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    Modeling of coke formation and catalyst deactivation in propane dehydrogenation over a commercial Pt-Sn/γ-Al2O3 catalyst

    , Article Petroleum Science and Technology ; Volume 31, Issue 23 , 2013 , Pages 2451-2462 ; 10916466 (ISSN) Niknaddaf, S ; Soltani, M ; Farjoo, A ; Khorasheh, F ; Sharif University of Technology
    Propane dehydrogenation was carried over a commercial Pt-Sn/γ-Al 2O3 catalyst at atmospheric pressure and reaction temperatures of 580, 600, and 620°C and WHSV of 11 h-1 in an experimental tubular quartz reactor. Propane conversions were measured for catalyst time on stream of up to nine days. The amounts of coke deposited on the catalyst were measured after one, three, six, and nine days on stream using a thermogravimetric differential thermal analyzer (TG-DTA) for each reaction temperature. The coke formation kinetics was successfully described by a coke formation model based on a monolayer-multilayer mechanism. In addition, catalyst deactivation was presented by a time-dependant... 

    The effects of SiO 2 and K 2O on glass forming ability and structure of CaOTiO 2P 2O 5 glass system

    , Article Ceramics International ; Volume 38, Issue 4 , 2012 , Pages 3281-3290 ; 02728842 (ISSN) Ahmadi Mooghari, H. R ; Nemati, A ; Eftekhari Yekta, B ; Hamnabard, Z ; Sharif University of Technology
    The effects of SiO 2 and K 2O were investigated on the glass forming ability (GFA) and structural characteristics of CaOTiO 2P 2O 5 system. Differential thermal analyzer (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), FT-IR and 31P magic angle spinning NMR methods were applied for characterizations of the system. Unwanted crystallization in the initial three components base glass composition was observed by adding SiO 2 and crystalline phases such as TiP 2O 7, rutile (TiO 2) and cristobalite (SiO 2) were formed in it. The results showed that K 2O prevents crystallization of glasses and promotes the formation of glass. FT-IR and X-ray diffraction showed that the addition...