Insights into bimetallic synergistic effect towards γ-valerolactone production under Co doped Zr-TiO2

Co doped into 5% Zr-TiO2 (Co@5% Zr/-TiO2) was prepared by a simple, facile sol-gel method, and employing in the catalytic transfer hydrogen (CTH) process starting from ethyl levulinate (EL) to γ-valerolactone (GVL). Lewis/Brønsted acid ratio and BET surface area increased with the incorporation of Co into Ti-Zr-O support. In addition, the synergistic effect between Co-Zr in TiO2 enhanced the strong acid strength sites. Co@5% Zr-TiO2 exhibited the highest catalytic performance (EL conversion 95%, GVL yield 88%) under optimum condition (0.2 M EL, 15 mL 2-PrOH, 190 °C, 11 h). Noticeably, Co@5% Zr-TiO2 exhibited higher stability in 4th recycling experiments as compared to 5% Zr-TiO2 under identical condition. From computational calculation, EL adsorption process was more spontaneous with ΔEad= -8.240 eV. The protonation process made the reactants get close to the surface with a bonded O12-Ti2.179 Å and O6-Zr of 2.376 Å. Finally, GVL showed a strong leaving trend after the formation. © 2022