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A solid oxide fuel cell (SOFC) was developed for the direct utilization of dry glycerol to produce electricity at 800°C. A state-of-art SOFC anode was covered by a thin (< 10 μm) electrocatalyst layer based on a Ni-modified perovskite and ceria. This electrocatalyst layer worked as an internal integrated fuel processor to convert glycerol in syngas...
Citations
... Fuel cells are regarded as the fourth generation of power-generating technology, following thermal power, hydropower, and nuclear power, because they have benefits over traditional thermal power generation, such as increased efficiency and lower emissions [3,4]. The solid oxide fuel cell (SOFC) is a highly advantageous fuel cell type due to its diverse range of coupling possibilities with various systems [5,6]. More crucially, combining SOFC with gas turbines (GT) to create SOFC-GT hybrid systems that can reach high electrical and thermal efficiencies is particularly appealing [7,8]. ...
Different approaches have been suggested for the waste heat recovery of high-temperature exhausted gas of a solid oxide fuel cell (SOFC). In such systems, mostly gas turbine (GT) and organic Rankine cycle (ORC) are added as bottoming systems to the SOFC (Configuration 1). However, the SOFC-GT-ORC has a considerable amount of waste energy which can be recovered. In the present research, the waste energy of ORC in the heat rejection stage and the residual exhausted gas of the system were recovered by a thermoelectric generator (TEG) and a hot water unit, respectively. Then, the extra produced power in the TEG was directed to a proton exchange membrane electrolyzer and a reverse osmosis desalination unit (RODU) for hydrogen and potable water outputs. The performance of SOFC-GT, Configuration 1, and Configuration 2 was compared through a 4E (energy, exergy, exergy-economic, and environmental) analysis. In the best performance point, the exergy efficiency and unit cost of product (UCOP) of SOFC-GT were obtained as 69.41% and USD 26.53/GJ. The exergy efficiency increased by 2.56% and 2.86%, and the UCOP rose by 0.45% and 12.25% in Configurations 1 and 2. So, the overall performance of Configuration 1 was acceptable and Configuration 2 led to the highest exergy efficiency, while its economic performance was not competitive because of the high investment cost of RODU.
... This approach consisted of a protective/functional layer coated on the Ni-YSZ (anode). When the suitable material is chosen, this coating film offers significant benefits as a precatalytic layer, transforming the organic fuel (ethanol [22], biogas [23,24], glycerol [25]) to electricity with a low or null carbon formation, mitigating the deactivation of the cell and without a drastic increase in ohmic losses [22]. Such an approach has demonstrated promising achievements using dry biofuels and paved the way for a mode that achieved the highest fuels conversion efficiency combined with simple process management. ...
Solid oxide fuel cell (SOFC) is a mature opportunity for producing power energy in remote areas like islands, where access to the electrical grid is not favoured, and gas distribution is the only viable approach. In this context, generally, biogas represents the most convenient fuel resources in these areas. However, the direct use of biogas in SOFCs is still an issue to be solved due to its negative effect on the conventional Ni-YSZ anode. In this study, to overcome this issue, we suggested using a protective layer coated on the anode of a commercial SOFC. A nickel manganite showing mixed ionic and electronic conductivity tailored specifically for this approach was investigated. The preliminary characterisations showed that the formation of a Ruddlesden-Popper (RP) n = 1 structure supporting fine encapsulated particles based on Ni was formed around 800 °C in consequence of the reducing environment. The electrochemical experiments carried out for 270 h demonstrated for the coated cell significant stability in the presence of dry biogas, albeit an ageing effect was noticed in the electrical percolation of both cell electrodes. The post mortem analyses revealed an attractive redox property for the nickel manganite, which partially returned to the RP n = 2 phase. Moreover, the absence of carbon deposits on the anode suggests possible applications for this approach.
... However, a new class of materials corresponding to "exsolved perovskite" has been recently used as fuel electrodes for SOC cells [37][38][39][40][41][42][43]. These materials have a unique morphology based on a substrate with mixed ionic and electronic conductivity (MIEC) supporting encapsulated fine particles that originate from the segregation of metals from the MIEC's bulk [44,45]. ...
The co-electrolysis of CO2 and H2O at an intermediate temperature is a viable approach for the power-to-gas conversion that deserves further investigation, considering the need for green energy storage. The commercial solid oxide electrolyser is a promising device, but it is still facing issues concerning the high operating temperatures and the improvement of gas value. In this paper we reported the recent findings of a simple approach that we have suggested for solid oxide cells, consisting of the addition of a functional layer coated to the fuel electrode of commercial electrochemical cells. This approach simplifies the transition to the next generation of cells manufactured with the most promising materials currently developed, and improves the gas value in the outlet stream of the cell. Here, the material in use as a coating layer consists of a Ni-modified La0.6Sr0.4Fe0.8Co0.2O3, which was developed and demonstrated as a promising fuel electrode for solid oxide fuel cells. The results discussed in this paper prove the positive role of Ni-modified perovskite as a coating layer for the cathode, since an improvement of about twofold was obtained as regards the quality of gas produced.
