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Open AccessArticle

Revealing the Effect of Nickel Particle Size on Carbon Formation Type in the Methane Decomposition Reaction

State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Qingdao 266580, China
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Catalysts 2020, 10(8), 890; https://doi.org/10.3390/catal10080890
Received: 16 July 2020 / Revised: 3 August 2020 / Accepted: 5 August 2020 / Published: 6 August 2020
Carbon species deposition is recognized as the primary cause of catalyst deactivation for hydrocarbon cracking and reforming reactions. Exploring the formation mechanism and influencing factors for carbon deposits is crucial for the design of rational catalysts. In this work, a series of NixMgyAl-800 catalysts with nickel particles of varying mean sizes between 13.2 and 25.4 nm were obtained by co-precipitation method. These catalysts showed different deactivation behaviors in the catalytic decomposition of methane (CDM) reaction and the deactivation rate of catalysts increased with the decrease in nickel particle size. Employing TG-MS and TEM characterizations, we found that carbon nanotubes which could keep catalyst activity were more prone to form on large nickel particles, while encapsulated carbon species that led to deactivation were inclined to deposit on small particles. Supported by DFT calculations, we proposed the insufficient supply of carbon atoms and rapid nucleation of carbon precursors caused by the lesser terrace/step ratio on smaller nickel particles, compared with large particles, inhibit the formation of carbon nanotube, leading to the formation of encapsulated carbon species. The findings in this work may provide guidance for the rational design of nickel-based catalysts for CDM and other methane conversion reactions. View Full-Text
Keywords: nickel particle size; CDM; encapsulated carbon; carbon nanotube nickel particle size; CDM; encapsulated carbon; carbon nanotube
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MDPI and ACS Style

Liang, W.; Yan, H.; Chen, C.; Lin, D.; Tan, K.; Feng, X.; Liu, Y.; Chen, X.; Yang, C.; Shan, H. Revealing the Effect of Nickel Particle Size on Carbon Formation Type in the Methane Decomposition Reaction. Catalysts 2020, 10, 890.

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