From methane to hydrogen, carbon black and water
Résumé
Most of the total world production of hydrogen comes from vapor cracking of methane. Even though methane is the least carbogen of all hydrocarbons, steam conversion of one ton of methane is accompanied by the emission of about four tons of CO2 into the atmosphere. Simple thermolysis of methane being no more endothermic than the vapor cracking reaction, cracking methane without any oxygen into carbon and hydrogen should, theoretically, be no more energy-expensive than existing processes. To be effective, such a thermolysis needs a very high temperature reaction which, with recent improvements in plasma technology, is now accessible. The main advantage of carrying out thermolysis at high temperature is that, while producing hydrogen, reaction conditions may also be favourable for carbon black production. From physical considerations related to existing processes, the authors present a theoretical study which could open the way to new plasma-assisted processes. More anecdotally, a certain number of natural gas resources remain unexploited due to their isolation; it is theoretically possible to transform these resources into carbon and water without any external energy supply. It would then be possible to irrigate the desert while producing a solid state product whose transport may be easier than gas.