Crystal Faces‐Tailored Oxygen Vacancy in Au/CeO₂ Catalysts for Efficient Oxidation of HMF to FDCA

Abstract

Developing an efficient catalyst to upgrade 5-hydroxymethylfurfural (HMF) to high-value-added downstream chemicals is of great significance in biomass conversion. Nanorod (110)-, nanocube (100)-, and nanooctaheron (111)-CeO 2 -supported Au nanoparticles were prepared to investigate the intrinsic effect of CeO 2 crystal faces on the oxidation of HMF to 2,5furandicarboxylic acid (FDCA). The experimental results and density functional theory calculation revealed that the concentration of oxygen vacancy (V O ) for exposed specific crystal faces was crucial to the oxygen adsorption ability, and Au/nanorod-CeO 2 with the highest V O concentration promoted the forma-tion of more oxygen active species (superoxide radical) on CeO 2 (110) crystal face than ( 100) and ( 111) crystal faces. Besides, the higher V O concentration could provide a strong adsorption ability of HMF, greatly boosting the activation of HMF. Thus, these results led to a superior catalytic activity for HMF oxidation over Au/nanorod-CeO 2 (FDCA yield of 96.5 %). In-situ Fourier-transform (FT)IR spectroscopy uncovered the HMF oxidation pathway, and the possible catalytic mechanism was proposed. The deep insight into the role of regulation for crystal faces provides a basis for the rational design of highly active facets for the oxidation of HMF and related reactions.

A Review on Green and Efficient Synthesis of 5-Hydroxymethylfurfural (HMF) and 2,5-Furandicarboxylic Acid (FDCA) from Sustainable Biomass

“…98 Similarly, another study using Au/nanorod-CeO 2 for HMF oxidation showed that increased oxygen vacancies in the catalyst crystal faces increased the FDCA yield from HMF. 99 Another catalytic effect of the support is the reducibility of the catalysts. The reducibility of oxides used in the catalyst also affects the O 2 availability for the reaction.…”

“…Excess doping results in low HMF conversion and FDCA yield . Similarly, another study using Au/nanorod-CeO 2 for HMF oxidation showed that increased oxygen vacancies in the catalyst crystal faces increased the FDCA yield from HMF . Another catalytic effect of the support is the reducibility of the catalysts.…”

Oxygen Vacancy-Induced Metal–Support Interactions in AuPd/ZrO2 Catalysts for Boosting 5-Hydroxymethylfurfural Oxidation

“…44,45 Since O v was closely related to O ads , the peak area ratio of O ads /(O ads + O latt ) could reflect the O v concentration of catalysts. 46,47 The analysis results are summarized in Table 2. It could be found that the introduction of CA was helpful to increase the O v concentration of catalysts, and the catalyst Au 3 Pd 1 /ZrO 2 @HNTs-1.0CA had a higher relative content of O ads (56.10%), indicating that it had a high O v concentration.…”

“…As displayed in Figure 10a, for the standard HMF solution, the peaks of hydroxyl and aldehyde groups of HMF were located at 3198 and 1657 cm −1 , respectively. 47,53 The characteristic peak at 1520, 1392, and 1278 cm −1 is C�C in the structure of the HMF furan ring, and the characteristic peak of C−O−C in the furan ring was located at 1186 and 1018 cm −1 . 47 However, for the in situ FT-IR spectra of the saturated adsorption of HMF on catalysts, the position of hydroxyl shifted slightly, while the peak positions of the other characteristic groups remained almost unchanged, which suggested that HMF was vertically adsorbed on the catalyst.…”

Coupling Natural Halloysite Nanotubes and Bimetallic Pt–Au Alloy Nanoparticles for Highly Efficient and Selective Oxidation of 5-Hydroxymethylfurfural to 2,5-Furandicarboxylic Acid

“…In this context, much effort has been devoted to developing heterogeneous catalysts for the selective oxidation of HMF to FDCA. Noble metals such as Pt, ,, Au, − Pd, − and Ru , catalysts are commonly employed due to their excellent catalytic activity, but the product selectivity and catalyst stability are still unsatisfactory. Because the oxidation of HMF to FDCA involves several oxidation steps and various intermediate products, even this process may generate byproducts, which make it difficult to obtain high FDCA selectivity .…”