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Catalytic transfer hydrogenation (CTH) reaction is considered as a potential route for upgrading bio-based carbonyl compounds to their corresponding alcohols.

As-synthesized Ni-based Lewis acidic catalysts, with tunable concentrations of β-Ni(OH) 2 and γ-NiOOH, were tested on the conversion of sugars to methyl lactate (MLA) in near-critical methanol solutions. The concentration of γ-NiOOH increased with an increase in the Ni(NO 3 ) 2 •6H 2 O/2-methylimidazole (Ni/2-Hmim) molar ratio. Compared to β-Ni(OH) 2 , the γ-NiOOH showed more mesopores in the catalyst, which facilitated the diffusion of reactant and products. Ni/2-Hmim-4 [Ni(NO 3 ) 2 • 6H 2 O/2-methylimidazole molar ratio = 4] exhibited the best catalytic activity. Under optimal conditions (180 °C for 12 h), the highest MLA yield was 41.9% on the conversion of glucose. Ni/2-Hmim-4 was employed to convert disaccharides to MLA. Notably, for sucrose, the reaction afforded a 38.7% MLA yield at 200 °C for 12 h. The catalyst was reusable for at least three cycles.