IR spectral study of the effect of the reaction medium on the state of cobalt in a 10% Co/Al2O3 catalyst for aliphatic hydrocarbons from CO and H2

Diffuse scattering IR spectroscopy was used to study the 10% Co/Al₂O₃ catalyst for the synthesis of aliphatic hydrocarbons from CO and H₂. Ionic and metallic cobalt forms were identified in the IR spectroscopy. The adsorption of CO on these forms is accompanied by the appearance of linear and bridged complexes. After prolonged treatment of the catalyst by a CO + 2H₂ mixture, the ions and surface of metallic cobalt remain available for the adsorption of CO. Modification of the surface of metallic cobalt occurs upon the action of the reaction medium. This modification is seen in a bathochromic displacement of the IR bands for the adsorbed and linear CO forms. This displacement is accompanied by a reduction in the strength of the metal-carbon bond in the Co^o-CO complex.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2640–2643, November, 1990.     

Synthesis of hydrocarbons from CO and H2 in the presence of Co-Ru and Co-Pd catalysts containing aluminum oxide

The influence of additions of 0.1–0.5% Pd or Ru in a 10% Co/Al₂O₃ catalyst on its activity and selectivity in the synthesis of liquid hydrocarbons from CO and H₂ has been studied. It has been shown that the bimetallic systems make it possible to carry out the synthesis of hydrocarbons with a higher extent of conversion of CO and a higher yield of C ₅ ⁺ carbons in comparison with the original Co catalyst. Co-Ru catalysts exhibit exceptionally high selectivity (up to 80%) with respect to the formation of liquid products. It has been demonstrated by temperature-programmed reduction (TPR) that the introduction of Pd an dRu promotes the reduction of Co at lower temperatures and the formation of cobalt aluminates.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 60–64, January, 1992.     

Methane conversion by various metal, metal oxide and metal carbide catalysts

The progress in the field of methane conversion into higher hydrocarbons including aromatics and oxygenated compounds in the recent five years will be reviewed shortly, together with a new type of the methane conversion reaction with carbon monoxide at lower temperatures (600–700 K) by supported group VIII metal catalysts. Benzene was formed selectively among hydrocarbons in the CH₄–CO reaction over silica-supported Rh, Ru, Pd and Os catalysts under atmospheric pressure. Both CH₄ and CO were required for benzene formation, and only ethane and ethylene were formed besides benzene. The amount of C₃–C₅ hydrocarbons was negligible, which suggests that a completely different mechanism from the CO–H₂ reaction may be operating over these catalysts despite of the similarity in the reaction conditions with the CO–H₂ reaction. The mechanism of benzene formation was studied deeply by means of kinetical investigation as well as infrared spectroscopy and isotopic tracer method in connection with that of CO hydrogenation.     

Synthesis of hydrocarbons from CO and H2 on SiO2 supported iron-cobalt clusters

Bimetallic catalysts (Fe+Co)/SiO₂ were prepared by impregnation of SiO₂ with solutions of carbonyl clusters [FeCo₃(CO)₁₂][(C₂H₅)₄N], [Fe₃Co(CO)₁₃][(C₂H₅)₄N], HFeCo₃(CO)₁₂, [Fe₅CoC(CO)₁₆][(C₂H₅)₄N], and Co₂(CO)₈, Fe(CO)₅. At 20 °C, no reaction occurs between the compounds supported and the surface of the support. The stability of the supported clusters to thermodecarboxylation in a hydrogen atmosphere depends on their composition and is the highest for the catalyst [FeCo₃(CO)₁₂]^–/SiO₂. The catalytic properties of supported clusters in CO hydrogenation are mostly determined by the preactivation technique. The properties of Fe-Co catalysts which were pretreated at high temperatures, are in general similar to those of standard metal catalysts. Product distribution for the same samples prepared without preactivation does not fit the Schulz-Flory equation. The catalyst HFeCo₃(CO)₁₂/SiO₂ favors the formation ofC ₁–C₁₁ hydrocarbons in the temperature range of 468–473 K; the catalyst [Fe₃Co(CO)₁₃]^–/SiO₂ gives ethylene in the temperature range of 453–473 K.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1079–1085, June, 1993.     

