Influence of the microstructure on the catalytic properties of SOFC anodes under dry reforming of methane

Lanzini, Andrea; Guerra, Cosimo; Leone, Pierluigi; Santarelli, Massimo; Smeacetto, Federico; Fiorilli, Sonia Lucia; Gondolini, Angela; Mercadelli, Elisa; Sanson, Alessandra; Brandon, Nigel P.

doi:10.1016/j.matlet.2015.10.171

Cited by 18 publications

(11 citation statements)

References 14 publications

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“…It has been used for gas sensors, oxygen pumps, thermal barrier coatings for gas-turbines, as an electrolyte and in combination with Ni as an anode material for solid oxide fuel cells. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] In addition, hydrogenation, reforming and oxidative methane coupling activity have been reported for ZrO 2 materials. [18][19][20][21] Recent catalytic applications include acting as an efficient growth template for distinct carbon materials such as nanotubes or disordered graphite layers.…”

Section: Introductionmentioning

confidence: 99%

Surface Reactivity of YSZ, Y₂O₃, and ZrO₂toward CO, CO₂, and CH₄: A Comparative Discussion

et al. 2016

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The C1-surface chemistry of catalytically and technologically relevant oxides (YSZ, ZrO 2 and Y 2 O 3) towards CH 4 , CO and CO 2 was comparatively studied by electrochemical impedance (EIS) and spectroscopic (FT-IR) methods. Highly correlated in-situ measurements yield a consistent picture with respect to qualitative and quantitative surface modifications as a function of temperature and gas phase composition. This includes a detailed study of carbon deposition in methane and adsorption of CO and CO 2 , but also proof of the strong influence of surface chemistry. On all studied oxides, carbon deposited during methane treatment grows dynamically forming interconnected islands and eventually a continuous conducting carbon layer at T ≥ 1073 K. Before methane dissociation via gas phase radical reactions/H-abstraction and carbon growth, a complex redox interplay of total oxidation, formate and carbonate formation leads to associated surface and grain conductivity changes. For CO adsorption, these measurements yield data on the time-and temperature dependence of the adsorbate-and carburization-induced conductivity processes. In that respect, an equivalent circuit model in dry CO allows to disentangle the different contributions of grain interiors, grain boundaries and electrode contributions. For YSZ, temperature regions with different charge carrier activation energies could be identified, perfectly corresponding to significant changes in surface chemistry. Hydroxyl groups, carbonates or formates strongly influence the impedance properties, suggesting that the conductivity properties of YSZ e.g. in a realistic reforming gas mixture cannot be reduced to exclusive bulk ion conduction. Due to the different degree of hydroxylation and the different ability to chemisorb CO and CO 2 , the influence of the surface chemistry on the electrochemical properties is varying strongly: in contrast to ZrO 2 , the impact of the studied C1-gases on YSZ and Y 2 O 3 is substantial. This also includes the re-oxidation/re-activation behavior of the surfaces.

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Section: Introductionmentioning

confidence: 99%

Surface Reactivity of YSZ, Y₂O₃, and ZrO₂toward CO, CO₂, and CH₄: A Comparative Discussion

et al. 2016

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“…Further studies indicated that the cathode performance is better when the diameter of the nanofibers is sufficiently small [33,35]. Other studies [36,37] confirmed the significant influence of the microstructure and intrinsic properties of the basic components on the cathode performance.…”

Section: Introductionmentioning

confidence: 85%

A Theoretical Model for the Triple Phase Boundary of Solid Oxide Fuel Cell Electrospun Electrodes

et al. 2019

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Electrospinning is a new state-of-the-art technology for the preparation of electrodes for solid oxide fuel cells (SOFC). Electrodes fabricated by this method have been proven to have an experimentally superior performance compared with traditional electrodes. However, the lack of a theoretic model for electrospun electrodes limits the understanding of their benefits and the optimization of their design. Based on the microstructure of electrospun electrodes and the percolation threshold, a theoretical model of electrospun electrodes is proposed in this study. Electrospun electrodes are compared to fibers with surfaces that were coated with impregnated particles. This model captures the key geometric parameters and their interrelationship, which are required to derive explicit expressions of the key electrode parameters. Furthermore, the length of the triple phase boundary (TPB) of the electrospun electrode is calculated based on this model. Finally, the effects of particle radius, fiber radius, and impregnation loading are studied. The theory model of the electrospun electrode TPB proposed in this study contributes to the optimization design of SOFC electrospun electrode.

