Theoretical Study Of Hydrogen And Methane Mixed Storage

Hydrogen fuel is a clean renewable energy.Now,as fossil fuels are decreasing,people hope to replace fossil fuels with hydrogen fuel.However,there is a huge obstacle to the development of hydrogen economy,the low capacity of storage medium,that is,the hydrogen fuel stored in the unit volume is very small.Although the combustion energy of a methane molecule is three times of a hydrogen molecule.However,the repulsion between methane molecules is stronger than of the hydrogen molecules,so the adsorption of methane molecules in the same medium is less than the hydrogen molecules.The repulsion between hydrogen and methane is moderate,so this kind of mixed storage can make full use of the open metal surface.The repulsion between hydrogen and methane is moderate,so this kind of mixed storage can make full use of the open metal surface.In this paper,we use the first principle calculation as the basis to calculate two different storage media,in order to verify our conjecture.The first model is the use of graphene as the substrate and the lithium atom of the alkali metal atom as an adsorbed atom.The three cases of adsorption of pure hydrogen molecules,pure methane molecules,hydrogen molecules and methane molecules by lithium ion adsorption are calculated respectively.When adsorbing hydrogen molecules alone,the storage capacity is 6.8 wt%.After mixing hydrogen molecules with methane molecules,the storage capacity of hydrogen is 13.6 wt%.From the calculation results,it can be seen that in a system using an alkali metal as an adsorbed atom,the storage capacity of the storage system can be greatly improved by mixing and storing the methane molecules and hydrogen molecules.The second model uses a graphene nanoribbon as a substrate,with the 3d transition metal atom helium as an adsorbed atom.In the same way,we calculated the three cases of adsorption of pure hydrogen molecules,pure methane molecules,and mixed adsorption of hydrogen molecules and methane molecules by scandium ions.When only hydrogen molecules are adsorbed,the storage capacity is 9.1 wt%.When hydrogen molecules and methane molecules are mixed and stored,the storage capacity equivalent to hydrogen is 14 wt%.Through this system,we once again verified our conclusion that the mixed storage of methane molecules and hydrogen molecules can increase the storage capacity of storage systems.The method that we proposed can be applied to most storage media with open metal sites.Relevant experts and scholars have proposed that many hydrogen storage models have open metal sites.Our storage method can increase the storage capacity of these hydrogen storage systems on the existing basis.It provides new ideas and directions for related research.