Development of clean technology for the production of triols

An alternative clean production technology was developed for the synthesis of two triols, trimethylolpropane (2,2-di(hydroxymethyl)butan-1-ol) and tri methylolethane (2,2-di(hydroxymethyl)propan-1-ol) starting from formaldehyd e, propionaldehyde and butyraldehyde; the technology is based on the use of solid heterogeneous catalysts in the key process steps, aldolization and a ldol hydrogenation. Catalyst screening and kinetic experiments with propion aldehyde and butyraldehyde showed that the desired aldols can be obtained w ith a high yield and selectivity when anion exchangers with amine groups ar e used as heterogeneous catalysts and the reaction is carried out in aqueou s environment. Suitable reaction temperatures are 50-80 degrees C with form aldehyde:propion or butyraldehyde ranging from 3:1 to 4:1. In the second pr ocess step, the excess of formaldehyde was separated from the reaction mixt ure with atmospheric distillation in the presence of excess of water. Catal yst screening and kinetic experiments showed that nickel-chromium and coppe r-chromium are the most suitable catalysts for the aldol hydrogenation. The experiments carried out at 50-80 degrees C and 40-80 bar hydrogen gave 100 % yields of trimethylolpropane and trimethylolethane. A process scheme for the continuous production of trimethylolpropane and trimethylolethane was p roposed.