Conversion of D-Fructose into Ethyl Lactate Over a Supported SnO2–ZnO/Al2O3 Catalyst

Abstract

The study is directed to the search of a simple effective catalyst for ethyl lactate obtained from fructose as renewable raw material. A series of SnO2-containing oxides prepared by impregnation of alumina were characterized by several techniques in order to determine their textural and acid-base properties. The transformation of a 13% fructose solution in 98% ethanol over SnO2/Al2O3 catalysts using autoclave rotated with 60 rpm at 160 °C for 3 h was studied. It was found that doping SnO2/Al2O3 samples with ZnO improves selectivity towards ethyl lactate. The supported SnO2-ZnO/Al2O3 catalyst provides 100% fructose conversion with 55% yield of ethyl lactate at 160 °C. A possible scheme of fructose transformation into ethyl lactate on L-acid IVSn4+ sites is discussed.

Homogeneous and Heterogeneous Catalysis of Glucose to Lactic Acid and Lactates: A Review

“… 82 Coupling SnO 2 with ZnO on an Al 2 O 3 support instead of Nb 2 O 5 addresses this problem by decreasing the Lewis acid site density, avoiding a high 5-HMF yield while keeping a high lactate yield. 79 Hence, the main parameters driving the catalytic reaction are the surface Lewis acid site density and strength.…”

“… However, Sn has a high concentration of Lewis acid sites, which leads to high lactate yields but also to the formation of more dehydration products . Coupling SnO 2 with ZnO on an Al 2 O 3 support instead of Nb 2 O 5 addresses this problem by decreasing the Lewis acid site density, avoiding a high 5-HMF yield while keeping a high lactate yield . Hence, the main parameters driving the catalytic reaction are the surface Lewis acid site density and strength.…”