Highly efficient and selectivity controllable aerobic oxidation of ethyl lactate to ethyl pyruvate over VxOy/NC catalysts†

Abstract

Developing effective catalysts for the selective oxidative dehydrogenation of ethyl lactate (EL) to value-added ethyl pyruvate (EP) is of great significance in biomass utilization. Herein, a series of V_xO_y/NC_P (P denotes the NC precursor) catalysts were synthesized by a convenient impregnation–decomposition method, which can effectively catalyze EL to EP with high activity and stability. These catalysts were characterized by XRD, N₂ physisorption, XRF, SEM, TEM, XPS, and H₂-TPR in detail. When methenamine was used as the precursor, 98% EL conversion and 99% EP selectivity were achieved at 130 °C for only 0.5 h of the reaction, outperforming most catalysts in the literature. The high activity of V_xO_y/NC_methenamine is attributed to the presence of a large amount of pyridinic-N and low valence vanadium species. H₂-TPR results show that V_xO_y/NC_methenamine presents the lowest reduction temperature and highest H₂ consumption, which is also consistent with the experimental results. Moreover, this catalyst could be reused for at least five cycles without significant deactivation.