Homogeneous hydrogenation of carboxylic acids from biomass
Résumé
Sugar cane is known for its sweet juice, it is also a source of other biosourced molecules that can be valued. This plant is traditionally grown for extracting sugar and obtaining ethanol. After extraction of the sugar in factories, the sugar cane juice still contains many interesting compounds [1], such as carboxylic acids. In this work, we seek to enhance succinic acid (chosen as a model molecule) by homogeneous catalysis to obtain products with economic interest for industries. The compounds that we are looking for are Tetrahydrofuran (THF), ł-butyrolactone (GBL), and especially the 1,4-Butanediol (BDO), because of their potential as biosourced solvents, intermediates in synthesis reactions, or as a monomers for polymer synthesis. This research focuses on the hydrogenation of succinic acid by an active catalytic based on a Ru complex [Ru(acac)3/triphos] [2,3,4], using ethanol as solvent. Figure 1 : 1,4-BDO synthesis from succinic acid and esters catalyzed by Ru complexes In order to obtain a better selectivity and maximum yield of 1,4-BDO, different reaction parameters were optimized, such as temperature, pressure, reaction time, presence of additives, etc. Better results were obtained at 60 bar H2 and 150°C, leading to a complete succinic acid conversion and 1,4-BDO yields up to 90%. In purpose to reach the industry requirements, these optimum operating conditions will be applied to more complex biosourced acids, in order to obtain high added value products from sugar cane waste.