Electrocatalytic Oxidation of 5‐Hydroxymethylfurfural into the Monomer 2,5‐Furandicarboxylic Acid using Mesostructured Nickel Oxide
F. Joschka Holzhäuser, Tobias Janke, Fatma Öztas, Cornelia Broicher, Regina Palkovits
Abstract
Abstract Transforming biomass based compounds with renewable electrical energy into products presents a promising approach towards development of a circular economy. Herein, 5‐hydroxymethylfurfural (HMF), derivable from cellulose and hemicellulose, is successfully electrochemically converted into 2,5‐furandicarboxylic acid (FDCA). The reactions are performed in alkaline aqueous solutions using commercial nickel oxide (NiO) or a mesostructured nickel oxide derived by CMK‐1 templating (NiO‐CMK‐1). Both catalytic activity and the selectivity of FDCA are highly dependent on the catalyst structure. NiO‐CMK‐1 facilitates multiple times higher FDCA selectivity (>80%) compared with commercial NiO (30%). Electrochemical analyses emphasize a net‐current density for NiO of 2 mA cm −2 whereas for NiO‐CMK‐1 the net‐current density increases significantly to above 4 mA cm −2 . The exposed material surface and structure of the catalysts are analyzed via nitrogen physisorption and powder X‐ray diffraction revealing that both NiO and NiO‐CMK‐1 possess a face‐centered cubic crystal structure but distinctly different exposed surface areas. Since NiO‐CMK‐1 enables remarkably improved catalytic activity for the oxidation of HMF, a recycling study is conducted with five consecutive catalytic cycles emphasizing the technological potential of this approach.