Technical challenges for developing thermal methane cracking in small or medium scales to produce pure hydrogen - A review

Hydrogen is an important chemical commodity and plays a key role in the clean, secure and affordable energy scenarios of the future. There is a significant interest in the development of small plants for hydrogen generation besides other plants where hydrogen has been consumed as raw material and it is because of the very high cost of compression and transportation of hydrogen. Thermal methane cracking (TMC) is an alternative process for high purity hydrogen manufacturing along with the traditional commercial processes such as steam reforming, coal gasification, partial oxidation, and water electrolysis. Employing the TMC process for very high purity hydrogen production on a small or medium-scale plant with the minimum requirement of separation units is the main incentive of this review. Given the results of the review, using catalysts for TMC can decrease the working temperature to below 800 °C but it could create some significant issues, especially catalyst deactivation (a low catalyst life due to carbon deposition), so it is not yet a viable method to employ on the production plants. On the other hand, supplying the heat of reaction and reactor blockages are two basic challenges for a non-catalytic reaction way.