K3AlH6 → 3KH + Al + 3/2H2 (613 K, ∆H = 70 kJ·mol−1 H2; 1.4 wt %H2), 3KH → 3K + 3/2H2 (703 K, 1.4 wt %H2). These reactions were demonstrated reversible without catalysts addition at relatively low hydrogen pressure and temperatures. The addition of TiCl3 was found to decrease the working temperature of the first dehydrogenation step of 50 K, but no variations were recorded for the last two reaction steps. Organic hydrogen carriers Unsaturated organic compounds can store huge amounts of hydrogen. These Liquid Organic Hydrogen Carriers (LOHC) are hydrogenated for storage and dehydrogenated again when the energy/hydrogen is needed. Using LOHCs, relatively high gravimetric storage densities can be reached (about 6 wt-%) and the overall energy efficiency is higher than for other chemical storage options such as producing methane from the hydrogen. Both hydrogenation and dehydrogenation of LOHCs requires catalysts. It was demonstrated that replacing hydrocarbons by hetero-atoms, like N, O etc. improves reversible de/hydrogenation properties. Cycloalkanes Research on LOHC was concentrated on cycloalkanes at an early stage, with its relatively high hydrogen capacity (6-8 wt %) and production of COx-free hydrogen. Heterocyclic aromatic compounds (or N-Heterocycles) are also appropriate for this task. A compound featuring in LOHC research is (NEC) but many others do exist. Dibenzyltoluene, which is already used as a heat transfer fluid in industry, was identified as potential LOHC. With a wide liquid range between -39 °C (melting point) and 390 °C (boiling point) and a hydrogen storage density of 6.2 wt% dibenzyltoluene is ideally suited as LOHC material. Formic acid has been suggested as a promising hydrogen storage material with a 4.4wt% hydrogen capacity. Cycloalkanes reported as LOHC include cyclohexane, methyl-cyclohexane and decalin. The dehydrogenation of cycloalkanes is highly endothermic (63-69 kJ/mol H2), which means this process requires high temperature. Dehydrogenation of decalin is the most thermodynamically favored among the three cycloalkanes, and methyl-cyclohexane is second because of the presence of the methyl group. Research on catalyst development for dehydrogenation of cycloalkanes has been carried out for decades. Nickel (Ni), Molybdenum (Mo) and Platinum (Pt) based catalysts are highly investigated for dehydrogenation. However, coking is still a big challenge for catalyst's long-term stability. The addition of second metal such as W,Ir, Re, Rh and Pd etc. and/or promoter (such as Ca) and selection of suitable support (such as CNF and Al2O3) are effective against coking. For cyclohexane, there are two dehydrogenation mechanisms,