New heterogeneous Pb oxide catalysts for lactide production from an azeotropic mixture of ethyl lactate and water

• We investigated new heterogeneous catalysts for producing lactide from ethyl lactate.
• Pb oxides were unique and efficient heterogeneous catalysts for this reaction.
• PbO catalyst worked well for ethyl l-lactate in the presence of water.
• PbO catalyst was not leached out during reaction and recovery process.
• Lactide was produced from fermentation broth of ammonium lactate using PbO catalyst.

The heterogeneous PbO, PbO2 and Pb3O4 gave the comparable oligomer yield, oligomer Mw, lactide yield and l-lactide selectivity from ethyl l-lactate with the conventional homogeneous Sn(Oct)2. PbO was also active for ethyl l-lactate containing water as an impurity in distillation process, while Sn(Oct)2 was not active in that condition. No leaching of PbO catalyst was observed during the reaction as well as the recovery process. The recovered catalyst showed no notable loss of activity. By combining this PbO-based catalyst technology with the advanced precipitation process for producing l-ethyl lactate from ammonium l-lactate, l-lactide could be selectively produced in high yield.

Figure optionsDownload as PowerPoint slide