7 figures, 3 tables.-- This article is part of the 2022 Pioneers in Energy Research: Anders Lyngfelt special issue., A major challenge in biomass chemical looping gasification (BCLG) is the conversion of CH4 and light hydrocarbons to syngas (CO + H2) when the goal is the use for bioliquid fuel production. In this work, tests were performed in a batch fluidized bed reactor to determine the catalytic effect on the CH4 reforming reaction of oxygen carriers used in the BCLG process. Three ores (ilmenite, MnGB, and Tierga), one waste (LD slag), and five synthetic materials (Fe10Al, Fe20Al, Fe25Al, Cu14Al, and Ni18Al) were analyzed. These results were compared to those obtained during ∼300 h of continuous biomass gasification operation in a 1.5 kWth BCLG unit. The low-cost materials (ores and waste) did not show any catalytic effect in the CH4 reforming reaction, and as a consequence, the CH4 concentration values measured in the syngas produced in the continuous prototype were high. The synthetic oxygen carriers showed a catalytic effect in the CH4 reforming reaction, increasing this effect with increasing temperature. With the exception of the Ni-based oxygen carrier (used as a reference), the Cu-based oxygen carrier, working at 940 °C, showed the best catalytic properties, in good agreement with the low CH4 concentration values measured in the syngas generated in the continuous unit. The tests performed in a batch fluidized bed reactor were demonstrated to be very useful in determining the catalytic capacity of oxygen carriers in the CH4 reforming reaction. This fact is highly relevant when a syngas with a low CH4 content is desired as a final product., This work was supported by ENE2017-89473-R AEI/FEDER, UE, and the CO2SPLIT Project, Grant PID2020-113131RB-I00, funded by MICIN/AEI/10.13039/501100011033. Iván Samprón thanks the Spanish Ministerio de Ciencia, Innovación y Universidades (MICIU) for the PRE2018-086217 predoctoral fellowship., Peer reviewed

8 figures, 5 tables.-- Supplementary information available., Power-to-methane (PtM) systems may allow fluctuations in the renewable energy supply to be smoothed out by storing surplus energy in the form of methane. These systems work by combining the hydrogen produced by electrolysis with carbon dioxide from different sources to produce methane via the Sabatier reaction. The present work studies PtM systems based on the CO supplied by the chemical looping combustion (CLC) of biomass (PtM-bioCLC). Life- cycle- assessment (LCA) was performed on PtM-bioCLC systems to evaluate their environmental impact with respect to a specific reference case. The proposed configurations have the potential to reduce the value of the global warming potential (GWP) climate change indicator to the lowest values reported in the literature to date. Moreover, the possibility of effectively removing CO from the atmosphere through the concept of CO negative emissions was also assessed. In addition to GWP, as many as 16 LCA indicators were also evaluated and their values for the studied PtM-bioCLC systems were found to be similar to those of the reference case considered or even significantly lower in such categories as resource use-depletion, ozone depletion, human health, acidification potential and eutrophication. The results obtained highlight the potential of these newly proposed PtM schemes., This work was supported by Grant PDC2021-121190-I00 funded by MCIN/AEI/10.13039/501100011033 and by the European Union NextGenerationEU/PRTR and also by Grant PID2020-113131RB-I00 funded by MICIN/AEI/10.13039/501100011033. A.N. and L.M.G. gratefully acknowledge Grant RTI2018-096294-B-C31 funded by MCIN/AEI/10.13039/501100011033 and “ERDF A way of making Europe”., Peer reviewed

7 figures, 6 tables., Biogas is a renewable fuel generated in the anaerobic digestion of organic material. The expansion of biogas as a bioenergy source in the next decades leads to find new ways for its energy exploitation such as the Chemical Looping technologies. In this work, a low-cost Fe-based residue was used as oxygen carrier in two processes with biogas, namely Chemical Looping Combustion (CLC) and Chemical Looping Reforming (CLR). CLC process is focused on the energy production with CO2 capture. CLC experiments showed higher methane combustion efficiency (∼86%) than those referred in literature with other low-cost Fe-based materials. CLR process is dedicated to the production of syngas or hydrogen without CO2 emissions. Ni- or Cu-based oxygen carrier had been successfully used in order to catalyse the methane reforming. Here, the Fe-based material was also used for CLR. The biogas composition facilitated dry reforming of biogas to obtain syngas. In the dry-CLR of biogas, it was possible to reach about 55% methane conversion with a yield to syngas of 1.3 mol (CO + H2)/mol CH4. A suitable management of the effluent gas is proposed to maximize CH4 conversion and syngas yield, which includes CO2 separation, H2 purification and CH4 recirculation. Both results confirm the potential of the energy use of biogas under these technologies and the promising results with the new oxygen carrier developed., This work was supported by Grant PID2020-113131RB-I00 funded by MICIN/AEI/10.13039/501100011033CO2SPLIT (CO2SPLIT project). [...]. A. Cabello also thanks the Grant IJC2019-038908_I funded by MCIN/AEI/10.13039/501100011033., Peer reviewed

