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Sn–Al-MCM-41 oxide catalysts were synthesized, characterized, and used in glycerol etherification reaction with benzaldehyde. The materials obtained offered heterogeneous Lewis and Bronsted acid sites. The direct functionalization of glycerol with benzaldehyde formed cyclic acetals of high commercial value. The best reaction conditions pointed to a conversion up to 95% of glycerol and final yield of cyclic acetals up to 75%, at a temperature of 120 °C and 240 min using Sn25 catalyst. Moreover, 2-phenyl-1,3-dioxan-5-ol (6-membered cyclic ring) was the most observed products, in cis and trans isomer forms with values above 70%. The temperature presented a positive effect, increasing the glycerol conversion but favored the formation of undesired molecules, such as benzoic acid and benzyl alcohol. The reaction equilibria shifted, due to the high concentration of benzaldehyde, which was useful for a higher yield of cyclic acetals. Time was an important reaction variable, as the selectivity to cyclic acetals may change significantly according to reaction time.