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  • 1
    Electronic Resource
    Electronic Resource
    Comparison of Alkali Metal Promoted MgO Catalysts for Their Surface Acidity/Basicity and Catalytic Activity/Selectivity in the Oxidative Coupling of Methane (1997)
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 68 (1997), S. 177-186 
    Details
    ISSN: 0268-2575
    Keywords: oxidative coupling of methane ; alkali metal promoted MgO catalysts ; surface acidity ; surface basicity ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Alkali metal (viz. Li, Na, K, Rb and Cs) promoted MgO catalysts (with an alkali metal/Mg ratio of 0·1) calcined at 750°C have been compared for their surface properties (viz. surface area, morphology, acidity and acid strength distribution, basicity and base strength distribution, etc.) and catalytic activity/selectivity in the oxidative coupling of methane (OCM) to C2-hydrocarbons at different temperatures (700-750°C), CH4/O2 ratios (4·0 and 8·0) in feed, and space velocities (10320 cm3 g-1 h-1). The surface and catalytic properties of alkali metal promoted MgO catalysts are found to be strongly influenced by the alkali metal promoter and the calcination temperature of the catalysts. A close relationship between the surface density of strong basic sites and the rate of C2-hydrocarbons formation per unit surface area of the catalysts has been observed. Among the catalysts calcined at 750°C, the best performance in the OCM is shown by Li-MgO (at 750°C). © 1997 SCI.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of support on surface basicity and catalytic activity in oxidative coupling of methane of Li-MgO deposited on different commercial catalyst carriers (1998)
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 72 (1998), S. 99-104 
    Details
    ISSN: 0268-2575
    Keywords: oxidative coupling of methane ; Li-MgO catalyst ; catalyst supports ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Deposition of Li-MgO catalyst on commonly used supports (containing SiO2, Al2O3, SiC, ZrO2, HfO2, etc.) causes a drastic reduction in the catalytic activity/selectivity for the oxidative methane coupling reaction and also in both the total and strong surface basicity. The decrease in the catalytic activity/selectivity and basicity is attributed to strong chemical interactions between the catalyst and support which occur during the high temperature (750°C) calcination/pretreatment of the catalyst. The chemical interactions result in catalytically less active binary and ternary metal oxides containing Li and/or Mg, thus deactivating the Li-MgO catalyst by consuming its active components. © 1998 SCI
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Simultaneous oxidative conversion and CO2 or steam reforming of methane to syngas over CoO-NiO-MgO catalyst (1998)
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 73 (1998), S. 345-350 
    Details
    ISSN: 0268-2575
    Keywords: CoO-NiO-MgO solid solution ; CO2 reforming of methane ; steam reforming of methane ; oxidative conversion of methane to syngas ; coupling of exothermic and endothermic reactions ; conversion of methane to CO and H2 ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: CO2 reforming, oxidative conversion and simultaneous oxidative conversion and CO2 or steam reforming of methane to syngas (CO and H2) over NiO-CoO-MgO (Co: Ni: Mg=0·5: 0·5:1·0) solid solution at 700-850°C and high space velocity (5·1×105 cm3 g-1 h-1 for oxidative conversion and 4·5×104 cm3 g-1 h-1 for oxy-steam or oxy-CO2 reforming) for different CH4/O2 (1·8-8·0) and CH4/CO2 or H2O (1·5-8·4) ratios have been thoroughly investigated. Because of the replacement of 50 mol% of the NiO by CoO in NiO-MgO (Ni/Mg=1·0), the performance of the catalyst in the methane to syngas conversion process is improved; the carbon formation on the catalyst is drastically reduced. The CoO-NiO-MgO catalyst shows high methane conversion activity (methane conversion 〉80%) and high selectivity for both CO and H2 in the oxy-CO2 reforming and oxy-steam reforming processes at ≥800°C. The oxy-steam or CO2 reforming process involves the coupling of the exothermic oxidative conversion and endothermic CO2 or steam reforming reactions, making these processes highly energy efficient and also safe to operate. These processes can be made thermoneutral or mildly exothermic or mildly endothermic by manipulating the process conditions (viz. temperature and/or CH4/O2 ratio in the feed). © 1998 Society of Chemistry Industry
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Poisoning of Pd-carbon catalysts by sulphur, chloro and heavy metal compounds in liquid phase hydrogenation of o-nitrophenol to o-aminophenol (1998)
