Active Oxygen Species Promoted Catalytic Oxidation of 5-Hydroxymethyl-2-furfural on Facet-Specific Pt Nanocrystals

Abstract

The aerobic oxidation of alcohols and aldehydes over noble metal catalysts is a critical reaction for the catalytic conversion of carbohydrates into value-added chemicals from biomass. However, to fully understand the reaction mechanism, in particular the role of O2 and the generated active oxygen species in these reactions is still a challenging target. In the present work, the sub-10 nm Pt nanocrystals with cubic (Pt-NCs), octahedral (Pt-NOs) and spherical (Pt-NSs) morphologies were synthesized and used as catalysts in aerobic oxidation of HMF. Through experimental and computational investigations, the facet-dependent O2 conversion pathway and catalytic oxidation performance were discussed. The molecular O2 tends to be dissociated to generate •OH on Pt(100) surface, but prefers to be reduced to •O2on Pt(111) surface. Moreover, Pt-NCs enclosed by the {100} facets exhibited significantly enhanced catalytic activity than Pt-NOs enclosed by the {111} facets and Pt-NSs, in particular for alcohol oxidation step. Based on the experimental data and density functional theory (DFT) calculations, an active oxygen species promoted dehydrogenation mechanism for aerobic oxidation of HMF was proposed. The dehydrogenation of alcohol group is more favourable on the Pt(100) surface with an assistance of •OH, which are the dominant active oxygen species on the Pt(100) surface. We anticipate that this work would provide a new insight into the role of active oxygen species in aerobic oxidation of alcohols and aldehydes over noble metal catalysts.

Tuning the Selective Adsorption Site of Biomass on Co3O4 by Ir Single Atoms for Electrosynthesis

“…It was reported that the desorption temperature of HMF is less than 200 °C since it would be pyrolyzed to CO 2 and H 2 O subsequently. [ 4a,18 ] Therefore, the HMF‐TPD measurement was conducted between 75 and 200 °C. The Ir‐Co 3 O 4 showed higher desorption temperature (144 °C) for HMF molecules than Co 3 O 4 (108 °C), implying stronger HMF adsorption.…”

2,5-Furandicarboxylic acid production via catalytic oxidation of 5-hydroxymethylfurfural: Catalysts, processes and reaction mechanism

“…2(a) further demonstrates that the choices preference of soluble bases in the HMF oxidation reactions listed in Tables 1-3 were closely correlated with reaction time and temperature, although determined primarily by the activity of catalysts. The structural parameters of catalysts like particle size, exposed crystal planes, and metal-support interaction have obvious effects on the reaction turnover frequency [25][26][27][28][29][30][31][32]. Siyo et al [25] reported that the Pd nanoparticles (NPs) with a mean diameter of 1.8 nm in an alkaline aqueous solution (T = 90°C, p O2 = 0.1 MPa) afforded up to 90% yield of FDCA.…”

“…However, the situation is different for the single-crystalline Pt nanocrystals with particle size of sub-10 nm. Yu et al [28] found that Pt-NCs enclosed by the (100) facets exhibited higher catalytic activity compared with Pt-NOs enclosed by the (111) facets and Pt nanospheres (Pt-NSs), mainly due to the fact that OH created on Pt(100) facet is more active for the dehydrogenation of HMFCA to form FFCA compared with the O 2 generated on Pt (111) facet. Recently, Jiang et al [29] found that the activity in the productivity of FDCA by the atomic Pd catalyst supported on MnO 2 was over twice that of its Pd nanoparticle counterpart.…”

The Size‐Dependent Catalytic Performances of Supported Metal Nanoparticles and Single Atoms for the Upgrading of Biomass‐Derived 5‐Hydroxymethylfurfural, Furfural, and Levulinic acid

“…For example, Yu and coworkers investigated the facet-dependent activity of Pt metal by employing sub-10 nm Pt nanocrystals with nanooctahedral (PtÀ NO), nanocubic (PtÀ NC), and nanospherical (PtÀ NS) morphologies. [80] Pt nanocrystals were prepared using a polyol alcohol method, which involves the dropwise addition of a solution of AgNO 3 , H 2 PtCl 6 .6H 2 O, and PVP into the boiling ethylene glycol. The nanocrystals with different morphologies were prepared by changing the concentration of AgNO 3 and by varying the refluxing time.…”