Effect of preliminaey heating on the physicochemical properties of 10% Co/Al2O3 catalyst and its behavior in hydrocarbon synthesis from CO and H2

The effect of preliminary heating of 10% Co/Al₂O₃ in air at 20–600°C on its surface composition, reducibility, and adsorption properties has been studied by programmed thermal reduction (PTR), IR spectroscopy, and DTA. It has been shown that increasing the pretreatment temperature strengthens the interaction between cobalt and the carrier, resulting in an increase in the fraction of weakly bound adsorbed CO on the surface of the reduced catalyst. The activity of Co/Al₂O₃ has been studied in the Fischer-Tropsch synthesis and it has been proposed that the centers of weakly bound linear forms of CO adsorption are involved in the formation of C₂ ⁺ hydrocarbons from CO and H₂.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2444–2450, November, 1991.     

Physico-chemical properties of metallosilicate supports and cobalt catalysts based on them

The specific surface and the porosity of silicate supports (SiO₂, ZrO₂ · SiO₂, CoO · SiO₂) were determined. The adsorption properties and the reducing ability of the catalysts containing 10 % Co were studied. The spectra of the thermo-programmed desorption of CO below 250°C possess two signals typical of the adsorption of the catalyst on the oxide and metal phases. The formation of liquid hydrocarbons from CO and H₂ is assumed to proceed at surface bifunctional centers.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 668–672, April, 1993.     

Influence of preliminary treatment on activity and selectivity of Co-alumosilicate catalyst in hydrocarbon synthesis from CO and H2

The temperature and medium of preliminary treatment of 10% Co/SiO ₂·Al₂O₃ influence the activity and selectivity in hydrocarbon synthesis from CO and H₂. Treatment with NH₃ reduces the yield. Increasing the treatment temperature leads to a loss of activity and a change in the composition of hydrocarbons formed. The reason for deactivation is a change in the catalyst surface texture, its adsorptive properties, and the ability to be reduced.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1709–1713, August, 1990.     

Synthesis of hydrocarbons and alcohols from CO and H2 in the presence of CO-Rh catalysts

Catalysts of 4.5% Co- 0.1% Rh- 5:10% Cu/TiO ₂ display high activity in the synthesis from CO and H₂ of a mixture of hydrocarbons and alcohols at 250–300°C and pressures of 0.1–6.0 MPa; these catalysts are more selective than traditional Co catalysts with respect to alcohol formation.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1707–1709, August, 1990.     

Methanol Decomposition in a Water–Methanol Equimolar Mixture on a Nickel-Promoted Copper–Zinc–Cement Catalyst

Methanol decomposition in a water–methanol equimolar mixture is studied in the presence of a nickel-promoted copper–zinc–cement catalyst. Methanol decomposition at 200–300°C on the oxide and reduced forms of the catalyst yields a gas with an H₂/CO ratio close to two. The use of an equimolar CH₃OH–H₂O mixture under analogous conditions enables obtaining gaseous products with a hydrogen concentration up to 75 vol %.     

Infrared spectroscopy study of adsorption and coadsorption of carbon monoxide and hydrogen on Ru/Al203

IR spectroscopy was used to study CO adsorption and coadsorption with H₂ on 5% Ru/Al₂O₃. By variation of sample pretreatment, CO pressures, contact time and temperature several surface species were identified: mono– and multicarbonyl species formed with ruthenium in different oxidation state and on various sites of the catalyst surface. During CO and H₂ coadsorption and interaction, a new band at 2030 cm^–1 was registered. It was assigned to a 'hydrocarbonyl' species on the metal particles. Thermal stability of some CO species was studied. Most stable and least reactive species was found to be a multicarbonyl giving rise to bands at 1980 and 2060 cm^–1.     

