Kinetic Modelling of Propane Dehydrogenation over a Pt–Sn/hierarchical SAPO-34 Zeolite Catalyst, Including Catalyst Deactivation

2017 ◽  
Vol 42 (4) ◽  
pp. 344-360
Author(s):  
Milad Komasi ◽  
Shohreh Fatemi ◽  
Seyed Hesam Mousavi
Keyword(s):  
Catalyst Deactivation ◽  
Kinetic Modelling ◽  
Coke Formation ◽  
Fixed Bed ◽  
Reaction Network ◽  
Normal Pressure ◽  
Fixed Bed Reactor ◽  
Propane Dehydrogenation ◽  
Coke Deposition ◽  
Formation Kinetic

Pt–Sn/hierarchical SAPO-34 was synthesised and kinetically modelled as an efficient and selective catalyst for propylene production through propane dehydrogenation. The kinetics of the reaction network were studied in an integral fixed-bed reactor at three temperatures of 550, 600 and 650 °C and weight hourly space velocities of 4 and 8 h−1 with a feed containing hydrogen and propane with relative molar ratios of 0.2, 0.5 and 0.8, at normal pressure. The experiments were performed in accordance with the full factorial experimental design. The kinetic models were constructed on the basis of different mechanisms and various deactivation models. The kinetics and deactivation parameters were simultaneously predicted and optimised using genetic algorithm optimisation. It was further proven that the Langmuir–Hinshelwood model can well predict propane dehydrogenation kinetics through lumping together all the possible dehydrogenation steps and also by assuming the surface reaction as the rate-determining step. A coke formation kinetic model has also shown appropriate results, confirming the experimental data by equal consideration of both monolayer and multilayer coke deposition kinetic orders and an exponential deactivation model.

scholarly journals Analysis and Model-Based Description of the Total Process of Periodic Deactivation and Regeneration of a VOx Catalyst for Selective Dehydrogenation of Propane

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1374
Author(s):  
Andreas Brune ◽  
Andreas Seidel-Morgenstern ◽  
Christof Hamel
Keyword(s):  
Catalyst Deactivation ◽  
Process Development ◽  
Coke Formation ◽  
Fixed Bed ◽  
Reaction Network ◽  
Fixed Bed Reactor ◽  
Side Reactions ◽  
Model Based ◽  
Total Process

This study intends to provide insights into various aspects related to the reaction kinetics of the VOx catalyzed propane dehydrogenation including main and side reactions and, in particular, catalyst deactivation and regeneration, which can be hardly found in combination in current literature. To kinetically describe the complex reaction network, a reduced model was fitted to lab scale experiments performed in a fixed bed reactor. Additionally, thermogravimetric analysis (TGA) was applied to investigate the coking behavior of the catalyst under defined conditions considering propane and propene as precursors for coke formation. Propene was identified to be the main coke precursor, which agrees with results of experiments using a segmented fixed bed reactor (FBR). A mechanistic multilayer-monolayer coke growth model was developed to mathematically describe the catalyst coking. Samples from long-term deactivation experiments in an FBR were used for regeneration experiments with oxygen to gasify the coke deposits in a TGA. A power law approach was able to describe the regeneration behavior well. Finally, the results of periodic experiments consisting of several deactivation and regeneration cycles verified the long-term stability of the catalyst and confirmed the validity of the derived and parametrized kinetic models for deactivation and regeneration, which will allow model-based process development and optimization.

Methane Dry Reforming over Ni-Co/Al2O3: Kinetic Modelling in a Catalytic Fixed-bed Reactor

2017 ◽  
Vol 15 (6) ◽  
Author(s):  
Yacine Benguerba ◽  
Mirella Virginie ◽  
Christine Dumas ◽  
Barbara Ernst
Keyword(s):  
Catalyst Deactivation ◽  
Kinetic Modelling ◽  
Fixed Bed ◽  
Dry Reforming ◽  
Fixed Bed Reactor ◽  
Coke Deposition ◽  
Dry Reforming Of Methane ◽  
Reactor Model ◽  
Reverse Water Gas Shift ◽  
Different Temperatures

