Dynamic simulation of the CO2 methanation in a micro-structured fixed-bed reactor

Fixed-bed tubular reactors are used widely in chemical process industries, for example, selective hydrogenation of acetylene to ethylene in a naphtha cracking plant. A dynamic model is required when the effect of large fluctuations with time in influent stream (temperature, pressure, flow rate, and/or composition) on the reactor performance is to be investigated or automatically controlled. To predict approximate dynamic behavior of adiabatic selective acetylene hydrogenation reactors, we proposed a simple 1-dimensional model based on residence time distribution (RTD) effect to represent the cases of plug flow without/with axial dispersion. By modeling the nonideal flow regimes as a number of CSTRs (completely stirred tank reactors) in series to give not only equivalent RTD effect but also theoretically the same dynamic behavior in the case of isothermal first-order reactions, the obtained simple dynamic model consists of a set of nonlinear ODEs (ordinary differential equations), which can simultaneously be integrated using Excel VBA (Visual BASIC Applications) and 4th-order Runge-Kutta algorithm. The effects of reactor inlet temperature, axial dispersion, and flow rate deviation on the dynamic behavior of the system were investigated. In addition, comparison of the simulated effects of flow rate deviation was made between two industrial-size reactors.Keywords: Dynamic simulation, 1-D model, Adiabatic reactor, Acetylene hydrogenation, Fixed-bed reactor, Axial dispersion effect

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Contactless temperature measurements under static and dynamic reaction conditions in a single-pass fixed bed reactor for CO2 methanation

Journal of CO2 Utilization ◽

10.1016/j.jcou.2018.03.016 ◽

2018 ◽

Vol 25 ◽

pp. 158-169 ◽

Cited By ~ 5

Author(s):

Christian Schüler ◽

Moritz Wolf ◽

Olaf Hinrichsen

Keyword(s):

Fixed Bed ◽

Temperature Measurements ◽

Fixed Bed Reactor ◽

Dynamic Reaction ◽

Reaction Conditions ◽

Co2 Methanation ◽

Single Pass

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High Selectivity and Stability of Nickel Catalysts for CO2 Methanation: Support Effects

Catalysts ◽

10.3390/catal9010024 ◽

2018 ◽

Vol 9 (1) ◽

pp. 24 ◽

Cited By ~ 13

Author(s):

Jeremías Martínez ◽

Edgar Hernández ◽

Salvador Alfaro ◽

Ricardo López Medina ◽

Guadalupe Valverde Aguilar ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Sol Gel ◽

Fixed Bed ◽

Tetragonal Zirconia ◽

Nickel Catalysts ◽

Fixed Bed Reactor ◽

Molar Ratio ◽

Methane Formation ◽

Co2 Methanation ◽

X Ray

In this work, we present an investigation concerning the evaluation of the catalytic properties of Ni nanoparticles supported on ZrO2, SiO2, and MgAl2O4 for CO2 hydrogenation to methane. The supports were prepared by coprecipitation and sol-gel, while Ni was incorporated by impregnation (10–20 wt %). X-ray diffraction, nitrogen physisorption, temperature-programmed reduction, H2 pulse chemisorption, Raman spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy were the main characterization techniques employed. A laboratory fixed-bed reactor operated at atmospheric pressure, a temperature range of 350–500 °C, and a stoichiometric H2/CO2 molar ratio was used for catalyst evaluation. The most outstanding results were obtained with nickel catalysts supported on ZrO2 with CO2 conversions of close to 60%, and selectivity to methane formation was 100% on a dry basis, with high stability after 250 h of reaction time. The majority presence of tetragonal zirconia, as well as the strong Ni–ZrO2 interaction, were responsible for the high catalytic performance of the Ni/ZrO2 catalysts.

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Kinetics and Reactor Design Aspects of Selective Methanation of CO over a Ru/γ-Al2O3 Catalyst in CO2/H2 Rich Gases

Energies ◽

10.3390/en12030469 ◽

2019 ◽

Vol 12 (3) ◽

pp. 469 ◽

Cited By ~ 4

Author(s):

Panagiota Garbis ◽

Christoph Kern ◽

Andreas Jess

Keyword(s):

