Formation of Active Sites of Carbon Nanofibers Growth in Self-Organizing Ni–Pd Catalyst during Hydrogen-Assisted Decomposition of 1,2-Dichloroethane

Abstract

The Ni−Pd alloys synthesized by the coprecipitation method were studied as precursors for the selforganizing particles catalyzing the growth of carbon nanofibers. The addition of palladium was found to enhance both the activity, stability, and productivity of the catalyst in the hydrogen-assisted decomposition of 1,2-dichloroethane. The evolution of reflex (331) for the 95Ni−5Pd sample treated under the reaction conditions has revealed the formation of the interstitial solid solution phase Ni x Pd 1−x C δ . According to data of scanning electron microscopy, the formation of separated particles active in carbon growth takes place by 18th minute of exposure with the reaction mixture. After 60 min of interaction the bulk Ni−Pd alloy undergoes complete disintegration with formation of dispersed active centers sized in a range of 0.4−0.6 μm. The elemental mapping of the formed particles showed that palladium is uniformly distributed within the bulk of active particles. The obtained carbon product is represented by prolonged carbon fibers with segmental structure.

[NiEn3](MoO4)0.5(WO4)0.5 Co-Crystals as Single-Source Precursors for Ternary Refractory Ni–Mo–W Alloys

“…This means that, according to the data of the laboratory powder diffraction study, it is impossible to conclude that the CCP is homogeneous. The powder diffraction study at the ID22 ESRF beamline allowed us to perform PXRD data collection using an instrument with one of the narrowest instrumental resolutions [26]. The average FWHM of the lines in the three obtained diffraction patterns coincide well and are smaller than in the case of the laboratory powder diffraction study.…”

“…At 510 • C, an additional fcc-Ni 1−x W x binary alloy was obtained. Double-carbide Ni 2 W 4 C was detected above 660 • C as was Ni 6 W 6 C at 860 • C. These phases were proposed as an active catalyst for the synthesis of carbon nanotubes and carbon nanofibres [25,26] and as cathode materials for the synthesis of hydrogen by water electrolysis [27]. It is expected that the thermolysis of the co-crystallization product (CCP) of [NiEn 3 ]MoO 4 and [NiEn 3 ]WO 4 can lead to the formation of ternary alloys and carbides.…”

Carbon Nanofiber-Based Functional Nanomaterials for Sensor Applications

“…The gas phase flow catalysis method directly heats the catalyst precursor, and introduces it into the reaction chamber together with the hydrocarbon gas in the form of gas. The catalyst and the hydrocarbon gas are decomposed of different temperature zones, and the decomposed catalyst atoms are gradually aggregated into the nanoscale particles and then the CNFs produced on the nanoscale catalyst particles [33,34]. Since the catalyst particles decomposed from the organic compound can be distributed in a three-dimensional space, and the amount of volatilization of the catalyst can be directly controlled, the yield per unit time of this method is large and continuous production is possible.…”

Scaling up the Process of Catalytic Decomposition of Chlorinated Hydrocarbons with the Formation of Carbon Nanostructures

“…Doping nickel with other metals (Cr, Co, Cu, Mo, W, Pd, Pt) results in the enhanced activity and elongated stability of Ni-based catalysts [11,21,22]. It should be emphasized that both bulk alloys and specially prepared porous alloy systems can serve as precursors of self-organizing catalysts [11,23]. In this case, the initial alloy samples undergo rapid disintegration under the action of an aggressive chlorine-containing medium.…”

“…In the present work, 1,2-dichloroethane (DCE) was used as a representative of the mentioned class of organochlorine compounds. The Ni-Pd alloy with palladium content of 5 wt% was chosen as a catalyst providing high enough efficiency [23,41]. Three different reactor types were examined.…”