Kinetics of Methane Decomposition in the Catalytic Liquid Metal Reactor for Hydrogen Production

Liquid metal catalytic pyrolysis of methane is an emerging technology for the efficient production of hydrogen without CO2 emissions. In this paper，a numerical model for catalytic methane pyrolysis within a liquid metal cracking reactor was introduced. Experimental data from our in-house liquid metal hydrogen production platform align closely with the model's predictions，which demonstrated a strong correlation between experimental findings and model outcomes. The model was constructed by integrating the catalytic thermal decomposition of methane at the gas-liquid interface，the non-catalytic pyrolysis processes within bubbles，and the fluid dynamics during bubble ascent. This framework harmoniously combines the kinetics of catalytic and non-catalytic reactions with fluid dynamics. Our approach utilizes parameters such as gas volumetric，flow rate，pressure，gas composition temperature and the inherent properties of the liquid metal（density，viscosity，and surface tension）to forecast both bubble dimensions and gas content within the melt. The model accurately predicted the methane conversion under different temperatures，methane flow rates，and liquid metal heights during the catalytic methane pyrolysis experiment using liquid copper-bismuth alloy（Cu0.45Bi0.55）. In addition，the gas holdup，superficial gas velocity，and pressure distribution along the height of the liquid metal during the catalytic methane pyrolysis process were obtained. Closely matching experimental data with model predictions provides compelling evidence of the model's robustness and reliability. The proposed model would be useful for reactor optimization and high hydrogen scale-up. © 2024 Higher Education Press Limited Company. All rights reserved.