Synthesis-dependent surface properties of Mo–Ti oxides for levulinic acid upgrading to biofuels

This study investigates the effect of synthesis parameters on the catalytic performance of Mo–Ti oxide materials in the esterification of levulinic acid (LA) with various alcohols. Three sol-gel synthesis strategies were used for the catalyst’s preparation, without additives, using malic acid as complexing agent and polyethylene glycol as surfactant and templating agent. The samples were characterized by structural and surface-sensitive techniques. Detailed kinetic investigations were conducted for the esterification of LA with butanol, assessing the effect of temperature, alcohol-to-acid molar ratio, catalyst loading and activation energy. Catalysts prepared in the absence of any additives or in the presence of a templating agent exhibit comparable activities, both exceeding that of the catalyst obtained with a complexing agent. This behavior is consistent with the smaller Mo 6 ⁺/Mo 5 ⁺ surface ratio and with the greater density of acid sites per unit surface area. Our results highlight the critical importance of synthesis strategy in tuning the surface composition and acidity of Mo–Ti catalysts for biomass-derived molecule conversion.