Research advances of molten metal systems for catalytic cracking of methane to hydrogen and carbon

Abstract

The catalytic cracking of methane represents one of the most promising alternatives for hydrogen production that avoids the high carbon emissions associated with steam methane reforming. The utilization of molten metal systems in this process effectively mitigates the detrimental effects caused by traditional solid catalyst deactivation and carbon deposition, thereby enabling simultaneous production of turquoise hydrogen and valuable carbon. This article first introduces fundamental principle of the catalytic cracking of methane using the molten metal systems. Subsequently, it provides a classification overview of molten metal systems, including molten single metal systems, molten metal alloy systems, and molten metal-salt hybrid systems. For each molten metal system, a comprehensive analysis is provided on the metallic components, catalytic methane conversion and hydrogen production effects, carbon product structure, as well as the key influencing factors. Additionally, the kinetics and mechanisms of catalytic methane cracking in these systems are briefly discussed. Finally, suggestions for future research development are presented: (1) Strengthening the research and development of a molten technology system characterized by high catalytic activity, low volatility, and cost-effectiveness is essential; (2) A thorough elucidation of the mechanisms underlying catalytic methane conversion and carbon formation in molten metal systems is required; (3) Investigating effective methodologies to enhance the added value of carbon by-products is crucial.