Continuous Flow Synthesis of High Valuable N-Heterocycles via Catalytic Conversion of Levulinic Acid

Graphitic carbon nitride (g-C₃N₄) was successfully functionalized with a low platinum loading to give rise to an effective and stable catalytic material. The synthesized g-C₃N₄/Pt was fully characterized by XRD, N₂ physisorption, XPS, SEM-Mapping, and TEM techniques. Remarkably, XPS analysis revealed that Pt was in a dominant metallic state. In addition, XPS together with XRD and N₂ physisorption measurements indicated that the g-C₃N₄ preserves its native structure after the platinum deposition process. g-C₃N₄/Pt was applied to the catalytic conversion of levulinic acid to N-heterocycles under continuous flow conditions. Reaction parameters (temperature, pressure, and concentration of levulinic acid) were studied using 3 levels for each parameter, and the best conditions were employed for the analysis of the catalyst's stability. The catalytic system displayed high selectivity to 1-ethyl-5-methylpyrrolidin-2-one and outstanding stability after 3 h of reaction.