Alternating copolymerization of ethylene with carbon monoxide on a supported palladium catalyst

The kinetics of the alternating copolymerization of ethylene with carbon monoxide has been studied in the presence of a palladium catalyst immolized on a polymer support in various media (methanol, toluene, heptane). In the case of hydrocarbon solvents, the activity of the supported catalyst is commensurable with the activity of a homogeneous system in methanol. The melting temperature of the resulting copolymer and its molecular mass depend on the solvent nature. The IR reflectance spectra of the active palladium complex and the ethylene-carbon monoxide copolymer are measured.     

Cooligomerization of carbon monoxide with cyclic olefins on supported palladium catalysts

The cooligomerization of CO with cyclic olefins, such as norbornene, 5-vinyl-2-norbornene, and dicyclopentadiene, in toluene in the presence of supported palladium catalysts containing 2,2’-bipyridine as a ligand is studied. It is shown that, during copolymerization, opening of the double bond in a ring occurs, while in the case of 5-vinyl-2-norbornene, vinyl bond C=C is not involved in the reaction. When ethylene is added to the reaction mixture, it does not participate in polymer-chain growth. The yield of the process is commensurable with the yield attained in the case of a homogeneous catalytic system, and the conversion of olefins is as high as 47%. The copolymers in the solid state occur in the form of spiroketal structures that, during dissolution, transform into ketone structures to different extents.     

Ruthenium phosphine complexes as catalysts of alternating copolymerization of ethylene and carbon monoxide

The properties of the ruthenium (II) phosphine complexes [Ru(dppe)₂(OTs)₂] and [Ru{PhP(CH₂CH₂CH₂PPh₂)₂}(OTs)₂] as catalysts of alternating copolymerization of ethylene and carbon monoxide were studied. The catalytic activity of these complexes in the absence of cocatalysis is low, but it is substantially increased in the presence of trifluoroacetic acid or 1,4-benzoquinone. These compounds are the first ruthenium complexes which catalyze copolymerization of ethylene and CO. Translated fromAkademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1119–1121, June, 2000.     

Terpolymerization of carbon monoxide, ethylene and styrene in the presence of supported palladium catalyst

Terpolymers of carbon monoxide with ethylene and styrene are synthesized in the presence of supported palladium catalyst in toluene and heptane medium for the first time. The terpolymerization rate exceeds the rate of carbon monoxide and ethylene copolymerization. The maximum terpolymer yield amounts 7.9 g per g of supported catalyst per hour or 321 g per g of palladium per hour. The influence of reaction temperature, pressure, 1.4-benzoquinone amount and co-monomers mole ratio on the yield and the composition of terpolymer have been studied. The NMR ¹³C data obtained testify to a distribution of ethylene and styrene units in terpolymer with the predominance of short blocks at equal contents of comonomer units.     

Effect of the nature of the support on the activity of palladium catalysts for oxidation of carbon monoxide

We have studied the catalytic activity of TiN_0.65, TiO₂, Al₂O₃, and palladium catalysts supported on them in the oxidation of carbon monoxide. The order in which the activities of the supported catalysts vary, Pd/Al₂O₃>Pd/TiO₂>Pd/TiN_0.65, is the reverse of the activity series for the supports. This is explained by the effect of transfer of electron density from the palladium to the substrate. Taras Shevchenko Kiev University, 64 Vladimirskaya ul., Kiev 252033, Ukraine, G. V. Kurdyumov Institute of the Physics of Metals, National Academy of Sciences of Ukraine, 36 Akademika Vernadskogo bul’var, Kiev-142 252642, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 34, No. 2, pp. 118–121, March–April, 1998.     

Influence of electronic state of rhodium in supported bimetallic catalysts on catalytic activity and selectivity in carbon monoxide hydrogenation reactions

Data on the mechanism and kinetics of the hydrogenation of carbon monoxide to saturated hydrocarbons and alcohols over supported bimetallic rhodium-containing catalysts are summarized and correlated. Rankings of specific catalytic activity and selectivity of Rh-M′/Al₂O₃ catalysts in relation to the chemical nature of M′, and hence in relation to the electronic state of the rhodium, are interpreted from a common point of view. On the basis of the interrelations that were found between the physicochemical and catalytic properties of these bimetallic systems, ground rules were formulated for selecting monotypical catalysts for the selective hydrogenation of carbon monoxide. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 4, pp. 199–218, July–August, 1997.     