Abstract The dry reforming of CH4 was investigated in a catalytic fixed-bed reactor to produce hydrogen at different temperatures over supported bimetallic Ni-Co catalyst. The reactor model for the dry reforming of methane used a set of kinetic models: The Zhang et al model for the dry reforming of methane (DRM); the Richardson-Paripatyadar model for the reverse water gas shift (RWGS); and the Snoeck et al kinetics for the coke-deposition and gasification reactions. The effect of temperatures on the performance of the reactor was studied. The amount of each species consumed or/and produced were calculated and compared with the experimental determined ones. It was showed that the set of kinetic model used in this work gave a good fit and accurately predict the experimental observed profiles from the fixed bed reactor. It was found that reaction-4 and reaction-5 could be neglected which could explain the fact that this catalyst coked rapidly comparatively with other catalyst. The use of large amount of Ni-Co will lead to carbon deposition and so to the catalyst deactivation.

scholarly journals Process Intensification of the Propane Dehydrogenation Considering Coke Formation, Catalyst Deactivation and Regeneration—Transient Modelling and Analysis of a Heat-Integrated Membrane Reactor

Catalysts ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1056
Author(s):  
Jan P. Walter ◽  
Andreas Brune ◽  
Andreas Seidel-Morgenstern ◽  
Christof Hamel
Keyword(s):  
Membrane Reactor ◽  
Inner Core ◽  
Catalyst Deactivation ◽  
Catalyst Activity ◽  
Coke Formation ◽  
Fixed Bed ◽  
Packed Bed ◽  
Membrane Reactors ◽  
Propane Dehydrogenation ◽  
Heat Integration

A heat-integrated packed-bed membrane reactor is studied based on detailed, transient 2D models for coupling oxidative and thermal propane dehydrogenation in one apparatus. The reactor is structured in two telescoped reaction zones to figure out the potential of mass and heat integration between the exothermic oxidative propane dehydrogenation (ODH) in the shell side, including membrane-assisted oxygen dosing and the endothermic, high selective thermal propane dehydrogenation (TDH) in the inner core. The developing complex concentration, temperature and velocity fields are studied, taking into account simultaneous coke growth corresponding with a loss of catalyst activity. Furthermore, the catalyst regeneration was included in the simulation in order to perform an analysis of a periodic operating system of deactivation and regeneration periods. The coupling of the two reaction chambers in a new type of membrane reactor offers potential at oxygen shortage and significantly improves the achievable propene yield in comparison with fixed bed and well-established membrane reactors in the distributor configuration without inner mass and heat integration. The methods developed allow an overall process optimization with respect to maximum spacetime yield as a function of production and regeneration times.

Effect of Shape and Modification over ZSM-5 Catalyst on Methanol to Gasoline

2014 ◽  
Vol 1008-1009 ◽  
pp. 295-299 ◽  
Author(s):  
Xiao Feng Gao ◽  
Chuan Min Ding ◽  
Wei Li Liu ◽  
Lin Feng Fan ◽  
Gang Song ◽  
...  
Keyword(s):  
Molecular Sieves ◽  
Coke Formation ◽  
Fixed Bed ◽  
Mesoporous Structure ◽  
Catalytic Performance ◽  
Carbon Accumulation ◽  
Fixed Bed Reactor ◽  
Coke Deposition ◽  
Methanol To Gasoline ◽  
Naoh Solution

Fixed bed reactor was used to explore the catalytic performance of ZSM-5 catalysts with the forms of flake and strip in methanol to gasoline (MTG) reaction. The catalyst samples were characterized by XRD, BET and SEM. The strip ZSM-5 catalyst was modified by 0.4 Molar NaOH solution, which was denoted by TZSM-5/AT. The results show that ZSM-5 molecular sieves could be effectively dispersed to prevent carbon accumulation when extruded with binder. So the coke deposition resistance capacity of strip ZSM-5 has significantly enhancement comparing with flake ZSM-5. Mesoporous structure in strip zeolites formed after NaOH treatment, which could prevent coke formation and further improve catalyst life. The conversion of methanol remains above 80% over 140 hours on alkali-modified strip ZSM-5 operating at atmospheric pressure, 380°C and weight hourly space velocities (WHSV) of 1.5 h-1.

