Integrated modeling of methane pyrolysis and carbon nanotube synthesis by the thermal plasma

Methane pyrolysis has demonstrated its applicability for efficient production of clean hydrogen and valuable carbon co-products in the form of carbon black [1] and carbon nanotubes (CNTs) [2]. The growth of higher-value carbon co-product, i.e., CNTs requires the presence of metallic nanoparticles which serve as a catalyst. The pyrolysis process is often hindered by intense formation of soot which leads to contamination of the valuable carbon products and waste of the carbon feedstock. We have developed an integrated model of methane pyrolysis by the thermal plasma which includes a gas-phase chemistry model, a soot formation model, a model of catalytic nanoparticle nucleation and growth in the gas phase, as well as a model of carbon nanotube growth on the catalyst particle surfaces. The model of nanoparticle formation is benchmarked by results of molecular dynamics (MD) simulations and nanoparticle properties derived from density functional theory (DFT) modeling. The model is used to determine optimal conditions for the methane pyrolysis process in terms of high methane conversion degree, CNT synthesis yield and purity.

[1] L. Fulcheri, Int. J. Hydrog. Energy 48, 2920 (2023).

[2] M. Pasquali & C. Mesters, Proc. Natl. Acad. Sci., 118, e2112089118 (2021).