Polymer Electrolyte Membrane ◽

Fixed Bed ◽

Kinetic Equations ◽

Fixed Bed Reactor ◽

Water Gas Shift ◽

Co2 Methanation ◽

Co Methanation ◽

Electrolyte Membrane ◽

Selective Co Methanation ◽

Water Gas

Polymer electrolyte membrane fuel cells (PEMFCs) for household applications utilize H2 produced from natural gas via steam reforming followed by a water gas shift (WGS) unit. The H2-rich gas contains CO2 and small amounts of CO, which is a poison for PEMFCs. Today, CO is mostly converted by addition of O2 and preferential oxidation, but H2 is then also partly oxidized. An alternative is selective CO methanation, studied in this work. CO2 methanation is then a highly unwanted reaction, consuming additional H2. The kinetics of CO methanation in CO2/H2 rich gases were studied with a home-made Ru catalyst in a fixed bed reactor at 1 bar and 160–240 °C. Both CO and CO2 methanation can be well described by a Langmuir Hinshelwood approach. The rate of CO2 methanation is slow compared to CO. CO2 is directly converted to methane, i.e., the indirect route via reverse water gas shift (WGS) and subsequent CO methanation could be excluded by the experimental data and in combination with kinetic considerations. Pore diffusion may affect the CO conversion (>200 °C). The kinetic equations were applied to model an adiabatic fixed bed methanation reactor of a fuel cell appliance.

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Non-intrusive Time-POD for Optimal Control of a Fixed-Bed Reactor for CO2 Methanation

IFAC-PapersOnLine ◽

10.1016/j.ifacol.2021.08.229 ◽

2021 ◽

Vol 54 (3) ◽

pp. 122-127

Author(s):

Jens Bremer ◽

Jan Heiland ◽

Peter Benner ◽

Kai Sundmacher

Keyword(s):

Optimal Control ◽

Fixed Bed ◽

Fixed Bed Reactor ◽

Co2 Methanation

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HAZOP study of a fixed bed reactor for MTBE synthesis using a dynamic approach

Chemical Papers ◽

10.2478/s11696-007-0078-4 ◽

2008 ◽

Vol 62 (1) ◽

Cited By ~ 5

Author(s):

Juraj Labovský ◽

Zuzana Švandová ◽

Jozef Markoš ◽

L’udovít Jelemenský

Keyword(s):

Steady State ◽

Dynamic Simulation ◽

Fixed Bed ◽

Fixed Bed Reactor ◽

Inlet Temperature ◽

Potential Hazard ◽

Process Unit ◽

Feed Composition ◽

Tertiary Butyl ◽

Wide Range

AbstractA methodology for hazard investigation based on the integration of a mathematical model approach into hazard and operability analysis is presented. This approach is based on mathematical modelling of a process unit where both steady-state analysis, including analysis of the steady states multiplicity and stability, and dynamic simulation are used. The dynamic simulation serves for the investigation of consequences of failures of the main controlled parameters, i.e. inlet temperature, feed temperature and feed composition. This simulation is also very useful for the determination of the influence of failure duration on the reactor behaviour. On the other hand, the steady state simulation can predict the reactor behaviour in a wide range of failure magnitude and determine the parametric zones, where shifting from one steady state to another one may occur. A fixed bed reactor for methyl tertiary-butyl ether synthesis was chosen to identify potential hazard and operational problems of a real process.

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Thermodynamic Insight in Design of Methanation Reactor with Water Removal Considering Nexus between CO2 Conversion and Irreversibilities

Energies ◽

10.3390/en14237861 ◽

2021 ◽

Vol 14 (23) ◽

pp. 7861

Author(s):

Sayed Ebrahim Hashemi ◽

Kristian M. Lien ◽

Magne Hillestad ◽

Sondre K. Schnell ◽

Bjørn Austbø

Keyword(s):

Energy Use ◽

Homogeneous Model ◽

Fixed Bed ◽

Energy Systems ◽

Fixed Bed Reactor ◽

Water Removal ◽

Intermediate Water ◽

Co2 Conversion ◽

Co2 Methanation ◽

In Series

The inevitable nexus between energy use and CO2 emission necessitates the development of sustainable energy systems. The conversion of CO2 to CH4 using green H2 in power-to-gas applications in such energy systems has attracted much interest. In this context, the present study provides a thermodynamic insight into the effect of water removal on CO2 conversion and irreversibility within a CO2 methanation reactor. A fixed-bed reactor with one intermediate water removal point, representing two reactors in series, was modeled by a one-dimensional pseudo-homogeneous model. Pure CO2 or a mixture of CO2 and methane, representing a typical biogas mixture, were used as feed. For short reactors, both the maximum conversion and the largest irreversibilities were observed when the water removal point was located in the middle of the reactor. However, as the length of the reactor increased, the water removal point with the highest conversion was shifted towards the end of the reactor, accompanied by a smaller thermodynamic penalty. The largest irreversibilities in long reactors were obtained when water removal took place closer to the inlet of the reactor. The study discusses the potential benefit of partial water removal and reactant feeding for energy-efficient reactor design.

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