Eco-Friendly Synthesis of SO₃H-Containing Solid Acid via Mechanochemistry for the Conversion of Carbohydrates to 5-Hydroxymethylfurfural

Abstract

A green, efficient, and facile ball-milling-assisted strategy was proposed to design an SO3H-containing solid acid for biomass valorization, where −SH groups were grafted on a natural clay attapulgite by wet ball milling with 3-mercaptopropyltrimethoxysilane (MTPS), followed by the oxidation of −SH to −SO3H with H2O2 at room temperature. The mechanism of the −SO3H functionalization by the ball-milling process was investigated, and the investigation indicated that the MTPS was grafted on the attapulgite through hydrolysis and condensation, which was induced by the mechanical forces of ball milling. Characterization, including SEM, EDX (energy-dispersive X-ray spectrometry), NH3-TPD, TGA, FT-IR, elemental analysis, and XPS, confirmed the success of −SO3H modification on attapulgite with a total acidity of 1.81 mmol/g. Harsh conditions involving a corrosive sulfonating agent, organic solvent, or high temperature in traditional methods are avoided in the developed approach. The prepared catalyst displayed a high activity toward the transformation of biomass-derived carbohydrates (glucose, fructose, cellobiose, sucrose, starch, and cellulose) into the more valuable chemical 5-hydroxymethylfurfural due to the synergy effect of MgO and −SO3H sites on the catalyst. Moreover, the catalyst showed excellent stability and recyclability for five recycles without loss of activity. This study provides a novel green method for the preparation of an SO3H-containing heterogeneous catalyst, which should have great application potential in other processes of biomass valorization.

Effective hydrolysis of polysaccharides by activated attapulgite

“…The band at 1540 cm −1 on ATP‐S was also enhanced, and this is attributed to Brønsted acid sites, indicating that the acidic properties of Brønsted acid were augmented after H 2 SO 4 activation. According to Chesalov et al ., an increase of the SO 4 2− content results in the higher acidity of Brønsted acid sites, proving that the acid properties of ATP can be transformed by H 2 SO 4 activation 24,27,28 . Besides that, the band of Lewis acid sites at 1450 cm −1 also augmented after the modification, implying that the amount of Lewis acid sites also increased.…”

“…According to Chesalov et al, an increase of the SO 4 2− content results in the higher acidity of Brønsted acid sites, proving that the acid properties of ATP can be transformed by H 2 SO 4 activation. 24,27,28 Besides that, the band of Lewis acid sites at 1450 cm −1 also augmented after the modification, implying that the amount of Lewis acid sites also increased. According to Xavier et al, the emerging Lewis acid sites might be related to the cation (Al, Mg, Si) and oxygen forming polyhedrons, since some zeolitic water and structural OH groups on the attapulgite were removed in the thermal activiation.…”

Weak-acid biochar catalyst prepared from mechanochemically-activated biomass and humic acid for production of 5-hydroxymethylfurfural

“…Practically, sulfonated-based solid materials are developed and used as Brønsted acid catalysts to synthesize 5-HMF (Karimi et al 2021;Perez and Dumont 2021;Zhao et al 2018). Most methods used for preparing sulfonated-materials require sulfuric acid, harsh conditions and can release toxic gases, all of which do not meet the principles of green chemistry (Sun et al 2020). Thus, more environmentally-friendly methods for synthesis of solid acid catalysts are needed.…”

High-Yield and High-Efficiency Conversion of HMF to Levulinic Acid in a Green and Facile Catalytic Process by a Dual-Function Brønsted-Lewis Acid HScCl4 Catalyst

“…However, due to the water-insoluble characteristics and the robust structure of cellulose, the reaction of the conversion of cellulose to LA usually needs harsh reaction conditions, and the LA yield is low. Various studies on the synthesis of LA from cellulose, glucose, and fructose have been performed, − and different catalysts, including solid acids, , inorganic acids, and ionic liquids (ILs), − have been investigated. However, these catalysts studied thus far suffer shortcomings, such as expensive starting materials, harsh experimental conditions, and complicated synthesis and purification operations.…”