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

Abstract

Hydrothermal 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-SO 3 H) 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-SO 3 H exhibited an ordered mesoporous structure. The N 2 Brunauer-Emmett-Teller surface areas of the HOMC and HOMC-SO 3 H were determined to be 112 and 87 m 2 /g, respectively, and the average pore sizes were 11.0 and 15.1 nm, respectively. X-ray photoelectron spectroscopy data confirmed that À SO 3 H groups were successfully introduced onto the HOMC surface by the sulfonation process, and a surface acid concentration of 5.9 mmol/g HOMC-SO 3 H was determined by acid-base titration. The HOMC-SO 3 H 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.

Synthesis of ethyl levulinate from cellulose over a double acid site catalyst

“…The BET surface areas of the OOMC-SO 3 H and Al-OCS-0.1 were also decreased while the average pore sizes were increased (Table 1). In previous work, 35 a similar phenomenon occurred after OMC was sulfonated using H 2 SO 4 . After sulfonation, the BET surface area of the OMC was decreased by 45 m 2 g −1 and the average pore size increased by 4.1 nm.…”