Preferential oxidation of carbon monoxide on supported gold catalysts

Catalyst precursors containing 1% Au were synthesized by the impregnation of Al₂O₃ and CeO₂-Al₂O₃ supports with an aqueous solution of HAuCl₄ followed by drying, treatment with aqueous ammonia for the removal of chlorine residues, and final drying at 90°C. The oxidation of CO in gas containing ～1 vol % O₂, ～1 vol % CO, 60 vol % H₂, and the balance N₂ on the activated catalysts was studied. In a number of experiments, to 18 vol % water was added to the gas mixture. The activation of precursors by the initial gas was studied. It was found that the prolonged storage of a precursor in air made its activation difficult to perform. The 1%Au/Al₂O₃ catalyst activated by the gas mixture stably operated in the preferential oxidation of CO at room temperature with the occurrence of the reaction in the mode of catalyst surface ignition (a hot spot at the bed inlet) under a change in the feed gas flow rate by a factor of 3. The effect of the presence of additional CO₂ (to 39 vol %) on the oxidation of H₂ was studied: the catalyst activity decreased. Because the reaction of CO₂ reduction to CO did not occur, the effect can be due to the adsorption of CO₂ on gold. The effect of the addition of water vapor to the feed gas was studied with the use of 1%Au/CeO₂-Al₂O₃ as an example. The exo/endo effects related to the adsorption/desorption of water on the catalyst surface were detected upon steam supply and shutoff at a bed temperature of 100–150°C. It was noted that the addition of water vapor to a certain level favorably affected the selectivity (decreased the residual concentration of CO). The boundary water concentration, at which the effect became negative, depended on catalyst bed temperature. The higher was the bed temperature, the greater amount of water could be added until the manifestation of a negative effect.     

Copolymerization of carbon monoxide with ethylene in the presence of palladium phosphine complexes

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2181–2182, September, 1990.     

Alternating copolymerization of carbon monoxide and vinyl arenes using [N,N] bidentate palladium catalysts

The alternating copolymers of carbon monoxide (CO) and vinyl arene monomers, namely aromatic polyketones, are a family of attractive engineering plastic. In the catalytic synthesis of this kind of polymeric materials, [N,N] bidentate palladium catalysts represent the most successful catalytic systems. In this review, we introduce the present status of polyketone synthesis, with a focus on the aromatic polyketones made from vinyl arene and CO. We also address the palladium-catalyzed CO/vinyl arene alternating copolymerization mechanism. A variety of [N,N] bidentate palladium catalysts bearing 2,2′-bipyridine, 1,10-phenanthroline, α-diimine, and pyridine-imine ligands are surveyed for CO/vinyl arene copolymerization. The effects of vinyl arene monomer, counteranion, and solvent on copolymerization are also discussed. The copolymerization stereochemistry including chain end-control and enantiomorphic site control mechanisms is introduced. This review aims to promote the design of [N,N] bidentate palladium catalysts for CO/vinyl arene copolymerization for the development of high-performance aromatic polyketones.     

Radical-initiated copolymerization of carbon monoxide and ethylenimine in the presence of ethylene

The radical-initiated copolymerization of carbon monoxide and ethylenimine in the presence of ethylene was studied quantitatively. Carbon monoxide copolymerized with difficulty with ethylenimine with α,α′-azobisisobutyronitrile as radical initiator. In the presence of a small amount of ethylene, however, a remarkable amount of crystalline powdery poly-β-alanine (nylon 3) was obtained. The crystalline copolymer, which mainly consists of nylon 3 and contains a small amount of nylon 5 and other substances of higher homologous nylon structure, was obtained in the presence of a large amount of ethylene. This copolymer scarcely contained any ketone structure. Increasing the total feed of the equimolar mixture of the monomers increased the conversion of total monomer and nylon 3 content in the copolymer formed. The effect of increasing carbon monoxide content in this system was to increase both the conversion and the nylon 3 content in the copolymer. In both cases the copolymers were almost identical with nylon 3. Increased ethylene content in the monomer feed, however, increased the conversion and the content of higher homologous nylon structures, such as nylon 5 and 7. From the results it was concluded that ethylene was involved not only in the propagation reaction but also particularly in the initiation reaction.     