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 73 (1998), S. 336-340 
    Details
    ISSN: 0268-2575
    Keywords: Pd-carbon catalyst ; liquid phase hydrogenation ; o-nitrophenol ; o-aminophenol ; catalyst poisoning ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The poisoning of Pd-carbon (4·1% Pd) catalysts by thiophene, dichloroethane, mercuric chloride and lead, zinc and mercuric acetates at different concentrations (0-5000 g m-3) in the liquid phase hydrogenation of o-nitrophenol to o-aminophenol (at 308 K and H2 pressure of 1508 kPa) in a three-phase stirred slurry reactor has been investigated. The hydrogenation activity of the catalyst is drastically reduced due to the presence of these poisons in the reaction mixture, even at a very low concentration of poison (20 g m-3). Among the poisons, mercuric acetate was found to be the most potent. © 1998 Society of Chemical Industry
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Surface properties of magnesium oxide obtained from basic magnesium carbonate: Influence of preparation conditions of magnesium carbonate (1995)
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 64 (1995), S. 407-413 
    Details
    ISSN: 0268-2575
    Keywords: basic magnesium carbonate ; magnesium oxide ; surface area ; surface basicity ; base strength distribution ; catalyst preparation (precipitation) ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Surface area, total basicity and base strength distribution (weak, strong and intermediate strength basic sites) of magnesium oxide obtained from basic magnesium carbonate (by its decomposition at 873 K) prepared by precipitation using different magnesium slats, precipitating agents and precipitating conditions (viz. concentration of magnesium salt. pH, temperature, mode of mixing and ageing period) have been thoroughly investigated. The total basicity and base strength distribution of the different magnesium oxide samples have been determined by step-wise thermal desorption of carbon dioxide from 323 to 1253 K. The chemical composition of basic magnesium carbonate and the surface properties and carbon dioxide content of magnesium oxide are found to be strongly influenced by the aforementioned preparation conditions of basic magnesium carbonate.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jctb.280640414
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  • 6
    Electronic Resource
    Electronic Resource
    Surface Properties of CaO (or BaO)-La2O3-MgO Catalysts and Their Performance in Oxidative Coupling of Methane (1997)
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 69 (1997), S. 63-69 
    Details
    ISSN: 0268-2575
    Keywords: oxidative coupling of methane ; CaO-La2O3-MgO ; BaO-La2O3-MgO ; surface acidity ; surface basicity ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: -CaO-La2O3-MgO and BaO-La2O3-MgO catalysts with different compositions have been studied for their bulk and surface properties (viz. crystal phases, surface area, acidity/acid strength distribution, basicity/base strength distribution, etc.) and catalytic activity/selectivity in the oxidative coupling of methane (OCM) at different processing conditions (reaction temperature, 700-850°C; CH4/O2 ratio in feed, 3·0, 4·0 and 8·0 and GHSV, 102000 and 204000 cm3 g-1 h-1). The surface acidity and strong basicity of La2O3-MgO are found to be increased due to the addition of a third component (CaO or BaO), depending upon its concentration in the catalyst. The addition of CaO or BaO to La2O3-MgO OCM catalyst causes a significant improvement in its performance. Both the CaO- and BaO-containing catalysts show a high activity and selectivity at 800°C, whereas, the activity and selectivity of BaO-containing catalysts at 700°C is lower than that of CaO-containing catalysts. © 1997 SCI.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxidative coupling of methane and oxidative dehydrogenation of ethane over strontium-promoted rare earth oxide catalysts (1998)
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 71 (1998), S. 167-172 
    Details
    ISSN: 0268-2575
