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Vanadium-dependent haloperoxidases (VHPOs) from

Reversible solid oxide cells (rSOC) can convert excess electricity to valuable fuels in electrolysis cell mode (SOEC) and reverse the reaction in fuel cell mode (SOFC). In this work, a five - cell rSOC short stack, integrating fuel electrode (Ni-YSZ) supported solid oxide cells (Ni-YSZ parallel to YSZ vertical bar CGO parallel to LSC-CGO) with an active area of 100 cm(2), is tested for cyclic durability. The fuel electrode gases of H-2/N-2:50/50 and H-2/H2O:20/80 in SOFC and SOEC mode, respectively, are used during the 35 reversible operations. The voltage degradation of the rSOC is 1.64% kh(-1) and 0.65% kh(-1) in SOFC and SOEC mode, respectively, with fuel and steam utilisation of 52%. The post-cycle steady-state SOEC degradation of 0.74% kh(-1) suggests improved lifetime during rSOC conditions. The distribution of relaxation times (DRT) analysis suggests charge transfer through the fuel electrode is responsible for the observed degradation. (C) 2022 The Author(s). Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.

Bacterial meroterpenoids constitute an important class of natural products with diverse biological properties and therapeutic potential. The biosynthetic logic for their production is unknown and defies explanation via classical biochemical paradigms. A large subgroup of naphthoquinone-based meroterpenoids exhibits a substitution pattern of the polyketide-derived aromatic core that seemingly contradicts the established reactivity pattern of polyketide phenol nucleophiles and terpene diphosphate electrophiles. We report the discovery of a hitherto unprecedented enzyme-promoted α-hydroxyketone rearrangement catalysed by vanadium-dependent haloperoxidases to account for these discrepancies in the merochlorin and napyradiomycin class of meroterpenoid antibiotics, and we demonstrate that the α-hydroxyketone rearrangement is potentially a conserved biosynthetic reaction in this molecular class. The biosynthetic α-hydroxyketone rearrangement was applied in a concise total synthesis of naphthomevalin, a prominent member of the napyradiomycin meroterpenes, and sheds further light on the mechanism of this unifying enzymatic transformation.

A solid oxide short stack composed of 6 Ni-YSZ supported cells, YSZ electrolyte and GDC-LSC oxygen electrode has been tested for 10,700 hours in steam electrolysis. Initial degradation was followed by a global stabilization of the performance after lowering the current density, with a degradation rate below 0.5% kh(-1). Post-test analysis has been conducted on two repeating units (RUs) to highlight the most significant microstructure alterations. Nickel depletion was observed in the hydrogen electrode close to the interface with the electrolyte. Formation of small pores in the electrolyte was detected along the grain boundaries. A consequent detachment related to this phenomenon was observed in proximity of the GDC compatibility layer. At the oxygen electrode side, the formation of a approximate to 1 mu m dense mixed layer of GDC and YSZ was observed. Strontium from the LSC electrode migrated through GDC pores and reacted with YSZ, forming evident SrZrO3 inclusions. Distinct accumulation of silicon at the Ni/YSZ interface and chromium on the GDC barrier layer have been observed in both RUs. Despite this range of alterations observed, the stack degradation remained limited, testified from the fact that performance decay between 4,000 and 10,000 hours of operation was virtually nil.

Halogenated pyrroles (halopyrroles) are common chemical moieties found in bioactive bacterial natural products. The halopyrrole moieties of mono- and dihalopyrrole-containing compounds arise from a conserved mechanism in which a proline-derived pyrrolyl group bound to a carrier protein is first halogenated and then elaborated by peptidic or polyketide extensions. This paradigm is broken during the marine pseudoalteromonad bacterial biosynthesis of the coral larval settlement cue tetrabromopyrrole (1), which arises from the substitution of the proline-derived carboxylate by a bromine atom. To understand the molecular basis for decarboxylative bromination in the biosynthesis of 1, we sequenced two Pseudoalteromonas genomes and identified a conserved four-gene locus encoding the enzymes involved in its complete biosynthesis. Through total in vitro reconstitution of the biosynthesis of 1 using purified enzymes and biochemical interrogation of individual biochemical steps, we show that all four bromine atoms in 1 are installed by the action of a single flavin-dependent halogenase: Bmp2. Tetrabromination of the pyrrole induces a thioesterase-mediated offloading reaction from the carrier protein and activates the biosynthetic intermediate for decarboxylation. Insights into the tetrabrominating activity of Bmp2 were obtained from the high-resolution crystal structure of the halogenase contrasted against structurally homologous halogenase Mpy16 that forms only a dihalogenated pyrrole in marinopyrrole biosynthesis. Structure-guided mutagenesis of the proposed substrate-binding pocket of Bmp2 led to a reduction in the degree of halogenation catalyzed. Our study provides a biogenetic basis for the biosynthesis of 1 and sets a firm foundation for querying the biosynthetic potential for the production of 1 in marine (meta)genomes.

