Supported ruthenium catalysts for the transformation of aqueous glycerol to hydrogen gas and lactic acid†

Abstract

Glycerol (GLY) is an attractive biobased platform chemical that produces valuable fine chemicals with a wide range of industrial applicability and has the potential to produce high-purity H₂ gas. Herein, we established an efficient method for selective production of H₂ gas and lactic acid (LA) from aqueous glycerol under mild reaction conditions (90–130 °C) over various supported ruthenium catalysts. Notably, we achieved a substantial yield of H₂ gas (n(H₂)/n(GLY) ratio of 1.4 with >99.9% H₂ purity) and LA (86%) from glycerol over Ru nanoparticles immobilized over a La(OH)₃ support (Ru/La(OH)₃) in contrast to bare Ru nanoparticles where we observed a n(H₂)/n(GLY) ratio of 1.6 with only 70% yield of LA as we reported previously. We could significantly boost the generation of both H₂ gas and LA by tuning the reaction parameters, including reaction time, temperature, base, and water concentrations. Furthermore, the effect of various support materials such as Mg(OH)₂, ZnO, ZrO₂, and TiO₂ was also tested for H₂ production from GLY under optimized reaction conditions. The employment of various characterization techniques to understand the physicochemical properties of the synthesized supported Ru catalysts revealed that the choice of support material significantly influenced the catalytic activity towards the selective production of H₂ and LA.