Ru(III) single site solid micellar catalyst for selective aqueous phase hydrogenation of carbonyl groups in biomass-derived compounds

Abstract

Catalytic processes in water have a lower environmental impact, cost, and toxicity than in organic solvents. Considering the high content of water in biomass, it would be natural to use aqueous phase catalytic technology for the production of valuable products. However, in the aqueous phase, most metal-based catalysts suffer from low activity, low selectivity and deactivation due to metal oxidation and leaching. In this paper, we propose a solid micellar Ru catalyst (Ru(III)@MCM) based on single-site Ru(III) species stabilized by cetyltrimethylammonium (CTA+) surfactant and immobilized in the walls of MCM-41 for the selective aqueous phase hydrogenation of carbonyl groups. This catalyst demonstrates exceptional selectivity, activity, and stability in comparison with conventional metallic catalysts. DFT modeling suggests that the reaction proceeds via heterolytic dissociation of hydrogen, forming a Ru-Hydride species, and subsequent hydride transfer to the carbonyl group. Water plays a key role in avoiding product inhibition.