Oxidative Esterification of 5‐Hydroxymethylfurfural under Flow Conditions Using a Bimetallic Co/Ru Catalyst

Abstract

Furanic di‐carboxylate derivatives of 5‐Hydroxymethylfurfural (HMF) are nowadays important in the polymer industry as they are used as building blocks for bio‐based polyesters. The high reactivity of HMF compels to avoid harsh synthetic conditions. Therefore, developing mild catalytic processes for its selective oxidation is a challenging task. Herein, we report the first oxidative esterification of HMF to dimethyl furan‐2,5‐dicarboxylate (FDCM) under flow conditions using oxygen as oxidant. For that purpose, a new series of nitrogen‐doped carbon‐supported bimetallic Co/Ru heterogeneous catalysts were prepared and characterized by XRD, XPS and N2 physisorption. These analyses revealed that the porosity of the materials and order of impregnation of the metals to the carbon supports lead to varying catalytic activities. Under optimized conditions the flow reactor showed a 15‐fold increase on the production of FDCM compared to batch conditions.

Recent advances in the oxidative esterification of 5-hydroxymethylfurfural to furan-2,5-dimethylcarboxylate

“…A bimetallic catalyst mixture of the Co x O y -N + RuO x N support on C-irregular or C-pellets nanoparticles (C-irregular shape with −20 + 40 mesh and cylindrical pellets with ∼0.8 mm diameter) has been investigated for the oxidative esterification of HMF in a flow regime. 78 98% HMF conversion and 57% FDMC yield were obtained using Co x O y -N + RuO x N@C-irregular as the catalyst. In comparison with the batch result (0.03 mmol h −1 ), more than 15-fold increase of FDMC production (0.47 mmol h −1 ) was obtained in the flow regime.…”

Atomically dispersed cobalt–nitrogen–carbon catalysts for efficient oxidative esterification of aromatic alcohols

“…E. Mejı ´a et al reported the oxidative esterification of HMF in a flow regime with excellent conversion and good selectivity using a Co x O y -N + RuO x -N@C-irregular catalyst. [12][13][14][15] Notably, most of the known catalyst systems for the esterification of aromatic alcohols under mild conditions are based on noble metals such as Au, Pd and Ru. 6,[16][17][18][19][20][21] Due to the natural scarcity and high price of noble metals, it is extremely important to develop non-noble metal-based catalysts as alternatives to traditional noble metal catalysts.…”

Mass transfer and reaction characteristics of homogeneously catalyzed aerobic oxidation of 5-hydroxymethylfurfural in slug flow microreactors

“…Microreactor operation allows a precise temperature control of such (aerobic) oxidation reactions and enhances safety (additionally due to low inventory and explosion suppression e.g., when using pure O 2 ) [72]. Very recently, the aerobic oxidation of HMF over heterogeneous catalysts has received research attentions in microreactors [73][74][75][76]. A wall-coated tube-in-tube polytetrafluoroethylene (PTFE) microreactor was used for the oxidation of HMF to DFF in dimethyl sulfoxide (DMSO) over a salen-transition metal core-shell (Fe 3 O 4 /SiO 2 /Mn) catalyst [74].…”

“…35% FDCA, which resulted in crystal formation due to the low solubility of FDCA in the solvent. Also, the oxidative esterification of HMF and methanol to FDCM using oxygen as the oxidant benefitted from operation in a packed bed microreactor with nitrogen-doped carbon-supported bimetallic Co/Ru as the solid catalyst [76]. In the microreactor the FDCM production rate was found over 15-fold higher than in batch reactors [76].…”