TY - GEN A1 - Gonzalez-Castano, Miriam A1 - Navarro de Miguel, Juan Carlos A1 - Boelte, Jens-H. A1 - Centeno, Miguel Angel A1 - Klepel, Olaf A1 - Arellano-García, Harvey T1 - Assessing the impact of textural properties in Ni–Fe catalysts for CO2 methanation performance T2 - Microporous and Mesoporous Materials N2 - In heterogeneous catalysis, the benefits of employing adequate textural properties on the catalytic performances are usually stated. Nevertheless, the quantification of the extent of improvement is not an easy task since variations on the catalysts’ specific areas and pore structures might involve modifications on a number of other surface catalytic features. This study establishes the impact of the catalyst textural properties on the CO2 methanation performance by investigating bimetallic Ni–Fe catalysts supported over carbon supports with different textural properties regarding surface area and pore structure. The comparable metal loading and dispersions attained for all systems enabled establishing forthright relationships between the catalyst textural properties and CO2 methanation rate. Once the influence of the external mass diffusions on the catalysts’ performance was experimentally discarded, the estimated Thiele modulus and internal effectiveness (φ and ηEff) values showed that the catalyst performance was majorly governed by the surface reaction rate whilst the pore size affected in no significant manner within the examined range (Dpore = 10.2 to 5.8 nm). Therefore, the rapport between the catalyst performance and surface area was quantified for the CO2 methanation reaction over Ni–Fe catalysts: increasing the surface area from 572 to 802 m2/g permit obtaining ca. 10% higher CO2 conversions. KW - Ni-Fe catalysts KW - CO2 methanation KW - Surface area KW - Pore size KW - Thiele modulus Y1 - 2021 U6 - https://doi.org/10.1016/j.micromeso.2021.111405 SN - 1387-1811 VL - 327 ER - TY - GEN A1 - González-Arias, Judith A1 - Gomez, X. A1 - Gonzalez-Castano, Miriam A1 - Sanchez, Marta Elena A1 - Rosas, J. G. A1 - Cara-Jiménez, Jorge T1 - Insights into the product quality and energy requirements for solid biofuel production: A comparison of hydrothermal carbonization, pyrolysis and torrefaction of olive tree pruning T2 - Energy N2 - For a bio-economy establishment, understanding the energy consumption needs to produce solid biofuels is a key point. Herein, olive tree pruning was treated by both dry (pyrolysis and torrefaction) and wet (hydrothermal carbonization) thermal treatments. Product yield, solid quality and energy consumption were assessed. The solids were characterized by means of chemical and thermogravimetric analysis. For all treatments, coal-like solid products were obtained, with higher heating values (HHV) of almost 30 MJ kg−1 in most of the conditions evaluated. Chars from pyrolysis presented the greater carbon content (between 76 and 85 wt%) but also the higher ash content (ranging from 6 to 9 wt%). From an energy consumption perspective, torrefaction registered the lowest energy consumption (between 5.85 and 20.76 MJ kg−1 char). The highest energy contents per kilogram of char produced were also reflected in torrefaction samples, with values around 11 MJ kg−1 char. Although the obtained HHVs were greater for pyrolysis chars the higher mass yields obtained in torrefaction makes it more profitable. The least severe conditions allowed to obtain a positive energy balance only with the solid phase considered. Nonetheless, further room for improvement is possible since the gas and liquid phases may also be valorised. KW - Hydrothermal carbonization KW - Slow pyrolysis KW - Torrefaction KW - Olive tree pruning KW - Biofuel Y1 - 2021 U6 - https://doi.org/10.1016/j.energy.2021.122022 SN - 0360-5442 VL - Vol. 238, part C (2022) ER - TY - GEN A1 - González-Castaño, Miriam A1 - Hani Kour, M. A1 - González-Arias, Judith A1 - Baena-Moreno, Francisco Manuel A1 - Arellano-García, Harvey T1 - Promoting bioeconomy routes: From food waste to green biomethane. A