Feasible coupling of CH4/H2 mixtures to H2 storage in liquid organic hydrogen carrier systems

The cheap CH4-containing hydrogen mixtures are available in petrochemical industry and nevertheless, their usage is limited because of economic issue. We herein demonstrate the impacts of CH4 fraction (fCH(4)) in CH4/H2 mixtures on the essential steps for liquid organic hydrogen carrier (LOHC) systems. In the preparation of Ru/ Al2O3 catalysts by thermolysis in CH4/H-2 mixtures, the fCH(4) affects the content of carbon formed by methane decomposition but not the size of Ru nanoparticles, indicating that it should be avoided to use a CH4/H-2 mixture with the fCH(4)of higher than 30%. When CH4/H2 mixtures are used for the hydrogenation of monobenzyltoluene, the higher fCH4 reduces the catalytic activity, particularly at high temperatures and H-2 partial pressures because of competitive adsorption of CH4 and H-2 on the Ru surface. Such an effect of CH4 is lessened under mild conditions, which is confirmed by the experiments using the same CH4/H-2 mixture for both catalyst preparation and hydrogenation reaction. Therefore, it is feasible to use the CH4/H-2 mixture of up to 30% fCH(4) for the preparation of Ru/A(2)O(3) and for stable H-2 storage performance at lower temperatures and H-2 partial pressures, thus enabling to couple the CH4/H-2 mixture to LOHC systems.

Automated summary

This study investigates the impacts of CH4 fraction on the essential steps for liquid organic hydrogen carrier systems. The results show that a CH4 fraction higher than 30% negatively affects the carbon content and catalytic activity, but has less impact under mild conditions.