Hydrogen generation behaviors of LiAlH4 and NH4Cl in Et2O, THF or DME

• Catalyst-free LiAlH4–NH4Cl-Ether exhibits high H2 yield of >5.31 wt% at 25 °C.
• H2 generation rule is affected by the kind of ethers and the reaction temperatures.
• New compounds with a similar molecular formula HAlNH·0.25Ether are found.
• The reaction mechanism is determined by comprehensive methods.

It is highly desirable to develop a technology with a high-density hydrogen generation at room temperature in the field of hydrogen energy. Ether solvents are proposed to improve the hydrogen generation properties of the reaction between LiAlH4 and NH4Cl (LiAlH4–NH4Cl) in this paper. The reactions in diethyl ether (LiAlH4–NH4Cl–Et2O), tetrahydrofuran (LiAlH4–NH4Cl-THF) and dimethoxyethane (LiAlH4–NH4Cl-DME) all exhibit good hydrogen generation performances with the H2 yields of about 5.50, 5.52 and 5.31 wt% respectively at 25 °C, which are obviously superior to the pyrolysis behaviors at high temperature of 170 °C required in hydrogen generation reaction of LiAlH4 and NH4Cl. It is found that the higher the LiAlH4 solubility in solvents, the faster the initial hydrogen generation kinetics; and the higher the by-product LiCl solubility in solvents, the shorter the reaction time. In addition, new compounds with a similar molecular formula HAlNH·0.25Ether (the Ether is Et2O, THF or DME) are found in the solid by-products.