Efficient conversion of levulinic acid into alkyl levulinates catalyzed by sulfonic mesostructured silicas

•SO3H-SBA-15 has been successfully used in the synthesis of alkyl levulinates.•Moderate acid strength and hydrophobicity is the key of the catalytic performance.•Alkyl levulinates yield close to 100% is achieved adjusting reaction conditions. Sulfonic mesoporous silicas have demonstrated an outstanding catalytic performance in the esterification of levulinic acid with different alcohols to produce alkyl levulinates, a family of chemicals considered to be excellent oxygenated fuel extenders for gasoline, diesel and biodiesel. Catalyst screening indicated that propylsulfonic acid-modified SBA-15 material was the most active one, among tested materials, due to a combination of moderately strong sulfonic acid sites with relative high surface hydrophobicity. Under optimized reaction conditions (T=117°C, ethanol/levulinic acid molar ratio=4.86/1 and catalyst/levulinic acid=7wt%) almost 100% of levulinic acid conversion was achieved after 2h of reaction, being negligible the presence of levulinic acid by-products or ethers coming from intermolecular dehydration of alcohols. The catalyst has been reused, without any regeneration treatment, up to three times keeping almost the high initial activity. Interestingly, a close catalytic performance to that achieved using ethanol has been obtained with bulkier alcohols.