profitability analysis based on a real case study in eastern Germany T2 - Journal of Environmental Management N2 - Profitability studies are needed to establish the potential pathways required for viable biomethane production in the Brandenburg region of Germany. This work study the profitability of a potential biomethane production plant in the eastern German region of Brandenburg, through a specific practical scenario with data collected from a regional biogas plant located in Alteno (Schradenbiogas GmbH & Co. KG). Several parameters with potential economic influence such as distance of the production point to the grid, waste utilization percentage, and investment, were analyzed. The results illustrate a negative overall net present value with the scenario of no governmental investment, even when considering trading the CO2 obtained throughout the process. Subsidies needed to reach profitability varied with distance from 13.5 €/MWh to 19.3 €/MWh. For a fixed distance of 15 kms, the importance of percentage of waste utilization was examined. Only 100% of waste utilization and 75% of waste utilization would reach profitability under a reasonable subsidies scheme (16.3 and 18.8 €/MWh respectively). Concerning the importance of investment, a subsidized investment of at least 70% is demanded for positive net present values. Besides, the sensitivity analysis remarks the energy consumption of the biogas upgrading stage, the electricity price, and the energy consumption of biogas production as major parameters to be tackled for the successful implementation of biogas upgrading plants. The results here obtained invite to ponder about potential strategies to further improve the economic viability of this kind of renewable projects. In this line, using the CO2 separated to produce added-value chemicals can be an interesting alternative. KW - Biomethane production KW - Biogas upgrading KW - Green energy KW - Governmental incentives KW - Waste valorization Y1 - 2021 U6 - https://doi.org/10.1016/j.jenvman.2021.113788 SN - 0301-4797 VL - 300 ER - TY - GEN A1 - González-Arias, Judith A1 - Baena-Moreno, Francisco Manuel A1 - González-Castaño, Miriam A1 - Arellano-García, Harvey T1 - Economic approach for CO2 valorization from hydrothermal carbonization gaseous streams via reverse water-gas shift reaction T2 - Fuel N2 - In this work the economic performance of valorizing the gaseous stream coming from hydrothermal carbonization (HTC) of olive tree pruning is presented as a novel strategy to improve the competitiveness of HTC. The valorization of the commonly disregarded gaseous stream produced in this thermochemical treatment was proposed via the Reverse Water–Gas Shift reaction. This allows to obtain syngas for selling and therefore improving the overall economic performance of the process. To this end, three plant sizes were selected (312.5, 625 and 1250 kg/h of biomass processing). The parameters with a higher share in the total cost distribution along with the revenues from the hydrochar and the syngas selling were further evaluated. The results evidenced that with the assumptions taken, the overall process is still not profitable. To reach profitability, syngas selling prices between 2.2 and 3.4 €/m3 are needed, revealing that this proposal is not economically attractive. Alternatively, a lack of competitiveness in the current market is revealed with hydrochar selling prices between 0.41 and 0.64 €/kg to make the project profitable. The catalyst cost, sharing approximately 20% of the total cost, is the parameter with the highest impact in the total economics of the process. The second one is the hydrogen price production, representing almost 16% of the total. Investment subsidies are also examined as a potential tool to cover part of the initial investment. These results evidenced that further efforts and measures are needed to push forward in the path towards circular economy societies. KW - Hydrothermal carbonization KW - CO2 waste valorization KW - Reverse water gas shift KW - Profitability analysis Y1 - 2022 U6 - https://doi.org/10.1016/j.fuel.2021.123055 SN - 0016-2361 VL - 313 SP - 1 EP - 7 ER - TY - GEN A1 - Tarifa, Pilar A1 - González-Castaño, Miriam A1 - Cazaña, F. A1 - Monzón, Antonio A1 - Arellano-García, Harvey T1 - Development of one-pot Cu/cellulose derived carbon catalysts for RWGS reaction T2 - Fuel N2 - A series of Cu-based catalysts promoted with Fe, Ce and Al supported on cellulose derived carbon (CDC) was prepared by biomorphic mineralization technique for the RWGS reaction. The excellent Cu dispersions (7 nm at ca. 30 wt% Cu) along with the resilience toward metal sintering attained in the entire catalysts series highlight one-pot decomposition of cellulose under reducing atmosphere as an excellent synthesis method which enable obtaining well-dispersed Cu nanoparticles. The influence of incorporating a second metal oxide over biomorphic mineralized Cu systems was also investigated. With the Cu-Ce system exhibiting the best catalyst performance of the catalysts’ series, the enhanced catalyst performances were majorly ascribed to the catalysts redox properties. The lineal relationships stablished between oxygen exchange capacity and CO2 conversion rates remarks the employed sequential H2/CO2 cycles as an effective methodology for screening the catalytic performance of Cu catalysts for RWGS reaction. KW - RWGS KW - Cu catalysts KW - Oxygen exchange capacity KW - Cellulose derived carbon Y1 - 2022 U6 - https://doi.org/10.1016/j.fuel.2022.123707 SN - 0016-2361 VL - Vol. 319 ER - TY - GEN A1 - Mahmood, Safdar A1 - González-Castaño, Miriam A1 - Penkova, Anna A1 - Centeno, Miguel Angel A1 - Odriozola, José Antonio A1 - Arellano-García, Harvey T1 - CO2 methanation on Ni/YMn1-xAlxO3 perovskite catalysts T2 - Applied Materials Today N2 - Seeking for advanced catalytic systems for the CO2 methanation reaction, the use of Ni supported catalysts over redox materials is often proposed. Profiting the superior redox properties described for layered perovskite systems, this work has investigated a series Ni supported YMn1-xAlxO3 (x = 0, 0.2, 0.5, 0.8, 1) perovskite catalysts. The obtained results evidenced the impact of the support nature on the systems redox properties and Ni-support interactions. Within the catalysts series, the greater methanation rates displayed by Ni/YMn0.5Al0.5O3 catalyst (0.748 mmolCO2,conv.s–1 gNi –1 at 400 ◦C and 60 L/gh) were associated to the interplay between the support redox properties and superior Ni dispersion. The improved redox behavior attained through the Al-incorporation (up to x = 0.5) was associated to the layered perovskite structures which, being distorted and constituted by smaller crystal sizes, facilitated the behavior of Mn redox couples as surface species readily interconverted. Exhibiting catalytic performances comparable to precious metals based catalysts, this work proposes the Ni/YMn0.5Al0.5O3 catalyst as an effective system for the CO2 methanation reaction. KW - CO2 methanation KW - Perovskites KW - Ni catalyst KW - Manganese KW - Aluminium Y1 - 2022 U6 - https://doi.org/10.1016/j.apmt.2022.101577 SN - 2352-9407 VL - 29 SP - 1 EP - 11 ER - TY - GEN A1 - González-Castaño, Miriam A1 - Baena-Moreno, Francisco Manuel A1 - Navarro de Miguel, Juan Carlos A1 - Miah, Kamal Uddin Mohammad A1 - Arroyo-Torralvo, Fátima A1 - Ossenbrink, Ralf A1 - Odriozola, José Antonio A1 - Benzinger, Walther A1 - Hensel, Andreas A1 - Wenka, Achim A1 - Arellano-García, Harvey T1 - 3D-printed structured catalysts for CO2 methanation reaction: Advancing of gyroid-based geometries T2 - Energy Conversion and Management N2 - This work investigates the CO2 methanation rate of structured catalysts by tuning the geometry of 3D-printed metal Fluid Guiding Elements (FGEs) structures based on periodically variable pseudo-gyroid geometries. The enhanced performance showed by the structured catalytic systems is mostly associated with the capability of the FGEs substrate geometries for efficient heat usages. Thus, variations on the channels