Guaiacol Hydrodeoxygenation over Iron–Ceria Catalysts with Platinum Single-Atom Alloy Clusters as a Promoter,ACS Catalysis

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Guaiacol Hydrodeoxygenation over Iron–Ceria Catalysts with Platinum Single-Atom Alloy Clusters as a Promoter
ACS Catalysis ( IF 11.3 ) Pub Date : 2021-10-06 , DOI: 10.1021/acscatal.1c03539
Congcong Li ₁ , Yoshinao Nakagawa _{1,

2} , Mizuho Yabushita ₁ , Akira Nakayama ₃ , Keiichi Tomishige _{1,

2}

Affiliation

A series of ceria-supported Fe catalysts with a trace amount of noble-metal modification (NM–Fe/CeO₂, NM = Pt, Ir, Pd, Rh, and Ru) were prepared by the co-impregnation method and used for guaiacol hydrodeoxygenation (HDO) to phenolic compounds at 673 K and atmospheric pressure. In the absence of H₂O, the addition of noble metal improved the initial activities but showed severer deactivation than Fe/CeO₂. Conversely, the addition of water showed little effect on the initial activity and helped to improve the stability of NM–Fe/CeO₂. Among all of the tested NM–Fe/CeO₂ catalysts, Pt–Fe/CeO₂ showed the highest guaiacol conversion. The X-ray absorption spectroscopy (XAS) characterization confirmed that the original structure of active FeO_x species, probably Fe₄O₆, was mostly preserved after the addition of Pt. The Pt modifier was completely reduced to form Pt₁Fe₄ single-atom alloy (Pt₁Fe₄ SAA) clusters during the guaiacol HDO reaction. These Pt₁Fe₄ SAA clusters probably promoted the reduction of FeO_x species to form the coordinatively unsaturated sites (CUS), which were the active sites for the HDO reaction. The presence of Pt₁Fe₄ SAA clusters also encouraged the dissociation of H₂O on Pt–Fe/CeO₂ to maintain the catalytic activity under the H₂O-containing conditions, as shown by the temperature-programmed surface reaction with H₂O (H₂O-TPSR). Characterization of spent catalysts with Raman spectroscopy, scanning transition electron microscopy (STEM), and XAS showed that the Pt–Fe/CeO₂ catalyst was deactivated by coke deposition and carburization of Fe₄O₆ clusters in the absence of H₂O, while the growth of coke species and the formation of inactive iron carbide were suppressed in the presence of H₂O.

中文翻译：

以铂单原子合金簇为促进剂的铁-二氧化铈催化剂上愈创木酚加氢脱氧

通过共浸渍法制备了一系列具有微量贵金属改性（NM-Fe/CeO ₂，NM = Pt、Ir、Pd、Rh和Ru）的氧化铈负载Fe催化剂并用于愈创木酚在 673 K 和大气压下加氢脱氧 (HDO) 生成酚类化合物。在不存在 H ₂ O的情况下，贵金属的加入提高了初始活性，但表现出比 Fe/CeO ₂更严重的失活。相反，水的加入对初始活性几乎没有影响，有助于提高 NM-Fe/CeO ₂的稳定性。在所有测试的 NM-Fe/CeO ₂催化剂中，Pt-Fe/CeO ₂表现出最高的愈创木酚转化率。X 射线吸收光谱 (XAS) 表征证实，添加 Pt 后，活性 FeO _x物种（可能是 Fe ₄ O ₆）的原始结构大部分得以保留。在愈创木酚 HDO 反应过程中，Pt 改性剂完全还原形成 Pt ₁ Fe ₄单原子合金（Pt ₁ Fe ₄ SAA）簇。这些 Pt ₁ Fe ₄ SAA 簇可能促进了 FeO _x物种的还原以形成配位不饱和位点 (CUS)，这是 HDO 反应的活性位点。Pt ₁ Fe的存在₄ SAA 簇还促进了 H ₂ O 在 Pt-Fe/CeO ₂上的解离，以在含H ₂ O 的条件下保持催化活性，如与 H ₂ O的程序升温表面反应（H ₂ O- TPSR）。用拉曼光谱、扫描跃迁电子显微镜 (STEM) 和 XAS 表征废催化剂表明，在不存在 H ₂ O的情况下，Pt-Fe/CeO ₂催化剂因焦炭沉积和 Fe ₄ O ₆簇的渗碳而失活，而H ₂的存在抑制了焦炭物种的生长和惰性碳化铁的形成哦。

更新日期：2021-10-15

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