1. Chemistry of the iron-chlorine thermochemical cycle for hydrogen production utilizing industrial waste heatMatjaž Valant, Uroš Luin, 2024, original scientific article Abstract: This research presents an inventive thermochemical cycle that utilizes a reaction between iron and HCl acid for hydrogen production. The reaction occurs spontaneously at room temperature, yielding hydrogen and a FeCl2 solution as a by-product. Exploring the thermal decomposition of the FeCl2 by-product revealed that, at conditions suitable for utilization of low-temperature industrial waste heat (250 °C), chlorine gas formation can be circumvented. Instead, the resulting by-product is HCl, which is readily soluble in water, facilitating direct reuse in subsequent cycles. The utilization of low-temperature industrial heat not only optimizes resource utilization and reduces operational costs but also aligns with environmentally sustainable production processes. From the kinetic studies the activation energy was calculated to be 45 kJ/mol and kinetics curves were constructed. They showed significant kinetics at room temperature and above but rapid decrease towards lower temperatures. This is important to consider during real-scale technology optimization. The theoretical overall energy efficiency of the cycle, with 100% and 70% heat recuperation, was calculated at 68.8% and 44.8%, respectively. In practical implementation, considering the efficiency of DRI iron reduction technology and free waste heat utilization, the cycle achieved a 41.7% efficiency. Beyond its energy storage capabilities, the Iron-chlorine cycle addresses safety concerns associated with large-scale hydrogen storage, eliminating self-discharge, reducing land usage, and employing cost-effective storage materials. This technology not only facilitates seasonal energy storage but also establishes solid-state energy reserves, making it suitable for balancing grid demands during winter months using excess renewable energy accumulated in the summer.
Keywords: chemical cycles, hydrogen production, thermal decomposition, reaction kinetics, iron, chlorine
Published in RUNG: 12.01.2024; Views: 3033; Downloads: 45
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8. In-situ XAS study of catalytic N[sub]2O decomposition over CuO/CeO[sub]2 catalystsMaxim Zabilsky, Iztok Arčon, Petar Djinović, Elena Tchernychova, Albin Pintar, 2021, original scientific article Abstract: We performed in‐situ XAS study of N 2 O decomposition over CuO/CeO 2 catalysts. The Cu K‐edge and Ce L 3 ‐edge XANES and EXAFS analyses revealed the dynamic and crucial role of Cu 2+ /Cu + and Ce 4+ /Ce 3+ ionic pairs during the catalytic reaction. We observed the initial formation of reduced Cu + and Ce 3+ species during activation in helium atmosphere at 400 °C, while concentration of these species decreased significantly during steady‐state nitrous oxide degradation reaction (2500 ppm N 2 O in He at 400 °C). In‐situ EXAFS analysis further revealed a crucial role of copper‐ceria interface in this catalytic reaction. We observed dynamic changes in average number of Cu‐Ce scatters under reaction conditions, indicating an enlarging the interface between both copper and ceria phases, where electron and oxygen transfer occurs.
Keywords: in-situ XAS, Cu EXAFS, CuO/CeO2 nanorod catalys, N2O decomposition
Published in RUNG: 29.01.2021; Views: 4589; Downloads: 0
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9. Mediterranean Coastal Lagoons: The Importance of Monitoring in Sediments the Biochemical Composition of Organic MatterMonia Renzi, Francesca Provenza, Sara Pignattelli, Lucrezia Cilenti, Antonietta Specchiulli, Milva Pepi, 2019, original scientific article Abstract: Transitional water ecosystems are targeted by the European Union (EU) Water Framework Directive (WFD, CE 2000/60) monitoring programs in coastal zones. Concerning sediments, activities performed for the WFD focus on a few variables concerning the biochemical composition of organic matter. Our research reports the effects of oxygen availability on the biochemical composition of organic matter in sediments to highlight levels of targeted variables in time and, according to the depth of sediment layer, both under oxygenated and anoxic conditions in a mesocosm study on sediment cores. Results provide evidence that tested factors of interest (i.e., disturbance type, oxygenic versus anoxic conditions; persistence time of disturbance, 0–14 days; penetration through sedimentary layers, 0–10 cm depth) are able to significantly affect the biochemical composition of organic matter in sediments. Large part of the variables considered in this study (total organic carbon (TOC), total phosphorous (TP), total sulphur (TS), Fe, carbohydrates (CHO), total proteins (PRT), biopolymeric carbon (BPC), chlorophyll-a (Chl-a) are significantly affected and correlated to the oxygenation levels and could be good early indicators of important changes of environmental conditions. Monitoring activities performed under WFD guidelines and management strategies of Mediterranean coastal lagoon ecosystems shall include the biochemical composition of organic matter in sediment to provide an exhaustive picture of such dynamic ecosystems.
Keywords: decomposition, transitional water ecosystems, organic loads, mesocosm, monitoring programs
Published in RUNG: 20.04.2020; Views: 4282; Downloads: 0
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