Jorge R. Frade

University of Aveiro | UA · Department of Materials and Ceramics Engineering

(Free download until 5 July 2022: https://authors.elsevier.com/c/1f4rI3iH4IG7C). In the present study, catalytic gasification of biomass was investigated by incorporation of a supported Fe2-xMnxO3 catalyst into the freeboard zone of a bubbling fluidized bed gasifier. The material was processed by combining incipient wetness impregnation with micro...

In this study, granulated siderite/concrete-based catalysts are proposed for in-situ applications in biomass steam gasification, seeking H2-enrichement by the contribution of water gas shift and CO2 adsorption. A cost-effective procedure has been applied for the preparation of granulated catalysts. Water Gas Shift reaction was studied in a fixed be...

The alkaline electrolytic production of iron is gaining interest due to the absence of CO2 emissions and significantly lower electrical energy consumption when compared with traditional steelmaking. The possibility of using an iron-bearing pseudobrookite mineral, Fe2TiO5, is explored for the first time as an alternative feedstock for the electroche...

MXenes, a family of two-dimensional (2D) transition metal carbides, nitrides and carbonitrides based on earth-abundant constituents, are prospective candidates for energy conversion applications, including photocatalysis. While the activity of individual MXenes towards various photocatalytic processes is still debatable, these materials were proved...

Liquid metals have emerged as potential materials for fuel cell and battery applications due to their suitable redox potentials, fast redox kinetics, and/or active participation in electrode reactions. In this work, we study the electrochemical oxidation behavior of antimony-lead melts by the use of a robust, yttrium-stabilized zirconia based, test...

The electrochemical reduction of iron oxides in alkaline media arises as a novel approach for ironmaking and iron-rich waste valorisation. Strong advantages and attractive aspects of alkaline electroreduction include lower electric energy consumption, absence of CO2 emissions, and non-polluting valuable by-products such as H2 and O2. Another potent...

Ceramics samples with the nominal composition [(ZrO2)0.95(Y2O3)0.05]1-x[PrOy]x and praseodymia contents of x = 0.05–0.15 were prepared by the direct firing of compacted 5YSZ + PrOy mixtures at 1450–1550 °C for 1–9 h and characterized for prospective applicability in reversible solid oxide cells. XRD and SEM/EDS analysis revealed that the dissolutio...

In this study, a novel Fe2-xNixTiO5 catalyst for potential applications in biomass gasification gas cleaning/upgrading was investigated. The material was successfully synthesized through combined mechanical activation and microwave firing. Catalytic steam reforming was studied in a fixed bed tubular reactor, using a mixture of toluene and naphthale...

Concrete was evaluated as low-cost catalyst for in-situ application in an autothermal 80 kWth pilot-scale bubbling fluidized bed direct (air) biomass gasifier. To improve the understanding of the observed phenomena, the process was also evaluated in smaller-scale reactive system, namely an externally heated 3 kWth bench-scale bubbling fluidized bed...

Tar compounds are inevitably present in the raw producer gas from biomass gasification and currently represent the main barrier for the commercial breakthrough of gasification technologies. In the present work, tar concentration in the producer gas from direct gasification of distinct types of residual forest biomass from eucalyptus in a 5 kWth bub...

This work explores the possibilities for the processing of Ni- and Ti3C2Tx (T = OH, O) MXene-containing composite electrodes, by co-pressing and plastic deformation or by etching of the electrodes prepared directly by self-propagation high-temperature synthesis (SHS). Various material design approaches were also explored. In order to tune the Ti3C2...

Manganese-substituted 5 mol.% yttria-stabilized zirconia (5YSZ) was explored as a prospective material for protective interlayers between electrolyte and oxygen electrodes in reversible solid oxide fuel/electrolysis cells. [(ZrO2)0.95(Y2O3)0.05]1-x[MnO y ] x (x = 0.05, 0.10 and 0.15) ceramics with cubic fluorite structure were sintered in air at 16...

In this study, 5Y-PSZ-based ceramics with 15 mol.% of manganese oxide were obtained from PSZ+MnO2 powders mixtures, by pressing and direct firing. The resulting materials show a stable cubic fluorite structure with only minor traces of segregated manganese oxides and relative density from 90% to 98%. The linear thermal expansion coefficient is in t...

The stability and reproducibility of the electric properties in n-type doped ZnO represent known bottlenecks towards potential thermoelectric applications. The degradation is promoted by the vanishing of the electronic defects on oxidation and irreversible exsolution of the phase impurities. This work proposes a microstructural mechanism showing th...

BaZrO3-based materials have been intensively researched due to their potential application as high-temperature proton conductors in devices such as proton ceramic fuel cells (PCFCs), separation membranes and electrolysers. Nonetheless, their implementation in these devices has often been constrained due to their processing difficulties, namely the...

