Efficient Aerobic Oxidation of Glucose to Gluconic Acid over Activated Carbon‐Supported Gold Clusters

Abstract

The catalytic performance of the atomically precise gold cluster-Au (PET) (PET=2-phenylethanethiolate), immobilized on activated carbon (AC), was investigated for the aerobic oxidation of glucose to gluconic acid. The Au (PET) /AC-120 catalysts, annealed at 120 °C in air, exhibited high catalytic activity and significantly better performance than the corresponding catalysts Au /AC-150 and Au /AC-300 (treated at 150 and 300 °C to remove the protecting thiolate ligands). The high activity of the robust Au cluster was a result of the partial ligand removal, providing catalytically active sites, which were evidenced by TEM, X-ray photoelectron spectroscopy, thermogravimetric analysis, and Fourier-transform IR spectroscopy. Au (PET) /AC-120 also showed excellent recyclability (up to seven cycles). The turnover frequency for the Au (PET) /AC-120 catalyst was 5440 h , which is higher than for the Pd/AC, Pd-Bi/AC, and Au/AC under identical reaction conditions. This new ultra-small gold nanomaterial is expected to find wide application in other catalytic oxidations.

Gold Catalysts for the Selective Oxidation of Biomass‐Derived Products

“…Similar results were obtained by Liu et al. comparing 2‐phenylethanethiolate stabilised Au clusters of 1.6 nm supported on activated carbon; partial ligand removal by calcination at 120 °C enhanced the catalytic activity up to 5,440 h −1 …”

Atomically Tailored Gold Nanoclusters for Catalytic Application

“…Second, the presence of ligands on NCs makes the mechanistic studies more complicated, but the roles of ligands are intriguing in enhancing the catalytic activity compared to bare clusters (e.g.,t he aerobic oxidation of glucose to gluconic acid [62] )a nd reversible control of product selectivity by thiol ligands (e.g., in the transfer hydrogenation of nitrobenzaldehyde derivatives [63] ). While some surface ligands may be detached during the reaction to expose active sites in certain reactions,f uture work should investigate the details of ligand effects,inp articular their effects in enantioselective catalysis.…”

Thermal control of the defunctionalization of supported Au25(glutathione)18 catalysts for benzyl alcohol oxidation

“…In contrast, fully defunctionalized clusters are essential for CO [20], alcohol [17,21], cyclohexane [22] and styrene [23–24] oxidation, as well as nitrobenzene hydrogenation [24]. Recently, a partially calcined Au 38 (2-phenylethanethiolate) 24 cluster supported on activated carbon (AC) exhibited high efficiency in glucose oxidation [25]. The full defunctionalization at higher temperature usually induces an increase in particle size and decrease of the catalytic activity [26].…”