Catalysis of Glucose to 5-Hydroxymethylfurfural using Sn-Beta Zeolites and a Brønsted Acid in Biphasic Systems

Abstract

Selective and efficient dehydration of glucose to 5-hydroxymethylfurfural (HMF) has been a widely explored concept recently, especially from the perspective of employing environmentally benign heterogeneous catalysts. However, there has been a relative paucity of data regarding the application of Sn-Beta zeolites, a category of catalysts that are very innocuous, inexpensive, and effective, toward evaluating bio-based conversions. Sn-Beta was shown to possess good Lewis acidity for catalyzing glucose isomerization to fructose in aqueous media at low pH and accelerating dehydration of glucose to HMF in a biphasic system with high yields. Sn-Beta zeolite with NH4F as the mineralizing agent (Sn-Beta-F) was a more effective catalyst for the selective dehydration of glucose to HMF. An optimal HMF yield of 53.0% was obtained over Sn-Beta-F zeolite in an acidic environment (pH 1) after 70 min at 190 °C. The reaction system was also effective for conversion of cellulose to HMF with a yield of 32.2% preliminarily.

Synergy of Lewis and Brønsted acids on catalytic hydrothermal decomposition of carbohydrates and corncob acid hydrolysis residues to 5-hydroxymethylfurfural

“…The explanation offered is that NaCl as an additive in aqueous solution can improve the partitioning of HMF into CPME phase by salting-out effect, whereby electrolytes alter the intermolecular bonding interactions between liquid components, decreasing the mutual solubility of the aqueous and organic phase38. The observations presented of glucose conversion to HMF in a biphasic system catalyzed by AlCl 3 /HCl in the aqueous phase are consistent with those found for glucose dehydration in a water/THF biphasic system catalyzed by Sn-Beta zeolite and HCl16.…”

“…Only small amount of LA was formed, which also be suppressed by the introduction of organic extracting solvent according to previous literatures1634. Additionally, less insoluble solid humins were observed when the addition of HCl is conducted, inferring that the formation of humins is attributed to Lewis acid sites.…”

“…In water-only system, the HMF yield and the reaction selectivity to HMF were low (24.0% and 30.5%, respectively) while the glucose conversion was 78.5%. Thus, as can be expected, many undesirable reactions took place, and even water-insoluble solid products were formed without the organic solvent CPME16. The addition of CPME did not increase glucose conversion significantly, but the use of a CPME-H 2 O biphasic system selectively enhanced the production of HMF by the transfer of HMF to the organic phase after its formation in the aqueous solution.…”

“…In comparison, Lewis acids not only offer highly selective glucose isomerization to fructose, but can also tolerate Brønsted acidity and high temperature. In our previous work, HMF yield exceeding 50% was achieved in a one-pot reactor, containing Lewis acidic Sn-Beta and Brønsted acidic HCl16. Other studies investigated advanced tandem heterogeneous Lewis/Brønsted acid catalysts for accelerating the degradation of sugars, such as dealuminated zeolites17, activated carbons18 solid superacid SO 4 2− /ZrO 2 -Al 2 O 3 1920.…”

Catalytic Conversion of Biomass-derived Carbohydrates into 5-Hydroxymethylfurfural using a Strong Solid Acid Catalyst in Aqueous γ-Valerolactone

“…Unfortunately, common Brønsted acids fail as effective catalysts with low HMF yield. It is widely acknowledged that, before dehydration, glucose first undergoes isomerization to fructose by Lewis acids such as metal chlorides (Zhao et al 2007), Sn-Beta (Román-Leshkov et al 2010;Yang et al 2015a), Sn-MCM-41 (Xu et al 2014), or enzymes . Although metal chlorides (such as CrCl3, AlCl3, SnCl4) are favored for this reaction, they are poisonous, corrosive, hazardous to human health, and also impractical to recycle.…”