Methane catalytic cracking by solid materials and molten media for hydrogen production: A review.

This article focuses on catalytic methane cracking as a promising low-carbon method for hydrogen production, emphasizing the use of solid catalysts and molten media to overcome the carbon dioxide emissions associated with conventional steam methane reforming (SMR). It reviews experimental studies on carbon-, nickel-, and iron-based solid catalysts, highlighting challenges such as catalyst deactivation due to carbon deposition and the advantages of inexpensive iron ores. The paper also details methane cracking in molten metals, alloys, and salts, noting that molten alloys generally offer higher methane conversion but suffer from carbon contamination, while molten salts yield higher-purity carbon by-products but lower conversion rates; two-phase molten media combining alloys and salts show potential for improved performance. Additionally, the article analyzes the reaction mechanisms of methane cracking and characterizes the morphology and purity of the solid carbon by-products, concluding with research directions aimed at catalyst design, mechanistic understanding, and industrial-scale application to advance clean hydrogen production.