Turquoise Hydrogen Energy Production by Methane Pyrolysis in Bubble Column Reactor: A Review of Catalytic Molten Media Formulation and Parametric Optimization

The turquoise hydrogen production route via methane (natural gas) pyrolysis by molten media catalysts is driven by its eco‐friendly credentials as it circumvents carbon dioxide emissions. In this article, the performance of numerous molten metals and salts towards hydrogen selectivity, methane conversion, and solid carbon quality, is analysed. With aims to provide guidance in the catalyst selection, formulation, and configuration in the bubble column reactor, we present: (i) the fundamental understanding in chemically formulating the molten metal catalyst system for optimal catalytic activity performance, and (ii) the approach in selecting eutectic molten salts for achieving high carbon product purity based on their relevant physical properties. We also review the effects of feed gas to inert ratio, temperature, gas hourly space velocity, and pressure on the pyrolysis performance, providing important insight into operating the reactor under optimal conditions. Finally, the challenges and feasibility of this technology are discussed.