Shielding the Hägg carbide by a graphene layer for ultrahigh carbon efficiency during syngas conversion

• 成果类型: Article
• 署名作者: Zhang, Xueqing; Li, Zhe; Sun, Wei; Zhang, Yuhua; Li, Jinlin; Wang, Li
• 署名单位: South Central Minzu University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-13633
• DOI: 10.1073/pnas.2407624121
• 发表日期: 2024-12-10
• 关键词: fischer-tropsch synthesis; iron-based catalysts; co hydrogenation; lower olefins; chi-fe5c2; performance; activation; nanotubes; mechanism; EVOLUTION

摘要

Fischer-Tropsch synthesis represents a key endeavor aimed at converting nonpetroleum carbon resources into clean fuels and valuable chemicals. However, the current state-of-the-art industrial FTS employing Fe-based catalysts is still challenged by the low carbon efficiency (<50%), mainly attributed to the prominent formation of CO2 and CH4 resulting from the nonregulated side water gas shift reaction. Herein, we describe a shielding strategy involving the encapsulation of the active H & auml;gg carbide (chi-Fe5C2) by a graphene layer, exhibiting excellent resilience under reaction conditions and exposure to air, thereby eliminating the need for reduction or activation before the Fischer-Tropsch synthesis reaction. The graphene layer helps to stabilize the H & auml;gg carbide active phase, and more importantly, greatly suppresses the side water gas shift reaction. Theoretical calculations suggest that graphene shielding inhibits the water gas shift reaction by reducing the absorption strength of OHx species. Remarkably, the optimum chi-Fe5C2@Graphene catalyst demonstrates a minimized CO2 and CH4 formation of only 4.6% and 5.9%, resulting in a high carbon efficiency (ca. 90%) for value-added products. These results are expected to inspire unique designs of Fe-based nanocomposite for highly efficient FTS with regulated carbon transfer pathways.