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Performance improvement of the proton-conducting solid oxide electrolysis cell coupled with dry methane reforming
(2023-02-28)
Patcharavorachot, Yaneeporn
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Chalee, Wissawa
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Saebea, Dang
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Arpornwichanop, Amornchai
The proton-conducting solid oxide electrolysis cell (H-SOEC) is a clean technology for syngas production from H<inf>2</inf>O and CO<inf>2</inf> through electrochemical and chemical reactions. However, it provides a low CO<inf>2</inf> conversion and produces a syngas product with a high H<inf>2</inf>O content. To improve the H-SOEC for syngas production, H-SOEC coupled with a dry methane reforming process (H-SOEC/DMR) was proposed in this work. The process flowsheet of the H-SOEC/DMR was developed and further used to evaluate the performance of the H-SOEC/DMR process. From the performance analysis of the H-SOEC/DMR process, it was found that the CO<inf>2</inf> and CH<inf>4</inf> conversions were higher than 90% and 80%, respectively, when the process was operated in the temperature range of 1073–1273 K. In addition, the result showed that a syngas product with a low H<inf>2</inf>O content could be obtained. Energy efficiency was then considered and the results indicated that the highest energy efficiency of 72.80% could be achieved when the H-SOEC/DMR process was operated at a temperature of 1123 K, pressure of 1 atm, and current density of 2500 A m−2. Based on a pinch analysis, a heat exchanger network was applied to the H-SOEC/DMR process that improved the energy efficiency to 81.46%. Finally, an exergy analysis was performed and showed that the H-SOEC/DMR unit had the lowest exergy efficiency as a high-temperature exhaust gas was released.
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Effect of sintering additives on barium cerate based solid oxide electrolysis cell for syngas production from carbon dioxide and steam
(2018-05-01)
Likhittaphon, S.
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Pukkrueapun, T.
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Seeharaj, P.
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Wetwathana Hartley, U.
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Laosiripojana, N.
The effect of sintering additives (NiO, Co<inf>2</inf>O<inf>3</inf>, and ZnO) on the performance of barium-cerate-based solid oxide electrolysis cell (SOEC) is investigated. The performance of the SOEC with different sintering additives is determined in terms of relative density, electrochemical performance, and catalytic activity toward reverse water gas shift reaction. BaCeO<inf>3</inf> (BC) and BaCe<inf>0.9</inf>Gd<inf>0.1</inf>O<inf>3−δ</inf> (BCG) are synthesized using conventional precipitation method, comparing to ultrasonic-assisted precipitation. The sintering additives promote both densification and grain growth. The relative density of the BCG without sintering additive is 69% while that of the BCG with 1 wt% of Co<inf>2</inf>O<inf>3</inf>, NiO and ZnO is 95%, 95% and 88%, respectively. The SEM images indicate that the BCG with sintering additives exhibits dense grains with relatively large grain size. Although the BGC with NiO and Co<inf>2</inf>O<inf>3</inf> exhibit maximum relative density, the sample with ZnO shows relatively highest conductivity with the lowest activation energy of conduction and the sample with NiO provides the largest CO yield and CO<inf>2</inf> conversion. The activation energy of conduction is found to be 375.41, 70.06, 66.86 and 61.80 kJ mol−1 for BCG, BCG with 1 wt% Co<inf>2</inf>O<inf>3</inf>, NiO and ZnO, respectively. The BCG with 1 wt% NiO provides the highest CO<inf>2</inf> conversion and CO yield at temperature below 700 °C (62% CO<inf>2</inf> conversion and 32% CO yield at 700 °C). Temperature program of oxidation (TPO) reveals that carbon deposition can cause the low CO yield at the operating temperature above 700 °C.
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Low-temperature preparation of BaCeO3 through ultrasonic-assisted precipitation for application in solid oxide electrolysis cell
(2015-06-20)
Kim-Lohsoontorn, P.
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Paichitra, C.
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Vorathamthongdee, S.
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Seeharaj, P.
Barium cerate (BaCeO<inf>3</inf>) was synthesized using conventional precipitation and ultrasonic-assisted precipitation. The effect of precipitation parameters (precipitation precursor, precipitation agent, agent concentration and temperature) significantly affected %perovskite formation and crystallite size of the product. Precipitation with 1 M (NH<inf>4</inf>)<inf>2</inf>C<inf>2</inf>O<inf>4</inf> induced the formation of a single-phase BaCeO<inf>3</inf> while precipitation with 5-20 M NaOH provided a mixed phase of BaCeO<inf>3</inf> and CeO<inf>2</inf>. The %perovskite increased as increasing precipitation temperature; however, the crystallite size of the product also increased. Increasing ultrasonic intensity (30 and 150 W cm-2) during precipitation was found to increase the %perovskite and to reduce crystallite size. The precipitation with 1 M (NH<inf>4</inf>)<inf>2</inf>C<inf>2</inf>O<inf>4</inf> agent, using ultrasonic intensity at 150 W cm-2, provided single phase BaCeO<inf>3</inf> with crystallite size of 18.4 nm after calcination at 900 °C for 4 h. The electrochemical performance of the BaCeO<inf>3</inf> cell under steam electrolysis condition (controlled voltage from OCV to 1.5 V; 20% H<inf>2</inf>O, 40% H<inf>2</inf>, and 40% N<inf>2</inf>) was measured (600-800 °C) and the activation energy of conduction was calculated to be 0.78 eV.
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Performance of ethanol-fuelled solid oxide fuel cells: Proton and oxygen ion conductors
(2007-09-15)
Jamsak, W.
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Assabumrungrat, S.
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Douglas, P. L.
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Laosiripojana, N.
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Suwanwarangkul, R.
This paper investigates the performance of ethanol-fuelled solid oxide fuel cells (SOFCs) with two types of solid electrolytes, namely oxygen ion-conducting (SOFC-O2-) and proton-conducting electrolytes (SOFC-H+). Our previous work reported that the SOFC-H+ shows superior theoretical performance over the SOFC-O2- electrolyte. However, in this work when all resistances are taken into account, the actual performance of the SOFC-O2- (Ni-YSZ|YSZ|YSZ-LSM) becomes significantly better than that of SOFC-H+ (Pt|SCY|Pt). The maximum power density of the SOFC-O2- is about 34 times higher than that of the SOFC-H+ when operated at an inlet H<inf>2</inf>O:EtOH ratio of 3, a fuel utilization factor of 80% and a temperature of 1200 K. Then the required values of the total resistance of the SOFC-H+ to achieve the same power density as the SOFC-O2- were determined. It was found that due to the superior theoretical performance of the SOFC-H+, it is not necessary to reduce the SOFC-H+ total resistance to the same values as the one for SOFC-O2-. The study also indicates that reduction of only the electrolyte resistance is not sufficient to improve the SOFC-H+ performance and, therefore, the other resistances including activation, electrodes and interconnect resistances need to be reduced simultaneously. Finally, the improvement of the electrolyte resistance by changing its resistivity and thickness is discussed. © 2007 Elsevier B.V. All rights reserved.
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