Oxidative Esterification of 5-Hydroxymethylfurfural into Dimethyl 2,5-Furandicarboxylate Using Gamma Alumina-Supported Gold Nanoparticles

Abstract

Gold nanoparticles (Au NPs) supported on a nanostructured gamma alumina (γ-Al 2 O 3 ) fiber can exhibit excellent catalytic activity for the conversion of 5-hydroxymethylfurfural to produce its ester derivative, dimethyl 2,5-furandicarboxylate (FDMC). γ-Al 2 O 3 was synthesized using a PEG surfactant to generate oxide fibers that randomly stack together into irregular shapes. The average particle sizes of the Au NPs are 1−6 nm, where the catalytically active Au (111) surface is the exposed facet. This 3D nanocatalyst architecture enhances the 5-hydroxymethylfurfural (HMF) oxidative esterification because HMF reactant molecules can readily diffuse into this fibrous structure and adsorb to active catalytic sites, while ester product molecules can diffuse out. Up to 99% HMF conversion and 90% FDMC selectivity can be obtained at a low reaction temperature of 45 °C, and the catalyst shows excellent recyclability. Increasing the Au content in the catalyst minimizes the requirement of a base for HMF conversion. Thus, the Au NPs supported on γ-Al 2 O 3 can drive HMF esterification to FDMC efficiently with high product selectivity under very mild reaction conditions, omitting the need for an additional esterification step of the HMF acid.

Research Progress of Highly Efficient Noble Metal Catalysts for the Oxidation of 5‐Hydroxymethylfurfural

“…[7a,33] Weerathunga et al prepared Au/γÀ Al 2 O 3 by chemical impregnation precipitation method, which has good catalytic activity in the conversion of HMF to dimethyl 2,5-furandicarboxylate (FDMC) (Figure 4). [34] Under mild conditions (low base and low temperature), the conversion of HMF and the selectivity of FDMC could reach 99 and 90 %, respectively. The excellent catalytic activity of Au/ γÀ Al 2 O 3 catalyst was due to the easy diffusion of HMF, intermediates, and FDMC in the 3D nanocatalyst structure and full contact with the active sites.…”

Recent advances in the chemical valorization of cellulose and its derivatives into ester compounds

“…Several supported metal catalysts with selective oxidation abilities were employed for this reaction, including gold, cobalt, manganese and palladium. [125][126][127][128][129][130][131][132][133][134][135] In addition, a variety of organic and inorganic base additives are also required to accelerate the reaction.…”

Base‐free Oxidative Esterification of HMF over AuPd/nNiO‐TiO2. When Alloying Effects and Metal‐support Interactions Converge in Producing Effective and Stable Catalysts

“…For all these reasons, the oxidative esterification to FDMC has recently moved into the limelight of research on chemo‐catalytic processes for HMF upgrading to value‐added chemicals. Although non‐precious metal based catalysts, in particular Co‐based and Mn‐based systems, have been successfully proposed in the literature, [15,18,37–44] noble‐metal based catalysts, specifically supported Au NPs, still remain the most studied catalysts for the oxidative esterification of HMF to FDMC [10,26,45–55] …”

“…Although non-precious metal based catalysts, in particular Co-based and Mn-based systems, have been successfully proposed in the literature, [15,18,[37][38][39][40][41][42][43][44] noble-metal based catalysts, specifically supported Au NPs, still remain the most studied catalysts for the oxidative esterification of HMF to FDMC. [10,26,[45][46][47][48][49][50][51][52][53][54][55] According to the literature, the reaction would proceed through an acetalization-oxidation-esterification mechanism (Scheme 1), although an alternative pathway involving alcohol oxidation to 2,5-diformylfuran (DFF) has been rarely reported. [18,37] The acetalization-oxidation-esterification mechanism implies the initial formation of a hemiacetal intermediate (A), which is unstable and cannot be detected by a gas chromatographic analysis.…”