Metal–organic frameworks as catalysts for fructose conversion into 5‐hydroxymethylfurfural: Catalyst screening and parametric study

Abstract

Hydroxymethylfurfural (5‐HMF) is a vital biomass‐derived platform chemical for the production of secondary value‐added chemicals. In this work, fructose conversion into 5‐HMF over metal–organic framework (MOF) has been considered. Several MOF‐based catalysts were synthesized and examined in fructose dehydration into 5‐HMF via a microwave‐assisted reactor. Each MOF's catalytic performance was evaluated concerning its surface area, pore size, and acid density. The results showed satisfactory fructose conversion levels for all studied MOFs in the range of 60%–99%. As a catalyst, zeolitic imidazolate frameworks (ZIFs) resulted in excellent fructose conversion, but interestingly, higher quantities of side products such as formic and levulinic acids were produced. The higher 5‐HMF yields, up to 90%, were obtained over the MIL‐101 (MIL, Materials Institute Lavoisier) family, such as MIL‐101‐SO3H. This result is ascribed to the fact that functionalized MOF possesses hydrothermal stability, high surface area, and suitable pore sizes.

Phosphazene-Based Covalent Organic Framework as an Efficient Catalyst (COF-1) for the Dehydration of Fructose to 5-HMF

“…Due to their permanent porosity, high surface area, facile synthesis, thermal stability, presence of active centers, and accessible voids, they show wide potential in catalysis, gas and energy storage, chemical sensing, photocatalysis, electronic devices, drug delivery, and so forth. In catalysis, COFs can be used as heterogeneous catalysts because of their unique functionality, uniform tunable pore sizes, and recoverability, which are more suitable for achieving excellent selectivity and catalytic activity than homogeneous catalysts. , Several functionalized COFs and metal–organic frameworks (MOFs) have also been active in the synthesis of HMF, especially from fructose. , But these are mainly encompassed by sulfonated acid groups; for instance, in 2015, the sulfonated 2D COF (TFP-DABA-COF-SO 3 H) was reported by Peng et al Due to the π-extended TFP-DABA network and the Brønsted acidity of −SO 3 H groups, fructose was enhanced toward dehydration into 97% HMF in DMSO . Subsequently, in 2019, Babaei et al.…”

“…23,24 Several functionalized COFs and metal−organic frameworks (MOFs) have also been active in the synthesis of HMF, especially from fructose. 4,25 But these are mainly encompassed by sulfonated acid groups; for instance, in 2015, the sulfonated 2D COF (TFP-DABA-COF-SO 3 H) was reported by Peng et al Due to the π-extended TFP-DABA network and the Brønsted acidity of −SO 3 H groups, fructose was enhanced toward dehydration into 97% HMF in DMSO. 21 Subsequently, in 2019, Babaei et al developed a sulfonated triazine-based COF, which was supported on SBA-15 to synthesize a Brønsted acidic MAM-CNC-COF-SO 3 H/SBA-15, and it led to a yield of HMF 78% in DMSO at 120 °C.…”

Quantification of the Microwave Effect in the Synthesis of 5-Hydroxymethylfurfural over Sulfonated MIL-101(Cr)

“…Since the discovery of the remarkable catalytic capabilities of MOFs for biomass conversion, a lot of work has been aimed at investigating the dehydration of various hexoses into hydroxymethylfurfural (5-HMF) over a wide range of pristine and modified MOFs. The acidic properties of some MOFs can, indeed, be further enhanced by adding functional groups such as nitro, sulfate, or phosphate to their structure to tune Brønsted and Lewis acid sites [68,69,[81][82][83][84]. The high activity and selectivity of sulfonated MOFs make -SO 3 H the 'functional group' of choice for these reactions [65,68,[84][85][86].…”

“…Merging microwave-responsive catalysts such as functionalized MOFs (polar absorber hybrid materials) with contemporary MW technology could contribute positively to sustainable biomass conversion towards useful renewable products. One type of MOF exhibiting high thermal and chemical stability, MIL-101(Cr), has been used as a solid catalyst for MW-assisted biomass conversion reactions [82,87,88]. The acronym "MIL" stands for "Material from Institut Lavoisier", while the number "101" refers to the fact that it was the first MOF developed at the Institut Lavoisier.…”

“…These MIL-101 analogues have also been assessed for 5-HMF production, but their performance does not meet that of MIL-101(Cr), especially in terms of stability [72]. Therefore, several studies selected the latter for further investigations on catalyst performance for biomass conversion [82,87,88].…”