Characterization and reactivity of Al2O3 supported Pd-Ni bimetallic catalysts for hydrodechlorination of chlorobenzene

Abstract

A series of Al2O3 supported bimetallic Pd-Ni catalysts were prepared by deposition–precipitation method. The physico-chemical properties of the catalysts were evaluated by different characterization techniques such as temperature programmed reduction (TPR), temperature programmed desorption of H2 (TPD), X-ray photoelectron spectroscopy (XPS), Braunner–Emmet–Teller (BET) surface area and pulse CO chemisorption. The activities of bimetallic Pd-Ni/Al2O3 catalysts were evaluated for continuous fixed bed gas phase hydrodechlorination of chlorobenzene operating at 140°C under atmospheric pressure. The activity profiles demonstrate that an exceptional activity and stability of Pd-Ni/Al2O3 catalysts is accomplished by judicial variation of Ni composition with respect to Pd, which had arrived at Pd and Ni in 0.5:0.5 (wt%) ratio, while high Ni loaded Pd-Ni catalysts exhibit poorer stability. The high activity and stability of optimal catalyst is invoked due to formation of very active Pd-Ni interfaces embedded with Pdδ+ species, whereas lower stability resulted in high Ni loaded catalysts is due to aggregation of Ni component on topical Pd surface. The activity of mono and bimetallic catalysts are well correlate with the characterization results.