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.