The objective of the current work is to support the design of a pilot hydrogen and electricity producing plant that uses natural gas (or biomethane) as raw material, as a transition option towards a 100% renewable transportation system. The plant, with a solid oxide fuel cell (SOFC) as principal technology, is intended to be the main unit of an electric vehicle station. The refueling station has to work at different operation periods characterized by the hydrogen demand and the electricity needed for supply and self-consumption. The same set of heat exchangers has to satisfy the heating and cooling needs of the different operation periods. In order to optimize the operating variables of the pilot plant and to provide the best heat exchanger network, the applied methodology follows a systematic procedure for multi-objective, i.e. maximum efficiency and minimum number of heat exchanger matches, and multi-period optimization. The solving strategy combines process flow modeling in steady state, superstructure- based mathematical programming and the use of an evolutionary-based algorithm for optimization. The results show that the plant can reach a daily weighted efficiency exceeding 60%, up to 75% when considering heat utilization.

This work presents the poisoning effect of organic oxo-silicon compounds (siloxanes) which are generally found in sewage biogas. Lifetime and durability associated with solid oxide fuel cell (SOFC) technology is strongly related to the amount of contaminants that reach the stack. Several experiments on Ni anode-supported (AS) single cells are performed in order to clarify the mechanism of degradation and also the possibility of cell performance recovery. Three experiments focus on the degradation and recovery of AS Ni-YSZ fed with H-2, co-feeding 5 ppm D4-siloxane (octamethylcyclotetrasiloxane, C8H24O4Si4) as representative compound for the organic silicon species, at 800 degrees C. A fourth experiment focuses on the durability of the AS Ni-YSZ cell with variable concentrations of the impurity (0-5ppm), during steady state polarization (0.25Acm(-2)) for 250 h, using simulated biogas-reformate fuel H-2/CO/CO2/H2O: irreversible degradation was observed with the D4-impurity feed in the anode gas. Post-test scanning electron microscopy (SEM) results indicate formation of SiO2(s) deposits, which block pores and reduce the TPB length.

Lifetime and durability issues connected with Solid Oxide Fuel Cell (SOFC) technology are strongly related to the amount of contaminants that reach the stack. In this study the focus is on organic silicon compounds (siloxanes) and their highly detrimental effects on the performance of SOFC Ni-YSZ anodes. The involved mechanism of degradation is clarified and quantified through several test runs and subsequent post-mortem analysis on tested samples. In particular, experiments on both Ni anode-supported single cells and 11-cell-stacks are performed, co-feeding D4-siloxane (octamethylcyclotetrasiloxane, C8H24O4Si4) as model compound for the organic silicon species which are generally found in sewage biogas. High degradation rates are observed already at ppb(v) level of contaminant in the fuel stream. Post-test analysis revealed that Si (as silica) is mostly deposited at the inlet of the fuel channel on both the interconnect and the anode side of the cell suggesting a relatively fast condensation-type process. Deposition of the Si was found on the interconnect and on the anode contact layer, throughout the anode support and the three phase boundary in the anode, correlating with the observed increase of polarization losses from the EIS analysis of tested cells. (C) 2015 Elsevier B.V. All rights reserved.

The vanadium-dependent chloroperoxidase Mcl24 was discovered to mediate a complex series of unprecedented transformations in the biosynthesis of the merochlorin meroterpenoid antibiotics. In particular, a site-selective naphthol chlorination is followed by a sequence of oxidative dearomatization/terpene cyclization reactions to build up the stereochemically complex carbon framework of the merochlorins in one step. Inspired by the enzyme reactivity, we developed a chemical chlorination protocol paralleling the biocatalytic process. These chemical studies led to the identification of previously overlooked merochlorin natural products.

A mechanistic study of the ring contraction of spirocyclopropane isoxazolidines to form β-lactams is reported. Based on experimental and computational investigations, we propose a concerted mechanism that proceeds with retention of configuration during cyclopropane cleavage.

