Preparation of sulfonated ordered mesoporous carbon and its use for the esterification of fatty acids

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• 作者：Li Peng ; An Philippaerts ; Xiaoxing Ke ; Jasper Van Noyen ; Filip De Clippel ; Gustaaf Van Tendeloo ; Pierre A. Jacobs ; Bert F. Sels
• 关键词：Mesoporous carbon ; Esterification ; Acid catalysis ; Sulfonation
• 刊名：Catalysis Today
• 出版年：2010
• 出版时间：26 February 2010
• 年：2010
• 卷：150
• 期：1-2
• 页码：140-146
• 全文大小：669 K

文摘

Mesoporous carbon, which can be replicated from mesoporous silica and whose surface is hydrophobic, can be an ideal catalyst for the esterification of fatty acids. Here we report an easy and low cost way to prepare sulfonic acid group-functionalized mesoporous carbon. A sample of calcined mesoporous silica SBA-15 was added to an aqueous sucrose solution followed by drying and calcination at different temperatures. In contrast to existing procedures, the obtained hybrid Si/C material was then first sulfonated in H₂SO₄, before the final removal of the silica template in order to stabilize the porous structure towards the liquid phase sulfonation treatment. Thus the silica–carbon composites, instead of the mesoporous carbon, were successfully sulfonated to introduce –SO₃H groups, while keeping the ordered mesoporous structure intact. The influence of carbonization temperature was investigated, suggesting an optimum temperature of 873 K. The SO₃H group-functionalized mesoporous carbon, denoted as CMK-3-873-SO₃H, was characterized by means of XRD, N₂ physisorption, SEM, FT-IR, elemental analysis and TEM. It followed that a uniform mesoporous carbon was obtained with an average pore size of 3.89 nm, a specific surface of 807 m²/g and a –SO₃H group loading of 0.39 meq/g of dry material. Compared with other solid acid catalysts, the resulting material shows enhanced activity in the acid-catalyzed esterification of oleic acid with methanol, and can be used repeatedly. The increased catalytic performance is attributed to the hydrophobic surface and larger pore size of the new catalyst. It can effectively accommodate long chain fatty acids and reject formed water, making the active sites easily accessible.