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“…Numerous metals such as Ni, Co and noble metals have been used as activator of DRM reaction and literature reports achieved results and open challenges [2,5,10,11]. Thermodynamic studies [12][13][14] indicate as best operating condition for the reaction high temperature (up to 900-1000 • C) and low pressure (1 bar). In particular, high pressure enhances both carbon and steam production.…”

Section: Ch 4 + Co 2 ↔ 2h 2 + 2comentioning

confidence: 99%

“…Literature reports also few experimental studies on the operation of SOFC with dry reforming mixtures. In general, main issue of this technology is degradation caused by carbon deposition [8][9][10][11][12] on SOFC anode. Therefore, the optimization of DRM operating conditions has to be investigated also in consideration of the effect of reformate composition on SOFC degradation.…”

Section: Ch 4 + Co 2 ↔ 2h 2 + 2comentioning

confidence: 99%

Steam vs. Dry Reformer: Experimental Study on a Solid Oxide Fuel Cell Short Stack

2018

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Solid Oxide Fuel Cell (SOFC) systems operating with methane usually are equipped with an external reformer to produce syngas. The conventional applied technology is steam methane reforming. Recent studies, instead, are presenting dry reforming as potential alternative. Advantages come from the substitution of steam with CO2 to be handled in the system, representing a potential strategy of CO2 reuse. This study compares, the performance of a SOFC short stack operating with dry reforming and with steam reforming mixtures respectively. Results show that higher performances can be obtained under same operating conditions, due to the high concentration of syngas (that has low content of inert species) produced via dry reforming. The analysis of different dry reforming concentrations shows that the amount of methane seems to be more relevant, in terms of voltage performances, than high hydrogen concentration. Among tested dry reforming compositions, the most performing exhibits an improvement of at least 5% in produced voltage in the range 150–375 mA cm−2 with respect to mixture produced by steam reforming (S/C ratio of 2.5). It was also proved that this performance enhancement does not imply greater thermal stresses, since stack temperature slightly reduces and lower temperature variations arise at anode and cathode when operating current varies.

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Influence of the microstructure on the catalytic properties of SOFC anodes under dry reforming of methane

Cited by 18 publications

References 14 publications

Surface Reactivity of YSZ, Y₂O₃, and ZrO₂toward CO, CO₂, and CH₄: A Comparative Discussion

Surface Reactivity of YSZ, Y₂O₃, and ZrO₂toward CO, CO₂, and CH₄: A Comparative Discussion

A Theoretical Model for the Triple Phase Boundary of Solid Oxide Fuel Cell Electrospun Electrodes

Steam vs. Dry Reformer: Experimental Study on a Solid Oxide Fuel Cell Short Stack

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Influence of the microstructure on the catalytic properties of SOFC anodes under dry reforming of methane

Cited by 18 publications

References 14 publications

Surface Reactivity of YSZ, Y2O3, and ZrO2toward CO, CO2, and CH4: A Comparative Discussion

Surface Reactivity of YSZ, Y2O3, and ZrO2toward CO, CO2, and CH4: A Comparative Discussion

A Theoretical Model for the Triple Phase Boundary of Solid Oxide Fuel Cell Electrospun Electrodes

Steam vs. Dry Reformer: Experimental Study on a Solid Oxide Fuel Cell Short Stack

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Surface Reactivity of YSZ, Y₂O₃, and ZrO₂toward CO, CO₂, and CH₄: A Comparative Discussion

Surface Reactivity of YSZ, Y₂O₃, and ZrO₂toward CO, CO₂, and CH₄: A Comparative Discussion