NiFe Layered Double Hydroxide-Derived Catalysts with Remarkable Selectivity for the Oxidation of 5-Hydroxymethylfurfural to 2,5-Furanedicarboxylic Acid under Base-Free Conditions

Abstract

In this work, we report the exciting discovery of inexpensive and durable catalysts for the selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furanedicarboxylic acid (FDCA) under base-free conditions. A nickel-iron layered double hydroxide (NiFe-LDH) precursor was first prepared then subjected to hydrothermal sulfidation with thioacetamide at 120 °C or thermal phosphidation with sodium hypophosphite at 400 °C to produce NiFeS and NiFeP-400 catalysts, respectively. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) showed these catalysts to contain FeNi2S4 and FeNi2P, respectively, as the dominant phases. The catalytic activity of each catalyst was optimized by studying the effect of the solvent, reaction temperature, oxidant, and reaction time on HMF conversions and product distributions. Under optimized conditions (acetonitrile solvent, 120 °C, tert-butanol peroxide as an oxidant, 12 h, respectively), the NiFeS catalyst afforded 100% HMF conversion with an 83.2% FDCA selectivity with the performance of the NiFeP-400 catalyst being almost identical (HMF conversion of 100%; FDCA selectivity of 82.7%). Both catalysts showed excellent stability over five cycles of catalyst tests with the catalysts able to be easily collected after use with a magnet. Based on the experimental findings, the similar reaction mechanisms used are to be proposed for HMF oxidation to FDCA over the two catalysts. Results show that metal sulfide-based and metal phosphide-based catalysts are promising alternatives to traditional noble metal-based catalyst for the valorization of bio-derived HMF.

Modulating vacancies of graphene supported FeNi2S4 electrocatalysts by radio-frequency plasma for overall water splitting

“…The Ni 3+ ions can serve as p-type dopant to introduce additional holes and as n-type dopant to introduce additional electrons. The peaks at 862.0 eV and 879.6 eV are the Ni satellite peaks [42,43]. In the high-resolution Ni 2p spectrum of FeNi 2 S 4 /P-rGO@X, the Ni 2p 3/2 peak linked to S shifts toward lower binding energy as the plasma treatment duration increases.…”

S, P modified CoFe-LDH derived CoFeS and CoFeP-400 catalysts efficiently catalyze the oxidation of HMF to FDCA

“…In our previous work, we obtained a certain yield of FDCA by catalytic oxidation of HMF with NiFe-LDH after vulcanization and phosphating. 27 In this work, we created new CoFeP- x and CoFeS catalysts by phosphidation or sulfurization of a precursor. The temperature at which the phosphidation takes place is indicated by x .…”