Optimizing CuNi catalysts for long-term vapor phase hydrogenation of levulinic acid to γ-valerolactone: Influence of the support on activity and stability

The conversion of biomass-derived levulinic acid (LA) to γ-valerolactone (GVL) is crucial for sustainable chemical and fuel production. This study evaluates the vapor phase hydrogenation of LA using Cu-Ni bimetallic catalysts supported on various metal oxides and their impact on the pathways of LA conversion. Specifically, we examine the influence of AlO₂, SiO₂, ZrO₂-SiO₂, and CeO₂-SiO₂ on catalyst performance and stability. Cu-Ni catalysts supported on SiO₂ modified with citric acid (SiO_2-CA) exhibited superior stability, while the one supported on Al₂O₃ showed higher activity. The enhanced performance of the SiO_2-CA-supported catalyst is attributed to its moderate acidity (379.3 µmol/g_cat) and resistance to sintering. Stability tests reveal that although both CuNi/Al₂O₃ and CuNi/SiO_2-CA catalysts deactivate over time, the latter demonstrates slower deactivation and better reactivation potential, maintaining conversion close to 80 % for 42 h. The study highlights the role of support in optimizing catalytic performance for LA hydrogenation.