Hydrogen production through hydrocarbon fuel reforming processes over Ni based catalysts

摘要

Hydrogen production through autothermal reforming (ATR) of hydrocarbon fuels (ethanol, methane) over Nibased catalysts was studied with a special focus on the role of metal-support interaction. The strength of Nisupport interaction was regulated by means of tailored modification of cerium oxide and aluminum oxide supports. The electronic, redox and structural properties of pre-and post-reaction Ni/Ce1-xMxOy and Ni/Ce1-xMxOy/Al2O3 (M= Zr, Gd, La, Mg) catalysts were studied in detail by TG-DTA, BET, XRD, HRTEM-EDX, HAADF-STEM, TPR, XPS and UV-vis DRS methods. It was found that the mode of Ni-support interaction controls the state, dispersion, and reducibility of Ni active component, and consequently, catalyst performance in ATR of hydrocarbon fuels. Among the tested modifiers (M= Zr, Gd, La, Mg), La has a more pronounced positive effect on the state and functionality of Ni/Ce1-xMxOy and Ni/Ce1-xMxOy/Al2O3 catalysts. The introduction of La as a modifier in the support composition enhances the metal-support interaction, which leads to a diminution of Nin+ reducibility. On the other hand, the improvement of the Ni dispersion and catalyst stability under the ATR reactions is achieved. The addition of a Pd-promoter makes it possible to optimize the reducibility of Nin+ strongly interacting with the support and provides the ability of Ni catalysts to the self-activation. The optimal support composition for Ni nanoparticles was designed that provides hydrogen yields which are close to the thermodynamic equilibrium values: similar to 55% (Ce0.8La0.2O1.9, ATP C2H5OH at 600 degrees C) and similar to 65% (30Ce(0.2)Zr(0.2)La(0.6)O(1.7)/Al2O3, ATP CH4 at 850 degrees C).