5 figures, 2 tables.-- Talk delivered at the 24th International Conference on Fluidized Bed Conversion, FBC24, at Chalmers University of Technology, in Gothenburg (Sweden)., Biomass Chemical Looping Gasification (BCLG) is a novel technology which permits the production of high purity, N2-free renewable syngas. In this work, the behavior of seven oxygen carriers, 4 low-cost (3 ores, and 1 waste) and 3 synthetic materials, was compared during continuous operation in a 1.5 kWth BCLG unit. For that, oxygen-to-fuel ratio (λ) and fuel reactor (FR) temperature were varied in a wide range of operating conditions. High carbon conversion, ηcc (> 95 %) and fuel conversion, Xb, (> 85%) were found for all the oxygen carriers. The same trends in the syngas composition were observed with low-cost and synthetic oxygen carriers when the λ and FR temperature were varied. However, the amount of syngas generated was higher for synthetic oxygen carriers due to their catalytic effect on CH4 conversion. In addition, tar concentration in the generated syngas was lower using synthetic oxygen carriers than with low-cost materials and these concentrations decreased with increasing FR temperature. Finally, lifetime values between 100 h and 900 h were determined for all the oxygen carriers, being the best ilmenite (600 h) among the low-cost materials and Fe10Al (900) among the synthetic ones., This work was supported by the CO2SPLIT project, Grant PID2020-113131RB-I00, funded by MICIN/AEI/10.13039/501100011033, and by the European Union´s Horizon 2020-Research and Innovation Framework Programme under grant agreement No 817841 (CLARA). I. Samprón thanks the Spanish Ministerio de Ciencia, Innovación y Universidades (MICIU) for the PRE-086217 pre-doctoral fellowship., Peer reviewed

11 figures, 5 tables.-- Supplementary information available., Biomass chemical looping gasification (BCLG) is a novel technology that enables the production of renewable syngas without the need for an external supply of energy or power while achieving negative carbon emissions. In this work, the behavior of a synthetic Cu-based (14 wt% CuO) oxygen carrier, Cu14Al_ICB, was tested for 45 h in a 1.5 kWth continuous unit using pine sawdust as fuel. The effect of the oxygen-to-fuel ratio (λ) and gasification temperature on syngas composition and gasification parameters, including fuel conversion, carbon capture, cold gas efficiency, and syngas yield, was studied. A decrease in the oxygen-to-fuel ratio increased molar flows of H2 and CO in the syngas, while an increase in gasification temperature mainly improved char gasification, also enhancing H2 and CO generation. High amounts of syngas with low CH4 molar flows (∼2.3 mol CH4/kg of dry biomass) were obtained under any conditions due to the catalytic effect of metallic copper on CH4 reforming reactions. Syngas yield values were achieved approximating those obtained with Ni-based solids. The oxygen carrier also had a very positive effect on tar removal, reaching tar concentration values similar to those obtained by operating under chemical looping combustion conditions. The attrition rate measured with this oxygen carrier was the lowest obtained to date for any oxygen carrier operating under BCLG conditions. In addition, the mechanical properties, reactivity, and oxygen transport capacity of the oxygen carrier were maintained throughout the campaign. Therefore, the Cu14Al_ICB oxygen carrier has proved to be an excellent material for the BCLG process., This work was supported by ENE2017-89473-R AEI/FEDER, UE, and the CO2SPLIT Project, Grant PID2020-113131RB-I00, funded by MICIN/AEI/10.13039/501100011033. I. Samprón thanks the Spanish Ministerio de Ciencia, Innovación y Universidades (MICIU) for the PRE2018-086217 predoctoral fellowship. A. Cabello is grateful for Grant IJC2019-038908-I funded by MICIN/AEI/10.13039/501100011033., Peer reviewed