... The authors of this mini-review have intensively worked on modified and exsolved perovskite for application as an anode in SOFCs for several years demonstrating an effective oxidation of various organic fuels directly fed to the cell [56][57][58][59][60][61][62][63]. The proper modification of commercial type ferrite-based perovskites, which are commonly used as an SOFC cathode, with small amounts of Ni has been demonstrated. ...
... (LSGM) [61], and BaCe0.9Y0.1O3-δ (BYCO)) and as a functional layer (pre-layer) for the anode of a commercial type cell (ASC-400B, ELCOGEN [62,63]). In the latter case, the SOFC consists of a dual-anode configuration where the modified perovskite acts as a catalytic pre-layer for the conversion of the organic molecules before these can reach the supporting Ni-YSZ anode. ...
... One important aspect of the previous studies carried out on modified perovskite electrocatalysts has regarded the reaction mechanisms involving the direct oxidation of dry organic fuels [62,63]. Figure 5 depicts the mechanisms suggested for the electrochemical conversion of ethanol. ...
Exsolved perovskites can be obtained from lanthanum ferrites, such as La0.6Sr0.4Fe0.8Co0.2O3, as result of Ni doping and thermal treatments. Ni can be simply added to the perovskite by an incipient wetness method. Thermal treatments that favor the exsolution process include calcination in air (e.g., 500 °C) and subsequent reduction in diluted H2 at 800 °C. These processes allow producing a two-phase material consisting of a Ruddlesden–Popper-type structure and a solid oxide solution e.g., α-Fe100-y-zCoyNizOx oxide. The formed electrocatalyst shows sufficient electronic conductivity under reducing environment at the Solid Oxide Fuel Cell (SOFC) anode. Outstanding catalytic properties are observed for the direct oxidation of dry fuels in SOFCs, including H2, methane, syngas, methanol, glycerol, and propane. This anode electrocatalyst can be combined with a full density electrolyte based on Gadolinia-doped ceria or with La0.8Sr0.2Ga0.8Mg0.2O3 (LSGM) or BaCe0.9Y0.1O3-δ (BYCO) to form a complete perovskite structure-based cell. Moreover, the exsolved perovskite can be used as a coating layer or catalytic pre-layer of a conventional Ni-YSZ anode. Beside the excellent catalytic activity, this material also shows proper durability and tolerance to sulfur poisoning. Research challenges and future directions are discussed. A new approach combining an exsolved perovskite and an NiCu alloy to further enhance the fuel flexibility of the composite catalyst is also considered. In this review, the preparation methods, physicochemical characteristics, and surface properties of exsoluted fine nanoparticles encapsulated on the metal-depleted perovskite, electrochemical properties for the direct oxidation of dry fuels, and related electrooxidation mechanisms are examined and discussed.
... The authors of this mini-review have intensively worked on modified and exsolved perovskite for application as anode in SOFCs for several years demonstrating an effective oxidation of various organic fuels directly fed to the cell [49][50][51][52][53][54][55][56]. Proper modification of commercial type ferrite-based perovskites commonly used as a SOFC cathode with small amounts of Ni has been demonstrated. ...
... This material has been investigated extensively in two main cell configurations consisting a single fuel electrode supported on three different types of supporting electrolytes (e.g. CGO [49], LSGM [54]and BYCO) and as a functional layer (pre-layer) for the anode of a commercial type cell (ASC-400B, ELCOGEN [55,56]). In the latter case, the SOFC consists of a dual-anode configuration where the modified perovskite acts as a catalytic pre-layer for the conversion of the organic molecules before these can reach the supporting Ni-YSZ anode. ...
... Moreover, it is needed to acquire more insights into the poor reaction kinetics of methane oxidation at the perovskite catalyst surface to improve the anode characteristics. [49][50][51][54][55][56] Several experiments carried out with organic fuels are summarized in table 2. In one cases, the exsolved perovskite has been studied for a 780 hrs in presence of a large excess of dry propane observing a decay of 1.1 10 -4 A h -1 . In principle a large excess of fuel suppress the partial pressure of water and CO2 formed during the electrochemical reaction occurring at the anode. ...
