Functionalized metal-organic frameworks with strong acidity and hydrophobicity as an efficient catalyst for the production of 5-hydroxymethylfurfural

In the dehydration of fructose to 5-hydroxymethyl furfural (HMF), in situ produced water weakens the acid strength of the catalyst and causes the rehydration of HMF, causing unsatisfactory catalytic activity and selectivity. In this work, a class of benzenesulfonic acid-grafted metal-organic frameworks with strong acidity and hydrophobicity is obtained by the direct sulfonation method using 4-chlorobenzenesulfonic acid as sulfonating agent. The resultant MOFs have a specific surface area of greater than 250 m(2).g(-1), acid density above 1.0 mmol.g(-1), and water contact angle up to 129 degrees. The hydrophobic MOF-PhSO3H exhibits both higher catalytic activity and selectivity than MOF-SO3H in the HMF synthesis due to its better hydrophobicity and olephilicity. Moreover, the catalyst has a high recycled stability. At last, fructose is completely converted, and 98.0% yield of HMF is obtained under 120 degrees C in a DMSO solvent system. The successful preparation of the hydrophobic acidic MOF provides a novel hydrophobic catalyst for the synthesis of HMF. (C) 2020 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.

Automated summary

In this study, a class of benzenesulfonic acid-grafted metal-organic frameworks with strong acidity and hydrophobicity were successfully prepared and applied in the catalytic conversion of fructose to HMF. Due to its better hydrophobicity and oleophilicity, the hydrophobic MOF exhibited higher catalytic activity and selectivity in the HMF synthesis.