High-Yield Synthesis of Ethyl Lactate with Mesoporous Tin Silicate Catalysts Prepared by an Aerosol-Assisted Sol–Gel Process

An aerosol-assisted sol–gel method is used to prepare mesoporous tin silicate catalysts that exhibit a record activity in the synthesis of ethyl lactate from dihydroxyacetone and ethanol. The method is based on the formation of an aerosol from a solution of precursors and surfactant. During the fast drying of the droplets, the surfactant self-assembles and the Sn-silica matrix is formed by polycondensation reactions. After calcination, the resulting material is composed of a true tin-silicon mixed oxide in the form of spherical microparticles with calibrated mesopores of 5–6 nm. Sn species are incorporated in the silica network, mainly in the form of single sites. This makes these catalysts highly active for the targeted reaction, as shown by record turnover numbers. The catalyst is recyclable and truly heterogeneous as it can be reused for several cycles and it does not leach.