The polycycles merochlorin A and B are complex halogenated meroterpenoid natural products with significant antibacterial activities and are produced by the marine bacterium Streptomyces sp. strain CNH-189. Heterologously produced enzymes and chemical synthesis are employed herein to fully reconstitute the merochlorin biosynthesis in vitro. The interplay of a dedicated type III polyketide synthase, a prenyl diphosphate synthase, and an aromatic prenyltransferase allow formation of a highly unusual aromatic polyketide-terpene hybrid intermediate which features an unprecedented branched sesquiterpene moiety from isosesquilavandulyl diphosphate. As supported by in vivo experiments, this precursor is furthermore chlorinated and cyclized to merochlorin A and isomeric merochlorin B by a single vanadium-dependent haloperoxidase, thus completing the remarkably efficient pathway.

A novel bioconjugation strategy is presented that relies on the coupling of diazonium terephthalates with amines in proteins. The diazonium captures the amine while the vicinal ester locks it through cyclization, ensuring no reversibility. The reaction is highly efficient and proceeds under mild conditions and short reaction times. Densely functionalized, complex natural products were directly coupled to proteins using low concentrations of coupling partners.

This paper presents the processing steps for producing thin planar and tubular oxygen separation membranes by thermoplastic forming of Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) with polystyrene (PS) and stearic acid (SA) as binder. The influence of powder content on the shape stability of thin membranes (tubular and planar structures) during the thermoplastic processing route was investigated. The effect of powder content on mixing torque and the rheological behavior were investigated. The effect of the powder content could be analytically described using the model proposed by Frankel and Acrivos. The deformation of free standing green bodies was investigated using disks. The result showed that increasing the powder content is remarkably effective to minimize the deformation of the membrane during the thermal debinding step. By using a high powder content (60 vol%) and a multicomponent binder system composed of PS, SA and paraffin wax (PW), it was possible to achieve disks and thin wall tubular structures without deformation after sintering. Using capillary rheometer an unexpected decrease in the total extrusion pressure was measured for the feedstock containing PW. The change in apparent activation energy between 800-1000 degrees C was not related to the membrane properties. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.

In this study, two short SOE stacks (6-cells) were characterized in steam-electrolysis mode. The first was based on Ni-YSZ supported cells with LSCF-based air electrodes. The second included LSC-based air electrodes specifically developed within the SOFC600 project. The stacks were fed with a 90% steam, 10% hydrogen mixture, and characterized between 600 and 700 degrees C. For the LSCF-based stack, an average cell voltage of 1.6V was reached at -1Acm(-2) and 700 degrees C, corresponding to 60% steam conversion. The LSC-based stack showed better performances, with 1.25V at -0.8Acm(-2) and 700 degrees C. Durability tests were performed around the thermoneutral voltage (1.35V) for resp. 2,400 (LSCF) and 1,500h (LSC). The average stack degradation rates were resp. +2.8% (kh)(-1) (LSCF) and +1.9% (kh)(-1) (LSC). Twelve load-cycles were also performed on the LSC-stack with no apparent degradation. In addition, co-electrolysis was performed between 750 and 850 degrees C by feeding the stack with a 60% H2O, 30% CO2, and 10% H-2 mixture. Ninety-five percent conversion was reached and the measured outlet syngas composition was close to that predicted by thermodynamics. Steam electrolysis tests were carried out in the same conditions for comparison. The stack performance in the co-electrolysis mode was slightly lower than in the electrolysis mode.

An alternative way to process data from polarization measurements for fuel cell model validation is proposed. The method is based on re- and subsampling of IV data, with which repetitive estimations are obtained for the model parameters. This way statistics such as standard deviations and correlations between the parameters may be experimentally derived. Histograms may also be produced, approximating the probability distributions that they follow. Two experimental case studies are discussed. In the first case, observations are made on the behavior of the parameter values for two mathematical models. As the number of data points (measurement points) employed in the estimation of the parameters increases, parameters with high variances converge to specific values. On the contrary, parameters with small variances diverge linearly. The parameters' histograms do not usually follow normal distributions rather they show a connection between the number of peaks in the graphs and correlations of the parameters. The second case study is an application on a fast degraded SOFC button cell, where the values and the histograms of the parameters are compared before and after degradation.