Porous 3 YTZ-Al2O3 membranes were processed aiming controlled cellular microstructures for potential separation and electrochemical applications. The processing method relies on emulsification of mixed suspensions of Al2O3 and 3 YTZ powders in sunflower oil. Taguchi experimental planning was used to seek guidelines for optimization of microstructur...

The present work aims to evaluate relevant effects of the size of substituting rare-earth cation on electrical conductivity and thermal expansion of donor-doped SrTiO3 as ceramic components of electrochemical solid electrolyte cells. A series of strontium titanate-based ceramics with a moderate doping level and different cation stoichiometry, Sr0.9...

Electrochemical reduction of iron oxides into zero-valent iron (ZVI, Fe0) is a promising alternative to the traditional methods used for iron production. The electrochemical deposition of Fe0 from hematite and hematite-based Fe2−xAlxO3 ceramic in alkaline suspensions (10 M of NaOH) was assessed at relatively low temperature (90 °C). Ceramic composi...

Highly porous zirconia ceramics for prospective use as separators in alkaline electrolysis cells have been processed by emulsification of paraffin in concentrated zirconia suspensions. Effects of processing parameters on porosity, cell size distribution, and pore interconnectivity are studied through Taguchi statistical design. The porosity of zirc...

Cellular ceramics were processed by slip casting of alumina suspensions emulsified with sunflower oil. A model behavior was derived on assuming that the templating dispersed phase and its droplet size distribution are retained as porosity in the resulting cellular ceramics, whereas the continuous ceramic suspension evolves to dense struts and thin...

The development of thermoelectrics for high-temperature applications imposes several essential requirements on the material properties. In some energy-conversion scenarios, the cost and thermal stability requirements may dominate over efficiency issues, making abundant, high-temperature-stable and low-toxic oxides attractive alternative thermoelect...

The feasibility of recycling red mud waste by its direct transformation into highly-porous cellular ceramics was successfully demonstrated. Ceramic materials with designed cellular porosity were processed by emulsification of red mud suspensions with liquid paraffin. Taguchi method was used to study the effects provided by varying the red mud load...

This paper reports a novel composite-based processing route for improving the electrical performance of Ca3Co4O9 thermoelectric (TE) ceramics. The approach involves the addition of metallic Co, acting as a pore filler on oxidation, and considers two simple sintering schemes. The (1-x)Ca3Co4O9/xCo composites (x = 0%, 3%, 6% and 9% vol.) have been pr...

This work aims at the preparation of multifunctional titania-based photocatalysts with inherent capabilities for thermal co-activation and stabilisation of anatase polymorph, by designing the phase composition and microstructure of rutile-silicon carbide mixture. The processing involved a conventional solid state route, including partial pre-reduct...

In this work, in-situ application of natural occurring ilmenite (FeTiO3) for upgrading the producer gas from a pilot-scale bubbling fluidized bed gasifier was performed and its influence on the gas characteristics and gasifier performance was analyzed. Without using ilmenite, the producer gas average composition (volumetric basis, dry gas) was 15.2...

Electrochemical reduction of low-conductive hematite-based ceramics represents a novel approach for iron recovery and waste valorisation. The process itself allows a flexible switching between hydrogen generation and iron reduction, important for the intermittent renewable-energy-powered electrolytic process. The present study focuses on the direct...

Perovskite-like LaNiO3-δ was evaluated as potential oxygen electrode material for solid oxide electrolysis cells. Compared to the Ruddlesden-Popper Lan+1NinO3n+1 (n = 1,2,3) counterparts, LaNiO3-δ exhibits higher p-type metallic-like conductivity under oxidizing conditions (450 S×cm-1 at 800°C for highly porous ceramics) together with a moderate th...

Zinc oxide (ZnO) has being recognised as a potentially interesting thermoelectric material, allowing flexible tuning of the electrical properties by donor doping. This work focuses on the assessment of tantalum doping effects on the relevant structural, microstructural, optical and thermoelectric properties of ZnO. Processing of the samples with a...

Olive mill wastewater is a challenging effluent, especially due to its toxicity related to the presence of phenolic compounds. Fenton’s process was analysed on the abatement of phenolic acids typically found in this kind of effluents. To overcome the main drawback of Fenton’s process, a waste from the aluminium industry commonly called red mud was...

Natural ilmenite has been proposed as potential low-cost catalyst for biomass gasification due to its mechanical stability and thermochemical properties at high temperature. Previously works demonstrated that ilmenite showed high activity in water-gas shift reactions, but its limited catalytic activity in tar conversion requires improved performanc...

