QUI_Articles
http://hdl.handle.net/10234/8618
2024-03-29T07:35:00ZThe role of the LATP particle size as a cornerstone of the cold sintering process
http://hdl.handle.net/10234/206067
The role of the LATP particle size as a cornerstone of the cold sintering process
Mormeneo-Segarra, Andrés; Ferrer Nicomedes, Sergio; Vicente-Agut, Nuria; Barba-Juan, Antonio
An innovative sintering technique, the Cold Sintering Process (CSP), has been employed to obtain dense Li1.3Al0.3Ti1.7(PO4)3 (LATP) Solid-State Electrolytes (SSE) by optimising the particle size (d50) of the starting powder. The CSP is carried out at 700 MPa, 150 ºC, and 90 min of sintering time, using acetic acid solution as Transient Liquid Phase (TLP). The CSP lowers the LATP sintering temperatures almost 1000 ºC. To study the electrical properties, an in operando Electrochemical Impedance Spectroscopy (EIS) technique has been used. The optimum d50 is 0.415 µm, yielding to competitive microstructure and electrical properties (ionic conductivity of 6.93·10−5 S cm−1 at 30 ºC, activation energy of 0.363 eV, and a relative density of 81.2 ± 0.8%). Relative density, ionic conductivity and TLP content must be balanced, because at small d50, although relative density is enhanced the ionic conductivity is reduced. A packing model has been used to understand this behaviour and the mass transfer mechanisms.
2024-02-13T00:00:00ZDrivers of divergent trends in tropospheric ozone hotspots in Spain, 2008–2019
http://hdl.handle.net/10234/205911
Drivers of divergent trends in tropospheric ozone hotspots in Spain, 2008–2019
Massague, Jordi; Escudero Tellechea, Miguel; Alastuey, Andres; Monfort, Eliseo; Gangoiti, Gotzon; Petetin, Hervé; Pérez García-Pando, Carlos; Querol, Xavier
This study aimed to investigate the causes of contrasting ozone (O3) trends in Spanish O3 hotspots between 2008 and 2019, as documented in recent studies. The analysis involved data on key O3 precursors, such as nitrogen oxides (NOx) and volatile organic compounds (VOCs), among other species, along with meteorological parameters associated with O3. The dataset comprised ground-level and satellite observations, emissions inventory estimates, and meteorological reanalysis.
The results suggest that the increasing O3 trends observed in the Madrid area were mostly due to major decreases in NOx emissions from the road transport sector in this urban VOC-limited environment, as well as variations in meteorological parameters conducive to O3 production. Conversely, the decreasing O3 trends in the Sevilla area likely resulted from a decrease in NOx emissions in a peculiar urban NOx-limited regime caused by substantial VOC contributions from a large upwind petrochemical area. Unchanged O3 concentrations in other NOx-limited hotspots may be attributed to the stagnation of emissions from sectors other than road transport, coupled with increased emissions from certain sectors, likely due to the economic recovery from the 2008 financial crisis, and the absence of meteorological variations favorable to O3 production.
In this study, the parameters influencing O3 varied distinctively across the different hotspots, emphasizing the significance of adopting an independent regional/local approach for O3 mitigation planning. Overall, our findings provide valuable insights into the causes of contrasting O3 trends in different regions of Spain, which can be used as a basis for guiding future measures to mitigate O3 levels.
