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Free keywords:
lignocellulosic Biomass, levulinic Acid, formic Acid, mesoporous ZrO2, γ-valerolactone, aqueous-phase hydrogenation
Abstract:
Monometallic Pt catalysts supported on mesoporous (MP) ZrO2 were prepared and utilized as catalysts in the aqueous-phase upgrading of lignocellulosic biomass-derived levulinic acid (LA) and formic acid (FA) serving as a sustainable reducing agent. Among the studied catalysts, 1.6Pt/MP-ZrO2 showed the highest LA conversion (97%) and a γ-valerolactone (GVL) yield (90%) at 513 K after 24 h of reaction is achieved. This high LA conversion and GVL yield obtained can be attributed to the high specific surface area (204 m2 g-1) and density of acid sites (136 µmol g-1), Pt dispersion (37%). Furthermore, this catalyst exhibits high stability after 96 hours of reaction time, i.e., four catalytic repetitions, with a GVL yield above 60% and no change in the crystal structure of the support. A high reaction temperature (533 K) tends to shift the reaction equilibrium from GVL to pentanoic acid (PA) which is formed with a yield of 22 % after 24 h. Even after increasing the complexity of the model mixture by adding vanillin (V) as a lignin-derived model compound to the aqueous solution of LA and FA, the catalyst remained stable and the hydrogenation of LA and V succeeded, resulting in 43% of GVL and 65 % of 2-methoxy-4-methylphenol (MMP) after 24 h at 513 K.
