Scientific Papers in SCI
2022
2022
Química de Superficies y Catálisis
Sustainable routes for acetic acid production: Traditional processes vs a low-carbon, biogas-based strategy
Martin-Espejo, JL; Gandara-Loe, J; Odriozola, JA; Reima, TR; Pastor-Pérez, LScience of the Total Environment, 840 (2022) 156663
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The conversion of biogas, mainly formed of CO2 and CH4, into high-value platform chemicals is increasing attention in a context of low-carbon societies. In this new paradigm, acetic acid (AA) is deemed as an interesting product for the chemical industry. Herein we present a fresh overview of the current manufacturing approaches, compared to potential low-carbon alternatives. The use of biogas as primary feedstock to produce acetic acid is an auspicious alternative, representing a step-ahead on carbon-neutral industrial processes. Within the spirit of a circular economy, we propose and analyse a new BIO-strategy with two noteworthy pathways to potentially lower the environmental impact. The generation of syngas via dry reforming (DRM) combined with CO2 utilisation offers a way to produce acetic acid in a two-step approach (BIO-Indirect route), replacing the conventional, petroleum-derived steam reforming process. The most recent advances on catalyst design and technology are discussed. On the other hand, the BIO-Direct route offers a ground-breaking, atom-efficient way to directly generate acetic acid from biogas. Nevertheless, due to thermodynamic restrictions, the use of plasma technology is needed to directly produce acetic acid. This very promising approach is still in an early stage. Particularly, progress in catalyst design is mandatory to enable low-carbon routes for acetic acid production.
September, 2022 | DOI: 10.1016/j.scitotenv.2022.156663
Materiales Avanzados
Pre-Roman and Republican amphorae (III-I centuries b.C.) from production contexts of the Guadalquivir Basin: technical and compositional characterization
Moreno-Megías, V.; García-Fernández, F.J.; Martín-del-Río, J.J.; Borreguero-Cid, M.; Sánchez-Soto, P.J.Boletín de la Sociedad Española de Cerámica y Vidrio, 61 (2022) 498-515
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The present work consists of an archaeometric investigation concerning ceramic samples, mostly unpublished, of the III-I centuries b.C. They were found in connection with kilns of the city of Sevilla (Archbishop's Palace) and the countryside (Arrabal zone, Carmona). They are identified with evolved variations of Iron Age amphorae of Punic and Turdetanian tradition, or already Roman typologies. The main objectives of this research include their technological and compositional characterization as well as the comparison of the characteristics of each manufacture tradition.
An assemblage of 13 samples has been studied through petrographic analysis of thin sections, chemical analysis (X-ray fluorescence) and mineralogical analysis (X-ray diffraction). The chemical results showed the silico-aluminous and calcitic character of the samples, with variable contents of iron oxide as well as other minor elements and traces. The statistical treatment of the data by multivariant analysis has differentiated 3 conglomerates and one sample as an outsider. The mineralogical analysis has identified 8 crystalline phases, several of them already present in the raw materials and others formed by thermal treatment. It is interesting to note the illite, identified as dehydroxylated phase, anorthite, diopside and gehlenite. The petrographical analysis has identified 3 different petro-groups, which are correlated by a compositional point of view with the original context of the samples. Thus, according to these results, it has been possible to distinguish the manufactures of Sevilla from the Roman shapes, the common ware and the imitation types of Carmona.
It has been discussed the possible solid-state reactions which yielded the crystalline phases identified by X-ray diffraction, besides an estimation of firing temperatures between 820-850 degrees C in an oxidant atmosphere. Finally, the possible sources for the raw materials used in the fabrication of these amphorae have been proposed in the Guadalquivir River valley, considering their illitic-calcitic characteristics.