    Keywords: oxidative coupling of methane ; oxidative dehydrogenation of ethane ; strontium-promoted rare earth oxide catalysts ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Sr-promoted rare earth (viz. La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Er and Yb) oxide catalysts (Sr/rare earth ratio = 0·1) are compared for their performance in the oxidative coupling of methane (OCM) to C2 hydrocarbons and oxidative dehydrogenation of ethane (ODE) to ethylene at different temperatures (700 and 800°C) and CH4 (or C2H6)/O2 ratios (4-8), at low contact time (space velocity = 102000 cm3 g-1 h-1). For the OCM process, the Sr-La2O3 catalyst shows the best performance. The Sr-promoted Nd2O3, Sm2O3, Eu2O3 and Er2O3 catalysts also show good methane conversion and selectivity for C2 hydrocarbons but the Sr-CeO2 and Sr-Dy2O3 catalysts show very poor performance. However, for the ODE process, the best performance is shown by the Sr-Nd2O3 catalyst. The other catalysts also show good ethane conversion and selectivity for ethylene; their performance is comparable at higher temperatures (≥800°C), but at lower temperature (700°C) the Sr-CeO2 and Sr-Pr6O11 catalysts show poor selectivity. © 1998 SCI.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Hydrothermal synthesis of gallosilicate (MFI) zeolite: Factors influencing crystallization kinetics and crystal size/growth (1998)
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 72 (1998), S. 176-182 
    Details
    ISSN: 0268-2575
    Keywords: hydrothermal synthesis of GaMFI zeolite ; crystallization kinetics ; crystal size ; crystal growth ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetics of the hydrothermal synthesis of gallosilicate (MFI) zeolite (under autogeneous pressure at 180°C) from a gel containing a source of silica (Na-trisilicate or fumed silica), gallium nitrate, templating agent (TPA-Br or TPA-OH), deionized water and sulfuric acid have been thoroughly investigated in order to understand the influence of various synthesis parameters (viz. gel composition, source of silica, template, method of gel preparation and pH of gel) on the crystallization kinetics and crystal size/growth of the zeolite. The zeolite samples were characterized for their crystallinity by XRD and crystal size and morphology by SEM. The crystallization rate and crystal size of the zeolite were found to be strongly influenced by the above synthesis parameters. © 1998 SCI
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxidative coupling of methane over Sm-promoted MgO: Influence of composition and preparation conditions (1997)
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 70 (1997), S. 325-330 
    Details
    ISSN: 0268-2575
    Keywords: oxidative coupling of methane ; Sm-promoted MgO ; activity/selectivity ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Influences of promoter concentration (or Sm/Mg ratio), precursor for MgO (viz. Mg-acetate, Mg-carbonate and Mg-hydroxide), calcination temperature of Sm-promoted MgO catalyst on the catalytic activity/selectivity in the oxidative coupling of methane (OCM) at different temperatures (650-850°C) and CH4/O2 ratios in feed (2·0-8·0) at a high space velocity (51600 cm3 g-1 h-1) have been investigated. The catalytic activity/selectivity of Sm-MgO catalysts in the OCM are found to be strongly influenced by the Sm/Mg ratio, precursor used for MgO and catalyst calcination temperature. The catalyst with Sm/Mg ratio of 0·11, prepared using magnesium acetate and magnesium carbonate as a source of MgO and calcining at 950°C, is found to be highly active and selective in the OCM process. A drastic reduction in catalytic activity/selectivity is observed when the catalyst is supported on low surface area porous catalyst carriers, indicating strong catalyst-support interactions. ©1997 SCI
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Surface basicity and acidity of alkaline earth-promoted La2O3 catalysts and their performance in oxidative coupling of methane (1998)
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 72 (1998), S. 125-130 
    Details
    ISSN: 0268-2575
    Keywords: oxidative coupling of methane ; Mg-promoted La2O3 ; Ca-promoted La2O3 ; Sr-promoted La2O3 ; Ba-promoted La2O3 ; surface acidity and basicity ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The catalytic activity and selectivity of La2O3 and alkaline earth (viz. Mg, Ca, Sr and Ba) promoted La2O3 (alkaline earth metal/La = 0·1) catalysts in the oxidative coupling of methane (OCM) to C2-hydrocarbons (at 800°C, CH4/O2 ratio = 4 or 8 and gas hourly space velocity = 102000 cm3 g-1 h-1) have been investigated. The acidity and basicity distributions on these catalysts are measured by the temperature programmed desorption (TPD) of NH3 and CO2 from 50°C to 950°C, respectively. Both the acidity and basicity of the La2O3 catalysts and their activity in the OCM are strongly influenced by the alkaline earth promoter and its concentration. Among the catalysts, Sr-promoted La2O3 (Sr/La = 0·1) is the most active and selective catalyst for the OCM process. This catalyst contains a larger number of strong basic sites and intermediate strength acid sites. © 1998 SCI
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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