Size-controlled Preparation of AC Supported Nano Pd Catalyst and Its Hydrogenation of 2,3,6-trichloropyridine

Pd/C catalysts were prepared by introducing complexone (nitrilotriacetic acid trisodium salt, NTA) into Pd precursor solutions, and then Pd particles were stabilized by the coordination of P2+ and NTA. Catalysts were characterized by XRD, XPS, TEM and H-2-TPR. Results show that compared with Pd/C catalyst prepared by an impregnation method, the average particle size of Pd could be effectively reduced by introducing NTA during preparation. Furthermore, Pd particles could be size -controlled by adjusting the amount of NTA. The average particle size of Pd is decreased from 5.7 nm to 2.1 nm by increasing NTA from 0.5 time to twice of Pd (molar ratio), but Pd particle size does not continue to decrease by furthur increasing the amount of NTA. When the average particle size is 4 nm (NTA:Pd=1:1), the optimum catalytic performance is achieved, i.e. the conversion is 100% and selectivity of 2,3-dichloropyridine is up to 76.86% after 6 h of reaction.