Acetalization of glycerol over sulfated UiO-66 under mild condition

Sulfated metal-organic framework has attracted much attention as a versatile heterogeneous acid for its strong acid strength, large surface area and regular pore channels. In this work, sulfated UiO-66 (UiOSO3H-x) was prepared via the direct oxidation of 2-mercaptobenzoic acid substituted UiO-66. The structure and property of the synthesized UiO-SO3H-x were characterized via XRD, FTIR, static water contact angles, XPS, TG-DTA, N2 adsorption-desorption, SEM and TEM in detail. It was found that sulfonic acid groups dispersed homogenously in the framework of UiO-SO3H-x. And UiO-SO3H-0.2 exhibited excellent performance and stability for the synthesis of solketal from surplus glycerol among the tested solid acids (H3PW12O40, Amberlyst-45, HY, HBEA, HZSM-5 and ZrHP). The detected conversion of glycerol reached 70.3% with a 99.8% selectivity toward solketal at 60 degrees C, and it could maintain its initial activity in five recycles. The highest TOF of each acid site in UiO-SO3H-0.2 reached 676.0 h-1. Moreover, it was versatile for the acetalization of glycerol with other ketones/aldehydes. (c) 2022 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

Automated summary

Sulfated metal-organic framework, with its strong acid strength, large surface area, and regular pore channels, has received significant attention as a versatile heterogeneous acid for various catalytic applications. In this study, sulfated UiO-66 (UiOSO3H-x) was successfully synthesized by direct oxidation of 2-mercaptobenzoic acid substituted UiO-66. The structure and properties of the synthesized UiO-SO3H-x were comprehensively characterized, and it was found that sulfonic acid groups were uniformly dispersed within the UiO-SO3H-x framework. UiO-SO3H-0.2 exhibited excellent catalytic performance and stability for the synthesis of solketal from surplus glycerol, surpassing other tested solid acids. The highest TOF of each acid site in UiO-SO3H-0.2 reached 676.0 h-1, and it demonstrated versatility for the acetalization of glycerol with other ketones/aldehydes.