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  • 1
    Electronic Resource
    Electronic Resource
    The stability of crude oil residues and factors affecting their decomposition during mild thermal treatment (1988)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 11 (1988), S. 89-94 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A number of topped crude oil residues were subjected to mild thermal cracking in the temperature range between 613 and 673K at N2 pressure of one atmosphere. It was found that the thermal stability of the six topped crude oils decreased in the order Brent 〈 Piper 〈 Auk 〈 Saudi Arabian 〈 Romashkinskaya 〈 Tia Juana Pesado. This was measured in terms of light end production (C1-C5 hydrocarbons). The asphaltene, sulphur and metal (nickel and vanadium) contents were also determined. The production of light ends, exemplified by methane, was found to be related to the metal asphaltene content of the crude oils, but the sulphur content exerted a moderating influence upon the extent of cracking. Hence, metal asphaltenes, probably as metal porphyrins, catalyse cracking but the presence of sulphur reduces that catalytic activity and can inhibit cracking. If cracking of long chain hydrocarbons is to be minimized, metal asphaltenes should be removed (preferably) or reduced in concentration or poisoned, in order to decrease their catalytic activity.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270110113
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  • 2
    Electronic Resource
    Electronic Resource
    The cocurrent downflow contactor (CDC) as a fixed bed and slurry reactor for catalytic hydrogenation (1995)
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 64 (1995), S. 55-65 
    Details
    ISSN: 0268-2575
    Keywords: catlytic hydrogenation ; three-phase reactors ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Cocurrent Downflow Contactor (CDC) has been studied as a three phase reactor and in addition, chemically enhanced mass transfer studies have confirmed the very high gas hold-up values previously indicated by photographic methods (εg = 0·5-0·6). Mass transfer measurements for the O2/H2O system have shown that volumetric mass transfer coefficients (kL a) are in the range 0·25-0·3 s-1 for unpacked and packed CDC reactors, while Co2+ ion-catalysed sulphite oxidation exhibited enhanced (kL a) are in the range 0·25-0·3 s-1 for unpacked and packed CDC reactors, while Co2+ ion-catalysed sulphite oxidation enhibited enhanced (kLa) values of 0·55 s-1 with interfacial areas in the range of 1000-6000 m2 m-3. A model first order reaction, the palladium-catlysed hydrogenation of itaconic acid, was examined both in a small stirred batch reactor and in the CDC. Low degrees of mass tranfer resistances were observed (both gas-liquid and liquid-solid) especially in the case of the CDC when used as a slurry and fixed bed reactor, with liquid-solid mass transfer resistances being the the range 1-10%. This was confirmed by energy of activation measurements in the range 30-45 kJ mol-1. The CDC was used in slurry and fixed bed form for the respective hydrogenation of the triglycerides, rapeseed and soyabean oils. The reaction was predominantly surface reaction rate controlled with energies of activation in the range 47-58 kJ mol-1, using palladium and nickel catlysts. Reaction selectivities were high, especially in respect of linolenate removal and the fixed bed CDC was slightly superior to the slurry reactor.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jctb.280640110
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  • 3
    Electronic Resource
    Electronic Resource
    Studies on the hydrogenation of cinnamaldehyde over Pd/C catalysts Presented in part at Clean Tech ’96, London, 19-21 June 1996. (1998)
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 72 (1998), S. 264-272 
    Details
    ISSN: 0268-2575
    Keywords: cinnamaldehyde ; selective hydrogenation ; promoter ; solvent effect ; mass transfer ; palladium catalyst ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The hydrogenation of cinnamaldehyde was investigated using a 5% Pd/C catalyst in a 250 cm3 stirred tank reactor and 500 cm3 autoclave. The experiments were carried out at 273-343 K and 0·1-1·1 MPa. Non-polar solvents, e.g. toluene, decane, methylcyclohexane, decalin, ether and heptane, and polar solvents such as methanol, ethanol, propan-1-o1, propan-2-ol, butan-1-ol and butan-2-ol were used to study the selectivity with respect to hydrocinnamaldehyde formation, the reaction kinetics and mass transfer. The additives, such as potassium acetate, ferrous chloride, ferrous sulphate and quinoline were incorporated into the catalyst in order to improve the catalyst selectivity, which was observed especially in the case of potassium acetate. © 1998 SCI
