ZrO2/SO4/Cu nanoparticles supported on reduced graphene oxide for selective oxidation of propylene glycol in continuous reactor

Abstract

In this study, a first effort at converting propylene glycol to hydroxyacetone using a continuous reactor was made. The method for creating copper-infused sulfated zirconium oxide heterogeneous bimetallic nanoparticles supported on reduced graphene oxide as the catalyst is described in the paper. The synthesized rGO/ZrO2(10%)/SO42−(4%)/Cu (5–20%) nano-catalyst, possessing various active Brønsted and Lewis acid sites were employed for the selective oxidation of the propylene glycol reaction. Utilizing affordable, easily accessible ingredients and a simple, straightforward synthesis process, the catalyst was created. XRD, FT-IR, BET, HR-SEM, HR-TEM, TGA, and temperature-programmed desorption (TPD) characterization techniques were employed to determine the stability, morphology, textural characteristics, and chemical properties of catalysts. The experiment involved the selective oxidation of propylene glycol (PG) in a continuous reactor at 90 °C, a WHSV of 1.0 h−1, a pressure of 10 bar, and an O2 flow rate of 1.0 mol h−1. Tert-butyl hydroperoxide (TBHP) was used as the solvent. Hydroxyacetone (HA) was the primary oxidation product, whereas methylglyoxal (MGO) was obtained as the secondary product. The study's findings show that rGO-supported sulfated zirconium oxide with 15% copper displayed outstanding catalytic activity and stability, outperforming the other studied catalysts in conversion (97.6%) and selectivity (99.4%). Further, excellent reusability with a negligible drop in HA selectivity was achieved even after seven consecutive runs in the presence of the rGO/ZrO2/SO4/Cu(15%). A successful copper impregnation into sulfated zirconia supported by rGO produced a long-lasting, stable hybrid nanostructure that had good stability and no metal leaching feature. The advantages and features of the current synthesis protocol are its efficiency, cost-effectiveness, eco-friendliness, and ease of preparation with readily available materials.