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  • 1
    Electronic Resource
    Electronic Resource
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    International journal of chemical reactor engineering 4.2006, 1, A20 
    ISSN: 1542-6580
    Source: Berkeley Electronic Press Academic Journals
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: A two-stage, micro trickle-bed reactor (for studies of the effects of hydrogen sulfide on hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) of Athabasca bitumen-derived heavy gas oil over commercial NiMo/Al2O3 catalyst) has been simulated. One dimensional homogeneous mass transfer and a two dimensional heat transfer models were developed. The essence of the simulation was to enhance the understanding of the effects of hydrogen sulfide in the hydrotreating catalyst bed in a two-stage mode and also to predict the catalyst requirements for deep HDS and HDN processes. The kinetic model used in the simulation was based on the Langmuir-Hingshelwood method of rate determination. Adsorption constants were estimated by non-linear least squares method. The kinetic models were tested on independent set of data and found to predict the experimental data satisfactorily. The mass transfer simulation considered the effects of variables such as temperature and catalyst loading or liquid hourly space velocity (LHSV) on the trends of hydrogen sulfide generation and, sulfur and nitrogen conversions along the catalyst bed. The model was numerically solved using a fourth-order Runge-Kutta technique. The 1:3 wt/wt catalyst loading with inter-stage hydrogen sulfide removal was found to give the best HDN and HDS activities. Simulated results showed that doubling the present catalyst mass and operating at 653 °C with inter-stage hydrogen sulfide removal would give 6 and 179 ppm product sulfur and nitrogen, respectively. On the other hand, without hydrogen sulfide removal, only 49 and 302 ppm product sulfur and nitrogen could be attained, respectively. The heat transfer simulation compared temperature profiles in the two-stage process to a single stage process for the 1:3 wt/wt catalyst loading at 653 K. The temperature regime in Stage II was found to be more uniform unlike Stage I and the single stage. Crank Nicholson algorithm was used to solve the 2-D partial differential equations.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial and engineering chemistry 24 (1985), S. 465-468 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial & engineering chemistry research 31 (1992), S. 1449-1457 
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 31 (1986), S. 33-39 
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Differentialthermoanalytische und thermogravimetrische Daten von den synthetischen, unter Verwendung von Reisschalenasche als Siliciumdioxidquelle hergestellten Na-Zeolithen NaX, P c , HS, Z-21 und Analcim werden angegeben. Die DTA-Kurven zeigen anfangs einen der Dehydratisierung zuzuschreibenden endothermen Peak, dem bei 800–850° ein exothermer folgt, der auf den Zusammenbruch der Zeolithstruktur zurückzuführen ist. Nur im Falle von Z-21 tritt dieser exotherme Peak erst bei 900° auf. Die mittels DTA festgestellten strukturellen Veränderungen wurden röntgendiffraktometrisch verifiziert.
    Abstract: Резюме Дизельные топлива с р азличным содержание м вокса были исследова ны усовершенствованны м методом дифференци ального термического анализ а (ДТА), согласно стандартным тестовы м методам. Из ДТА-кривы х были измерены следующие п араметры: начало температурно го пика, максимум темп ературного пика и площадь пика. Ис следовано изменение этих парам етров в зависимости о т таких стандартных характе ристик дизельных топлив, как температу ры помутнения, застыв ания, закупорки фильтра на холоду и содержанием воска и найдена для ни х линейная корреляци я. Коэффициенты коррел яции были вычислены согласно установлен ным уравнениям, котор ые были также использованы д ля определения стандартных парамет ров других образцов д изельного топлива на основе их Д ТА-кривых. Пределы точности усо вершенствованного м етода ДТА найдены удовлетвори тельными.
    Notes: Abstract The differential thermal analysis and thermogravimetric data on the synthetic sodium zeolite species NaX, P c , HS, Z-21 and analcime, prepared with silica from rice-husk ash, are presented. The DTA curves revealed the presence of an initial endotherm for dehydration, followed by an exotherm at around 800 to 850°, representing the structural change and dissociation of all these species, except in the case of zeolite Z-21. For the latter, the initial endotherm was followed by an endotherm in the 900° region. The structural changes inferred on the basis of the DTA curves were confirmed by X-ray diffraction analysis.
    Type of Medium: Electronic Resource
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