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Catalysis by intermetallic compounds III. The hydrogenation of buta-1,3-diene catalysed by cePd3-xAux alloys (1994)
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 60 (1994), S. 347-351 
    Details
    ISSN: 0268-2575
    Keywords: catalytic hydrogenation ; intermetallics ; buta-1,3-diene ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The intermetallic alloy series CePd3-x Aux (0 ≤ x ≤ 1) has been prepared from its constituent elements by carbon arc melting and employed as catalysts for the hydrogenation of buta-1,3-diene at 1 bar (101·5 kPa) total pressure in the temperature range 50-120°C. Selectivities for butene formation and initial butene distributions were very similar to those measured for CePd3 and Pd-rich CePd3-x Pdx alloys. Activity measurements showed that CePd2Au, was about three times more active than CePd3 despite having a surface which was shown by Auger electron spectroscopy (AES) to be deficient in Pd compared with the bulk and also compared with CePd3. Although a relationship appears to exist between catalyst activity and bulk electronic properties it can be only fortuitous and the surface electronic structure must be the important factor especially in view of the palladium-deficient surface.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jctb.280600403
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  • 5
    Electronic Resource
    Electronic Resource
    Catalytic hydrogenation of CO over the doped perovskite oxide YBa2Cu3O7-x catalysts (1998)
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 73 (1998), S. 389-397 
    Details
    ISSN: 0268-2575
    Keywords: characterization of doped perovskite oxide ; doped perovskite catalyst ; hydrogenation of carbon monoxide ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Perovskite oxide structured YBa2Cu3O7-x(YBCO) has been first prepared by carbonate precipitation and then modified with palladium or ruthenium by impregnation on the perovskite oxide, while cobalt was co-precipitated simultaneously in the same pH range with perovskite oxide. After characterization the catalysts were used in the temperature range 300-450°C, in the pressure range 1-9 atmospheres and for H2/CO ratios in the range 1-4 in a differential plug flow reactor for the hydrogenation of carbon monoxide to give hydrocarbons. The perovskite oxide (YBCO) 20% (w/w) and doped 2% (w/w) cobalt oxide catalyst were prepared by the wet chemical method from their nitrate solutions and oxidized at 950°C. Perovskite oxide (Dursun, G. & Winterbottom, J. M., J. Chem. Technol Biotechnol. 63 (1995) 113-16) was also doped with palladium and ruthenium metal by impregnation followed by oxidation at 250°C. The catalysts prepared were characterized by using TemperatureProgrammed Reduction (TPR) to observe the reduction temperature and also to measure total and metal surface area. The modified perovskite oxide on alumina, ruthenium- and cobalt-doped catalysts, has been shown to give a better conversion and also selectivity towards saturated hydrocarbons compared with palladium-doped catalyst. The temperature effect of these catalysts is more consistent, giving a steady increase of conversion with increasing temperature. Although increase of pressure increases the conversion, it causes very little change in product distribution. The activation energy of palladium- and ruthenium-doped, and cobalt co-precipitated catalysts for the reaction has been measured to be 55 kJ mol-1, 75 kJ mol-1 and 50 kJ mol-1 respectively. A general rate equation of the form r=k[H2]m[CO]n has been observed and found to be applicable at the pressures and temperatures used for the catalytic system studied and found to be m≌1·0 for palladium-doped, m≌1·2 for ruthenium-doped and m≌0·95 for cobalt co-precipitated catalysts as n becomes zero or negligibly less than zero. The mechanism of reaction to produce hydrocarbons from syngas has been deduced from the results. It appeared that the carbon monoxide insertion mechanism has been more evident for palladium-doped catalysts whereas the carbide mechanism plays the main role for the ruthenium-doped and cobalt co-precipitated catalysts. © 1998 Society of Chemical Industry
