Acid-Functionalized Mesoporous Polymer-Catalyzed Acetalization of Glycerol to Solketal, a Potential Fuel Additive under Solvent-Free Conditions

A mesoporous phenolsulfonic acid–formaldehyde polymeric acid catalyst was synthesized simply by condensation polymerization of p-phenolsulfonic acid and an aqueous solution of formaldehyde. The acid-functionalized polymer was used as a heterogeneous catalyst for glycerol acetalization with acetone for synthesis of solketal without the requirement of water removal from the reaction mixture. Solketal is extensively used as an additive for the formulation of petrol, diesel, and biodiesel. The effect of reaction parameters, such as the reaction temperature, time, catalyst loading, and glycerol/acetone molar ratio, on the glycerol conversion was exhaustively investigated in detail. Glycerol conversion of 97% and product selectivity of 100% were attained under the optimized reaction conditions: time of 4 h, temperature of 60 °C, catalyst loading of 8 wt %, and glycerol/acetone ratio of 5:1. Recycling of the used catalyst revealed good repeatability without any reactivation until the fourth cycle with a minimal reduction in the yield.