Abstract
By combining ionic liquids and supercritical carbon dioxide a new class of intensified processes comes into perspective. This is illustrated here in a novel conceptual design for Levodopa production based on a recently granted patent [M.C. Kroon, A. Shariati, L.J. Florusse, C.J. Peters, J. van Spronsen, G.J. Witkamp, R.A. Sheldon, K.E. Gutkowski, Process for carrying Out a chemical reaction, international Patent WO 2006/088348 A1 (2006)], which uses an ionic liquid and supercritical carbon dioxide as solvents in the slowest processing step. Compared to the conventional Levodopa production, the energy consumption in this processing step is reduced from 22.9 MJ/kg product to 17.4 MJ/kg product, the replacement of deactivated catalyst is reduced from 27G mg/kg product to 2.3 mg/kg product, solvent replacement is reduced from 2.68 kg/kg product to 0.03 kg/kg product and the variable costs, excluding raw materials, are reduced from 6.49 (sic)/kg product to 0.68 (sic)/kg product using this novel concept. However, the estimated investment costs of the novel process concept are expected to be higher (in the order of 14 M(sic)). Yet, the payback time is only 1.6 years. (C) 2008 Published by Elsevier B.V.