k-carrageenan nanocomposite as an efficient acidic bio-based catalyst for the synthesis of 5-hydroxymethylfurfural from fructose

A novel bio-based nanocomposite was designed based on a modification of halloysite with k-carrageenan via precipitation polymerization with acrylic acid in aqueous media. Various techniques such as X-ray diffraction (XRD), infrared spectroscopy (FT-IR), thermo gravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM) were conducted to verify the formation of the catalyst. After-ward, it was tested as a solid acid catalyst for the dehydration of fructose, resulting in the production of 5-hydrox-ymethylfurfural (HMF). Effective parameters, such as catalyst amount, temperature, and reaction time were optimized and it was revealed that 10 wt% catalysts at 100 degrees C gave the desired product (HMF, 97.9 % yield) in 35 min. The catalyst was also reusable and could be reused for up to four runs. k-carrageenan as a carbohydrate-containing acidic functionality in the backbone of prepared nanocomposite was successfully applied for improving the catalytic activity of halloysite. Thus, the present protocol can open up an innovative opportunity for the preparation of a bio-based catalytic system from naturally occurring components for the conversion of fructose to 5-hydroxymethylfurfural.