Preparation of a Sulfonic‐Acid‐Type Ordered Mesoporous Carbon Solid Acid via Hydrothermal Synthesis for the Transesterification of Waste Frying Oil

Abstract

AbstractHydrothermal carbonisation was used to synthesise hydrothermally ordered mesoporous carbon (HOMC), employing sucrose as the carbon source, a P123 block copolymer as the surfactant and tetraethyl orthosilicate as the silicon source. A high‐density sulfonic‐acid‐based solid acid catalyst (HOMC‐SO3H) was subsequently prepared via low‐temperature sulfonation of the HOMC with concentrated sulfuric acid. Transmission electron microscopy and small‐angle X‐ray diffraction analyses showed that both the HOMC and HOMC‐SO3H exhibited an ordered mesoporous structure. The N2 Brunauer‐Emmett‐Teller surface areas of the HOMC and HOMC‐SO3H were determined to be 112 and 87 m2/g, respectively, and the average pore sizes were 11.0 and 15.1 nm, respectively. X‐ray photoelectron spectroscopy data confirmed that −SO3H groups were successfully introduced onto the HOMC surface by the sulfonation process, and a surface acid concentration of 5.9 mmol/g HOMC‐SO3H was determined by acid‐base titration. The HOMC‐SO3H was applied to the transesterification of waste frying oil with methanol and a fatty acid methyl ester yield of 95 % was obtained after a 5 h reaction at 180 °C.