Optimized Process for Melt Pyrolysis of Methane to Produce Hydrogen and Carbon Black over Ni Foam/NaCl-KCl Catalyst

Abstract

Methane pyrolysis transforming CH4 into hydrogen without a CO2 byproduct is a potential hydrogen production process under the net-zero emission target. The melt pyrolysis of methane is a technology that could simultaneously obtain hydrogen and carbon products. However, its catalytic activity and stability are still far from satisfactory. In this work, a new strategy for the melt pyrolysis of methane to hydrogen production was proposed using Ni foam and molten NaCl-KCl. The increase in the amount of Ni foam was found to enhance the methane conversion rate from 12.6% to 18%. The process was optimized by the different amounts of catalysts, the height of the Ni foam layer, and the filling method of Ni foam, indicating that the methane conversion rate of the string method could reach 19.2% at 900 °C with the designed aeration device. Furthermore, we observed that the addition of molten salt significantly alleviated the carbon deposition deactivation of the Ni foam and maintained its macrostructure during the reaction. The analysis of the carbon products revealed that carbon black could be obtained.

Recent progress in melt pyrolysis: Fabrication and applications of high‐value carbon materials from abundant sources

“…Within molten methane pyrolysis processes, the structure of carbon products is predominantly dependent upon the properties of the molten catalyst. This arises from the fact that during the reaction, natural gas undergoes pyrolysis at the interface between the molten catalyst and gas bubbles, with the generated carbon atoms reorganizing within or on the catalyst's surface to synthesize carbon products 8,42,43 …”

“…This arises from the fact that during the reaction, natural gas undergoes pyrolysis at the interface between the molten catalyst and gas bubbles, with the generated carbon atoms reorganizing within or on the catalyst's surface to synthesize carbon products. 8,42,43 During the catalytic methane pyrolysis process utilizing molten media, distinct carbon materials with diverse structures can be obtained under varying catalysts and reaction conditions. In the context of catalytic processes, certain molten monometals and salts, characterized by their relatively subdued reactivity, demonstrate a propensity to yield diverse morphologies of amorphous carbon, such as Tin, KCl, NaCl, etc.…”