Synthesis of poly(carbon monoxide-co-ethylene-co-hexene) with supported palladium catalysts

The effect of conditions of carbon monoxide terpolymerization with ethylene and 1-hexene on the yield and composition of the terpolymer is investigated. The reaction is first carried out in toluene with the use of a supported palladium catalyst at different molar ratios of the olefins in the reaction solution. An increase in the hexene-to-ethylene molar ratio from 0.2 to 2.9 is accompanied by a decrease in the yield of the terpolymer by a factor of 2.8 and by a small increase in the molar fraction of hexene units in the terpolymer from 0.02 to 0.005?C0.06. The dependence of the amount of hexene units in the terpolymer on the olefin ratio differs from that obtained earlier in terpolymerization with propylene.     

负载金催化剂上CO氧化反应活性与金属氧化物载体中金属-氧结合能之间的关系

讨论了金属氧化物载体(MOx)对其负载纳米金催化剂(Au/MOx)上CO氧化反应的影响。采用典型的共沉淀法和沉积-沉淀法在完全相同的焙烧条件下制备了一系列MOx负载金催化剂,以CO氧化转化50%时的反应温度(T1/2)定量评价了MOx载体和Au/MOx催化剂的催化活性。进一步将MOx载体与相应Au/MOx催化剂的T1/2值之差对MOx载体的金属-氧结合能做曲线进行关联,发现二者呈明显的火山型关系。这一结果表明,采用具有适当金属-氧结合能(300–500 atom O)的MOx可大大提高沉积于其上的Au纳米颗粒的催化活性。     

An infrared study of species from ethylene,hydrogen and carbon monoxide adsorbed on palladium/silica catalysts

Two different procedures, A and B, for preparing palladium on silica catalysts give different infrared spectra, and to a large measure different surface species, from the adsorption of ethylene, hydrogen or carbon monoxide. A π-species (I) from ethylene is found on both catalyst preparations. On preparation A the other dominant species is probably the σ-diadsorbed species (II). On preparation B additional strong bands are tentatively interpreted in terms of a doubly π - bonded non-associatively adsorbed species (III). Only preparation B gives absorptions in the accessible region above 1300 cm^?1 which can be attributed to adsorbed hydrogen.

     

Influence of oxygen on catalytic properties of supported palladium catalysts in CO hydrogenation

It has been established that the addition of oxygen to synthesis gas has a positive effect of the activity and selectivity of supported palladium catalysts in methanol synthesis. The degree of the effect of oxygen depends on the chemical nature of the support and the conditions of catalysis, preceding the addition of oxygen to the reaction mixture. The probable causes for the influence of oxygen on the catalytic properties of palladium, supported on oxide supports, have been discussed.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 5, pp. 557–563, September–October, 1989.     

Effect of platinum and palladium additives on the surface state and catalytic activity of vanadium oxides in the oxidation of carbon monoxide

The Pt/V₂O₅ and Pd/V₂O₅ systems formed upon hydrogen reduction have catalytic activity in the oxidation of carbon monoxide exceeding the activity of Pt/Al₂O₃ and Pd/Al₂O₃. The transition from the low-activity to high-activity state on the Pt/V₂O₅ and Pd/V₂O₅ catalysts is characterized by temperature hysteresis and change in the kinetic equation. X-ray phase analysis (XPA), X-ray photoelectron spectroscopy (XPES), and X-ray spectral microanalysis were used to establish that prior reduction of V₂O₅ by hydrogen gives VO₂, V₆O₁₃, a-H _x V₂O₅, and b-H _x V₂O₅, which facilitates the formation of an active catalyst surface.     

A photoelectron spectroscopic study of the effect of particle size on the adsorbed state of carbon monoxide over supported palladium catalysts

UPS experiments on the adsorbed state of carbon monoxide over Pd/graphite model catalysts at 77–653 K have been performed. The CO-derived levels, (5σ + 1π) and 4σ, shift to higher with binding energy with decrease in the palladium particle size. Upon warming, the included levels on smaller Pd particles disappeared at much lower temperature than those on larger palladium particles.