Thermodynamic analysis of a cyclic water gas-shift reactor (CWGSR) for hydrogen production

Heidebrecht, Peter; Sundmacher, Kai

doi:10.1016/j.ces.2009.08.011

Cited by 32 publications

(23 citation statements)

References 14 publications

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“…Consequently, the gas outlet only shows one composition change. Heidebrecht et al conducted a wave analysis for a cyclic water-gas shift reactor to study the behavior of reaction fronts [21]. the equilibrium composition of second reaction step from FeO to Fe is on the reactant side, i.e.…”

Section: Simulationmentioning

confidence: 99%

“…However, the reaction equilibria, which are crucial for the process were neither considered in that work [19] nor in an optimization study on the same process conducted by Logist et al [20]. In a follow-up work by Heidebrecht and Sundmacher [21], a thermodynamic approach was used for the same process to consider the effects of equilibrium limitations.…”

Section: Introductionmentioning

confidence: 99%

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Continuous production of CO from CO2 by RWGS chemical looping in fixed and fluidized bed reactors

Wenzel

Rihko‐Struckmann

Sundmacher

2018

Chemical Engineering Journal

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A fixed bed and a fluidized bed reactor design for the reverse water-gas shift chemical looping (RWGS-CL) process with 80 wt% Fe 2 O 3 − Ce 0.5 Zr 0.5 O 2 as oxygen storage material (OSM) are analyzed and compared by process simulation. The influence of gas inlet flow velocity on the the reaction regime is investigated and feasible regions of operation for continuous CO production are identified. Two performance indicators are defined for the process: 1) the average CO concentration and 2) the OSM utilization. Optimization problems are solved to maximize the performance indicators and analyze their mutual dependency. The results are discussed in a Pareto plot. It is shown that a fixed bed reactor design is advantageous for the RWGS-CL process because of more degrees of freedom for operation compared to the fluidized bed reactor design. A quasi-continuous production of CO is demonstrated for both reactor designs. A steady CO production with an average CO mole fraction of x CO = 0.64 and an OSM utilization of 83.9% can be realized with two fixed bed reactors. The fluidized bed reactor configuration can potentially minimize problems associated with material sintering but the average CO concentration and OSM utilization are significantly lower compared to the fixed bed due to the limited operational freedom. The results indicate the importance of dynamic simulations for understanding and exploiting the kinetic and thermodynamic aspects of inherently dynamic processes like RGWS-CL to maximize process performance.

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Section: Simulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Continuous production of CO from CO2 by RWGS chemical looping in fixed and fluidized bed reactors

Wenzel

Rihko‐Struckmann

Sundmacher

2018

Chemical Engineering Journal

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“…The mixture of carbon dioxide with methane (CO 2 /CH 4 = 1) significantly decreases the reduction of iron oxide [13,17,18], because the carbon dioxide also acts as oxidizing agent [13,19]. Both CO 2 in the feed and product CO 2 have an effect on the iron oxide reduction rate.…”

Section: Introductionmentioning

confidence: 98%

Hydrogen Production from Methane and Carbon Dioxide by Catalyst-Assisted Chemical Looping

2011

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Hydrogen can be produced from a mixture of CH 4 and CO 2 , based on chemical looping techniques. A physical mixture of a Ni/Al 2 O 3 catalyst and Fe 2 O 3 -CeZrO 2 as oxygen storage material is used in the chemical looping. During the reduction step, CH 4 /CO 2 is converted over Ni/ Al 2 O 3 into syngas, which then reduces iron oxide, giving CO 2 and H 2 O. During re-oxidation of the oxygen storage material by steam, H 2 with ppm levels of CO x is produced.

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“…For this reason, the effects of the reoxidation with steam were studied on reduced CF450 and CF750 samples. Moreover, this step provides an additional source for H 2 , in the so-called Steam-Iron process, derived from the Thermochemical Reforming approach [66][67][68][69][70]. Table 1 reports the main morphological features of both used (reduced and then reoxidized) CF450 and CF750 samples, after partial and complete reduction; the reduction step was carried out at two different temperatures, 300°C and 420°C.…”

Section: Bulk Characteristics Of Used (Reduced and Then Reoxidized) Cmentioning

confidence: 99%

On the Role of Morphology of CoFeO₄ Spinel in Methanol Anaerobic Oxidation

et al. 2012

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A CoFe 2 O 4 inverse spinel calcined at two different temperatures (450°C and 750°C), in order to modulate the growth of the crystallites, has been employed in methanol anaerobic oxidation. A correlation between physico-chemical properties and catalytic performances of the material has been pursued. The study of both surface and bulk properties has been carried out by means of different experimental techniques, among which X-ray diffraction (XRD), transmission electron microscopy (TEM), and in situ FTIR spectroscopy. The FTIR study of both bulk and surface spectral features reveals that the calcination step is responsible for the different type of exposed surface sites, and as a consequence, for the different catalytic behaviour. As the use of the spinel as catalyst for methanol transformation into H 2 necessarily implies a regeneration step with steam, in order to recover the oxidative capacity of the solid, both surface and bulk features of the reoxidized solids have been also studied. All results reveal that the two samples, originally morphologically quite different from one another, become very similar after just one redox cycle. Still, it has been also demonstrated that both used materials irreversibly modify their surface properties after the reduction/oxidation process.

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Thermodynamic analysis of a cyclic water gas-shift reactor (CWGSR) for hydrogen production

Cited by 32 publications

References 14 publications

Continuous production of CO from CO2 by RWGS chemical looping in fixed and fluidized bed reactors

Continuous production of CO from CO2 by RWGS chemical looping in fixed and fluidized bed reactors

Hydrogen Production from Methane and Carbon Dioxide by Catalyst-Assisted Chemical Looping

On the Role of Morphology of CoFeO₄ Spinel in Methanol Anaerobic Oxidation

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Thermodynamic analysis of a cyclic water gas-shift reactor (CWGSR) for hydrogen production

Cited by 32 publications

References 14 publications

Continuous production of CO from CO2 by RWGS chemical looping in fixed and fluidized bed reactors

Continuous production of CO from CO2 by RWGS chemical looping in fixed and fluidized bed reactors

Hydrogen Production from Methane and Carbon Dioxide by Catalyst-Assisted Chemical Looping

On the Role of Morphology of CoFeO4 Spinel in Methanol Anaerobic Oxidation

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On the Role of Morphology of CoFeO₄ Spinel in Methanol Anaerobic Oxidation