Screening of different solid acid catalysts for glycerol acetylation

Different solid acid catalysts, sulfonic acid functionalized amorphous and mesoporous silicas, titania doped silica HMS, sulfated zirconia and niobic acid, were synthesized, characterized and tested in the esterification reaction of glycerol. Their catalytic performance was compared with that of commercial Amberlyst-15. Fresh and spent materials were analyzed by means of X-ray photoelectron spectroscopy, N2 adsorption isotherms and acid capacity measurements. Among all the catalysts the mesoporous sulfonic silica presented the best performance in term of reactivity, with the total conversion of glycerol in 30 min of reaction, and in term of stability, with no leaching of sulfonic groups of catalyst. The catalytic activity of the materials was related to their acid capacities as well as to the strength and surface density of acidic sites.

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► SO3H-SBA shows the best activity and selectivity for glycerol acetylation.
► SO3H-SBA exhibits high stability with no leaching of acidic groups during 5 cycles.
► The balance acid sites/surface density is a key factor for activity and selectivity.
► Despite high acidity, Amberlyst-15 shows low selectivity to triacetyl product.