The present work explores the preparation of fayalite α‐Fe2SiO4, the iron‐rich end‐member of the olivine solid‐solution series, as a tar removal catalyst for biomass gasification. The synthetic procedure was developed starting from the stoichiometric mixture of hematite and micron‐size silicon carbide and employing thermal treatments in controlled...

Titania-based ceramics with adjustable anatase-rutile fractions were obtained by milling of anatase, quartz and corundum precursors, uniaxial pressing and firing at 1100 °C. The influence of silica and alumina, combined with milling time and compaction pressure, was studied by design of experiments. The L9 orthogonal array with a three-level noise...

This work focuses on demonstration of reliable and versatile method for processing cellular mayenite (Ca12Al14O33) -based ceramics with designed porosity, with emphasis on potential catalytic applications. Highly porous (up to 82% of open porosity) monoliths were obtained by emulsification of liquid paraffin in aqueous suspensions of mixed CaCO3 an...

Free download for 50 days at: https://authors.elsevier.com/a/1YEFj~2-EvW7U A quaternary bioactive glass of high silica content was used as a model system for flexible design of powder characteristics obtained by ball milling. The dependence on milling time was used to demonstrate consistency with the expected correlation between comminution and cum...

This work aims to explore zirconium as a possible dopant to promote thermoelectric performance in bulk ZnO-based materials, both within the single-doping concept and on simultaneous co-doping with aluminum. At 1100–1223 K mixed-doped samples demonstrated around ∼2.3 times increase in ZT as compared to single-doped materials, reaching ∼0.12. The sim...

The applicability of perovskite-type SrVO3-δ in high-temperature electrochemical energy conversion technology is hampered by the limited stability domain of the perovskite phase. The present work aimed at a compromise between the phase stability and electrical performance by designing the solid solutions in the SrVO3-SrTiO3 system. Increasing titan...

In this work, the concept of biomass direct (air) gasification was demonstrated in a pilot-scale bubbling fluidized bed and the influence of in-situ application of low-cost catalytic materials on the produced gas characteristics and gasifier performance was analyzed. Three different low-cost catalysts were tested: bottom bed ashes resulting from co...

Iron oxides are attractive for a variety of applications, since they offer unique physical and chemical properties, while being abundant and environmentally friendly. Some of those potential applications, including electrochemical and catalytic systems, require ceramics with designed porosity and well-developed percolation networks. In the present...

Multimodal porous cellular alumina structures (monoliths) were prepared by an emulsion-gel casting technique using eco-friendly and inexpensive lipids such as corn oil, castor oil, margarine and their mixtures as the dispersed phase. The monoliths obtained showed good mechanical stability, exhibiting compressive strengths in the range of 8–50 N·mm⁻...

Zinc oxide (ZnO) has a very broad and versatile range of applications provided by high abundance, optical and electrical properties, which can be further tuned by donor substitution. Al-doped ZnO is probably the most thoroughly investigated material regarding thermoelectric properties. Fairly reasonable electrical properties of donor-doped zinc oxi...

A lignocellulosic residue from the pulp and paper industry (primary sludge) was employed to obtain carbon based fluorescent nanomaterials. The unprecedented preparation of the Carbon Quantum Dots (CQDs) was carried out using a microwave assisted reaction catalyzed by a solid acid catalyst, which induced the formation of CQDs. The obtained CDQs were...

Magnetite (Fe3O4) offers unique physical and chemical properties, being an important material for many industrial applications. Certain limitations on the application conditions are, however, imposed by the redox stability issue. Fine control of the iron oxidation states represents a challenge for materials engineering. The present work explores re...

Thermal properties of powders are critical material attributes that control temperature rise during tableting and roll compaction. In this study, various analytical methods were used to measure the thermal properties of widely used pharmaceutical excipients including microcrystalline cellulose (MCC) of three different grades (Avicel PH 101; Avicel...

Members of the perovskite solid solution BaZr1-xPrxO3-δ (0.2 ≤ x ≤ 0.8) with potential high-temperature electrochemical applications were synthesized via mechanical activation and high-temperature annealing at 1250 °C. Structural properties were examined by Rietveld analysis of neutron powder diffraction and Raman spectroscopy at room temperature,...

Cellular Al2TiO5 and Al2TiO5 – Al2O3 composite ceramics were obtained by emulsification of liquid paraffin in aqueous suspensions of mixed TiO2 + Al2O3 powders, with subsequent burnout of the organic phase and 2-step reactive firing at high temperatures. The reactants ratio and paraffin to suspension volume ratio were used as primary parameters to...

This work focuses on designing highly-porous cellular NiAl2O4-based spinel ceramics through combined suspension emulsification/reactive sintering and further decoration of the pore surfaces by Ni nanoparticles for potential applications in heterogeneous catalysis. Due to kinetic limitations and specific porous structure, the reduction occurs withou...