One of the major limitations of the nickel (Ni) - yttria-stabilized zirconia (YSZ) anode support for solid oxide fuel cells (SOFC) is its low capability to withstand transients between reducing and oxidizing atmospheres ("RedOx" cycle), owing to the Ni-to-NiO volume expansion. This work presents results on different anode supports fabricated by tape casting. Three compositions are prepared, as the outcome of a preceding design of experiment approach. The NiO proportion is 40, 50 and 60 wt% of the anode composite.

Oxygen permeability measurements of Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) disk shaped membranes fabricated by thermoplastic processing and sintered at different temperatures (1000–1100 °C), showed no influence of the grain size on the oxygen permeation fluxes. To further investigations, Electron Backscattered Diffraction (EBSD) and Conductive mode (CM) microscopy methods were used for texture analysis and observation of the local electrical behavior in the BSCF membranes, respectively. EBSD results revealed that the grain size of the membranes increased with increasing the sintering temperature from an average of 3.32 μm at 1000 °C to 18.25 μm at 1100 °C. Also, it was seen that there was no textural difference between the different samples. CM analysis demonstrated that the electronic conductivity of the grains and grain boundaries was similar in the membrane sintered at 1000 °C. Finally, the stability of the membrane under the operation conditions was tested, and it was found that the permeation flux was nearly constant at 900 °C after an operation time of more than 50 h, whereas oxygen permeation flux declined after a relative short time at 825 °C.

The total synthesis of Microcin SF608 is reported. Access to the octahydroindole core structure of Microcin SF608 relies on the TMSOTf/NEt(3)-mediated opening of an oxabicyclic ring system. Additional highlights of the synthetic strategy that is reported include a highly regioselective epoxide reduction and photolytic excision of a 3 degrees alcohol.

An axially chiral reactive precursor—a trans-configured Pd(II) chelate complex—toward the planar chiral bis-palladacycle FBIP-Cl, which was recently shown to be an excellent enantioselective catalyst for both aza-Claisen rearrangements and direct Michael additions, has been identified and allows us to explain the stereochemical outcome of the first reported direct diastereoselective bis-cyclopalladation. In contrast to the trans-configured chelate complex, its cis-configured counterpart turned out to be a dead end under the initial cyclopalladation conditions and required harsher conditions for C−H activation.

The effect of the bulk microstructure (grain size distribution, grain boundary composition on the oxygen transport properties of La0.5Sr0.5FeO3membranes was investigated. For this purpose, samples with different microstructures were prepared by modifying the sintering duration and/or temperature. The average grain sizes, ranging from 0.20 to 1.43μ m, were determined from SEM analysis. The oxygen transport properties of the samples were characterised by permeation measurement. The fluxes presented a change in the activation energy which was attributed to a change in the rate limiting step, from bulk diffusion at lower temperature ( 900°). Only the transport through the bulk was influenced by the microstructure, with the highest flux for the smallest grains. This would imply that oxygen transport occurs more rapidly along the grain boundaries that through the bulk. Grain and grain boundary compositions were analysed by TEM.

Electrochemical techniques were applied to a coulometric titration cell to study oxygen nonstoichiometry and transport in the perovskite-type oxide La0.4Ba0.6Fe0.8Co0.2O3-delta. Slow scan voltammetry (3mV/s) was used to obtain oxygen nonstoichiometry vs. the oxygen partial pressure (p(O2)) data. The voltammograms were further analysed using a simple defect model to yield the absolute value of the oxygen nonstoichiometry. Relaxation measurements were performed to obtain chemical diffusion and surface exchange coefficients. In particular, the suitability of converting the relaxation data to the frequency domain for analysis purpose was examined. Impedance spectroscopy measurements were also performed on the same cell to allow direct comparison. A satisfactory agreement was obtained for the chemical diffusion coefficients but the surface exchange coefficient values were systematically different by a factor 2 to 3. This discrepancy was attributed to the short-time extrapolation used in the numerical conversion procedure. Finally, other transport coefficients (ionic conductivity, DV and DO) were calculated from the chemical diffusion and nonstoichiometry data.

