Tannic acid adjusts Pd dispersity over Al2O3 for acetylene selective hydrogenation

Abstract

The design and preparation of homogeneously dispersed, stable palladium-loaded catalysts can lead to improved performance and are cost-effective. Herein, size-controlled PdNPs were anchored over α-Al₂O₃ using tannic acid (TA) as a dispersant or stabilizer via an impregnation method. Benefiting from the strong gripping/chelating ability of TA, forming a uniform crosslinked TA polymeric network, Pd on the α-Al₂O₃ support demonstrated a narrow particle size distribution of about 2.39 nm. For the acetylene selective hydrogenation process, Pd aggregation could be efficiently suppressed under reaction conditions. Without introducing any promoter, the as-prepared catalysts could exhibit a stable acetylene conversion of 92% with an ethylene selectivity of 93% during a single run for 60 days. In addition, a high turnover frequency (TOF) value (0.4 S⁻¹) could be achieved, which is higher than Pd/Al₂O₃ without TA modification. Thus, the catalysts show good prospects for industrial applications.