This work proposes a new approach for electrochemical reduction of hematite to magnetite and/or metallic iron, based on ceramic cathodes with designed microstructures. The processing method, involving emulsification of concentrated aqueous ceramic suspensions with melted paraffin, enables preparation of cellular hematite ceramics possessing open po...

The interplay of unique cation arrangement and redox coupling in ferrospinels offers a wide range of magnetic and catalytic properties, evaluated mostly for low and intermediate temperature applications. This work focuses on high-temperature properties of magnesium-substituted magnetite, for prospective high temperature applications such as electro...

Driven by a need to develop low-cost and thermally stable materials for thermoelectric applications, donor-substituted strontium titanate is considered as a promising alternative to traditional thermoelectrics. The complex defect chemistry of SrTiO3-based materials imposes various limitations on identifying the relevant effects exerted on the elect...

Changes in nominal composition of the perovskite (ABO3) solid solution Ba1-x(Zr,Pr)O3-δ and adjusted firing conditions at very high temperatures were used to induce structural changes involving site redistribution and frozen-in point defects, as revealed by Raman and photoluminescence spectroscopies. Complementary magnetic measurements allowed quan...

Cellular ceramics were prepared by emulsification of aqueous alumina suspensions with liquid paraffin, using collagen as a shape stabilizer and a dispersant to adjust viscosity. Rheological measurements of emulsions and microstructural analysis of the sintered samples were performed. The results show that the concentration of collagen, dispersant c...

Ln-substituted SrTiO3 is a promising material for energy conversion technologies such as thermoelectric generators and solid oxide fuel/electrolysis cells. In this study, formation of local structures enabling accommodation of excess oxygen in perovskite matrix of SrTiO3 and related redox behavior were assessed employing static lattice simulations...

Driven by environmental challenges and global movement to carbon-lean technologies, the pyroelectrolysis process for iron extraction from oxide melts is being proposed as an interesting alternative to the traditional steelmaking. Still, one of the critical issues impacting the prospects of this technology includes the development of appropriate ano...

This work explores the possibilities to design magnetite-based spinels through multiple simultaneous co-substitutions with transition metal cations, with emphasis on redox behavior and electronic transport. For the first time this approach was assessed for high-temperature applications, which is of particular interest for the development of consuma...

A promising concept of consumable anode materials for high-temperature pyroelectrolysis process, which is expected to overcome the environmental and economical impacts of classical extractive metallurgy, relies on substituted magnetite-based ferrospinels, presenting high electrical conductivity, appropriate refractoriness, and redox stability. The...

Magnesium aluminosilicates (MAS) represent a great importance for many electrical and catalytic applications. Recently, MAS-based glasses were considered as prospective for use as an electrolyte in steel making by molten oxide electrolysis process, an alternative electrometallurgical technique which offers prospects for environmental and economic a...

This work focuses on assessing the feasibility of cathodic iron extraction from the magnetite based precursors. For this, electrochemical processes at Fe3O4/alkaline electrolyte interface were screened by cycling voltammetry. Based on these results, one obtained guidelines for selecting the conditions (i.e., potential and temperature) where efficie...

Strontium vanadate-based perovskites are considered as promising anode materials for hydrocarbon-fueled solid oxide fuel cells due to high electronic conductivity, sulfur tolerance and resistance to coking, but possess a narrow phase stability domain precluding their use in practice. This study aimed at expanding the perovskite phase stability doma...

Phase relationships, transport properties and thermomechanical behavior of acceptor- and donor-co-substituted Gd2Ti2O7 were studied for possible application in solid oxide fuel cell anodes. The range of (Gd1-xCax)2(Ti1-yMoy)2O7-δ solid solutions with a cubic pyrochlore-type structure was found to be limited to 0.10 < x < 0.15 and 0.05 < y < 0.10 un...

Magnesium aluminosilicate glasses were proposed as molten electrolytes for iron pyroelectrolysis, an alternative electrometallurgical technique offering environmental and economic advantages over traditional steelmaking. This work focuses on mechanisms of iron incorporation in the glass network and related effects on physical properties. The study...

In recent years, the processing of porous ceramic materials with designed microstructural/physical properties, to be used in applications as catalysis, filtration, building, fuel cells, isolators, etc. was being strongly studied. Usually, porous ceramics is obtained by strategies as replication, gel casting and emulsification of ceramics suspension...

Transition aluminas have been intensively studied in last decades for a wide range of applications. More recently, processing strategies for porous cellular alumina were also proposed, targeting potential catalytic and separation applications for sustainable energy and chemical technologies. In this context, porous -alumina monoliths were prepared...