To Alloy or Not to Alloy? The Unexpected Power of Pd–Au Catalyst Physical Mixtures in Efficient HMF Oxidation to FDCA

IF 13.1 1区化学 Q1 CHEMISTRY, PHYSICAL

ACS Catalysis Pub Date : 2025-06-24 DOI:10.1021/acscatal.5c02908

Yani Peng, Xinyue Zhou, Xuzhao Liu, Min Hu, Boya Qiu, Yilai Jiao, Carmine D’Agostino, Jesus Esteban, Christopher M. A. Parlett, Xiaolei Fan

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Abstract

Bimetallic palladium (Pd) and gold (Au) systems are active for promoting the selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA), a key building block for producing polyethylene furanoate, a biobased polymer to substitute poly(ethylene terephthalate). Here, an FDCA yield of ∼99% was achieved over a physical mixture of 1.5 wt % Au/C and 1.5 wt % Pd/C (Pd/Au molar ratio of 5:1) under mild conditions (90 °C, 1 bar O₂), outperforming bimetallic core–shell Au@Pd/C (∼90% FDCA yield) or alloyed AuPd/C (∼73% FDCA yield) systems. To gain insights into the synergy between the two monometallic catalysts, a series of kinetic studies were conducted employing either HMF or its intermediates as substrates in catalytic oxidation systems over either Pd/C or Au/C. The results show distinct selectivity preference of the two catalysts: Pd/C favors the 2,5-diformylfuran pathway (DFF), while Au/C follows the 5-hydroxymethyl-2-furancarboxylic acid (HFCA) pathway, as well as the presence of base-induced Cannizzaro disproportionation (CD) reactions. The advantage of the physical mixture system is largely attributed to the synergy between the two metals, which promotes the DFF pathway (over the HFCA route) and suppresses CD reactions, facilitating a more rapid progression of the overall oxidation cascade process. Catalyst recycling studies reveal deactivation of the physical mixture system (FDCA yield dropped to 62% after 3 cycles), with detailed comparative characterization of the fresh and used catalysts identifying operando Pd leaching and subsequent deposition onto Au/C, forming a core (Au)–shell (Pd) structure, as the origin of the diminished activity. Our findings challenge the conventional view regarding the alloy superiority in the selective oxidation of HMF, showing that systems based on simple physical mixtures of monometallic catalysts could be a more effective and practical strategy for progressing FDCA production via selective HMF oxidation.

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合金还是不合金？钯金催化剂物理混合物在HMF高效氧化生成FDCA中的意外作用

双金属钯（Pd）和金（Au）体系在促进5-羟甲基糠醛（HMF）选择性氧化为2,5-呋喃二甲酸（FDCA）方面具有活性，FDCA是生产聚呋喃酸酯的关键组成部分，聚呋喃酸酯是一种替代聚对苯二甲酸乙酯的生物基聚合物。在温和条件下（90°C, 1 bar O2），在1.5 wt % Au/C和1.5 wt % Pd/C （Pd/Au摩尔比为5:1）的物理混合物中，FDCA产率达到了~ 99%，优于双金属核壳Au@Pd/C （~ 90% FDCA产率）或合金AuPd/C （~ 73% FDCA产率）体系。为了深入了解这两种单金属催化剂之间的协同作用，研究人员在Pd/C或Au/C催化氧化体系中使用HMF或其中间体作为底物进行了一系列动力学研究。结果表明，两种催化剂具有明显的选择性偏好：Pd/C倾向于2,5-二甲酰基呋喃（DFF）途径，而Au/C倾向于5-羟甲基-2-呋喃羧酸（HFCA）途径，并且存在碱诱导的Cannizzaro歧化（CD）反应。物理混合体系的优势很大程度上归功于两种金属之间的协同作用，它促进了DFF途径（而不是HFCA途径）并抑制了CD反应，促进了整个氧化级联过程的更快进展。催化剂回收研究揭示了物理混合体系失活（FDCA产率在3个循环后降至62%），并对新催化剂和旧催化剂进行了详细的比较表征，确定了operando Pd浸出并随后沉积在Au/C上，形成核(Au) -壳（Pd）结构，这是活性降低的原因。我们的研究结果挑战了关于合金在HMF选择性氧化中的优势的传统观点，表明基于单金属催化剂的简单物理混合物的系统可能是通过选择性HMF氧化来推进FDCA生产的更有效和实用的策略。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

ACS Catalysis CHEMISTRY, PHYSICAL-

CiteScore

20.80

自引率

6.20%

发文量

1253

审稿时长

1.5 months

期刊介绍： ACS Catalysis is an esteemed journal that publishes original research in the fields of heterogeneous catalysis, molecular catalysis, and biocatalysis. It offers broad coverage across diverse areas such as life sciences, organometallics and synthesis, photochemistry and electrochemistry, drug discovery and synthesis, materials science, environmental protection, polymer discovery and synthesis, and energy and fuels. The scope of the journal is to showcase innovative work in various aspects of catalysis. This includes new reactions and novel synthetic approaches utilizing known catalysts, the discovery or modification of new catalysts, elucidation of catalytic mechanisms through cutting-edge investigations, practical enhancements of existing processes, as well as conceptual advances in the field. Contributions to ACS Catalysis can encompass both experimental and theoretical research focused on catalytic molecules, macromolecules, and materials that exhibit catalytic turnover.