Mechanochemical Synthesis of Sulfonated Palygorskite Solid Acid Catalysts for Selective Catalytic Conversion of Xylose to Furfural

Abstract

A green, safe, and easy-operation method for the preparation of sulfonated palygorskite solid acid catalyst (PAL-SO 3 H) was developed by a mechanochemical process, where thiol groups (−SH) were grafted onto natural palygorskite by a high-speed shearing process with 3-mercaptopropyltrimethoxysilane in aqueous solution under mild conditions, followed by the oxidation of −SH to −SO 3 H groups. The as-prepared PAL-SO 3 H catalyst was applied in the catalytic conversion of biomass-derived xylose into furfural, and it showed excellent catalytic activity, and as high as 87% of furfural yield with 96% selectivity was achieved at 180 °C in 60 min reaction time in the γ-valerolactone−water mixture (95:5 v/v %). The PAL-SO 3 H catalyst was tolerant of high initial xylose loading concentration up to 120 g/L and exhibited good recyclability. This study provides a green and mild process for the synthesis of a sulfonated solid acid catalyst, which should have potential applications in many fields such as catalysis and adsorption.

Mini-Review on the Synthesis of Furfural and Levulinic Acid from Lignocellulosic Biomass

“…Sulfonated clay and zeolite were also used for the production of furfural. A green sulfonated palygorskite solid acid catalyst (PAL-SO 3 H) in a GVL-water mixture exhibited a high catalysis activity and good recyclability with a furfural yield of 87% from xylose at 180 • C for 1 h [60]. H-ZSM-5 zeolite as a catalyst in a GVL solvent efficiently converted corn cob into furfural with a 71.7% yield at 190 • C for 60 min.…”

Furfural manufacture from xylose : routes towards high selectivity and novel processes

“…The most common solvent for these studies, both in the production of furfural and HMF, is dimethylsulfoxide (DMSO), and it is used from highly aqueous to water-free systems (Table 2.1). [81][82][83][84][85][86][87][88][89][90][91][92][93][94][95] Highly aqueous conditions (7:3 v-v water-DMSO monophasic systems), paired with microwave heating and a metal catalyst (i.e., CrCl3 or Al(NO3)3), resulted in a relatively high fructose-to-HMF selectivity (approx. 65 mol%) when compared with fully aqueous monophasic conditions.…”

“…89 Using DMSO as the sole component of a monophasic system is rather common in the heterogeneously catalyzed production of furans both from xylose, glucose and fructose. 88,[90][91][92][93][94] Among heterogeneous catalysts, sulfonated solids (e.g., silica, carbon and palygorskite) are specifically used, always with sugar-to-furan selectivities >85 mol%. [90][91][92][93][94] Metal catalysts (e.g., Nb2O5) have also been successfully applied, specifically for the dehydration of fructose, with HMF production of approx.…”

“…88,[90][91][92][93][94] Among heterogeneous catalysts, sulfonated solids (e.g., silica, carbon and palygorskite) are specifically used, always with sugar-to-furan selectivities >85 mol%. [90][91][92][93][94] Metal catalysts (e.g., Nb2O5) have also been successfully applied, specifically for the dehydration of fructose, with HMF production of approx. 85-90 mol% selectivity.…”

“…Another polar organic solvent commonly used in sugar dehydration is tetrahydrofuran (THF; Table 2.2). 82,91,[95][96][97][98][99] In this solvent, additional analyses have been performed on the effect of polar aprotic solvents on the dehydration mechanism. 95 Specifically, experimental evidence and molecular dynamics simulations suggest that a mainly organic solvent environment (e.g., 9:1 v-v THF-water or dioxane-water), combined with catalytic amounts of Clanions, results in the stabilization of protonated transition states of the acid-catalyzed process, leading to significant increases in reactivity and selectivity (approx.…”