Metal carbonyl catalysis of carbon monoxide and formate reactions

The water gas shift reaction (CO + H₂O = CO₂+ H₂) is catalyzed by aqueous metal carbonyl systems derived from simple mononuclear carbonyls such as Fe(CO)₅ and M(CO)₆ (M = Cr, Mo, and W) and bases in the 140–200 °C temperature range. The water gas shift reaction in a basic methanol-water solution containing Fe(CO)₅ is first order in [Fe(CO)₅], zero order in [CO], and essentially independent of base concentration and appears to involve an associative mechanism with a metallocarboxylate intermediate [(CO)₄Fe-CO₂H]^–. The water gas shift reactions using M(CO)₆ as catalyst precursors are first order in [M(CO)₆], inverse first order in [CO], and first order in [HCO₂ ^–] and appear to involve a dissociative mechanism with formatometallate intermediates [(CO)₅M-OCHO]^–.The Reppe hydroformylation of ethylene to produce propionaldehyde and 1-propanol in basic solutions containing Fe(CO)₅ occurs at 110–140 °C. This reaction is second order in [Fe(CO)₅], first order in [C₂H₄] up to a saturation pressure >1.5 MPa, and inhibited by [CO]. These experimental results suggest a mechanism where the rate-determining step involves a binuclear iron carbonyl intermediate. The substitution of Et₃N for NaOH as the base facilitates the reduction of propionaldehyde to 1-propanol but results in a slower rate for the overall reaction.The homogeneous photocatalytic decomposition of the formate ion to H₂ and CO₂ in the presence of Cr(CO)₆ appears to be closely related to the water gas shift reaction. The rate of H₂ production from the formate ion exhibits saturation kinetics in the formate ion and is inhibited by added pyridine. The infrared spectra of the catalyst solutions indicate an LCr(CO)₅ intermediate. Photolysis of the Cr(CO)₆/formate system in aqueous methanol in the presence of an aldehyde RCHO (R =n-heptyl,p-tolyl, andp-anisyl) results in catalytic hydrogenation of the aldehyde to the corresponding alcohol RCH₂OH by the formate ion. Detailed kinetic studies onp-tolualdehyde hydrogenation by this method indicates saturation kinetics in formate ion, autoinhibition by thep-tolualdehyde, and a threshold effect for Cr(CO)₆ at concentrations >0.004 mol L^–1. The presence of an aldehyde can interrupt the water gas shift catalytic cycle by interception of an HCr(CO)₅ ^– intermediate by the aldehyde.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1533–1539, September, 1994.     

Selective oxidation of CO in excess hydrogen on copper—cerium-containing catalysts

Selective oxidation of CO that is in mixtures enriched in H₂ was studied to investigate catalytic properties of the 0.5—80% CuO/Ce_0.7Zr_0.3O₂ system. The catalysts were prepared by the combined decomposition of copper, cerium, and zirconyl nitrates at 300 °C. The systems studied are active and stable under mild conditions of the process (80—160 °C) and at high space velocities (to 100000 h^–1) of the reaction mixture (2% CO, 1% O₂, 40—50% H₂). With an increase in the CuO content in the catalysts up to 20%, the degree of CO removal achieves 60% (120 °C and V = 35000 h^–1) and further does not change appreciably. The contribution of oxygen participation into CO oxidation is virtually independent of the copper concentration in the sample and ranges from 65 to 75%. The dependences of the Arrhenius equation parameters for CO and H₂ oxidation on the catalyst composition were determined, which makes it possible to calculate the conversion of reactants and selectivity of CO conversion under the specified conditions of the process. The addition of CO₂ and H₂O (12—15%) to the reaction mixture decreases the catalyst activity and simultaneously increases the selectivity of CO oxidation to 100%. It is shown by the TPR and X-ray diffraction methods that the combined decomposition of the starting Cu²⁺, Ce³⁺, and ZrO²⁺ nitrates produces solid solutions of oxides with a high content of CuO. The reductive pre-treatment of fresh samples of the studied catalysts results in the destruction of the solid solution and formation of highly dispersed Cu particles on the surface of Ce—Zr—O. These particles are active in CO oxidation.     

稀土金属盐促进的Mo-Co-K硫化物基催化剂用于合成气选择性制乙醇等低碳混合醇

采用超声法在非水溶剂介质中制备了稀土金属La盐等促进的硫化钼基催化剂,考察了其CO加氢选择性合成乙醇等低碳混合醇的催化性能.在3.0MPa,330℃和H2/CO(体积比)=2.0的反应条件下,La促进的催化剂表现出较Mo-Co-K硫化物基催化剂更高的催化活性,CO转化率和产物中乙醇的分布可分别达到17.2%和53.4%.扫描电镜、透射电镜、X射线衍射和光电子能谱等表征结果表明,稀土金属La盐的加入改善了Mo-Co-K硫化物基催化剂的外观形貌和电子结构,对提高催化活性和乙醇的分布起到重要的作用.     

