Combination of Brønsted and Lewis Polymeric Catalysts for Efficient Conversion of Cellulose into 5‐Hydroxymethylfurfural (HMF) in Ionic Liquids

Abstract

Stable oil‐in‐water high internal phase emulsions (HIPEs) with an internal phase volume fraction of 85 % were stabilized using Tween 85. The prepared poly(HIPEs) were first investigated as adsorbents to treat water polluted with CrIII, and then the catalysts with Lewis acidic sites was synthesized. The catalysts with Brønsted acidic sites were obtained by ion‐exchanging. The as‐prepared HIPEs–CrIII (PEs–CrIII) and HIPEs–SO3H (PEs–SO3H) possess open‐cell structure, interconnecting pores, and strong acidity, they are utilized as highly efficient catalysts for the conversion of biomass to 5‐hydroxymethylfurfural (HMF). These results showed maximum production yields for cellulose, glucose, and fructose of 37.0 %, 58.0 %, and 80.8 %, respectively. PEs–CrIII and PEs–SO3H can be very easily recycled at least four times without significant loss of activity. Herein, a new method is presented to transform cellulose by using two catalysts in a one‐pot process for meeting the varying demands involved at different reaction stages.

Conversion of Glucose to 5-Hydroxymethylfurfural, Levulinic Acid, and Formic Acid in 1,3-Dibutyl-2-(2-butoxyphenyl)-4,5-diphenylimidazolium Iodide-Based Ionic Liquid

“…The % yield of HMF increased with increasing temperature. A high temperature was usually needed to promote the dehydration reaction of glucose; however, at the highest temperature tested, the HMF yield slightly decreased due to HMF transformation into LA and FA, as reported by others [8,34,41,45,46]. We conclude from this study that the optimum temperature for glucose conversion to HMF in [DBDIm]I with or without H 2 SO 4 was 100 • C. The best glucose conversion conditions were the operating temperature of 100 • C and the reaction time of 120 min in [DBDIm]I as both the solvent and Lewis acid, and H 2 SO 4 as a Brønsted acid catalyst.…”

The Direct Conversion of Cellulose into 5‐Hydroxymethylfurfural with CrCl3 Composite Catalyst in Ionic Liquid under Mild Conditions

“…Numerous catalysts have been applied to the conversion of carbohydrates into HMF, including inorganic or organic Brønsted acids, Lewis acids, bifunctional catalysts, etc . Among them, metal chlorides especially chromium chlorides (CrCl2 and CrCl3) perform as promising catalysts leading to a yield of approximately 70% from glucose .…”

Intensified 5‐Ethoxymethylfurfural Production from Biomass Components over Aluminum‐Based Mixed‐Acid Catalyst in Co‐Solvent Medium

“…A catalyst system consisting of both Lewis and Brønsted acids should be more efficient for this kind of reaction. Similar strategy was commonly utilized in the synthesis of HMF, levulinic acid and its esters from glucose‐based carbohydrates, in which Brønsted acid is mainly responsible for fructose dehydration and alcoholysis, and Lewis acid plays a vital role in the isomerization of glucose. To date, Lew et al .…”