Catalytic activity of heterogeneous acid catalysts derived from corncob in the esterification of oleic acid with methanol.

Sulfuric acid (H 2 SO 4) pretreated corncob-derived residue was used as a starting material to prepare solid acid catalysts using different sulfonation chemicals (H 2 SO 4 , p -toluenesulfonic acid (TsOH) and H 2 SO 4 /TsOH mixtures) for biodiesel production from the esterification of oleic acid with methanol. Effects of the different sulfonation agents on the properties of the derived carbon-based materials were investigated using various characterization techniques. Lignin residues were obtained after the H 2 SO 4 pretreatment step, and high lignin-containing carbon-based catalysts of ca. 69% (w/w) lignin were derived after sulfonation with H 2 SO 4. Employing TsOH or H 2 SO 4 /TsOH mixtures for sulfonation gave materials with a higher carbon/hydrogen (C/H) ratio, indicating a relatively effective carbonization compared to that with H 2 SO 4 sulfonation. The catalytic activity of the sulfonated corncob in the esterification of oleic acid with methanol was influenced by the acid density, acid strength and porous structure of the sulfonated materials. High methyl oleate yields (>80% after 8 h at 60 °C) were achieved using the acid catalyst obtained from either H 2 SO 4 or TsOH sulfonation, whereas those from H 2 SO 4 /TsOH sulfonation gave slightly lower yields. Thus, the use of the non-volatile TsOH solid as a 'greener' sulfonating agent for the production of carbon-based solid acid catalysts with a high catalytic activity in the esterification reaction is supported. • Corncob-derived residue can be as a starting material for the production for the esterification. • Both TsOH and H 2 SO 4 /TsOH mixtures can be used as effective sulfonating agents. • TSsOH sulfonated sample presented a considerable increase in surface area. • H 2 SO 4 and TsOH sulfonated materials gave high methyl oleate (FAME) yields. [ABSTRACT FROM AUTHOR]

Copyright of Renewable Energy: An International Journal is the property of Pergamon Press - An Imprint of Elsevier Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)