Review of the production of turquoise hydrogen from methane catalytic decomposition: Optimising reactors for Sustainable Hydrogen production

Hydrogen is gaining prominence in global efforts to combat greenhouse gas emissions and climate change. While steam methane reforming remains the predominant method of hydrogen production, alternative approaches such as water electrolysis and methane cracking are gaining attention. The bridging technology – methane cracking – has piqued scientific interest with its lower energy requirement (74.8 kJ/mol compared to steam methane reforming 206.278 kJ/mol) and valuable by-product of filamentous carbon. Nevertheless, challenges, including coke formation and catalyst deactivation, persist. This review focuses on two main reactor types for catalytic methane decomposition – fixed-bed and fluidised bed. Fixed-bed reactors excel in experimental studies due to their operational simplicity and catalyst characterisation capabilities. In contrast, fluidised-bed reactors are more suited for industrial applications, where efforts are focused on optimising the temperature, gas flow rate, and particle characterisation. Furthermore, investigations into various fluidised bed regimes aim to identify the most suitable for potential industrial deployment, providing insights into the sustainable future of hydrogen production. While the bubbling regime shows promise for upscaling fluidised bed reactors, experimental studies on turbulent fluidised-bed reactors, especially in achieving high hydrogen yield from methane cracking, are limited, highlighting the technology's current status not yet reaching commercialisation.