Search for: coke-formation
0.006 seconds

    Modeling of Pt-Sn/γ-Al2O3 deactivation in propane dehydrogenation with oxygenated additives

    , Article Korean Journal of Chemical Engineering ; Volume 30, Issue 1 , 2013 , Pages 55-61 ; 02561115 (ISSN) Samavati, A ; Fattahi, M ; Khorasheh, F ; Sharif University of Technology
    A reduction in catalyst activity with time-on-stream and formation of side products are the major problems associated with catalytic propane dehydrogenation. Coke formation on the catalyst surface is the most important cause for catalyst deactivation. Experiments have indicated that the presence of very small amounts of oxygenated additives such as water can reduce the amount of coke accumulated on the catalyst surface and enhance catalyst activity. Addition of water beyond an optimum level, however, would result in a loss of activity due to sintering of catalyst. Propane dehydrogenation over a Pt-Sn/γ-Al2O3 catalyst in the temperature range of 575 to 620 °C was investigated in the presence... 

    Simulation of Complex and Dry Reforming of Natural Gas to Produce Synthesis Gas And Their Technical and Economical Comparison

    , M.Sc. Thesis Sharif University of Technology Mollahassani Madjdabadi, mohammad Ali (Author) ; Kazemeini, Mohammad (Supervisor) ; Zamanian, Akbar (Supervisor) ; Baghalha, Morteza (Supervisor)
    In this study, two units of production of synthesis gas has been stimulated into 2 forms of natural gas complex (steam/Co2¬) reforming and dry reforming. They have been examined from technical and economical views. The product from this process is synthesis gas by the unit ratio of Hydrogen and Carbon Monoxide which is used in Arak petrochemical complex for producing 2EH. For producing this synthesis gas in 900C (reactor temperature) and 15 bar of total pressure , the ratio of feeding parts into reforming reactor for total input carbon (methane and other hydrocarbon) and Carbon dioxide gas and water vapor in representation ( [CH4 + other hydrocarbons : CO2 : H2O ] ) for complex reforming ... 

    Preparation, Evaluation and Investigation of NiO-MgO-SiO2 Catalyst Deactivation in Propane Reforming

    , Ph.D. Dissertation Sharif University of Technology Barzegari, Fatemeh (Author) ; Frahadi, Fathollah (Supervisor) ; Kazemeini, Mohammad (Supervisor) ; Rezaei, Mehran (Supervisor) ; Keshavarz, Ahmad Reza (Co-Supervisor)
    Synthesis gas (H2, CO) is widely used in chemical and petrochemical industries, utilized for methanol and ammonia production. Hydrogen is the main component of syngas which is considered as an appropriate alternative for fossil fuels. Catalytic steam reforming is one of the most common and economical pathway for syngas production. Light hydrocarbons such as propane which can easily be transported, stored and distributed, is a promising feed candidate for steam reforming. Catalyst deactivation along with low stability resulting from carbon formation and sintering is one of the main crucial problems in this process, leading to much research on the preparation of stable and coke resistant... 

    Coke formation possibility during production of reducing gas in large scale direct reduction plant

    , Article Ironmaking and Steelmaking ; Volume 34, Issue 2 , 2007 , Pages 115-123 ; 03019233 (ISSN) Sadri, M ; Vakhshouri, K ; Hashemi, M. M. Y. M ; Sharif University of Technology
    For the production of synthesis gas utilised in Midrex direct reduction plants, catalytic steam/CO2 hydrocarbon reforming in tubular reformer is the major process. Owing to the high heat input through the Midrex reformer tube wall, the endothermic nature of reforming reactions, low mass velocity of feed gas and large tube diameter, the catalyst bed is exposed to considerable axial and radial temperature gradients. These radial concentration and temperature gradients may create local areas with potential for carbon formation. To investigate this phenomenon, a rigorous two-dimensional model is developed for simulating the operation of a Midrex reformer which applies a dual catalyst loading... 

    A new approach to estimate parameters of a lumped kinetic model for hydroconversion of heavy residue

    , Article Fuel ; Vol. 134, issue , 2014 , pp. 343-353 Asaee, S. D. S ; Vafajoo, L ; Khorasheh, F ; Sharif University of Technology
    The effect of complexity level of a lumped kinetic model for heavy residue hydroconversion on estimated values of kinetic parameters was investigated in this work by imposing constraints for the parameter estimation algorithm of a complex six-lump kinetic model and deriving a simpler modified model from the complex model. Kinetic analysis was performed using available experimental data reported in the literature from a study on hydrocracking of Chinese Gudao vacuum residue in a bench-scale reactor using ammonium phosphomolybdate (APM) as a dispersed catalyst. The kinetic models also included coke formation reactions that had previously been ignored by most investigators due to the rather... 

    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... 

