Achieving Low Loadings yet Highly Active Catalysis by Ethylenediamine Promoted Dispersion of Palladium on Silica

Deactivation of supported metal nanoparticles due to sintering is a key issue in industrial catalysts. We report an efficient, low‐cost protocol for producing highly active and robust heterogeneous catalysts with low palladium loading (1.3%), high dispersion, and resistance to sintering. This is achieved using ethylenediamine (EN) as an inexpensive bidentate ligand for in situ complexation of Pd(II) ions in water, promoting stable impregnation and higher dispersion on a fumed silica support. Following EN decomposition in air at 225 °C for 48 h and subsequent hydrogen reduction, CO and H 2 chemisorption revealed a marked increase in Pd dispersion, from 6% at molar ratio n = 0 to 30% at n = 4, plateauing at n = 4–6, for this set of Pd: n EN samples. These Pd nanoparticles showed excellent catalytic activity and stability for propylene hydrogenation at 250°C. Consistent with the trend in dispersion, catalytic activity increased with increasing Pd: n EN ratio from n = 0 to 4, then plateaued at 93% for n = 4–6. Testing under higher space velocity confirmed that the catalyst retained both high activity and stability. In summary, EN could be an industrially applicable ligand that yields a fumed silica‐supported Pd catalyst suitable for hydrogenation.