scholarly journals Investigation of Isobutane Dehydrogenation on CrOx/MCM-41 Catalyst

2020 ◽  
Vol 39 (1) ◽  
pp. 109
Author(s):  
Zuhal Erol ◽  
Saliha Cetinyokus Kilicarslan ◽  
Meltem Dogan
Keyword(s):  
Atmospheric Pressure ◽  
Catalyst Deactivation ◽  
Catalyst Surface ◽  
Fixed Bed ◽  
Chromium Concentration ◽  
Fixed Bed Reactor ◽  
Coke Deposition ◽  
Catalyst Structure ◽  
Isobutane Dehydrogenation ◽  
Mcm 41

The syntheses of MCM-41 (Mobil Composition of Matter No. 41) supported chromium oxide cat-alysts at different chromium concentrations (4–10 % by mass) were carried out hydrothermally. The aim of this study was to determine the effect of chromium concentration in the catalyst structure on the chro-mate types and chromium oxidation states, as well as the activity of the catalyst in the isobutane dehydro-genation reaction. Inactive α-Cr2O3 crystals for isobutane dehydrogenation were shown to increase in the catalyst structure as the chromium loading increased. The highest amount of Cr6+ on the catalyst surface was detected in the catalyst (H4-MCM-41) with 4 % chromium by mass. Catalytic tests (T = 600 °C, P = atmospheric pressure, WHSV = 26 h–1) were performed under fixed bed reactor conditions. The high-est isobutane conversion (~60 %) and selectivity (~80 %) were observed on the H4-MCM-41 catalyst, which had the highest amount of Cr6+ and monochromate structures. Catalyst deactivation was not due to coke deposition but, rather, was caused by the formation of inactive α-Cr2O3 crystal structures.

Dimethyl Ether Conversion to Olefins over the SAPO-34/ZrO2 Catalysts: Effect of the ZrO2 Supporter

2011 ◽  
Vol 347-353 ◽  
pp. 3681-3684 ◽  
Author(s):  
Young Ho Kim ◽  
Su Gyung Lee ◽  
Byoung Kwan Yoo ◽  
Han Sol Je ◽  
Chu Sik Park
Keyword(s):  
Physicochemical Properties ◽  
Dimethyl Ether ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Coke Deposition ◽  
Light Olefins ◽  
Similar Activity ◽  
Dimethyl Ether Conversion ◽  
Zro2 Catalyst ◽  
Catalyst Lifetime

A SAPO-34 catalyst is well known to be one of the best catalysts for DME to olefins (DTO) reaction. Main products of the reaction were light olefins such as ethylene, propylene and butenes. However, the main problem is rapid deactivation of the SAPO-34 catalyst due to coke deposition during DTO reaction. In this study, various SAPO-34/ZrO2 catalysts added with ZrO2 were prepared for improving the lifetime and their physicochemical properties have been characterized by XRD and SEM. The DTO reaction over various SAPO-34/ZrO2 catalysts was carried out using a fixed bed reactor. All SAPO-34/ZrO2 catalysts showed similar activity and selectivity in the DTO reaction. The SAPO-34(9wt%)/ZrO2 catalyst was showed the best performance for the catalyst lifetime.