9 figures, 2 tables., Chemical Looping Gasification (CLG) has emerged recently as a promising technology for producing non N2-diluted syngas without the need for an external power supply or the expensive use of pure O2. Many studies have focused on development of oxygen carriers since they are considered a crucial factor in CLG processes. Fe2O3/Al2O3 (FeAl) oxygen carriers have been proposed due to previous experience in Chemical Looping Combustion (CLC). However, the aggressive conditions of gasification cause a decrease in the mechanical stability of the particles, which can be a challenge for their use in CLG. In this work, the operating conditions and Fe-content required to maintain the particle integrity of oxygen carrier particles during redox cycles in both CLC and CLG operations were determined. Long-term tests, consisting of 300 redox cycles, were conducted in a TGA to simulate the operation in a continuous unit and the results were compared with attrition data obtained from a 1.5 kWth CLG unit. Three oxygen carriers with varying Fe2O3-content (10, 20 and 25 wt%) were used, and three different solid conversions (0–25 %, 75–100 % and 0–100 %) were performed to emulate CLC or CLG atmospheres at three temperatures (850 °C, 900 °C and 950 °C). The evolution of the microstructure of particles was analyzed using a scanning electron microscope (SEM) and it was found that the lower the Fe2O3 content in the particles, the greater their stability in redox cycles, an increase in the reaction temperature led to a more rapid degradation of the oxygen carrier particles, and the solid conversion variation and degree of reduction/oxidation during redox cycles strongly influenced the evolution of the mechanical stability of the oxygen carrier particles., This work was supported by the CO2SPLIT Project, Grant PID2020-113131RB-I00, funded by MICIN/AEI/10.13039/501100011033. I. Samprón thanks the Spanish Ministerio de Ciencia, Innovación y Universidades (MICIU) for the PRE2018-086217 predoctoral fellowship., Peer reviewed

Under a Creative Commons license CC-BY-NC-ND 4.0, 1- Pictures of the platinum basket with fresh and used oxygen carrier particles at different solid conversion ΔXs, temperature, Fe2O3-content, and number of redox cycles. Figure S1. View of the samples after 300 redox cycles in TGA at different operating conditions. Figure S2. View of the samples as a function of the number of redox cycles. 2. SEM pictures and EDX analyses of Fe presence on different points of Fe20Al particles reacted at three solid conversions ΔXs. Figure S3. Fe content determined by EDX on Fe20Al particles after 300 redox cycles for different ΔXs. T=950 ºC, This work was supported by the CO2SPLIT Project, Grant PID2020-113131RB-I00, funded by MICIN/AEI/10.13039/501100011033. I. Samprón thanks the Spanish Ministerio de Ciencia, Innovación y Universidades (MICIU) for the PRE2018-086217 predoctoral fellowship., Peer reviewed

9 figures, 1 table., One of the main advantages of chemical looping gasification (CLG) in comparison to conventional gasification technologies is its potential to enhance in situ tar removal. This is due to the catalytic properties of the oxygen carrier used in the CLG process, which can facilitate tar oxidation, cracking, and reforming reactions under specific operating conditions. Furthermore, this catalytic effect can be harnessed to convert hydrocarbons (C1–C3), thereby increasing syngas production during the process. In this study, the catalytic activity of eight different oxygen carriers (two ores, two wastes, and four synthetic materials) was examined in a batch fluidized bed reactor. The reactions were mainly conducted at three temperatures (850, 900, and 950 °C), utilizing benzene and ethylene as model compounds. The results revealed that the ores and wastes exhibited a low catalytic effect over benzene and ethylene conversion at low temperatures, although this effect was increased with a rising temperature. Conversely, the synthetic materials demonstrated higher catalytic activity in the benzene and ethylene conversion reactions, which also increased with higher temperatures. It should be noted that the Cu/Al oxygen carrier achieved nearly complete conversion of benzene and ethylene at temperatures exceeding 900 °C. Methane production was observed in most of the experiments, indicating its role as an intermediate in the conversion of tar byproducts. Additionally, the Cu/Al oxygen carrier exhibited a promising catalytic performance in methane conversion. These findings highlight the potential of certain synthetic oxygen carriers, such as the Cu/Al oxygen carrier, to serve as effective catalysts for the removal of tar byproducts and light hydrocarbons during CLG processes., This work was supported by the CO2SPLIT project,Grant PID2020-113131RB-I00, funded by MICIN/AEI/10.13039/501100011033.I.S. thanks the Spanish Ministerio de Ciencia Innovación y Universidades (MICIU) for the PRE2018-086217 predoctoral fellowship., Peer reviewed

