(449d) Hydrogenation of Polyhydroxyl Aromatics in Water

Production of biorenewable chemicals from biomass is one of the major challenges for sustainability [1]. One way to obtain biorenewable chemicals from biomass is through a hybrid process, utilizing sugar as a feedstock. The hybrid process takes advantage of the high selectivity of biological reactions and high reactivity of thermochemical reactions. One process of interest starts with glucose, which can be enzymatically converted [2] to the bridge molecule, myo-inositol [3]. Myo-inositol can subsequently be dehydrated to highly oxygenated aromatics, such as phloroglucinol, which has potential to produce higher value chemicals, such as phenol or resorcinol.

Noble metals, such as platinum and palladium, are widely used as hydrogenation catalysts [4]. Using a Platinum catalyst, we find that the first step in upgrading phloroglucinol is hydrodeoxygenation to resorcinol and phenol, followed by hydrogenation of the aromatic ring. We show that hydrodeoxygenation is thermodynamically preferred to direct hydrogenation of the aromatic ring through molecular dynamics calculations. We believe that the steric hindrance, caused by the hydrogen bonding between phloroglucinol and surrounding water molecules, inhibits the direct hydrogenation of the aromatic ring. We also use reactive force field potential to model different reaction networks in both the gas and aqueous phase to discover the most probable reaction pathways for phloroglucinol hydrogenation.  

[1] A. J. Ragauskas, et al., Science 311, 484 (2006).

[2] S. Atssumi, T. Hanai, and J. C. Liao, Nature 451, 86 (2008).

[3] K. Sanderson, Nature 444, 673 (2006).

[4] J. C. Serrano-Ruiz, and J. A. Dumesic, Green Chem. 11, 1101 (2009).