September, 2022 | DOI: 10.1016/j.bsecv.2021.03.008
Química de Superficies y Catálisis
Hydrogen production from landfill biogas: Profitability analysis of a real case study
Vidal-Barrero, F; Baena-Moreno, FM; Preciado-Cardenas, C; Villanueva-Perales, A; Reina, TRFuel, 324 (2022) 124438
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Hydrogen is not only considered as a cornerstone within renewable energy portfolio but it is also a key enabler for CO2 valorisation being a central resource for industrial decarbonization. This work evaluates the profitability of hydrogen production via combined biogas reforming and water-gas shift reaction, based on a real case scenario for landfill biogas plant in Seville (Spain). A techno-economic model was developed based on a process model and the discounted cash-flow method. A biogas flow of 700 m(3)/h (input given by the landfill biogas plant) was used as plant size and the analysis was carried out for two different cases: (1) use of already available energy sources at the industrial plant, and (2) solar energy generation to power the process. The economic outputs obtained showed that under the current circumstances, this hydrogen production route is not profitable. The main reason is the relatively low current hydrogen prices which comes from fossil fuels. A revenues analysis indicates that hydrogen from biogas selling prices between 2.9 and 5.7 euro/kg would be needed to reach profitability, which are considerably higher than the current hydrogen cost (1.7 euro/kg). A subsidy scheme is suggested to improve the competitiveness of this hydrogen production process in the short-medium term. A cost analysis is also performed, revealing that electricity prices and investment costs have a high impact on the total share (23-40% and 8-22%, respectively). Other potential costs reduction such as catalyst, labour and manteinance & overhead are also evaluated, showing that cutting-down production costs is mandatory to unlock the potential of hydrogen generation from biogas. Our work showcases the techno-economic challenge that green energy policies face in the path toward sustainable societies.
September, 2022 | DOI: 10.1016/j.fuel.2022.124438
Materiales para Bioingeniería y Regeneración Tisular
Sol-Gel Synthesis of Endodontic Cements: Post-Synthesis Treatment to Improve Setting Performance and Bioactivity
Song, X; Diaz-Cuenca, AMaterials, 15 (2022) 6051
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The sol-gel process is a wet chemical technique that allows very fine control of the composition, microstructure, and final textural properties of materials, and has great potential for the synthesis of endodontic cements with improved properties. In this work, the influence of different sol-gel synthesis variables on the preparation of endodontic cement based on calcium silicate with Ca/Si stoichiometry equal to 3 was studied. Starting from the most optimal hydraulic composition selected, a novel second post-synthesis treatment using ethanol was essayed. The effects of the tested variables were analyzed by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, nitrogen physisorption, and Gillmore needles to determine the setting time and simulated body fluid (SBF) immersion to measure the bioactive response in vitro. The results indicated that the sol-gel technique is effective in obtaining bioactive endodontic cements (BECs) with high content of the hydraulic compound tricalcium silicate (C3S) in its triclinic polymorph. The implementation of a novel post-synthesis treatment at room temperature using ethanol allows obtaining a final BEC product with a finer particle size and a higher CaCO3 content, which results in an improved material in terms of setting time and bioactive response.
September, 2022 | DOI: 10.3390/ma15176051
Tribología y Protección de Superficies
Influence of the carbon incorporation on the mechanical properties of TiB2 thin films prepared by HiPIMS
Sala, N; Abad, MD; Sanchez-Lopez, JC; Crugeira, F; Ramos-Masana, A; Colominas, CInternational Journal of Refractory Metals & Hard Materials, 107 (2022) 105884
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Nanostructured TiB2 and TiBC thin films with carbon contents up to 11 at. % were prepared by physical vapor deposition using high power impulse magnetron sputtering (HiPIMS) technology. The influence of carbon incorporation during the deposition of TiB2 coatings was investigated on the chemical composition, microstructure and mechanical properties by means of scanning electron microscopy, atomic force microscopy, x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), nanoindentation, scratch test, calotest and adhesion Daimler-Benz test. The results indicated that small additions of carbon up to 3 at. % improved the mechanical behavior and increased the adhesion of the TiB2 thin films. Hardnesses up to 37 GPa were reached and the adhesion of the coating to AISI D2 steel substrates increased from 11 to 18 N. XRD and XPS results showed that the carbon atoms are either occupying interstitial sites within the hexagonal structure of the TiB2 or forming bonds with titanium and boron atoms. The preferred orientation of the films determined by XRD also changed with the increasing carbon content in the (001) crystalline plane.
September, 2022 | DOI: 10.1016/j.ijrmhm.2022.105884
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