The effect of the bulk microstructure (grain size distribution, grain boundary length) on the oxygen transport properties of permeation membranes is investigated in this work. For this purpose, La0.5Sr0.5FeO3-? samples with different microstructures have been prepared by modifying the sintering duration and/or temperature. The average grain sizes, ranging from 0.20 to 1.43 micron, were determined from SEM analysis. The oxygen transport properties of these samples were characterised by permeation measurement as a function of temperature in an air/argon oxygen partial pressure gradient. The fluxes presented a change in the activation energy which was attributed to a change in the rate limiting step, from bulk diffusion at lower temperature (900°C). Only the transport through the bulk was influenced by the microstructure, with the highest flux for the smallest grains. At 800°C, the fluxes were respectively 0.06, 0.03 and 0.01 micromol/cm2s through 1 mm thick samples of average grain sizes of 0.20, 0.63 and 1.43 micron, respectively. This would imply that oxygen transport occurs more rapidly along the grain boundaries than through the bulk. Grain boundary structure and composition were analysed by TEM.

Three perovskite-type compounds of composition La0.4Ca0.6Fe1-xCoxO3-d (x=o, o.25 and 0.5) were investigated for use as oxygen separation membranes for the partial oxidation (POX) of methane to syngas. Special attention was given to the question of their stability in real operating conditions. A permeation set-up was specially designed to measure oxygen fluxes through these materials when placed in a strong pO2 gradient. It also facilitated testing the long-term stability of the specimen. Permeation measurements performed in an air/argon gradient between 800 and 1000 °C showed that the highest fluxes were obtained with the highest content of cobalt (La0.4Ca0.6Fe0.5Co0.5 O3-d =La0.4Ca0.6Fe0.75Co0.25 O3-d >La0.4Ca0.6FeO3-d ). In addition, comparison between the fluxes of samples of different thickness gave clear evidence of surface limitations in the oxygen transport. The long-term stability test showed opposite trends: only the two lowest Co containing compounds (x = 0 and 0.25) sustained and air/(Ar + H2) gradient over more than 600 h. The other (x = 0.5) broke shortly after the introduction of H2. In the presence of H2, the oxygen flux was increased by a factor 10 compared to Ar and reached 0.83 mmol/cm2s for La0.4Ca0.6Fe0.75Co0.25O3-d at 900°C. Post-operation SEM examination of the cross-section and both surfaces revealed that the surface exposed to H2 had started to decompose resulting in the formation of a thin porous layer but the bulk of the material remained unchanged.

Serine proteases play key roles in many biological processes and are associated with several human diseases such as thrombosis or cancer. During the search for selective inhibitors of serine proteases, a family of linear peptides named the aeruginosins was discovered in marine cyanobacteria. We herein report an entry route into the synthetically challenging core fragment of these natural products. Starting from the common oxabicyclic building block 11, we accessed the octahydroindole core of the aeruginosins, exemplified by the total synthesis of microcin SF608 (2). Key to the synthetic strategy is a highly efficient nucleophilic opening of an oxabicyclo[2.2.1]heptane producing the hydroindole motif of microcin SF608. Moreover, during the synthetic efforts we have observed an unusual regioselective epoxide reduction. Detailed experimental studies of this reaction led us to propose a mechanistic rationale involving intramolecular hydrogen atom delivery by a carbamate NH group to control the regioselectivity of the homolytic epoxide cleavage.

The degradation of the electrochemical performance of solid oxide fuel cell (SOFC) devices is a major hurdle to overcome before commercialisation. The interplay between the phenomena and the long testing times complicate the research, which highlights the relevance of modelling to propose mitigation approaches. This study comprises two parts. This Part II proposes approaches for the simulation of the degradation induced by: (i) interconnect corrosion, (ii) loss of ionic conductivity of the ion-conducting materials, (iii) nickel particle growth in the anode, (iv) chromium contamination and (v) formation of insulating phases in the cathode. The literature survey highlights the lack of data for a completely consistent calibration of the models, despite the simplifications. The support for the implementation is the electrochemical model validated in Part I and a two-dimensional model of the cell and interconnection system. The cathode largely contributes to the degradation. The local overpotential predominantly governs chromium contamination, which can promote the formation of insulating phases, as operation proceeds. The local electronic current density has comparatively a weak direct influence on the degradation. Qualitative agreement with experimental data from the literature could be achieved, without dedicated adjustments of the parameters. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3596435] All rights reserved.