diameter resulted in ca. 25% greater CO2 conversions values at intermediate temperature ranges. The highest void fraction evidenced in the best performing catalyst (3D-1) favored the radial heat transfer and resulted in significantly enhanced catalytic activity, achieving close to equilibrium (75%) conversions at 400 ◦C and 120 mL/min. For the 3D-1 catalyst, a mathematical model based on an experimental design was developed thus enabling the estimation of its behavior as a function of temperature, spatial velocity, hydrogen to carbon dioxide (H2/CO2) ratio, and inlet CO2 concentration. Its optimal operating conditions were established under 3 different scenarios: 1) no restrictions, 2) minimum H2:CO2 ratios, and 3) minimum temperatures and H2/CO2 ratio. For instance, for the lattest scenario, the best CO2 methanation conditions require operating at 431 ◦C, 200 mL/min, H2/CO2 = 3 M ratio, and inlet CO2 concentration = 10 %. KW - 3D-printing KW - Triply periodic minimal surfaces KW - Fluid guiding elements KW - CO2 methanation KW - Structured catalysts KW - Experiment design Y1 - 2022 U6 - https://doi.org/10.1016/j.enconman.2022.115464 SN - 2590-1745 VL - 258 ER - TY - GEN A1 - Medina Méndez, Juan Ali A1 - González-Castaño, Miriam A1 - Baena-Moreno, Francisco Manuel A1 - Arellano-García, Harvey ED - Kmiotek, M. ED - Kordos, A. T1 - CO2 methanation: on the modeling of reacting laminar flows in structured Ni/MgAl2O4 catalysts T2 - XXV Fluid Mechanics Conference, Rzeszów, Poland, 7-9 September 2022, Book of Abstracts Y1 - 2022 SN - 978-83-7934-590-8 SP - 98 EP - 100 PB - Publishing House of Rzeszów University of Technology CY - Rzeszów, Poland ER - TY - GEN A1 - Medina Méndez, Juan Ali A1 - González-Castaño, Miriam A1 - Baena-Moreno, Francisco Manuel A1 - Arellano-García, Harvey T1 - CO2 methanation: on the modeling of reacting laminar flows in structured Ni/MgAl2O4 catalysts T2 - Journal of Physics: Conference Series Y1 - 2022 UR - https://iopscience.iop.org/article/10.1088/1742-6596/2367/1/012015 U6 - https://doi.org/10.1088/1742-6596/2367/1/012015 IS - 2367 PB - IOP Publishing ER - TY - GEN A1 - Miah, Kamal Uddin Mohammad A1 - Kloshek, Alexander A1 - González-Castaño, Miriam A1 - Kehm, Christian A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Herstellen hocheffektiver Mikroreaktoren durch selektives Laserstrahlschmelzen T2 - DVS Congress 2022, Große Schweißtechnische Tagung, DVS Campus ; Kurzfassungen der Vorträge der Veranstaltung in Koblenz vom 19. bis 21. September 2022 ; (Langfassungen der Beiträge auf USB-Karte) N2 - Das pulverbasierte 3D-Metalldrucken ermöglicht die Fertigung von hochkomplexen Integralbauteilen, die als Trägerstruktur für Mikroreaktoren benutzt werden. Nach einer Beschichtung der Struktur mit einem Katalysatormaterial, können diese Mikroreaktoren höchst effizient für die CO2-Methanisierung eingesetzt werden. Durch die additive Fertigung mit dem selektiven Laserstrahlschmelzen (SLM) wurden adaptierte dreidimensionale periodische Gitterstrukturen mit sehr geringen Wandstärken hergestellt. Diese weisen ein sehr günstiges Verhältnis von Oberfläche zu Volumen (TPMS - Triply periodic minimal surface) auf. Des Weiteren zeigen die TPMS-Strukturen vorteilhafte Strömungseigenschaften, die sowohl für die Beschichtung mit dem Katalysator-Material als auch die Durchströmung mit den Reaktionsmedien im Betrieb essentiell sind. So ist es beispielsweise möglich, durch die Variation der Dimension einer TPMS-Struktur die Oberfläche pro Volumeneinheit, den hydraulischen Durchmesser des Reaktors und somit auch den Transportprozess des Fluids deutlich zu verbessern. Diese Faktoren ermöglichen eine effektivere Gas-Katalysator-Reaktion. Im Vergleich zu Mikroreaktorstrukturen aus den traditionellen Herstellungsverfahren liefern die additiv gefertigten Strukturen sowohl eine höhere CO2-Umwandlungsrate als auch eine CH4-Selektivität innerhalb des diffusionskontrollierten Bereichs. Y1 - 2022 SN - 978-3-96144-189-1 SP - 708 EP - 713 PB - DVS Media GmbH CY - Düsseldorf ER -