Recyclable Co3O4/NaF for hydrogen generation from ethyl acetate: The promoting effect between Co3O4 and NaF

Abstract

Secondary reforming of oxygenated organic compounds is the key to opening up the industrial chain of hydrogen production from organic matter. In this work, a low-cost and high-efficiency Co3O4/NaF catalyst with recyclable re-preparation was developed to solve the application bottleneck that existing commercial reforming catalysts were expensive and difficult to recycle after deactivation and discarded. Ethyl acetate was selected as the representative oxygenated organic compound for hydrogen generation via autothermal reforming was studied. The results showed that the Co3O4/NaF catalysts efficiently produced hydrogen from ethyl acetate, and the 7.5 %-Co3O4/NaF catalyst achieved 82.7 % hydrogen yield at 600 °C, 100 % ethyl acetate conversion and 16 h running stability. And the used catalyst after once recyclable re-preparation is restored to the initial hydrogen production level of fresh catalyst. Combined with XRD, N2 adsorption/desorption, FE-SEM, H2-TPR and in situ DRIFTS analysis, it was found that the surface micro-structure of the Co3O4/NaF catalyst was dense, and its specific surface area was ultra-small less than 0.5 m2·g−1, which broke through the limitation that low specific surface catalyst was difficult to obtain high-mass catalytic activity. The hydrogen production from ethyl acetate via autothermal reforming over the Co3O4/NaF catalyst was a rapid surface reaction. In addition, DFT calculations confirmed that NaF could effectively adsorb ethyl acetate molecule with an adsorption energy of −0.438 eV/molecule, and the combination of Co3O4 and NaF promoted more efficient adsorption of ethyl acetate molecules by Co3O4/NaF, with an adsorption energy of −0.836 eV/molecule. The F atom in NaF can induce electrons migration from the Co atom in Co3O4 to the F atom, which improved the redox properties and hydrogen production activity of the Co3O4/NaF catalyst.