2 figuras.-- Abstract de la comunicación oral de Tecnologías para la generación sostenible de energía presentada en la XVI Reunión del Grupo Español del Carbón (Reunión GEC 2023), celebrada en Gijón del 22 al 25 de octubre de 2023., La gasificación de biomasa mediante procesos de Chemical Looping (BCLG) permite la producción de gas de síntesis renovable que puede ser utilizado para la obtención de numerosos productos como diésel, gasolina, metanol o amoniaco. La tecnología BCLG se basa en el uso de un transportador sólido de oxígeno que
circula entre dos lechos fluidizados interconectados, donde se produce de manera separada la gasificación
de biomasa y la generación de energía requerida por la propia gasificación, obteniendo un gas de síntesis
de alta pureza sin dilución en N2 y sin el uso de O2 puro. En este trabajo se estudió el efecto de cuatro
transportadores de oxígeno sintéticos sobre la composición del gas de síntesis y la formación de alquitranes en una unidad BCLG de 1.5 kWt operando en continuo. Las partículas de transportador frescas y usadas se caracterizaron para determinar su vida útil., Esta publicación es parte del proyecto de I+D+i “CO2SPLIT”, PID2020-113131RB-I00, financiado por MICIN/AEI/10.13039/501100011033. I. Samprón agradece al MICIU la concesión de la ayuda predoctoral PRE2018-086217., Peer reviewed

2 figuras.-- Abstract de la comunicación oral de Tecnologías para la generación sostenible de energía presentada en la XVI Reunión del Grupo Español del Carbón (Reunión GEC 2023), celebrada en Gijón del 22 al 25 de octubre de 2023., El Pacto Verde de la UE prevé alcanzar la neutralidad climática en 2050. Esto significa una transición de
los combustibles fósiles a las fuentes de energía renovables y de una economía basada en el carbono a
una basada en el hidrógeno. Esto es muy importante para sectores que dependen de combustibles con alta
densidad energética, como la aviación. La mejor solución a corto plazo es el uso de bio-queroseno, porque
así la aviación continúa haciendo uso de la infraestructura actualmente existente, reduciéndose los costes de
la transición [1]. Sin embargo, hoy en día, la producción de queroseno sintético adolece de una baja eficiencia
de proceso y unos costes elevados. Para abordar este problema se propone la implementación de un nuevo
proceso de Chemical Looping, CO2 Splitting (CO2SPLIT), para obtención de CO a partir de CO2 e H2 verde
como ruta para la producción de biocombustibles a través del proceso de síntesis Fischer-Tropsch (F-T) [2].
El principio del proceso CO2SPLIT es similar al del proceso conocido como Chemical Looping Combustion
(CLC) [3], pero el proceso CO2SPLIT utiliza tres reactores en lugar de dos. En el Reactor de Reducción (RR),
el transportador de oxígeno (TO) se reduce con H2 verde. El TO reducido pasa al Reactor de CO2 (RC) donde
es parcialmente oxidado con CO2, generándose CO que se utilizará en la relación H2/CO adecuada para el
proceso F-T. Finalmente, en el Reactor de Oxidación (RO) el TO se oxida completamente con aire, quedando
preparado para un nuevo ciclo.
El reto dentro del proceso de CO2SPLIT es encontrar un transportador de oxígeno, que además de poseer
buenas características físicas, como alta dureza mecánica, ha de poseer una elevada reactividad en las
diferentes reacciones, dar una alta conversión y evitar la tendencia a la aglomeración. En este trabajo se han
estudiado TOs basados en Fe., Esta publicación es parte del proyecto de I+D+i “CO2SPLIT”, PID2020-113131RB-I00, financiado por MICIN/
AEI/10.13039/501100011033. A. García-Domínguez agradece al MICIN y al FSE+ la concesión de la ayuda
predoctoral PRE2021-098211, Peer reviewed

6 figures, 5 tables.-- Supplementary information available., Biogas conversion is a renewable alternative for producing hydrogen. In this work, dry reforming of simulated biogas was performed in a 1 kWth continuous chemical looping reforming (CLR) unit in which the oxygen required for the partial oxidation of biogas to CO and H2 is supplied by an oxygen carrier. The performance of two different oxygen carriers (an iron oxide-based residue and a synthetic material based on an iron-manganese mixed oxide) was evaluated. The residue was capable of performing the dry reforming of biogas to a larger extent than the synthetic oxygen carrier. To enhance hydrogen yield, NiO addition was also considered with both materials. The presence of NiO increased methane conversion and H2 selectivity for both oxygen carriers. A value of approximately 2.6 mol H2/mol CH4 was achieved with both materials with the presence of only 2.7 wt% NiO in the bed., This work was supported by CO2SPLIT project, Grant PID2020-113131RB-I00 funded by MICIN/AEI/10.13039/501100011033 and the Gobierno de Aragón – Dpto. de Ciencia, Universidad y Sociedad del Conocimiento - Project LMP166_21. The authors thank HeGo Biotec GmbH for providing FerroSorp® DGp material and Sumitomo Seika Europe for providing agglomerant PEO-1 for granulation. A. Cabello also thanks the Grant IJC2019-038908_I funded by MCIN/AEI/10.13039/501100011033., Peer reviewed

