Abstract
Cu-promoted NiMgAl catalysts derived from hydrotalcites were synthesized by the urea hydrolysis method for ethanol steam reforming. The effect of Cu content on catalytic properties of the NiMgAl catalysts was studied. These catalysts were characterized by X-ray diffraction, thermogravimetric and differential analyses, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and temperature-programmed reduction. The addition of small amounts of Cu to NiMgAl catalysts leads to the increase of surface Ni species and the enhancement of Ni(2+) reducibility. The Ni(0.5)Cu(0.1)Mg(2.4)Al catalyst with Cu/Ni ratio of 0.2 exhibits the higher activity and stability, showing no apparent deactivation during 20 h on stream at 700 A degrees C, whereas Ni(0.5)Mg(2.5)Al catalyst suffers severe deactivation only after 10 h on stream. This improved performance is closely related to smaller nickel particles well dispersed on the catalyst surface. The Ni(0.5)Cu(0.1)Mg(2.4)Al catalyst exhibits strong resistance to coke formation and the sintering of nickel particles.