Electronic–Oxygen Synergy at Ca-Fe Dual-Metal Interfaces for Selective Syngas Regulation in Biomass Chemical Looping Gasification
This study reveals the efficient catalytic role of Ca-Fe-based oxygen carriers (Ca<sub>2</sub>Fe<sub>2</sub>O<sub>5</sub>) in biomass chemical looping gasification. With oxygen carrier introduction, the CO yield doubled (0.13 Nm<sup>3</sup>/kg→0.26 Nm&...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-03-01
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| Series: | Molecules |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1420-3049/30/7/1471 |
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| Summary: | This study reveals the efficient catalytic role of Ca-Fe-based oxygen carriers (Ca<sub>2</sub>Fe<sub>2</sub>O<sub>5</sub>) in biomass chemical looping gasification. With oxygen carrier introduction, the CO yield doubled (0.13 Nm<sup>3</sup>/kg→0.26 Nm<sup>3</sup>/kg), with 76.10% selectivity. Steam co-feeding further increased the H<sub>2</sub> yield from 0.19 Nm<sup>3</sup>/kg to 0.72 Nm<sup>3</sup>/kg, significantly elevating the H<sub>2</sub>/CO ratio to 2.62. Combined with density functional theory (DFT), the micro-mechanism of reduced oxygen carrier surfaces activating CO<sub>2</sub>/H<sub>2</sub>O was elucidated. CO<sub>2</sub> (adsorption charge −0.952 |e|) and H<sub>2</sub>O (adsorption charge −0.612 |e|) chemically adsorb at the CaO(111)/Fe(110) interface, where Fe atoms (charges 0.433 |e|, 0.927 |e|) act as electron donors to drive efficient molecule activation. CO<sub>2</sub> undergoes single-step splitting (CO<sub>2</sub>→CO* + O*), with the desorption energy barrier (<i>E</i><sub>a</sub> = 1.09 eV, 105.17 kJ/mol) determining the reaction rate. H<sub>2</sub>O splits via two-step cleavage (H<sub>2</sub>O→HO* + H*→2H* + O*), which is rate-limited by the first step (<i>E</i><sub>a</sub> = 0.42 eV, 40.52 kJ/mol). Simultaneously, the reduced oxygen carrier achieves oxidative regeneration through surface O* lattice incorporation. This work atomically reveals the “electron transfer–oxygen transport” synergy at the Ca-Fe bimetallic interface, establishing a theoretical framework for the directional regulation of the syngas composition and the design of high-performance oxygen carriers. |
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| ISSN: | 1420-3049 |