Gold Nanoclusters Confined in a Supercage of Y Zeolite for Aerobic Oxidation of HMF under Mild Conditions

Abstract

Au nanoclusters with an average size of approximately 1 nm size supported on HY zeolite exhibit a superior catalytic performance for the selective oxidation of 5‐hydroxymethyl‐2‐furfural (HMF) into 2,5‐furandicarboxylic acid (FDCA). It achieved >99 % yield of 2,5‐furandicarboxylic acid in water under mild conditions (60 °C, 0.3 MPa oxygen), which is much higher than that of Au supported on metal oxides/hydroxide (TiO2, CeO2, and Mg(OH)2) and channel‐type zeolites (ZSM‐5 and H‐MOR). Detailed characterizations, such as X‐ray diffraction, transmission electron microscopy, N2‐physisorption, and H2‐temperature‐programmed reduction (TPR), revealed that the Au nanoclusters are well encapsulated in the HY zeolite supercage, which is considered to restrict and avoid further growing of the Au nanoclusters into large particles. The acidic hydroxyl groups of the supercage were proven to be responsible for the formation and stabilization of the gold nanoclusters. Moreover, the interaction between the hydroxyl groups in the supercage and the Au nanoclusters leads to electronic modification of the Au nanoparticles, which is supposed to contribute to the high efficiency in the catalytic oxidation of HMF to FDCA.

Advances in Base-Free Oxidation of Bio-Based Compounds on Supported Gold Catalysts

“…The basic medium provides higher reaction rates and, in the majority of cases, is essential to get a high catalytic activity. However, the basic medium also favors HMF degradation and requires a final neutralization step, which is not desirable from the environmental and Au-based catalysts have been reported to perform this reaction in water and in the presence of an excess of base with high yields of FDCA [56][57][58][59][60][61]. Au-containing bimetallic catalysts were developed in order to improve the catalytic performance, but required the use of a homogenous base [33,58,[62][63][64][65][66][67].…”

Insights into the reaction mechanism for 5-hydroxymethylfurfural oxidation to FDCA on bimetallic Pd–Au nanoparticles

“…Many researchers have focused their attention on the study of the best material and reaction conditions for improving FDCA yield [14][15][16][17]. So far, catalyst stability and productivity are low, but the possibility to obtain both high product purity and better process sustainability makes this catalyst type highly interesting.…”

Selective oxidation of 5-hydroxymethyl furfural over non-precious metal heterogeneous catalysts

“…The literature survey for the oxidation of HMF to FDCA indicated that this reaction has been performed using stoichiometric amounts of oxidants and expensive catalytic systems containing noble metals such as Pt [17][18][19][20][21][22], Pd [23][24][25][26], Au [27][28][29][30][31][32], Ru [33], or their alloys [34][35][36][37][38][39][40][41]. In addition, the presence of a base is crucial in order to facilitate the desorption of the resulted acid from the catalytic surface.…”