Solid-oxide electrolyzer based power-to-methane is promising for large-scale energy storage as well as biogas upgrading by efficiently converting intermittent renewable power and CO2 (e.g., in biogas) into synthetic methane. Either air or pure oxygen can be employed in solid oxide electrolyzers for anode sweeping and thermal management. This work investigates the optimal conceptual design of a variety of power-to-methane layouts to (i) identify the effect of sweep-gas type on system performance and (ii) compare different concepts for biogas upgrading. Bi-objective optimization is performed to understand the trade-off between system efficiency and methane production with the effects of the key design variables. The results indicate that oxygen sweep only marginally affected the system performance (6% reduction in methane production at the same system efficiency). The methanation inside the electrolyzer helped achieve a higher system efficiency (over 90%) by maintaining the electrolyzer temperature as high as possible. Unlike most biogas-upgrading systems, which behaved similarly to the standalone power-to-methane system, with an efficiency range of 70–86%, the direct biogas-electrolysis performed within a wide efficiency range (52–88%) and a reduced methane yield (50% less than the other systems operating at 70% efficiency). The detrimental methane reforming inside the electrolyzer was limited by increasing the reactant conversion and the electrolysis pressure. The various solid-oxide electrolyzer based power-to-methane concepts showed promising results for biogas upgrading applications. The practical choice of biogas-upgrading concepts will depend on the requirement of operational flexibility to handle variable renewable power considering different gas storage and carbon capture technologies.

Power-to-methane technologies have been regarded as a promising alternative to offer small- or large-scale, long-timescale (daily/weekly/seasonal) energy storage as well as the opportunity of utilizing CO2. The performance of the core component, the electrolyzer, largely determines how well a power-to-methane system can perform, making high-temperature solid-oxide electrolysis attractive because of its inherent high electrical efficiency. More importantly, solid-oxide electrolysis uniquely allows co-electrolysis of steam and CO2 for producing syngas, the composition of which can be readily, flexibly adjusted to synthesize different hydrocarbon fuels. In this paper, for both steam- and co-electrolysis, we comprehensively and comparatively investigate several critical design issues of a solid-oxide electrolyzer based power-to-methane system with fixed-bed methanation reactor and membrane-based methane upgrading: (1) system-level heat integration, (2) the impacts of operating variables (e.g., operating voltage, reactant utilization, anode/cathode feed ratio, and operating pressure of the methanation reactor and membrane) on system performances, (3) the competitiveness of the electrolyzer operation with pure oxygen production, and (4) the possibility of avoiding electrical heating, which is necessary for thermoneutral operation to heat up the electrolyzer feeds to the required temperature. To achieve this target, a multi-objective optimization platform with integrated heat cascade calculation is employed with experimentally-calibrated component models. The results show that, for both steam- and co-electrolysis, there is a trade-off between system efficiency and methane yield: pursuing a higher efficiency generally reduces the methane yield, which is a consequence of electrochemistry, stack cooling and system-level heat integration. Instead of sweep air, pure oxygen production is preferred only at small current density, which delivers the highest system efficiency but the lowest methane yield. When the electrolyzer operates exothermically, methane production and the total power consumption can vary in much wider ranges than those with the electrolyzer operating under thermoneutral mode, which leads to potential enhancement of operation flexibility and reliability. The co-electrolysis coupling with strongly-exothermic syngas methanation, in general, offers better heat-integration opportunity with sweep air, but less with pure oxygen production. In addition, several design heuristics, e.g., the operating pressure of the electrolyzer and methanation reactor, are concluded to potentially guide practical applications.

Electrochemical Impedance Spectroscopy (EIS) is extensively used to characterize Solid Oxide Cells (SOCs) to extract information on the elementary loss mechanisms. However, these individual mechanisms usually overlap in the frequency domain, requiring dedicated data processing for unambiguous identification. A powerful method for discriminating process contributions is the analysis by the Distribution of Relaxation Times (DRT). The de-convoluted spectrum of SOC generally presents, six peaks from mHz to hundreds of kHz. DRT peak-to-process attribution is often obtained by experimental sensitivity analysis. In the study, six parameters have been systematically varied: temperature, current density, partial pressure of O2 at the oxygen electrode, partial pressure of steam at the fuel electrode, total flow rates and fuel composition. The effect of wires inductance and different cell geometries has also been analyzed. The study provides detailed information about the contribution of the elementary processes to the total losses over a wide range of operation regimes. It further refines peak-to-process attributions by using a dynamic numerical model that includes gas and solid phase transport coupled with charge transfer and chemical reactions. Moreover, the non-univocal literature attribution of processes in the middle frequency range is clarified: strongly overlapping peaks cannot be separated even by DRT.