    Kinetic modeling of propane dehydrogenation over an industrial catalyst in the presence of oxygenated compounds

    , Article Reaction Kinetics, Mechanisms and Catalysis ; Volume 107, Issue 1 , 2012 , Pages 141-155 ; 18785190 (ISSN) Barghi, B ; Fattahi, M ; Khorasheh, F ; Sharif University of Technology
    Springer  2012
    The aim of this study was to develop an appropriate kinetic model for propane dehydrogenation (PDH) over an industrial Pt-Sn/γ-Al 2O 3 catalyst in the presence of small amounts of oxygenated compounds. Experimental data were obtained from a previous study where catalytic PDH was carried out in a laboratory scale reactor at atmospheric pressure in the temperature range of 575-620 °C in the presence of small amounts of water or methanol. The kinetics of the main dehydrogenation reaction was described and the effects of water and methanol on coke deposition and catalyst sintering were considered in a catalyst deactivation model to explain the observed optimum level in the amount of added... 

    Modeling catalyst deactivation in dehydrogenation of ethylbenzene to styrene

    , Article AIChE Annual Meeting, Conference Proceedings, 13 March 2011 through 17 March 2011 ; March , 2011 ; 9780816910670 (ISBN) Babaei, J ; Baghalha, M ; Sharif University of Technology
    Long-term deactivation of a commercial K-promoted Fe 2O 3 catalyst used in the dehydrogenation of ethylbenzene to styrene monomer was studied using 30 months of operating data of three industrial SM radial fixed bed adiabatic reactors. The Langmuir-Hinshelwood, Hougen-Watson model (LHHW) was used for reaction kinetics modeling. The kinetics of coking from ethylbenzene and styrene and the short-term deactivation function due to the quick coke formation were also considered in the model. The kinetics of long-term deactivation of the catalyst for ethylbenzene dehydrogenation to styrene between 550 and 630 °C were determined by allowing the effects of temperature and time on the catalyst... 

    The effect of oxygenate additives on the performance of PtSnγ - Al2O3 catalyst in the propane dehydrogenation process

    , Article Scientia Iranica ; Volume 18, Issue 6 , December , 2011 , Pages 1377-1383 ; 10263098 (ISSN) Fattahi, M ; Khorasheh, F ; Sahebdelfar, S ; Zangeneh, F. T ; Ganji, K ; Saeedizad, M ; Sharif University of Technology
    The effect of oxygenate modifiers on the performance of PtSnγAl 2O3 catalyst in dehydrogenation of propane was studied. Dehydrogenation reaction was carried out in a fixed-bed quartz reactor in the temperature range of 575620 °C. Two types of oxygenate modifiers, namely water and methanol, were added to the feed. The optimum amounts of water for reaction temperatures of 575, 600 and 620 °C were 84, 120 and 140 ppm, respectively. The optimum amounts of methanol for the same reaction temperatures were 9.9, 25 and 50 ppm, respectively. Any further addition of water or methanol beyond these optimum levels resulted in a loss in activity. The addition of water or methanol led to the formation of... 

    Preparation of mesoporous nanostructure NiO–MgO–SiO2 catalysts for syngas production via propane steam reforming

    , Article International Journal of Hydrogen Energy ; Volume 45, Issue 11 , 2020 , Pages 6604-6620 Barzegari, F ; Kazemeini, M ; Farhadi, F ; Rezaei, M ; Keshavarz, A ; Sharif University of Technology
    Elsevier Ltd  2020
    In this research, the propane steam reforming (PSR) as a promising alternative route over a mesoporous NiO–MgO–SiO2 catalyst to produce syngas (SG) was undertaken. This catalyst was prepared using a co-precipitation method followed by hydrothermal treatment. The influence of such catalyst preparation factors as the hydrothermal time and temperature, pH and calcination temperature on the physicochemical characteristics of the prepared samples were examined. Next, these materials were characterized through the BET-BJH, XRD, TPR, and FTIR analyses. The thermal stability of this catalyst was tested through the TGA and DTA techniques. Furthermore, the deactivation of the calcined catalysts at... 

    Thermodynamic analysis of application of organic Rankine cycle for heat recovery from an integrated DIR-MCFC with pre-reformer

    , Article Energy Conversion and Management ; Volume 67 , 2013 , Pages 197-207 ; 01968904 (ISSN) Vatani, A ; Khazaeli, A ; Roshandel, R ; Panjeshahi, M. H ; Sharif University of Technology
    This work deals with waste heat recovery from a proposed direct internal reforming molten carbonate fuel cell (DIR-MCFC), including an integrated pre-reformer. In this regard, some advantages are attainable over exhaust gas recycling. For instance, due to low temperature in the pre-reformer, carbon deposition and coke formation resulting from higher hydrocarbons can be eliminated. In this study, the cathode outlet provides the heat requirement for the pre-reforming process. After partial heat recovery from the cathode outlet, the stream still has a considerable energy and exergy (352.55 °C and 83.687 kW respectively). This study investigates waste heat recovery from the proposed DIR-MCFC,...