Effect of the catalyst properties on the performance of a reverse flow reactor for methane combustion in lean mixtures

Hevia, Miguel A.G.; Ordóñez, Salvador; Dı́ez, Fernando V.

doi:10.1016/j.cej.2006.10.028

Cited by 18 publications

(26 citation statements)

References 38 publications

(57 reference statements)

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“…In the previous works, working with particulate fixed-bed reactors, we have observed that it is difficult to get stable operation working with not very active catalysts, such as metal oxides. 20 It is widely accepted that Pd-based noble metal catalysts are the most active for methane combustion, 2 but it is also well known that the most common supports, such as alumina or silica, can present thermal deactivation at the reaction temperatures. As a result, alternative supports were proposed, being zirconia-based ones the most promising because of their high thermal stability.…”

Section: Experimental Devicementioning

confidence: 99%

“…4 The reverse-flow reactor (RFR) is an alternative treatment for gaseous emissions containing hydrocarbons, based on the catalytic combustion. Its main advantage is the high thermal efficiency, which allows the autothermal operation (with low temperature feeding and without auxiliary fuel), even for emissions with very low hydrocarbon concentration (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) C of adiabatic temperature rise). 5 This technique also allows the treatment at low pressures, contrary to other innovative combustion techniques such as catalytic gas turbines or superadiabatic lean catalytic combustion.…”

Section: Introductionmentioning

confidence: 99%

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Monoliths as suitable catalysts for reverse‐flow combustors: Modeling and experimental validation

Marín¹,

Ordóñez²,

Dı́ez³

2010

AIChE Journal

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The performance of a bench-scale monolithic reverse-flow reactor (RFR) for methane combustion has been experimentally studied in this work. The influence of the different operating parameters, such as total gas flow rate (2.5 Â 10(STP)), methane inlet concentration (1000-5500 ppm), and switching time (300-900 s) on the reactor performance (outlet conversion and stability), has been experimentally determined. The validation of a heterogeneous one-dimensional dynamic model for monolithic beds with the obtained experimental data allows the use of this model to simulate the behavior of industrial-scale reactors. In the second part of the work, a systematic comparison of particulate and monolithic RFRs is carried out through design curves. Reactor length for 99% outlet conversion and the corresponding pressure drop is determined for varying operating conditions (surface velocity and inlet methane concentration).

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Section: Experimental Devicementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Monoliths as suitable catalysts for reverse‐flow combustors: Modeling and experimental validation

Marín¹,

Ordóñez²,

Dı́ez³

2010

AIChE Journal

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“…According to Hevia, et al [12], the one-dimensional model is sometimes accurate enough to describe the behavior of a reverse flow reactor at the laboratory scale. The radial profiles of temperature and concentration may be neglected because of the relatively small diameter of the reactor when compared to its length (very small radial Biot number).…”

Section: Mathematical Model In Reverse Flow Reactormentioning

confidence: 99%

“…In the mass balance for the solid phase (Eqs. (3) and (4)), the transient term was neglected, assuming a pseudo-steady state condition [12].…”

Section: Mathematical Model In Reverse Flow Reactormentioning

confidence: 99%

Homogeneity of Continuum Model of an Unsteady State Fixed Bed Reactor for Lean CH4 Oxidation

et al. 2014

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Abstract. In this study, the homogeneity of the continuum model of a fixed bed reactor operated in steady state and unsteady state systems for lean CH 4 oxidation is investigated. The steady-state fixed bed reactor system was operated under once-through direction, while the unsteady-state fixed bed reactor system was operated under flow reversal. The governing equations consisting of mass and energy balances were solved using the FlexPDE software package, version 6. The model selection is indispensable for an effective calculation since the simulation of a reverse flow reactor is time-consuming. The homogeneous and heterogeneous models for steady state operation gave similar conversions and temperature profiles, with a deviation of 0.12 to 0.14%. For reverse flow operation, the deviations of the continuum models of thepseudo-homogeneous and heterogeneous models were in the range of 25-65%. It is suggested that pseudo-homogeneous models can be applied to steady state systems, whereas heterogeneous models have to be applied to unsteady state systems.

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“…In the designing aspect, to the lean methane oxidation on dynamic conditions, research led to the determination of catalyst for improved performance of the dynamic reactor [3]- [5]. Research related with the reaction rate in dynamic conditions is still limited to the suitability of the use of models of the reaction mechanism.…”

Section: Introductionmentioning

confidence: 99%

Determination of Model Kinetics for Forced Unsteady State Operation of Catalytic CH₄Oxidation

Effendy

Wardhono

2016

MATEC Web of Conferences

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Abstract. The catalytic oxidation of methane for abating the emission vented from coal mine or natural gas transportation has been known as most reliable method. A reverse flow reactor operation has been widely used to oxidize this methane emission due to its capability for autothermal operation and heat production. The design of the reverse flow reactor requires a proper kinetic rate expression, which should be developed based on the operating condition. The kinetic rate obtained in the steady state condition cannot be applied for designing the reactor operated under unsteady state condition. Therefore, new approach to develop the dynamic kinetic rate expression becomes indispensable, particularly for periodic operation such as reverse flow reactor. This paper presents a novel method to develop the kinetic rate expression applied for unsteady state operation. The model reaction of the catalytic methane -Al 2 O 3 catalyst was used with kinetic parameter determined from laboratory experiments. The reactor used was a fixed bed, once-through operation, with a composition modulation in the feed gas. The switching time was set at 3 min by varying the feed concentration, feed flow rate, and reaction temperature. The concentrations of methane in the feed and product were measured and analysed using gas chromatography. The steady state condition for obtaining the kinetic rate expression was taken as a base case and as a way to judge its appropriateness to be applied for dynamic system. A Langmuir-Hinshelwood reaction rate model was developed. The time period during one cycle was divided into some segments, depending on the ratio of CH 4 /O 2 . The experimental result shows that there were kinetic regimes occur during one cycle: kinetic regime controlled by intrinsic surface reaction and kinetic regime controlled by external diffusion. The kinetic rate obtained in the steady state operation was not appropriate when applied for unsteady state operation. On the other hand, the kinetic rate expression obtained in the unsteady state operation fitted quite well. It was proven that in one cycle period the kinetic rate would always shift according to the ratio of CH 4 /O 2 .

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Effect of the catalyst properties on the performance of a reverse flow reactor for methane combustion in lean mixtures

Cited by 18 publications

References 38 publications

Monoliths as suitable catalysts for reverse‐flow combustors: Modeling and experimental validation

Monoliths as suitable catalysts for reverse‐flow combustors: Modeling and experimental validation

Homogeneity of Continuum Model of an Unsteady State Fixed Bed Reactor for Lean CH4 Oxidation

Determination of Model Kinetics for Forced Unsteady State Operation of Catalytic CH₄Oxidation

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Effect of the catalyst properties on the performance of a reverse flow reactor for methane combustion in lean mixtures

Cited by 18 publications

References 38 publications

Monoliths as suitable catalysts for reverse‐flow combustors: Modeling and experimental validation

Monoliths as suitable catalysts for reverse‐flow combustors: Modeling and experimental validation

Homogeneity of Continuum Model of an Unsteady State Fixed Bed Reactor for Lean CH4 Oxidation

Determination of Model Kinetics for Forced Unsteady State Operation of Catalytic CH4Oxidation

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Determination of Model Kinetics for Forced Unsteady State Operation of Catalytic CH₄Oxidation