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    The cocurrent downflow contactor-a novel reactor for gas-liquid-solid catalysed reactions (1994)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 17 (1994), S. 307-312 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Cocurrent Downflow Contactor (CDC) has been developed as a mass transfer and reactor device, with and without addition of tangential (swirl) flow, giving gas hold-up (Eg) values of 0.5-0.75, interfacial areas in the range 1000-6000 m2m-3 liquid and kLa values in the range of 0.15-1.55 s-1 for absorption using the O2/H2O system. It has been studied as a catalytic slurry reactor for the hydrogenation of (i) itaconic acid and (ii) triglycerides catalysed by Pd and Ni catalysts. The reactions were observed to be largely surface-reaction rate controlled, due to the very efficient mass transfer (kLa up to 11.75 s-1 under reaction conditions) and application of swirl flow-enhanced reaction rates. The CDC has recently been found to be capable of operating as a fixed bed reactor, thus eliminating a downstream catalyst separation problem (therefore more cost effective), and is superior in its mass transfer characteristics to other known devices. Scale-up can be undertaken without loss of performance efficiency.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270170504
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  • 7
    Electronic Resource
    Electronic Resource
    Catalysis by intermetallic compounds I. A comparison of the catalytic behaviour of CePd3, ZrPd3 and Pd sponge for buta-1,3-diene hydrogenation and but-1-ene hydroisomerisation (1994)
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 60 (1994), S. 305-315 
    Details
    ISSN: 0268-2575
    Keywords: hydrogenation ; catalysts ; intermetallics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The hydrogenation of buta-1,3-diene and more briefly, the hydroisomerisation of but-1-ene catalysed by powdered CePd3, ZrPd3 and Pd sponge has been studied in a fixed bed continuous flow microreactor at 1 bar (101·5 k Pa) total pressure and in the temperature range 45-225°C. The two intermetallics (CePd3, ZrPd3) exhibited greater selectivity for butene formation than palladium, especially at high buta-1,3-diene conversions. The superior selectivity of the intermetallics was demonstrated further under the more demanding conditions, whereby but-1-ene was added to the feed buta-1,3-diene in the ratio C4H8/C4H6 = 24. The kinetics and apparent energies of activation were determined for the hydrogenation and isomerisation reactions. In the case of buta-1,3-diene hydrogenation, the kinetics suggest that for Pd sponge, hydrogen and buta-1,3-diene adsorb on similar sites, whereas in the case of the intermetallics different sites may be involved for hydrogen and buta-1,3-diene adsorption, which may result from palladium - metal oxide interactions. In the case of but-1-ene isomerisation, double bond migration appears to occur via addition-abstraction mechanisms on all three catalysts but in the case of the intermetallics hydrogenation and isomerisation involve different rate determining steps.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jctb.280600312
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  • 8
    Electronic Resource
    Electronic Resource
    Catalysis by intermetallic compounds II. The behaviour of the pseudobinary alloy systems CeRh3-x Pdx and ZrRh3-xPdx for buta-1,3-diene hydrogenation (1994)
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 60 (1994), S. 337-345 
    Details
    ISSN: 0268-2575
    Keywords: catalysis ; intermetallics ; diene hydrogenation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The hydrogenation of buta-1,3-diene in the temperature range 45-110°C at 1 bar (101·5 kPa) total pressure has been studied using the pseudo-binary alloy systems MRh3-x Pdx (M = Ce, Zr; 0 ≤ x ≤ 3) as catalysts. Characterisation studies show that surface and bulk Rh/Pd ratios are very similar but the surfaces were enriched particularly in cerium, with strong indications of oxide formation. Similar conclusions can be drawn with respect to zirconium but to a smaller extent. Differencs in product distributions, particularly in butene distributions are discussed in terms of two mechanisms which can interpret differences between the Rh-rich system and the Pd-rich system in respect of cis/trans-but-2-ene ratios.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jctb.280600402
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