Activation conditions of bentonite supports over gold-based catalysts for production of lactic acid from glycerol

It was investigated the lactic acid production by glycerol oxidation using % 1 Au/bentonite catalysts in alkaline medium. The reactions were performed in a 100 mL volume three-necked and round-bottomed flask placed in an oil bath over a period of 4 h at 90 degrees C reaction temperature and atmospheric pressure. 1 wt% Au based bentonite catalysts were prepared by incipient to wetness method. Gold metal is chosen for catalyst active material since it is active under mild conditions and activation conditions of support material were investigated. Bentonite supports, activated under different conditions (temperature and acidic medium) were used as supports. Results of bentonite supported studies showed that the use of heterogeneous catalysts was necessary and bentonite activation improved catalytic activity, but the application of chemical activation negatively affected lactic acid selectivity. The highest glycerol conversion (76%) has been obtained with 1 wt% Au catalyst that the support was activated by thermally and chemically at 700 degrees C and 1 M HCl. And also the maximum lactic acid amount (18%) was obtained with this catalyst. The chemical activation of the support material at high acid concentration has caused a high conversion and lactic acid selectivity.