Exsolved perovskites can be obtained from lanthanum ferrites, such as La0.6Sr0.4Fe0.8Co0.2O3, as result of Ni doping and thermal treatments. Ni can be simply added to the perovskite by an incipient wetness method. Thermal treatments include calcination in air (e.g., 500 °C) and subsequent reduction in diluted H2 at 800 °C to favor the exsolution process. The chemistry of the nanoparticles exsoluted on the substrate surface can be further modulated by a post treatment in air. These processes allow to produce a two-phase material consisting of a Ruddlesden-Popper type structure and a solid oxide solution e.g. α-Fe100-y-zCoyNizOx oxide. The formed electro-catalyst shows sufficient electronic conductivity under reducing environment at the SOFC anode. Outstanding catalytic properties are observed for the direct oxidation of dry fuels in SOFCs, including H2, methane, syngas, methanol, glycerol and propane. This anode electrocatalyst can be combined with full density electrolyte based on Gadolinia-doped Ceria or with La0.8Sr0.2Ga0.8Mg0.2O3 (LSGM) or BaCe0.9Y0.1O3-δ (BYCO) to form a complete perovskite structure-based cell. Moreover, the exsolved perovskite can be used as a coating layer or catalytic pre-layer of a conventional Ni-YSZ anode. Beside the excellent catalytic activity, this material also shows proper durability and tolerance to sulphur poisoning. In this mini review, preparation methods, physico-chemical characteristics, surface properties of exsoluted and core-shell nanoparticles encapsulated on the metal-depleted perovskite substrate surface, electrochemical properties for the direct oxidation of dry fuels and related electrooxidation mechanisms are examined and discussed.
... In other words, the thickness and porosity of catalytic layer requires being compatible with the anode support to avoid interference on gas flow [129]. Large mass transport constraints were observed for glycerol due to the diffusion of this large organic molecule through the electrocatalytic layer [134]. Fig. 15(a) shows the various polarization curves recorded during the durability test of ethanol-fed SOFC. ...
Porosity is a key property that plays a crucial role in enhancing the performance of solid oxide fuel cell (SOFC) electrodes. The addition of pyrolyzable pore-formers to the electrode materials of SOFCs can generate suitable porous microstructures with the required porosity, pore sizes, and morphology. The present review provides details on the characterization and microstructural analysis, firing profile, electrical conductivity, mechanical strength, and gas permeability of the porous electrodes of SOFCs. A better understanding of these relationships can help to design optimized porous microstructures for generating higher power densities of the cells.
Liquid biofuels (LBFs) that are renewable and sulfur-free, are one important part of future energy supplements. The advantage of ready availability of LBFs with high efficiencies and clean emissions is highly favored by solid oxide fuel cells (SOFCs), and wide applications in power generation, transportation, and aviation are expected. Direct and indirect utilizations are believed to have great significance in using short-chain and long-chain LBFs, respectively. Still, an overall summarization relevant to these fuels’ usage, including both SOFC technologies and reforming processes, is messy and incomplete. Therefore, significant work has been done to integrate this information into a review. Here, the catalogs of LBFs are summarized, and SOFC fundamentals are discussed to offer basic views of LBFs utilization. SOFC anodes and reforming catalysts are thoroughly discussed for direct and indirect utilization, respectively, and approaches for enhancements around the problems such as carbon deposition and active metal sintering are also included.
Intermediate Temperature Solid Oxide Fuel Cells: Electrolytes, Electrodes and Interconnects introduces the fundamental principles of intermediate solid oxide fuel cells technology. It provides the reader with a broad understanding and practical knowledge of the electrodes, pyrochlore/perovskite/oxide electrolytes and interconnects which form the backbone of the Solid Oxide Fuel Cell (SOFC) unit. Opening with an introduction to the thermodynamics, physiochemical and electrochemical behavior of Solid Oxide Fuel Cells (SOFC), the book also discusses specific materials, including low temperature brownmillerites and aurivillius electrolytes, as well as pyrochlore interconnects.
This book analyzes the basic concepts, providing cutting-edge information for both researchers and students. It is a complete reference for Intermediate Solid Oxide Fuel Cells technology that will be a vital resource for those working in materials science, fuel cells and solid state chemistry.
The direct application of glycerol in solid oxide fuel cell (SOFC) for power generation has been demonstrated experimentally but the detailed mechanisms are not well understood due to the lack of comprehensive modeling study. In this paper, a numerical model is developed to study the glycerol-fueled SOFC. After model validation, the simulated SOFC demonstrates a performance of 7827 A m⁻² at 0.6 V, with a glycerol conversion rate of 49% at 1073 K. Then, parametric analyses are conducted to understand the effects of operation conditions on cell performance. It is found that the SOFC performance increases with decreasing operating voltage or increasing inlet temperature. However, increasing either the fuel flow rate or steam to glycerol ratio could decrease the cell performance. It is also interesting to find out that the contribution of H2 and CO to the total current density is significantly different under various operating conditions, even sometimes CO dominates while H2 plays a negative role. This is different from our conventional understanding that usually H2 contributes more significantly to current generation. In addition, cooling measures are needed to ensure the long-term stability of the cell when operating at a high current density.
