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A series of N-doped porous carbons with different textural properties and N contents was prepared from a mixture of algae and glucose and their capability for the separation of CO 2 /CH 4 , C 2 H 6 /CH 4 , and CO 2 /H 2 binary mixtures under different conditions (bulk pressure, mixture composition, and temperature) were subsequently assessed in great detail. It was observed that the gas (C 2 H 6 , CO 2 , CH 4 , and H 2 ) adsorption capacity at different pressure regions was primarily governed by different adsorbent parameters (N level, narrow micropore volume, and BET specific surface area). More interestingly, it was found that N-doping can selectively enhance the heats of adsorption of C 2 H 6 and CO 2 , while it had a negligible effect on those of CH 4 and H 2 . The adsorption equilibrium selectivities for separating C 2 H 6 /CH 4 , CO 2 /CH 4 , and CO 2 /H 2 gas mixture pairs on the porous carbons were predicted using the ideal adsorbed solution theory (IAST) based on pure-component adsorption isotherms. In particular, sample NAHA-1 exhibited by far the best performance (in terms of gas adsorption capacity and selectivity) reported for porous carbons for the separation of these three binary mixtures. More significantly, NAHA-1 carbon outperforms many of its counterparts ( e.g. MOFs and zeolites), emphasizing the important role of carbonaceous adsorbents in gas purification and separation.more » « less
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Abstract The equimolar C2H2‐CO2reaction has shown promise for carbon nanotube (CNT) production at low temperatures and on diverse functional substrate materials; however, the electron‐pushing mechanism of this reaction is not well demonstrated. Here, the role of CO2is explored experimentally and theoretically. In particular,13C labeling of CO2demonstrates that CO2is not an important C source in CNT growth by thermal catalytic chemical vapor deposition. Consistent with this experimental finding, the adsorption behaviors of C2H2and CO2on a graphene‐like lattice via density functional theory calculations reveal that the binding energies of C2H2are markedly higher than that of CO2, suggesting the former is more likely to incorporate into CNT structure. Further, H‐abstraction by CO2from the active CNT growth edge would be favored, ultimately forming CO and H2O. These results support that the commonly observed, promoting role of CO2in CNT growth is due to a CO2‐assisted dehydrogenation mechanism.
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null (Ed.)To directly use a CO 2 –CH 4 gas mixture for power and CO co-production by proton-conducting solid oxide fuel cells (H-SOFCs), a layer of in situ reduced La 0.6 Sr 0.2 Cr 0.85 Ni 0.15 O 3−δ (LSCrN@Ni) is fabricated on a Ni–BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3−δ (BZCYYb) anode-supported H-SOFC (H-DASC) for on-cell CO 2 dry reforming of CH 4 (DRC). For demonstrating the effectiveness of LSCrN@Ni, a cell without adding the LSCrN@Ni catalyst (H-CASC) is also studied comparatively. Fueled with H 2 , both H-CASC and H-DASC show similar stable performance with a maximum power density ranging from 0.360 to 0.816 W cm −2 at temperatures between 550 and 700 °C. When CO 2 –CH 4 is used as the fuel, the performance and stability of H-CASC decreases considerably with a maximum power density of 0.287 W cm −2 at 700 °C and a sharp drop in cell voltage from the initial 0.49 to 0.10 V within 20 h at 0.6 A cm −2 . In contrast, H-DASC demonstrates a maximum power density of 0.605 W cm −2 and a stable cell voltage above 0.65 V for 65 h. This is attributed to highly efficient on-cell DRC by LSCrN@Ni.more » « less
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1029/2022GB007478
