Efficient Aerobic Oxidation of 5‐Hydroxymethylfurfural in Aqueous Media with Au–Pd Supported on Zinc Hydroxycarbonate

Abstract

Bimetallic catalysts with Au–Pd supported on zinc hydroxycarbonate (ZOC) were synthesized by a simple deposition–precipitation method and analyzed by transmission electron microscopy to have a narrow‐size distribution of predominantly 1–2 nm. The prepared Au–Pd/ZOC catalysts exhibited excellent activity towards 5‐hydoxymethylfurfural (HMF) oxidation in water in the presence of the base NaHCO3 at benign conditions of 80 °C and 3 bar O2, resulting in quantitative yield of 2,5‐furandicarboxylic acid (FDCA). The addition of base not only enhanced the yield of FDCA but also stabilized the support ZOC by preventing ZOC from the reaction with formed carboxylic acid intermediates/products, thus allowing Au–Pd/ZOC to be recycled for at least six times without significant loss of activity. The basicity of ZOC could play an important role in obtaining the improved yield of FDCA as compared to other supports.

Metal Catalysts for the Efficient Transformation of Biomass‐derived HMF and Furfural to Value Added Chemicals

“…Bimetallic catalysts of Au have also been efficiently explored for the oxidative upgradations of furans . Pasini et al.…”

“…Bimetallic catalysts of Au have also been efficiently explored for the oxidative upgradations of furans. [184][185][186][187][188][189][190][191] Pasini et al employed the oxidation of HMF over TiO 2 -supported monometallic Au and bimetallicA u-Cu catalysts, where the bimetallic Au-Cu/TiO 2 catalysts exhibited higherF DCA yield as compared to monometallic. [184] Furthermore, Au-Cu/TiO 2 catalystp repared by the post-deposition of PVP-stabilizedA us ol over the mono-metallicC u/TiO 2 exhibited lower catalytic activity as compared to the presynthesized bimetallic Au-Cu.…”

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

“…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]. The basic medium provides higher reaction rates and, in the majority of cases, is essential to get a high catalytic activity.…”

Pt Nanoparticles Supported on Nitrogen‐Doped‐Carbon‐Decorated CeO2 for Base‐Free Aerobic Oxidation of 5‐Hydroxymethylfurfural

“…In the past decade, the selective oxidation of HMF to produce FDCA has advanced from the initial use of stoichiometric oxidantst ot he current metal-catalyzed aerobic oxidation processes. [6] For the latter,n oble metals (e.g.,A u, [7][8][9][10][11][12] Pt, [11,[13][14][15][16] Au-Cu, [9] Au-Pd, [17][18][19] Ru [20] )a re particularly active at appropriate oxygen pressures and reactiont emperatures. In most cases, however,h omogeneous base additives (e.g.,N a 2 CO 3 or NaOH) still are requiredt op romote this tandem reaction, particularly hydroxyl group oxidation.…”