Catalyst deactivation by coke deposition: Approaches based on interactions of coke laydown with pore structure

Catalytic hydropyrolysis via the introduction of external hydrogen into catalytic pyrolysis process using hydrodeoxygenation catalysts is one of the major approaches of bio-oil upgrading. In this study, hydrodeoxygenation of acetone over Mo/HZSM-5 and HZSM-5 were investigated with focus on the influence of hydrogen pressure and catalyst deactivation. It is found that doped MoO3 could prolong the catalyst activity due to the suppression of coke formation. The influence of hydrogen pressure on catalytic HDO of acetone was further studied. Hydrogen pressure of 30 bar effectively prolonged catalyst activity while decreased the coke deposition over catalyst. The coke formation over the HZSM-5 and Mo/HZSM-5 under 30 bar hydrogen pressure decreased 66% and 83%, respectively, compared to that under atmospheric hydrogen pressure. Compared to the test with the HZSM-5, 35% higher yield of aliphatics and 60% lower coke were obtained from the Mo/HZSM-5 under 30 bar hydrogen pressure. Characterization of the spent Mo/HZSM-5 catalyst revealed the deactivation was mainly due to the carbon deposition blocking the micropores and Bronsted acid sites. Mo/HZSM-5 was proved to be potentially enhanced production of hydrocarbons.

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Inductive Heating Assisted-Catalytic Dehydrogenation of Tetralin as a Hydrogen Source for Downhole Catalytic Upgrading of Heavy Oil

Topics in Catalysis ◽

10.1007/s11244-019-01206-w ◽

2019 ◽

Vol 63 (3-4) ◽

pp. 268-280 ◽

Cited By ~ 4

Author(s):

Abarasi Hart ◽

Mohamed Adam ◽

John P. Robinson ◽

Sean P. Rigby ◽

Joseph Wood

Keyword(s):

Catalyst Deactivation ◽

Oil Quality ◽

Coke Formation ◽

Coke Deposition ◽

Conventional Heating ◽

Inductive Heating ◽

Catalytic Dehydrogenation ◽

Catalytic Upgrading ◽

Bed Temperature

AbstractThe Toe-to-Heel Air Injection (THAI) combined with a catalytic add-on (CAPRI, CATalytic upgrading PRocess In-situ) have been a subject of investigation since 2002. The major challenges have been catalyst deactivation due to coke deposition and low temperatures (~ 300 °C) of the mobilised hot oil flowing over the catalyst packing around the horizontal well. Tetralin has been used to suppress coke formation and also improve upgraded oil quality due to its hydrogen-donor capability. Herein, inductive heating (IH) incorporated to the horizontal production well is investigated as one means to resolve the temperature shortfall. The effect of reaction temperature on tetralin dehydrogenation and hydrogen evolution over NiMo/Al2O3 catalyst at 250–350 °C, catalyst-to-steel ball ratio (70% v/v), 18 bar and 0.75 h−1 was investigated. As temperature increased from 250 to 350 °C, tetralin conversion increased from 40 to 88% while liberated hydrogen increased from 0.36 to 0.88 mol based on 0.61 mol of tetralin used. The evolved hydrogen in situ hydrogenated unreacted tetralin to trans and cis-decalins with the selectivity of cis-decalin slightly more at 250 °C while at 300–350 °C trans-decalin showed superior selectivity. With IH the catalyst bed temperature was closer to the desired temperature (300 °C) with a mean of 299.2 °C while conventional heating is 294.3 °C. This thermal advantage and the nonthermal effect from electromagnetic field under IH improved catalytic activity and reaction rate, though coke formation increased.

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Core-Shell Structures in PdCu Catalysts and their Influence on the Prevention of Catalyst Deactivation by Altered Coke Deposition

Microscopy and Microanalysis ◽

10.1017/s1431927607081366 ◽

2007 ◽

Vol 13 (S03) ◽

Author(s):

M-M Pohl ◽

J Radnik ◽

V N Kalevaru ◽

A Martin

Keyword(s):

Catalyst Deactivation ◽

Shell Structures ◽

Coke Deposition ◽

Core Shell

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Integration of Thermal Treatment and Catalytic Transformation for Upgrading Biomass Pyrolysis Oil

International Journal of Chemical Reactor Engineering ◽

10.2202/1542-6580.1559 ◽

2007 ◽

Vol 5 (1) ◽

Cited By ~ 14

Author(s):

Beatriz Valle ◽

Ana Guadalupe Gayubo ◽

Alaitz Atutxa ◽

Ainhoa Alonso ◽

Javier Bilbao

Keyword(s):

Thermal Treatment ◽

Thermal Degradation ◽

Fluidized Bed ◽

Catalyst Deactivation ◽

Fluidized Bed Reactor ◽

Coke Deposition ◽

Catalytic Transformation ◽

Pyrolysis Oil ◽

Bio Oil ◽

Oil Components

The upgrading of bio-oil by catalytic transformation upon acidic catalysts is aimed at adapting its composition to that of conventional fuel, or at obtaining petrochemical raw materials, such as olefins and aromatics. A further alternative of growing interest for bio-oil upgrading is catalytic reforming for obtaining H2. The viability of any of these alternatives requires minimizing both the plugging problems that arise in the reactor when the bio-oil is fed and the rapid deactivation of the catalyst, which are associated with the thermal degradation of the lignocellulosic components. In this paper, the catalytic transformation of bio-oil (obtained by fast pyrolysis of vegetable biomass) in a fluidized bed reactor upon a Ni-HZSM-5 zeolite catalyst has been studied, and special attention has been paid to the design of the feed preheating zone. Operation in a single-unit (U-shaped steel tube) for the thermal treatment of the bio-oil (in the downward zone of the U-tube) and its catalytic transformation (in a fluidized bed located in the upward zone of the U-tube) has been compared with operation in a two-unit system, where both steps are carried out in separate units connected through a thermostated line (U-shaped tube for thermal treatment, followed by a fluidized bed reactor for catalytic transformation). It has been proven that a separate step of thermal treatment prior to the catalytic transformation notably improves the global process of bio-oil upgrading. Firstly, it contributes to minimizing coke deposition on the acidic catalyst, mainly the deposition of "thermal" coke (which is associated with the thermal degradation of the bio-oil components at high temperatures), leading to an important attenuation of catalyst deactivation. Secondly, the bio-oil components degraded in the thermal treatment can subsequently be subjected to another upgrading treatment (by steam activation or pyrolysis) in order to obtain a high quality char, which involves upgrading the entire bio-oil.

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

Progress in Reaction Kinetics and Mechanism ◽

10.3184/146867817x14954764850397 ◽

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.

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

International Journal of Chemical Reactor Engineering ◽

10.1515/ijcre-2016-0170 ◽

2017 ◽

Vol 15 (6) ◽

Cited By ~ 5

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.

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