Effect of Gold Particles Size over Au/C Catalyst Selectivity in HMF Oxidation Reaction

Megías‐Sayago, Cristina; Lolli, Alice; Bonincontro, Danilo; Penkova, Anna; Albonetti, Stefania; Cavani, Fabrizio; Odriozola, José Antonio; Ivanova, Svetlana

doi:10.1002/cctc.201901742

Cited by 49 publications

(44 citation statements)

References 31 publications

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“…Generally, catalysts with larger mean particle sizes were more active in FDCA synthesis, i.e., alcohol oxidation, in line with previous reports [43,57,58]. This might be due to the presence of surface steps, which are active in β-H removal [58], also considering that the reactions were carried out with excess NaOH [52]. This step is also an important part of the reaction mechanism in HMF oxidation, which probably follows a dehydrogenation mechanism [51,59].…”

Section: Discussionsupporting

confidence: 88%

“…Consequently, oxygen is most probably activated on the Au particles in the present study as well, also considering the unlikely activation on the support. However, the used model only applies to particles with a size of more than 4 nm [52], which is larger than the mean sizes of particles used in this study also considering the small fraction of particles in this range for AuZ2.7 and AuZ2.9. Thus, the observed differences in catalytic activity can be attributed to the smaller particle sizes studied here.…”

Section: Discussionmentioning

confidence: 97%

“…In addition, particles in the nanometer range rather than small clusters were most active in the oxidation of alcohols [44]. Recently, Megías-Sayago et al [52] studied HMF oxidation over Au particles in the range of 4-40 nm supported on carbon. In contrast to our study, both the HMF conversion and HFCA yield were independent from the particle size at the larger particle sizes.…”

Section: Discussionmentioning

confidence: 99%

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The Influence of the Gold Particle Size on the Catalytic Oxidation of 5-(Hydroxymethyl)furfural

et al. 2020

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For the production of chemicals from biomass, new selective processes are required. The selective oxidation of 5-(Hydroxymethyl)furfural (HMF), a promising platform molecule in fine chemistry, to 2,5-furandicarboxylic acid (FDCA) is considered a promising approach and requires the oxidation of two functional groups. In this study, Au/ZrO 2 catalysts with different mean particle sizes were prepared by a chemical reduction method using tetrakis(hydroxymethyl)phosphonium chloride (THPC) and tested in HMF oxidation. The catalyst with the smallest mean particle size (2.1 nm) and the narrowest particle size distribution was highly active in the oxidation of the aldehyde moiety of HMF, but less active in alcohol oxidation. On the other hand, increased activity in FDCA synthesis up to 92% yield was observed over catalysts with a larger mean particle size (2.7 nm), which had a large fraction of small and some larger particles. A decreasing FDCA yield over the catalyst with the largest mean particle size (2.9 nm) indicates that the oxidation of both functional groups require different particle sizes and hint at the presence of an optimal particle size for both oxidation steps. The activity of Au particles seems to be influenced by surface steps and H bonding strength, the latter particularly in aldehyde oxidation. Therefore, the presence of both small and some larger Au particles seem to give catalysts with the highest catalytic activity.Catalysts 2020, 10, 342 2 of 13 oxidation of HMF has gained great interest in recent years. Selective oxidation of HMF can for example give 5-hydroxymethyl-2-furancarboxylic acid (HFCA) or 2,5-diformylfuran. One of the most important oxidation products is 2,5-furandicarboxylic acid (FDCA), [11,12] which is produced via the oxidation of both functional groups of HMF (Scheme 1). The structural similarity of FDCA to terephthalic acid led to its consideration as one of the twelve important molecules that can be produced from sugar-containing biomass feedstock [11,12]. Therefore, FDCA may be used in future bio-based polymers thus overcoming the need of petrochemical-based terephthalic acid [13,14]. Synthetic approaches for FDCA synthesis include stoichiometric oxidation reactions [15] as well as catalytic routes with mostly molecular oxygen. The latter range from bio-[16,17] to electro-[18-20] and metal catalysis. Current FDCA production is based on the homogeneously catalyzed AMOCO process, which is carried out in acetic acid solvent at 125 • C and 70 bar air in the presence of a Cu/Mn/Br catalyst [21]. In addition, heterogeneous metal catalysts have been applied in HMF oxidation. Especially supported noble metals like Pt [22][23][24] or Pd [25][26][27] are catalytically active in this reaction. Among others, supported gold-based catalysts show high activity in the oxidation of HMF with oxygen to FDCA [28][29][30][31][32][33][34][35]. For example, Au supported on CeO 2 nanoparticles allowed the production of FDCA in 96% yield after 5 h at 130 • C [28].Catalysts 2020, 10, x FOR PEER REVIEW 2 of...

