Bimodal cesium hydrogen salts of 12-tungstosilicic acid, Cs x H4- x SiW12O40, as highly active solid acid catalysts for transesterification of glycerol tributyrate with methanol

• Published in: Journal of catalysis Vol. 318; p. 34
• Main Authors: Iwase, Yukari, Sano, Shogo, Mahardiani, Lina, Abe, Ryu, Kamiya, Yuichi
• Format: Journal Article
• Language: English
• Published: San Diego Elsevier BV 01.10.2014
• Subjects: Acids; Catalysis; Catalysts; Chemical compounds
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2014.07.008

* Cs x H4-x[SiW12O40] (Cs- x ) with both micropores and mesopores are synthesized. * Mesopores are formed by treatment of microporous Cs- in refluxing ethanol. * Mesopores are formed only from microporous Cs- with low Cs content. * Post-treatment of bimodal Cs- in sulfuric acid enhances catalytic performance. * Post-treated Cs- exhibits high catalytic activity for biodiesel production reaction. Bimodal Cs x H4- x [SiW12O40] (Cs x -bimodal ) with mesopores interconnected with micropores were synthesized from microporous Cs x H4- x [SiW12O40] (Cs -micro ) with x =1.0-2.5, which were prepared in advance by titrating an aqueous solution of H4[SiW12O40] with an aqueous solution of Cs2CO3, followed by treatment in refluxing ethanol to mainly dissolve the H4[SiW12O40] in the particles. Mesopore size distributions and their pore volumes changed depending on x in Cs -micro . Microporous Cs2.5-micro transformed into bimodal Cs2.5-bimodal with mesopores having average diameters of 3.7nm and large mesopore volumes. Although Cs2.5-bimodal exhibited only low catalytic activity for the decomposition of isopropyl acetate, post-treatment in H2SO4 enhanced the catalytic activity due to substitution of the Cs+ ions on the surface with H+ . H2SO4-treated Cs -bimodal showed high activity toward transesterification of glyceryl tributyrate with methanol due to its strong acid strength and mesoporosity.