Hydrothermal Conversion of Carbohydrates into Lactic Acid with Alkaline Catalysts

In this paper, alkaline hydrothermal experiments of glucose, fructose and xylose, the model compounds of carbohydrate biomass, were conducted in a batch reactor in the temperature range of 250 to 350°C to examine the production of lactic acid. Result showed that the formation of lactic acid in a hydrothermal reaction of glucose, fructose and xylose could be promoted notably by using NaOH, KOH and Ca(OH)₂ as alkaline catalysts.The yield of lactic acid from glucose, fructose and xylose followed the sequence of fructose > glucose > xylose with NaOH as alkaline catalyst. For fructose, high lactic acid yields of 43.5% with NaOH and 46% with KOH on the carbon base were obtained at the temperature of 300°C.