Transformation of glucose into added value compounds in a hydrothermal reaction media

• Process intensification of glucose valorization by supercritical water.
• Direct injection of catalyst to the supercritical water reactor.
• Production of glycolaldehyde from glucose in supercritical water medium.
• Lactic acid from glucose under supercritical water conditions using NaOH as catalyst.

In this study, the chemical transformation of glucose into added value products (lactic acid and 5-hydroxymethylfurfural) was analyzed using a hydrothermal reaction medium. A continuous pilot plant that operates up to 400 °C, 30 MPa and residence times between 0.004 s and 50 s was used in order to study the process. The reactions of glucose in hot pressurized water were analyzed at 300 °C, 350 °C, 385 °C and 400 °C; the pressure was fixed at 23 MPa and 27 MPa for the experiments. No lactic acid was found at those conditions. High yield of glycolaldehyde (80%, w/w) was found operating at 400 °C and 27 MPa with reaction times of 20 s. Two additives (H2O2 and NaOH) were added in different experiments to improve the lactic acid production. The maximum yield of lactic acid was 57% (w/w) carbon basis using NaOH (0.5 M) as catalyst at 27 MPa and 400 °C with 20 s of residence time. It was observed that the pH of the medium plays an important role in the selectivity of the process.

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