｐｔ／Ｍｎ摩尔比，反应温度，时间和溶剂等对催化活性及选择性的影响，此催化剂有良好的稳定性，重     

Fe—Co双金属催化剂对纳米碳管规模化生产的影响

在C2H2和N2的氛围下,以Fe－Co双金属氧化物为催化剂,利用催化裂解法大量制备了多壁纳米碳管,实验结果表明,以Fe－Co双金属氧化物为催化剂制备纳米碳管的产量明显高于Fe或Co单独存在时所得的纳米碳管的产量,且Fe摩尔分数为0.2时效果最佳;同时发现,在制备的产品中存在很多螺旋形的纳米碳管,此方法工艺简单,有利于纳米碳管的规模化、大批量生产,为纳米碳管的深入研究及广泛应用打下了基础。     

水溶性双金属催化剂在硝基化合物加氢反应中的协同效应

采用水溶性催化剂在两相体系下进行的催化反应既保持了均相催化剂的优点，又可通过简单的相分离达到使产物与催化剂分离的目的［’1．对于水溶性催化剂在两相体系中催化加氢反应，文献中大多采用水溶性铐一瞬、铱一脚和钉一碟络合物为催化剂对a、“不饱和醛、酮、酸等化合物的选择加氢进行考察［’‘．然而对水溶性把一脚络合物催化加氢反应性能研究的报道甚少［‘j．在多相催化中，双（或多）金属的协同效应是常见的现象，但在均相及高分子负载的催化体系中双（或多）金属的协同效应的报道较少［‘］．我们曾报道了高分子负载的Pd／RU双…