9 figures. 3 tables.-- Published as part of Energy & Fuels virtual special issue “2024 Pioneers in Energy Research: Juan Adanez”., The EU Green Deal aims to achieve climate neutrality by 2050. This means a transition from fossil fuels to renewable energy sources. In the aviation sector, this paradigm shift will require a long period of time so that one of the best short-term options is the synthesis of biokerosene. However, the production of synthetic kerosene suffers currently from low efficiency and high costs. To reduce the cost and enhance the yield of this process, a promising option is Chemical Looping CO2 Splitting technology, which converts CO2 into CO, providing together with green H2 the raw materials for the aviation biofuel production process chain through the Fischer–Tropsch synthesis. A key aspect for the deployment of chemical looping CO2 splitting technology lies in developing suitable oxygen carriers. In this work, a preliminary screening of 18 Fe-based materials with a wide variety of supports (CaAl2O4, MgAl2O4, Zr-doped hydrotalcites, CaO, MgO, ZrO2, SiO2, and TiO2) was carried out evaluating their physicochemical properties (mechanical resistance, reactivity and redox conversion) by means of crushing strength and thermogravimetric analysis tests. On the basis of these properties, the most promising oxygen carriers to be used in a Chemical Looping CO2 Splitting system were selected. The best candidates were those prepared by the mechanical mixing method using Zr-doped synthetic hydrotalcite, ZrO2, Mg-doped ZrO2, SiO2/ZrO2 (50:50), and Mg-doped TiO2 as supports., This work was supported by the CO2SPLIT Project, grant PID2020-113131RB-I00, funded by MICIN/AEI/10.13039/501100011033. A.O.G.-D. thanks to MICIN and FSE+ the PRE2021-098211 predoctoral fellowship., Peer reviewed

4 figures, 7 tables.-- Work presented at 37th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, held on 30th June - 4th July, 2024, in Rhodes (Greece)., Bioenergy coupled with carbon capture utilization and storage (BECCUS) is an attractive greenhouse gas mitigation technology that can produce negative CO2 emissions by combining bioenergy resources with the utilization or geological storage of the captured CO2.
The main objective of this work was to evaluate the technical and economic feasibility of two BECCUS technologies based on chemical looping concept with two biomass waste as fuels, i.e., swine manure and pine sawdust, for the production of thermal energy and a pure CO2 stream that is subsequently used as raw material in agricultural greenhouses. Direct use of solid biomass resources was considered for the Chemical Looping with Oxygen Uncoupling (CLOU) option, whereas biogas production was the starting point for Chemical Looping Combustion (CLC).
The profitability of the chemical looping scenarios was assessed through the Levelized Cost of CO2 (LCOCO2). This parameter was estimated at 218.31 €/t CO2 for the CLC scenario, a value much higher than those for the CLOU scenarios (73.04 - 87.32 €/t CO2) due to the limited conversion degree of the carbon present in the fuel waste to biogas and the need for an additional experimental plant to the CLC unit, i.e., the biogas production plant. Comparing the CLOU scenarios, the economic analysis revealed that the profitability of the biomass-fueled chemical looping facility was markedly sensitive to the selling price of the biomass resource. Furthermore, the values of the LCOCO2 parameter for the CLOU scenarios were lower than those estimated in other research studies that implemented BECCUS technologies and utilized the captured CO2 for identical purposes. Therefore, it can be concluded that CLOU processes fed with biomass are a very attractive BECCUS technology for heat generation where, in addition, the pure CO2 stream obtained at the outlet of the fuel reactor can be considered a marketable, high value-added product., This work was supported by the UPCLOU project (Grant PDC2021-121190-I00 funded by MCIN/AEI /10.13039/501100011033 and by European Union Next GenerationEU/PRTR) and the CO2SPLIT project (Grant PID2020-113131RB-I00/ AEI/10.13039/501100011033). A. Cabello is also grateful for Grant IJC2019-038908-I funded by MCIN/AEI/10.13039/501100011033., Peer reviewed

