Abstract
Hydrogen(H2)is a promising renewable energy which finds wide applications as the world gears toward low-carbon economy.However,current H2 production via steam methane reforming of natural gas or gasification of coal are laden with high CO2 footprints.Recently,methane(CH4)pyrolysis has emerged as a potential technology to generate low-carbon H2 and solid carbon.In this review,the current state-of-art and recent progress of H2 production from CH4 pyrolysis are reviewed in detail.Aspects such as funda-mental mechanism and chemistry involved,effect of process parameters on the conversion efficiency and reaction kinetics for various reaction media and catalysts are elucidated and critically discussed.Temper-ature,among other factors,plays the most critical influence on the methane pyrolysis reaction.Molten metal/salt could lower the operating temperature of methane pyrolysis to＜1000 ℃,whereas plasma technology usually operates in the regime of＞1000 ℃.Based on the reaction kinetics,metal-based cata-lysts were more efficient in lowering the activation energy of the reaction to 29.5-88 kj/mol from that of uncatalyzed reaction(147-420.7 kj/mol).Besides,the current techno-economic performance of the pro-cess reveals that the levelized cost of H2 is directly influenced by the sales price of carbon(by-product)generated,which could offset the overall cost.Lastly,the main challenges of reactor design for efficient product separation and retrieval,as well as catalyst deactivation/poisoning need to be debottlenecked.
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