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Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

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The Influence of the Gold Particle Size on the Catalytic Oxidation of 5-(Hydroxymethyl)furfural

et al. 2020

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“…In addition, they hit the right size regime reported to be active for Au-based catalysts for HMF to FDCA oxidation. [51] Consequently, these lasergenerated catalysts are ideal candidates for studying the influence of the Ag content on the catalytic activity and selectivity, presented in the following section.…”

Section: Full Papermentioning

confidence: 99%

Selective Aerobic Oxidation of 5‐(Hydroxymethyl)furfural over Heterogeneous Silver‐Gold Nanoparticle Catalysts

et al. 2020

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Bimetallic silver-gold alloy nanoparticles on zirconia with varying Ag/Au ratios were designed by a rational approach and tested as catalysts for the selective oxidation of the promising biomass platform molecule 5-(hydroxymethyl)furfural (HMF). For this purpose, colloidal Ag x Au 10-x particles with molar compositions x = 1/3/5/7/9 were prepared by laser ablation in liquids, a surfactant-free method for the preparation of highly pure nanoparticles, before adsorption on zirconia. In-depth characterization of the supported catalysts evidenced alloyed nanoparticles with distinct trends of the surface and bulk composition depending on the overall Ag/Au molar ratio as determined by X-ray photoelectron spectroscopy (XPS) and Xray absorption spectroscopy (XAS), respectively. To uncover the synergistic effect of the Ag/Au ratio, the catalysts were further studied in terms of the catalytic activity and selectivity in HMF oxidation. Either the aldehyde moiety or both functional groups of HMF were selectively oxidized depending on the Ag/Au composition resulting in 5-hydroxymethyl-2-furan-carboxylic acid (HFCA) or 2,5-furandicarboxylic acid (FDCA), respectively. Optimization of the reaction conditions allowed the quantitative production of HFCA over most catalysts, also after re-use. Only gold rich catalysts Ag 1 Au 9 /ZrO 2 and particularly Ag 3 Au 7 /ZrO 2 were highly active in FDCA synthesis. While Ag 3 Au 7 /ZrO 2 deactivated upon re-use due to sintering, no structural changes were observed for the other catalysts and all catalysts were stable against metal leaching. The present work thus provides fundamental insights into the synergistic effect of Ag and Au in alloyed nanoparticles as active and stable catalysts for the oxidation of HMF.

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“…The fine tuning of such parameters can lead to very active systems. For instance, by alloying Au with another metal (such as Cu [22,23] or Pd [24,25]) it is possible to effectively enhance FDCA yield, or by choosing suitable supports catalytic activity can be positively affected [26] and/or base addition can be avoided [27][28][29]. Besides the textural properties that have been shown to play a prominent role, pore dimension and acid/base sites can be considered of crucial importance [30].…”

Section: Introductionmentioning

confidence: 99%

Pd/Au Based Catalyst Immobilization in Polymeric Nanofibrous Membranes via Electrospinning for the Selective Oxidation of 5-Hydroxymethylfurfural

et al. 2020

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Innovative nanofibrous membranes based on Pd/Au catalysts immobilized via electrospinning onto different polymers were engineered and tested in the selective oxidation of 5-(hydroxymethyl)furfural in an aqueous phase. The type of polymer and the method used to insert the active phases in the membrane were demonstrated to have a significant effect on catalytic performance. The hydrophilicity and the glass transition temperature of the polymeric component are key factors for producing active and selective materials. Nylon-based membranes loaded with unsupported metal nanoparticles were demonstrated to be more efficient than polyacrylonitrile-based membranes, displaying good stability and leading to high yield in 2,5-furandicarboxylic acid. These results underline the promising potential of large-scale applications of electrospinning for the preparation of catalytic nanofibrous membranes to be used in processes for the conversion of renewable molecules.

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Effect of Gold Particles Size over Au/C Catalyst Selectivity in HMF Oxidation Reaction

Cited by 49 publications

References 31 publications

The Influence of the Gold Particle Size on the Catalytic Oxidation of 5-(Hydroxymethyl)furfural

The Influence of the Gold Particle Size on the Catalytic Oxidation of 5-(Hydroxymethyl)furfural

Selective Aerobic Oxidation of 5‐(Hydroxymethyl)furfural over Heterogeneous Silver‐Gold Nanoparticle Catalysts

Pd/Au Based Catalyst Immobilization in Polymeric Nanofibrous Membranes via Electrospinning for the Selective Oxidation of 5-Hydroxymethylfurfural

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