Simulation of chlorine-mediated autothermal methane pyrolysis for hydrogen production

Abstract

Given the present need to access a large-scale supply of hydrogen in the short-term, methane pyrolysis for hydrogen production could be utilized as a transition technology, since existing natural gas infrastructures can be exploited. Here, a novel chlorine-mediated pyrolysis process is presented that overcomes the considerable challenges posed by the input of external energy in the direct methane pyrolysis. By operating at a methane to chlorine inlet ratio of roughly 1.5 to 1, the heat released by the exothermic chlorination reaction can be leveraged to generate hydrogen by pyrolysis in addition to the hydrogen chloride. A downstream hydrochloric acid electrolysis enables the chlorine to be recycled and produces further hydrogen resulting in an overall hydrogen yield of 99%. An approximate cost calculation highlights the main costs of the process and reveals the high outlays for the electrolysis unit.