Glycerol selective oxidation to lactic acid over platinum–vanadium bimetallic catalysts supported on activated carbon

Abstract

Environmental consciousness made humankind focus on sustainable and low carbon footprint fuels, and biodiesel is one such fuel. As biodiesel production increases, so does the surplus production of glycerol, necessitating the development of methods to convert glycerol into more valuable products. In this study, activated carbon-supported Pt–V bimetallic catalysts were synthesized and evaluated for selective glycerol oxidation to lactic acid. The physicochemical properties of the prepared catalysts were thoroughly evaluated using various advanced characterization techniques, such as field emission transmission electron microscopy (FETEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), N₂-sorption analysis, and X-ray photoelectron spectroscopy (XPS). The bimetallic catalysts performed better than monometallic Pt and V catalysts, indicating the synergistic effect. The 1 : 1 weight ratio of Pt : V (1Pt–1V/AC) showed excellent activity towards lactic acid production from glycerol oxidation with a yield of 80% at 100% glycerol conversion under moderate reaction conditions (NaOH/glycerol = 1 : 1 mol mol⁻¹, 4400 glycerol/metal molar ratio, 473 K, 5 bar air, 12 h reaction time). The 1Pt–1V/C bimetallic catalyst also showed good stability up to four cycles with only minor activity loss in the first cycle.