Catalytic conversion of renewable products to fine-chemicals

The dramatic increase of petroleum oil price has made the development of alternative renewable resources extremely urgent. In this context the catalytic conversion of biomass to levulinic acid (LA) and its successive hydrogenation to gamma-valerolactone (GVL) appears very promising. LA is a platform chemical with various potential uses: it can be used as solvent, antifreeze and as starting material for polymers and pharmaceutical compounds and its ester, ethyl levulinate, can be used as oxygenate additive for diesel fuels. On the other hand GVL can be used in perfumes and food industries as well in polymer synthesis. Many starting materials such as glucose, sucrose, starch, cellulose, crops or cellulosic wastes have been used to produce LA. In this context a new process for the conversion of waste biomass which involves the use of a dilute acid in the presence of an electrolyte has been patented. The optimum conditions are different for the different starting materials and the main reactions parameters are: type and concentration of acid and electrolyte, reaction temperature, duration and biomass/water ratio. The obtained levulinic acid can be successively hydrogenated to give GVL in a multi-step process from conversion of biomass. The performances of supported commercial ruthenium catalysts have been investigated adopting very mild reaction conditions. The optimization of the reaction conditions allows to reach very high activities working under mild conditions. A temperature as low as 50 °C is sufficient to allow the complete conversion of the substrate in very short reaction times with total selectivity to GVL without formation of other by-products.