Supplementary material for Use of a high-entropy oxide as an oxygen carrier for chemical looping [Dataset]
1. Batch fluidized bed methodology: The following methodology was used during the fluidized bed testing: i. The reactor was heated up in an N2 stream of 850 ml/min at a rate of 20 °C /min until the OC started to release O2, then the gas was switched to 11 vol% of O2 with N2 for balance. Note that th...
| Autores: | , , , , , |
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| Tipo de recurso: | conjunto de datos |
| Fecha de publicación: | 2024 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/354968 |
| Acceso en línea: | http://hdl.handle.net/10261/354968 |
| Access Level: | acceso abierto |
| Palabra clave: | High entropy oxygen carriers Fluidized bed Syngas http://metadata.un.org/sdg/7 Ensure access to affordable, reliable, sustainable and modern energy for all |
| Sumario: | 1. Batch fluidized bed methodology: The following methodology was used during the fluidized bed testing: i. The reactor was heated up in an N2 stream of 850 ml/min at a rate of 20 °C /min until the OC started to release O2, then the gas was switched to 11 vol% of O2 with N2 for balance. Note that the same mixture of air and N2 was used to regenerate the oxygen carrier (OC) after the Chemical Looping Oxygen Uncoupling (CLOU) and syngas reactions. Once the temperature and O2 concentration had stabilized, the redox cycle was initiated. ii. Oxygen release and regeneration (CLOU) was tested in an N2 atmosphere for 300 s, or until the concentration of oxygen released dropped to 0. Specifically, the oxygen concentration was recorded together with the total amount of oxygen released and the conversion of the high entropy oxygen carrier (HEOC). During regeneration, it was determined whether the HEOC was able to capture all of the previously released oxygen and how much time this required at each temperature. iii. After the oxygen release and regeneration cycles, redox reactivity experiments were performed at 950 °C using syngas (50 vol% H2 and 50 vol% CO) as the reactant. During the redox cycles the stream initially consisted of inert gas (120 s) followed by syngas (10-20 s) and inert gas (120 s) before finally being oxidized in an air and N2 mixture (until complete regeneration). The regeneration and oxidation was carried out in the same way as in the CLOU cycles. During these experiments, the reactivity of the OC in the presence of syngas and its capacity for converting syngas to CO2 and H2O were analyzed. iv. The ability of the HEOC to release oxygen and regenerate was retested after the syngas experiments. For this purpose, the experiments shown in point i were performed again and the results obtained before and after syngas combustion were compared. To a achieve fast cooling of the bed the furnace was opened at the end of the last cycle, which led to a cool down from 950 °C to 500 °C at a rate of 90 °C/min. The gas used to fluidize the bed during the cooling period is the same as in the previous oxidation step.-- 2. HEOC Reactivity in TGA and Batch Fluidized Bed Reactor: 2.1 TGA reactivity. As can be seen from Figure S1, the oxidation, after reduction with either H2 or CLOU, shows a two step behavior in the reactivity, with one very fast initial step followed by a slower step, that cannot be attributed to different redox reactions. Even so, the OC conversion was complete for both redox reactions and the reactivity was maintained during the redox cycles. The CH4 reactivity was measured at 800 °C by reduction with a gas mixture containing 15 % CH4 and 20 % H2O. The reduction reactivity (Figure S2a) increased in a single step and reached the same value independent of the calcination temperature. The oxidation was complete and fast (see Figure S2b) and the OC conversion was maintained over the redox cycles. Still, the reactivities with CH4 were not remarkable compared to other OCs 18.-- 3. HEOC characterization: 3.1 SEM-EDX Figure S7 shows SEM images and EDX mappings of the fresh HEOC_1100 (Figure 13a,b,c) as well as oxidized particles from the batch fluidized bed after 30h of operation and a cool down from 950 °C, at a rate of 90 °C/min (Figure S7d,e,f). It is apparent that the particles do not show any shape modifications after use in the batch fluidized bed reactor. In addition, a homogeneous distribution of the five elements can, in general, be observed inside the particles. However, there are subdomains enriched in Mg (red zones in Figure S7c,f), which are more frequent in the fresh particles.-- Under a Creative Commons license CC BY NC ND 4.0. |
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