Determination of Trace Impurities of H2, O2, Ar, N2, CO, CO2, and Hydrocarbons in High-Purity Monosilane by Gas Chromatography

Procedures were proposed for the determination of impurities of permanent gases (H₂, O₂, Ar, N₂, and CO), carbon dioxide, and hydrocarbons in high-purity monosilane by gas chromatography with detection limits of 1–3 ppm, 2 ppm, and 0.02–0.04 ppm, respectively, which are lower by 1–2 orders of magnitude than those published in the literature. The procedures make it possible to check the compliance of the purity of monosilane with present standards of microelectronics (TU 48-0513-057.0-91).     

Metallosilicates as supports of Co catalysts for the synthesis of liquid hydrocarbons from CO and H2

The effect of the nature of the silicate support on the activity and selectivity of 10%. Co/M silicate catalysts (where M=Cu, Zn, Ce, Ti, Hf, La, Al, Zr, Co, Mg) in the synthesis of hydrocarbons from CO and H₂ has been established. Co and Zr catalysts have been shown to provide the highest catalytic efficiency. The yield of liquid hydrocarbons in their presence exceeds 120 g m^–3.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 480–482, March, 1993.     

The oxidative stream reforming of methane to syngas in a thin tubular mixed-conducting membrane reactor

The oxidative stream reforming of methane (OSRM) to syngas, involving coupling of exothermic partial oxidation of methane (POM) and endothermic steam reforming of methane (SRM) processes, was studied in a thin tubular Al₂O₃-doped SrCo_0.8Fe_0.2O_3−δ membrane reactor packed with a Ni/γ-Al₂O₃ catalyst. The influences of the temperature and feed concentration on the membrane reaction performances were investigated in detail. The methane and steam conversions increased with increasing the temperature and high conversions were obtained in 850–900 °C. Different from the POM reaction, in the OSRM reaction the temperature and H₂O/CH₄ profoundly influenced the CO selectivity, H₂/CO and heat of the reaction. The CO selectivity increased with increasing the temperature or decreasing the H₂O/CH₄ ratio in the feed owing to the water gas shift reaction (H₂O + CO → CO₂ + H₂). And the H₂ selectivity based on methane conversion was always 100% because the net steam conversion was greater than zero. The H₂/CO in product could be tuned from 1.9 to 2.8 by adjusting the reaction temperature or H₂O/CH₄. Depending on the temperature or H₂O/CH₄, furthermore, the OSRM process could be performed auto-thermally with idealized reaction condition.     

Photoluminescence and FT-IR studies of the dissociative adsorption of H2 on the active ZrO2 catalyst and its role in the hydrogenation of CO

Photoluminescence and FT-IR studies of the adsorption of H₂ on ZrO₂ catalysts have been performdd to clarify the true natuee of active surface sites for the activaiion of H₂ in connection with the CO — H₂ reaction on the catalyst. The results indicate that the coordinatively unsaturated surface sites with different coordination numbers are generated on the surfaces by evacuation at temperatures higher than 600 K. These surface sites of lower coordination play a significant role in the reversible and irreversible dissociative adsorption of H₂ on the active ZrO₂ catalyst. The former seems to act as active hydrogen species for the CO — H₂ reaction to form branched hydrocarbons on the ZrO₂ catalyst.     

Methanol synthesis from CO2-H2 and from CO-H2 under atmospheric pressure over Pd and Cu catalysts

Under atmospheric pressure, methanol was produced from CO₂–H₂ over Pd/ZnO and from CO–H₂ over Pd/MgO catalyst. Similar support effects were observed over Cu catalysts.     

Carbonylation of olefins and alcohols with carbon monoxide in presence of catalyst system: BF3·H2O-liquid SO2

Conclusions The carbonylation of olefins, with branching at the double bond, and of tertiary alcohols with CO at –30° and atmospheric pressure, in the presence of the catalyst system: BF₃· H₂O-liquid SO₂, leads to the formation of mixtures of ,-dialkylalkanoic acids in 79–100°. yield.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2331–2334, October, 1977.     

Transformations of methyl ester of cyclohexanecarboxylic acid in the presence of Co-kieselguhr catalyst

Conclusions The methyl ester of cyclohexanecarboxylic acid in the presence of a precipitated Co-kieselguhr catalyst, at atmospheric pressure and temperatures of 350–450°, undergoes a number of transformations with the formation of mainly coke, benzene, toluene, cyclohexene, cyclohexane, and the gaseous products: CO₂, CO, CH₄, and H₂.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 870–871, April, 1971.