11 figures, 5 tables.-- Published as part of Energy & Fuels special issue “Celebrating Women in Energy Research”., The main pillar in the advancement of chemical looping (CL) technology is the development of oxygen carriers that are reactive and mechanically resistant without neglecting their cost and environmental impact. In this work, the applicability of a waste with a high iron oxide content in different processes based on the chemical looping (CL) concept is analyzed. Experiments were performed in a TGA apparatus under conditions that would be present in different CL processes: chemical looping combustion (CLC), chemical looping reforming or gasification (CLR or CLG), and chemical looping water or CO2 splitting (CLWS or CO2SPLIT). The oxygen carrier performed well even under highly reduced conditions and maintained its reactivity. Independently of the redox transformation considered, it was observed that iron migration to the surface of FS_GR particles took place. The high rate index with methane found in the transformation Fe2O3/Fe3O4 made this material promising for CLC. FS_GR material also met the reactivity requirements set for the CO2SPLIT process. Thus, it will be further considered as a potential oxygen carrier for diverse CL applications., This work was supported by CO2SPLIT project grant PID2020-113131RB-I00 funded by MICIN/AEI/10.13039/501100011033 and the Gobierno de Aragón – Dpto. de Ciencia, Universidad y Sociedad del Conocimiento - Project LMP166_21. B.Z. acknowledges the “Juan de la Cierva” Program (IJCI-2016-30776)., Peer reviewed

8 figures 2 tables.-- Work presented at the 7th International Conference on Chemical Looping, September 29 – October 2, 2024, Banff, Alberta, Canada, The transition from fossil fuels to renewable energy sources and from a
carbon-based economy to a hydrogen-based economy brings with it a major
drawback: the energy density of fuel decreases. This fact is very important for sectors
such as aviation, which depends on fuels with high energy density. Therefore, to
reduce CO2 emissions in the aviation sector, the best short-term solution is to replace
fossil aviation kerosene with alternative fuels such as bio-kerosene. However, today,
synthetic kerosene production suffers from low process efficiency and high costs. To
address this problem, trying to significantly increase efficiency and reduce costs, a
new Chemical Looping process (CLCO2SPLIT) is being implemented to obtain CO
from CO2 and green H2 as a route for the production of aviation biofuels through the
Fischer-Tropsch (F-T) synthesis process. The principle of the CLCO2SPLIT process
is similar to the well-known Chemical Looping Combustion (CLC) process, but the
CLCO2SPLIT process uses three reactors instead of two. The development of
suitable oxygen carriers is one of the key aspects for the proof-of-concept of the
CLCO2SPLIT process. Therefore, the main objective of this work was to carry out a
preliminary screening of a wide variety of materials based on iron oxide, both
synthetic and mineral, evaluating their physicochemical properties (mechanical
resistance, tendency to agglomeration, chemical stability, reactivity and redox
conversion) by means of crushing strength tests, thermogravimetric analyses, and
redox cycles in a batch fluidized bed reactor. It was found that the best candidates for
the process were the synthetic Fe-based oxygen carriers prepared using Zr-doped
hydrotalcite, SiO2:ZrO2 (50:50), and Mg-doped ZrO2 as supports., This work was supported by the CO2SPLIT Project, Grant PID2020-113131RB-I00, funded
by MICIN/AEI/10.13039/501100011033. A.O. García-Domínguez thanks to MICIN and
FSE+ the PRE2021-098211 predoctoral fellowship., Peer reviewed

6 figures, 2 tables.-- Work presented at the 6th International Conference on Chemical Looping, 19-22 September 2022, Zaragoza, Spain., Power-to-methane (PtM) systems may allow mitigating the fluctuations in
renewable energy supply by storing the energy in the form of methane. In these
systems, hydrogen produced by electrolysis is combined with carbon dioxide from
different sources to produce methane through Sabatier reaction. The present work
analyzes PtM systems based on CO2 supply from Chemical Looping Combustion
(CLC) units running on biomass (PtM-bioCLC). Life-cycle-assessment of PtM-
bioCLC systems was done to evaluate their environmental impact respect a specific
reference case. It was concluded that the configurations proposed have the potential to
decrease the value of the climate change indicator, the global warming potential
(GWP), to the lowest values reported to date in literature. Moreover, the possibility to
effectively remove CO2 from the atmosphere realizing the concept of CO2 negative
emissions was also demonstrated. Besides GWP, up to 16 LCA indicators were also
evaluated and their values for the PtM-bioCLC systems analyzed were similar to those
found in the reference case or even significantly lower in some of the categories such
as resource use/depletion (RUE), ozone depletion (POF), human health (RI),
acidification (AC) and eutrophication (EUT and EUM). Results obtained highlight the
potential of these newly proposed PtM schemes., This work was supported by Grant PDC2021-121190-I00 funded by
MCIN/AEI/10.13039/501100011033 and by the European Union NextGenerationEU/PRTR
and also by Grant PID2020-113131RB-I00 funded by MICIN/AEI/10.13039/501100011033.
A.N. and L.M.G. gratefully acknowledge Grant RTI2018-096294-B-C31 funded by
MCIN/AEI/10.13039/501100011033 and “ERDF A way of making Europe”, Peer reviewed

