Composite of gum arabic and halloysite as a bio-based acidic catalyst for efficient synthesis of 5-hydroxymthylfurfural

A novel acidic bio-based composite has been synthesized via covalent conjugation of two acidic natural compounds, i.e. halloysite clay mineral and Gum Arabic. Measurement of the acidity of the composite confirmed that its acidity was higher than that of individual components. Halloysite-Gum Arabic composite was successfully applied as a biocompatible catalyst for the dehydration of fructose to 5-hydroxymthylfurfural. The reaction conditions were also optimized via Response Surface Method (RSM) and it was found that using 30 mg catalyst per 0.1 mmol fructose led to 99.2% product yield at 100 °C in 105 min. Gratifyingly, the as-prepared composite was recyclable for seven consecutive runs and only insignificant loss of activity was observed after each run. Notably, the recycled catalyst was structurally and morphologically stable.