Catalytical conversion of carbohydrates in subcritical water: A new chemical process for lactic acid production

• Published in: Journal of molecular catalysis. A, Chemical Vol. 239; no. 1; pp. 151 - 157
• Main Authors: Bicker, M., Endres, S., Ott, L., Vogel, H.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 14-09-2005; Elsevier
• Subjects: Biomass; Catalysis; Chemistry; Exact sciences and technology; General and physical chemistry; Salt effect; Supercritical water; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Biomass; Catalysis; Salt effect; Supercritical water; Water; Catalytic reaction; Cobalt Ions; Nickel Ions; Zinc Ions; Supercritical state; Conversion; Transition metal Ions; Copper Ions; Carbohydrate; Lactic acid
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/j.molcata.2005.06.017

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In the last years the production of lactic acid has increased due to growing polymer markets (biodegradable synthetics), elevated demand in the chemical sector (oxygenated chemicals, ecologically friendly solvents) and many applications in the food industry. At present, the annual lactic acid production is about 100,000
t, most of that from the fermentation of carbohydrates. The disadvantages of this process are small space-time-yields and the production of stoichiometric amounts of salt. In pure sub- and supercritical water (SCW) only small amounts of lactic acid are obtained from the degradation of carbohydrates. But by adding small quantities of metal ions such as Co(II), Ni(II), Cu(II) and Zn(II) to that reaction media, the lactic acid yield is increased up to 42% (g
g
−1) starting from sucrose and 86% (g
g
−1) starting from dihydroxyacetone at 300
°C and 25
MPa. Zn(II) gave the best results with regard to the lactic acid yield. The function of the catalyst in the complex reaction network of carbohydrate degradation is discussed. An alternative lactic acid production process is proposed.