2023-01-01T00:00:00ZMulti-step oxidative carboxylation of olefins with carbon dioxide by combining electrochemical and 3D-printed flow reactors
http://hdl.handle.net/10234/205850
Multi-step oxidative carboxylation of olefins with carbon dioxide by combining electrochemical and 3D-printed flow reactors
Iglesias, Diego; Tinajero Naranjo, Cristopher Alberto; Marchetti, Simone; Roppolo, Ignazio; Zanatta, Marcileia; Sans, Victor
The selective oxidation of alkenes to form epoxides followed by the cycloaddition of CO2 is a sustainable and cost-efficient method to generate functional cyclic carbonates. The use of a continuous-flow process allows seamless integration of both reactions sequentially under tailored and optimised conditions for each of the transformations to produce the cyclic carbonates. Here, we successfully demonstrate olefin electrooxidation, followed by the cycloaddition of CO2 to produce cyclic carbonates employing 3D printed (3DP) reactors in continuous flow and without the need for intermediate purification steps. This approach is highly convenient since the electrolyte (ammonium salt) from the electrochemical reaction acts also as a catalyst in the cycloaddition reaction. Different parameters in the electrochemical oxidation were evaluated (e.g. solvent, electrode, electrolyte, concentrations and current intensity). Complete conversion and high selectivity (>80%) towards the formation of epoxide were observed. The electrolyte served as a catalyst for the cycloaddition reaction. The digital design of the 3DP reactor played a crucial role in efficient performance of the cycloaddition reaction, showing increased productivity (a space-time yield of 4.38 gprod h−1 L−1) compared to that of a coil and a packed bed reactor. Consecutive CO2 cycloaddition reactions were also evaluated and a global yield of 83% of cyclic carbonates was observed for styrene. The system exhibited stability and stable activity for at least 20 h.
2023-01-01T00:00:00ZEngineering and scaling-up ceramic tiles with humidity self-regulation functionality
http://hdl.handle.net/10234/205780
Engineering and scaling-up ceramic tiles with humidity self-regulation functionality
Castellano, Javier; Sanz-Solana, Vicente; Cañas Recacha, Eugeni; Sánchez, Enrique.
The humidity regulation in the interior spaces of buildings by means of passive solutions that do not require energy consumption is a topic of great interest due to the current needs for comfort and energy efficiency. This paper addresses the engineering of humidity regulating ceramic tiles that incorporate a functional coating formulated from gibbsite together with other common raw materials whose moisture regulating capacity has been demonstrated previously. A multi-layer coating tile system has been proposed, consisting of the following elements: an engobe layer, the functional coating with the regulating capacity, a decoration by inkjet technology and a protective topcoat glaze.
This system has been analysed with moisture adsorption–desorption tests. The moisture regulation capacity and the effect of the coating thickness on this property have been determined, allowing to optimise the functionality.
Finally, an analysis of the humidity regulation has been performed on the basis of demonstrators or small-sized cubicles that simulate the conditions of final use in rooms of buildings. The results show the different behaviour of the demonstrator with functional tiles in relation to conventional tiles, with an indoor ambient humidity that remains in the comfort zone for longer periods of time.; La regulación de humedad en espacios interiores mediante soluciones pasivas que no requieren consumo energético es un tema de gran interés debido a las necesidades actuales de confort y de eficiencia energética. Este trabajo aborda la ingeniería de baldosas cerámicas reguladoras de humedad que incorporan un recubrimiento funcional formulado a partir de gibbsita junto con otras materias primas comunes cuya capacidad reguladora de humedad ha sido demostrada previamente. Se ha propuesto un sistema de baldosa con recubrimiento multicapa compuesto por los siguientes elementos: una capa de engobe, el recubrimiento funcional con capacidad reguladora, una decoración por tecnología de inyección de tinta y un esmalte protector.
Este sistema ha sido analizado mediante ensayos de adsorción-desorción de humedad. Se ha determinado la capacidad de regulación de humedad y el efecto del espesor del recubrimiento sobre esta propiedad, lo que ha permitido optimizar la funcionalidad.
Finalmente, se ha realizado un análisis de la regulación de humedad mediante demostradores o pequeños cubículos que simulan las condiciones de uso final en estancias de edificios. Los resultados muestran el diferente comportamiento del demostrador con baldosas funcionales en relación con baldosas convencionales, con una humedad ambiental interior que se mantiene durante más tiempo en zona de confort.
2023-11-01T00:00:00Z