Catalytic conversion of 1,2-dichloroethane over Ni-Pd system into filamentous carbon material

The alloyed Ni-Pd system with Pd content of 3 wt.% was prepared by coprecipitation method followed by reduction in hydrogen atmosphere at 800 °C. The formation of single-phase solid solution with unit cell parameter a = 3.532(1) Å (determined by (331) reflex at 2θ ≈ 145°) corresponding to NiPd alloy with weight ratio 97:3 was confirmed by XRD analysis. Kinetic studies on catalytic conversion of 1,2-dichloroethane (DCE) over NiPd alloy into carbon nanomaterial (CNM) were performed in a flow reactor equipped with McBain balances in a temperature range of 580–700 °C. It was shown that interaction of DCE with NiPd system results in a fast disintegration of pristine alloy with formation of submicron (0.2-0.9 μm) particles, which efficiently catalyze the growth of segmented carbon filaments. According to Raman spectroscopy and transmission electron microscopy data, hydrogen concentration in reaction mixture strongly affects the structural features and density of segmented filaments. The average values of inter-segmental distance calculated from TEM micrographs of carbon filaments were found to be 96, 46, 16 nm for hydrogen concentration of 23, 36 and 47 vol.%, respectively. Strongly chemisorbed chlorine species were suggested to be responsible for the cyclic perturbations in carbon transfer and deposition. Obtained carbon nanomaterials were characterized with comparatively high specific surface area (300–400 m²/g) and extremely low bulk density (<0.03 g/ml).