Synthesis of ethyl lactate from triose sugars on Sn/Al2O3 catalysts

• Inexpensive and easily scalable alumina-supported Sn catalysts with different Sn loadings promote ethyl lactate formation from triose sugars and ethanol.
• Ethyl lactate yields of ≈70% are obtained on a 7.6 wt.% Sn/Al2O3 catalyst at 353 K.
• Catalyst preparation conditions, Sn content and reaction conditions affect the final ethyl lactate yield.
• Surface Lewis acid sites that increase with Sn loading participate in the kinetically relevant reaction steps.

Sn-promoted alumina catalysts with different Sn loadings (1–8 wt.%) were prepared by impregnation and characterized by N2 physisorption, X-ray diffraction, UV–vis-DRS, FTIR of pyridine and TPD of NH3. Surface Sn species present Lewis acid properties different from those of the alumina support; the number and strength of the surface Lewis centers increase with the Sn loading. These materials exhibit good catalytic performance for conversion of triose sugars, such as dihydroxyacetone, toward ethyl lactates at mild conditions. The catalyst preparation conditions, Sn content and reaction conditions affect the final ethyl lactate yield. Yields of ≈70% were obtained at 353 K after 7 h of reaction. Surface Sn species participate in the kinetically relevant reaction steps.

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