CHALLENGES FOR THE DEVELOPMENT OF NUMERICAL MODELS FOR METHANE PYROLYSIS WITH LIQUID METAL REACTORS

Abstract

Methane pyrolysis is a technology that is being postulated as an option within the Hydrogen economy. Pyrolysis allows gaseous hydrocarbons to be processed without directly emitting CO2, as it is carried out in the absence of oxygen, allowing its integration into the circular economy concept by producing two recoverable elements, such as solid carbon and hydrogen. It is currently classified as a form of turquoise hydrogen generation, as it shares characteristics of green hydrogen, as it does not emit carbon dioxide in the process, and blue hydrogen, as its primary resource is natural gas. There are several technological options to carry out the pyrolysis of natural gas, ranging from direct thermolysis, through the use of catalysts, the use of plasma arcs, or the development of hydrocarbon decomposition in liquid reaction media, such as molten salts or liquid metals. This communication will describe the main remains for the development of pyrolysis reactors with liquid metals, which are currently at Technology Readiness Level around TRL4, in order to advance towards industrially viable and competitive prototypes and demonstrators. That development requires creating numerical models that can be used for the engineering design of pyrolysis reactors. The design tools for this case must be capable of coupling multiphase and multicomponent fluid-mechanical evaluation, which takes into account the evolution of a gaseous phase (natural gas) into a liquid phase (liquid metal) with the formation of solids (carbon). The fluid dynamic calculation runs into the lack of experimental data that allow its validation, which becomes a critical aspect to be able to estimate the chemical kinetics of the reaction itself. This kinetics strongly depends on the residence time of the gas in the medium, and on the temperature. In this communication, those relations between the fluid-mechanical and chemical model that would allow the evaluation of the conversion of natural gas to hydrogen and carbon in the design of the reactor are analyzed. As a result, a series of experiments are proposed to validate these design tools for the pyrolysis process in liquid metal. Keywords: Decarbonization, Hydrogen, Circular economy, Carbon