Preparation and application of ordered mesoporous carbon-based solid acid catalysts for transesterification and epoxidation

Abstract

Ordered mesoporous carbon (OMC) was prepared via the inverse replication method using SBA-15 as a hard template and sucrose as a carbon precursor. OMC was sulfonated to obtain the solid acid catalysts, such as OMC-SS and OMC-DS, by heating with sulfuric acid or coupling with sulfanilic acid diazonium. TEM and small-angle X-ray diffraction (XRD) results showed that OMC, OMC-SS, and OMC-DS exhibited ordered porous structures. XPS and Raman analysis showed that OMC had graphite structure. N2-BET analysis indicated that OMC, OMC-SS, and OMC-DS had average pore diameters of 3.0–3.3 nm and exhibited bimodal mesopore size distributions. Moreover, N2-BET analysis revealed that OMC, OMC-SS, and OMC-DS had surface areas of 1411, 924 and 1001 m2/g, respectively. The surface acid contents of OMC-SS and OMC-DS were 3.9–4.0 mmol H+/ g and higher than those of OCM (2.8 mmol H+/g). FTIR results demonstrated that –SO3H was present on OMC-SS and OMC-DS. OMC-SS and OMC-DS were used to catalyze the transesterification and epoxidation of waste frying oil. The transesterification reactions catalyzed using OMC-SS and OMC-DS provided the maximum yields of fatty acid methyl esters of 90.3 ± 3.3% and 89.0 ± 2.1%, respectively. The double-bond conversion rates of epoxidation reactions catalyzed using OMC-SS and OMC-DS reached 77.2 ± 1.9% and 68.5 ± 2.6%, respectively. The epoxy yields of epoxidation reactions catalyzed using OMC-SS and OMC-DS were 70.3 ± 2.4% and 65.1 ± 1.8%, respectively.