High-yield 5-hydroxymethylfurfural synthesis via fructose dehydration catalyzed by a core-shell structured magnetic solid acid

The efficient synthesis of 5-hydroxymethylfurfural (HMF) constitutes a critical pathway for establishing sustainable biorefinery systems. To address the challenges of catalyst recovery difficulties and active site deactivation in conventional solid acid catalysts, a magnetic core-shell structured solid acid catalyst (Co@NC-SO₃H) for fructose dehydration to HMF was developed in this manuscript. The catalyst integrated sulfonic acid groups (-SO₃H) anchored on nitrogen-doped carbon nanotubes with in-situ immobilized cobalt nanoparticles, synergistically combining Brønsted acid sites with magnetic responsiveness. Comprehensive characterization through FT-IR (Fourier Transform Infrared Spectroscopy), XRD (X-Ray Diffraction), SEM (Scanning Electron Microscopy), and XPS (X-ray Photoelectron Spectroscopy) elucidated its microstructural evolution and elemental distribution. Systematic optimization of reaction parameters (temperature, solvent, reaction time, water content, and so on) achieved > 90 % yield of HMF, with 99 % conversion of fructose. The magnetic core-shell configuration enabled rapid catalyst separation via an external magnetic field, retaining > 90 % initial activity after 5 cycles with almost no metal leaching, demonstrating exceptional stability under hydrothermal conditions. This work advanced the development of catalysts for the dehydration of fructose to synthesize HMF, offering critical insights for advancing green and sustainable HMF production.