Metal-Support Synergy of Supported Gold Nanoclusters in Selective Oxidation of Alcohols

Abstract

Gold catalysts have been reported to exhibit good performance in aerobic oxidation of alcohols, but the intrinsic origin of the catalytic reactivity is still illusive. The catalyst preparation method, the morphology of the gold particles, and even the support might be key factors that determine the activity. Here, we prepared a series of gold catalysts with different supports, i.e., the hydrotalcite (HT), ZnO, MgO, Al2O3, and SiO2, by using the atomically controlled Au25 nanoclusters (NCs) as the gold precursor. The characterization results of the X-ray diffraction (XRD), UV-vis and transmission electron microscopy (TEM) show that the gold particles were mostly uniformly distributed on the supports, with a mean particle size within 3 nm. In aerobic oxidation of benzyl alcohol, the MgAl-HT- and Al2O3-supported Au25 NCs display good performances, with turnover frequency (TOF) values of ~2927 and 2892 h−1, respectively, whereas the SiO2-, MgO-, and ZnO-supported analogues show much inferior activity. The high resolution TEM and X-ray photoelectron spectra (XPS) results suggest that the interactions between gold and the supports in different samples are differing, which influences the morphology and the nature of gold. Our results further point to the importance of acid-base property of the support and the metal-support synergy rather than the gold particle size alone in achieving high-performance in selective alcohol oxidation. Moreover, this work provided a good way to design gold catalysts with controllable sizes that is crucial for understanding the reaction process in aerobic oxidation of alcohol.

Producing of cinnamyl alcohol from cinnamaldehyde over supported gold nanocatalyst

“…That meant the presence of aldehyde group might promote the hydrogenation of vinyl group on the Au/ZrO2 catalyst. From the results, the Au25/ZnAl-300 catalyst with moderate basicity and acidity [26,42] showed the highest selectivity, which indicated the typical basic or acidic supports might be detrimental to the selectivity for the hydrogenation of CAL to COL in this work.…”

Systematic Incorporation of Gold Nanoparticles onto Mesoporous Titanium Oxide Particles for Green Catalysts

“…The color of the composite particles distinctively changed from light pink to brown; this observation could imply the gradual increase of the AuNP loading onto the MPT particles. Although many AuNPs containing nanoscale particles exhibit distinctive surface plasmon resonance (SPR) bands in the visible spectrum [8,9,[33][34][35], these AuNPs incorporated on the MPT particles displayed flat SPRs across the entire wavelength. The near absence of detectable SPRs could be due to the relatively small size of the AuNPs formed within the pores and the scattering characteristics of the MPT host particles [36,37].…”

“…Nontoxic metal-based materials have been extensively fabricated to develop reactive catalysts that can be operational in environmentally friendly conditions for various chemical transformation reactions [1][2][3][4][5]. One attractive candidate is a colloidal form of nanoscale metal particles that can be prepared in green solution media (e.g., water and EtOH) and still show catalytic reactivity and recyclability [2,[6][7][8]. Among many metal nanoparticles, gold nanoparticles (AuNPs) have shown ideal characteristics due to their biocompatible nature and well-established preparation strategies for diverse structures [2,[9][10][11][12][13].…”

“…Among many metal nanoparticles, gold nanoparticles (AuNPs) have shown ideal characteristics due to their biocompatible nature and well-established preparation strategies for diverse structures [2,[9][10][11][12][13]. In this sense, bare and surface-modified AuNPs have been tested as catalysts in numerous chemical reactions, including dye degradation, reduction, oxidation, and coupling reactions [1,5,8,9,12,14,15]. However, designing catalytically active AuNPs and maintaining their reactivity in solution-based chemical reactions are still challenging tasks due to the limited surface areas and insufficient long-term stability.…”

Engineering Pt-Bi2O3 Interface to Boost Cyclohexanone Selectivity in Oxidative Dehydrogenation of KA-Oil

“…For example, Villa et al reported that the addition of Bi into PdAu/C can significantly improve the selectivity in ODH of benzyl alcohol because Bi blocks partial of active sites and suppress parallel reaction in ODH of benzyl alcohol [18]. In addition to geometric effect, creating metal-metal [15,19], metal-support [20] or metal-organic interfaces [14] to tune the electronic structures of metal nanoparticles is also an important strategy to regulate their adsorption behaviors. Among them, p-electron metal Bi, is frequently used as a modifier to engineer the electronic structure of Pd and Pt as it can donate electrons to these active species and prevent them from being overoxidized [21,22].…”