3 figures, 4 tables.-- Work presented at the Fluidized Bed Conversion Conference - FBC2024, 8-11th May 2022, Chalmers University of Technology (Sweden)., Biogas is mostly composed by CH4 and CO2 generated in the anaerobic digestion of organic matter.
However, other compounds present in lower amounts should be also taken into consideration during
biogas exploitation since they may cause operational problems. This is the case of siloxanes, which
decompose at high temperature generating silicates and SiO2, causing abrasion and leading to the
failure of equipment. Thus, biogas cleaning and upgrading constitutes the key challenge of the biogas
supply chain.
Chemical Looping Combustion (CLC) would allow direct use of biogas without prior cleaning, with
significant energy and economic advantages. In CLC, the oxygen required for combustion is supplied
by an oxygen carrier (metal oxide) that circulates between two reactors. In the reduction reactor, the
fuel is supplied and oxidized to CO2 and H2O while the oxygen carrier is reduced. In the oxidation
reactor, the reduced oxygen carrier is re-oxidized in air. Thus, CO2 capture is intrinsic to the process.
The objective of the present work was to analyse the possible effects of siloxanes in biogas CLC
processes by studying the reactivity and physicochemical changes of selected oxygen carriers during
combustion in a batch fluidized bed reactor.
Two representative oxygen carriers based on CuO and Fe2O3 were chosen considering the high
reactivity in the combustion of methane of Cu-based oxygen carriers and the resistance to sulphur
deactivation of Fe-based oxygen carriers. Hexamethyldisiloxane (L2) was selected as siloxane model
compound. It was found that siloxane decompose to produce a gaseous fraction and Si-based particles
that interact with the oxygen carrier. Part of the Si in these particles was concentrated in the surface of
the oxygen carrier particles in the form of SiO2 and silicates/aluminosilicates. This may have some
implications on the reactivity of the carriers and their fluidization properties; however, no operation
problems would be expected for the oxygen carriers tested in this work in a continuous combustion CLC
unit operated with real siloxane concentration., This work was supported by the European Regional Development Fund (ERDF) under the program
"Programa Operativo FEDER Aragón 2014-2020 - Construyendo Europa desde Aragón. Proyecto
BiosinCO2 (LMP180_18), and by the CO2SPLIT project, Grant PID2020-113131RB-I00, funded by
MICIN/AEI/10.13039/501100011033., Peer reviewed

9 figures, 3 tables.-- Work presented at 6th International Conference on Chemical Looping, 19-22 September 2022, Zaragoza, Spain., Biomass Chemical Looping Gasification (BCLG) is a novelty technology
which enables the production of renewable syngas without the need for external
power supply and achieving negative carbon emissions. In this work, the behavior a
synthetic Cu-based (14 wt% CuO) oxygen carrier, Cu14Al_ICB, was tested during 45
h in a 1.5 kWth continuous unit using pine sawdust as fuel. The effect of oxygen-to-
fuel ratio (𝛌) and gasification temperature on syngas composition and gasification
parameters, such as fuel conversion, carbon capture, cold gas efficiency, and syngas
yield, was studied. The decrease of oxygen-to-fuel ratio increased the concentration
of H2 and CO, while the increase in gasification temperature mainly improved char
gasification, also promoting H2 and CO generation. High amounts of syngas with low
CH4 concentrations (~2.3 mol/kg of dry biomass) were obtained at any condition due
to the catalytic effect of metallic copper on CH4 reforming reactions. Values of
syngas yield close to the obtained with Ni-based solids were achieved. The oxygen
carrier also had a high effect on tar removal, reaching tar concentration values similar
to those obtained by operating under Chemical Looping Combustion conditions. A
particle lifetime of ~8000 h was inferred for this oxygen carrier, which is the highest
lifetime obtained so far for an oxygen carrier working under BCLG conditions. In
addition, the mechanical properties, reactivity and oxygen transport capacity were
maintained during the campaign. Therefore, the Cu14Al_ICB oxygen carrier has
proven to be an excellent material for the BCLG process., This work was supported by ENE2017-89473-R AEI/FEDER, UE, and the CO2SPLIT
Project, Grant PID2020-113131RB- I00, funded by MICIN/AEI/10.13039/501100011033.
Iván Samprón thanks the Spanish Ministerio de Ciencia, Innovación y Universidades
(MICIU) for the PRE-086217 predoctoral fellowship. A. Cabello thanks the Grant IJC2019-
038908-I funded by MCIN/AEI/10.13039/501100011033., Peer reviewed