The Influence Of The Support On The Deactivation Behaviour of Pt-Sn Reforming Catalysts

2005 ◽  
Vol 3 (1) ◽  
Author(s):  
Ignacio Contreras ◽  
Gustavo Pérez ◽  
Tomás Viveros
Keyword(s):  
Active Sites ◽  
Catalyst Deactivation ◽  
Mixed Oxides ◽  
Kinetic Constant ◽  
Coke Formation ◽  
Formation Kinetic ◽  
Catalytic Behavior ◽  
Reforming Catalysts ◽  
Metal Support Interaction ◽  
S Model

The effect of Al2O3-ZrO2, Al2O3-TiO2 and Al2O3-La2O3 mixed oxides on the deactivation of bifunctional Pt-Sn/ Al2O3 reforming catalysts has been investigated. The n-heptane reforming at 500°C was used as a test reaction. Changes in the catalytic behavior due to differences of the acidity and the support-metal interaction were observed. Levenspiel´s and Beltramini´s deactivation models were developed assuming a series fouling for the carbonaceous deposits. Through the Beltramini’s model it was possible to distinguish the amount of acidity that participates in the deactivation processes. Both models successfully correlated with the experimental profiles of n-heptane activity decay. The following deactivation decreasing order, Al2O3-TiO2-1>Al2O3-ZrO2-25>Al2O3-TiO2-2> Al2O3>Al2O3-La2O3-10 was found with both deactivation models. A quasi-linear correlation between the deactivation order and the coke formation kinetic constant (Levenspiel’s parameters) was observed. The catalyst acidity and the n-heptane conversion were correlated with Beltramini’s model. It was found that a high acidity (12 X 10-17 acid sites/g cat.) or metal dispersion (83%) increases the catalyst deactivation and it is necessary to have a balance of active sites in order to have a catalyst working as a bifunctional catalyst. On the other hand, the auto-regeneration Beltramini’s parameter suggests that the lowest deactivation of the Pt-Sn/ Al2O3-La2O3-10 catalyst is attributed to the cleaning capacity of the active sites. It was observed that the highest deactivation (80-92%) of the platinum-tin catalysts supported in alumina-titania mixed oxides were a result of the strong metal-support interaction (SMSI) effect. The Pt-Sn/Al2O3-La2O3-10 showed the best catalytic behavior with high initial and residual conversions (70 and 48%, respectively) and low deactivation (17 %) at a 50-minute reaction time. Furthermore, in the Pt-Sn/Al2O3 catalyst, the benzene yield was 1%, while the Pt-Sn/Al2O3-La2O3-10 showed a total inhibition of benzene production yield at residual conversions.

scholarly journals Pt-Sn Supported on Beta Zeolite with Enhanced Activity and Stability for Propane Dehydrogenation

Catalysts ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 25
Author(s):  
Su-Un Lee ◽  
You-Jin Lee ◽  
Soo-Jin Kwon ◽  
Jeong-Rang Kim ◽  
Soon-Yong Jeong
Keyword(s):  
Catalytic Activity ◽  
Surface Area ◽  
High Surface ◽  
Coke Formation ◽  
Propane Dehydrogenation ◽  
Coke Deposition ◽  
Beta Zeolite ◽  
Lower Amount ◽  
Metal Catalyst ◽  
Beta Zeolites

With the growing global propylene demand, propane dehydrogenation (PDH) has attracted great attention for on-purpose propylene production. However, its industrial application is limited because catalysts suffer from rapid deactivation due to coke deposition and metal catalyst sintering. To enhance metal catalyst dispersion and coke resistance, Pt-based catalysts have been widely investigated with various porous supports. In particular, zeolite can benefit from large surface area and acid sites, which favors high metal dispersion and promoting catalytic activity. In this work, we investigated the PDH catalytic properties of Beta zeolites as a support for Pt-Sn based catalysts. In comparison with Pt-Sn supported over θ-Al2O3 and amorphous silica (Q6), Beta zeolite-supported Pt-Sn catalysts exhibited a different reaction trend, achieving the best propylene selectivity after a proper period of reaction time. The different PDH catalytic behavior over Beta zeolite-supported Pt-Sn catalysts has been attributed to their physicochemical properties and reaction mechanism. Although Pt-Sn catalyst supported over Beta zeolite with low acidity showed low Pt dispersion, it formed a relatively lower amount of coke on PDH reaction and maintained a high surface area and active Pt surfaces, resulting in enhanced stability for PDH reaction. This work can provide a better understanding of zeolite-supported Pt-Sn catalysts to improve PDH catalytic activity with high selectivity and low coke formation.

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