11 figures, 3 tables., In order to accomplish climate neutrality in 2050, the EU Green Deal aims to transition the aviation sector from fossil fuels to sustainable aviation fuels (SAFs). This transition will take time, so biokerosene synthesis is the most viable short-term option. Nevertheless, the biokerosene synthesis process is currently expensive and inefficient. In this context, chemical looping CO2 splitting technology presents advantages by reducing costs and improving efficiency by converting CO2 into CO. The resulting CO can be mixed with green H2 to produce syngas, which is the raw material for the Fischer–Tropsch synthesis process. Oxygen carrier development is essential to chemical looping CO2 splitting technology. This study investigates the agglomeration tendency and CO production capacity of nine Fe-based oxygen carriers. Among the selected materials, three were of natural origin (iron minerals and residues), while six were synthetically produced. The materials had diverse origins: four oxygen carriers had previously demonstrated satisfactory performance in chemical looping processes. The remaining five materials were chosen based on initial screening results. All nine materials were evaluated in a batch fluidized bed reactor; however, seven were discarded due to agglomeration during the experimentation. The two materials that did not agglomerate, ZrMg/Fe and HTZr(syn)/Fe, showed promising CO production capacities. Based on these results, both oxygen carriers were selected for the proof-of-concept in a chemical looping CO2 splitting continuous system., This work was supported by the CO2SPLIT Project, Grant No. PID2020-113131RB-I00, funded by MICIN/AEI/10.13039/501100011033. A.O. García-Domínguez thanks to MICIN and FSE+ the PRE2021-098211 predoctoral fellowship., Peer reviewed

12 figures, 5 tables., The increasing global demand for sustainable aviation fuels calls for innovative, scalable technological solutions, especially those that can efficiently utilize abundant CO2 sources. Among various CO2 utilization technologies, Chemical Looping CO2 Splitting emerges as a cost-effective, eco-friendly method for producing CO from CO2 and green H2, supporting the production of aviation biofuels via the Fischer-Tropsch synthesis., This work was supported by the CO2SPLIT Project, Grant PID2020-113131RB-I00, funded by MICIN/AEI/10.13039/501100011033, and by Gobierno de Aragón, Spain, Ref. T05_23R. A.O. García-Domínguez thanks MICIN and ESF+ for the predoctoral fellowship PRE2021-098211., Peer reviewed

Power-to-methane (PtM) systems may allow fluctuations in the renewable energy supply to be smoothed out by storing surplus energy in the form of methane. These systems work by combining the hydrogen produced by electrolysis with carbon dioxide from different sources to produce methane via the Sabatier reaction. The present work studies PtM systems based on the CO2 supplied by the chemical looping combustion (CLC) of biomass (PtM-bioCLC). Life- cycle- assessment (LCA) was performed on PtM-bioCLC systems to evaluate their environmental impact with respect to a specific reference case. The proposed configurations have the potential to reduce the value of the global warming potential (GWP) climate change indicator to the lowest values reported in the literature to date. Moreover, the possibility of effectively removing CO2 from the atmosphere through the concept of CO2 negative emissions was also assessed. In addition to GWP, as many as 16 LCA indicators were also evaluated and their values for the studied PtM-bioCLC systems were found to be similar to those of the reference case considered or even significantly lower in such categories as resource use-depletion, ozone depletion, human health, acidification potential and eutrophication. The results obtained highlight the potential of these newly proposed PtM schemes., This work was supported by Grant PDC2021-121190-I00 funded by MCIN/AEI/10.13039/501100011033 and by the European Union NextGenerationEU/PRTR and also by Grant PID2020-113131RB-I00 funded by MICIN/AEI/10.13039/501100011033. A.N. and L.M.G. gratefully acknowledge Grant RTI2018-096294-B-C31 funded by MCIN/AEI/10.13039/501100011033 and “ERDF A way of making Europe”.