Hydrogen Production Via Ethanol Steam Reforming Reaction Over Ni-Cu/Al₂O₃-MxOy(M=Mg,Zn,La) Catalysts

As fossil resources become insufficient and the continuous energy demands cause the pollution, hydrogen has became an alternative fuel due to its non-polluting nature. In particular, applying hydrogen to the fuel cell is a subject of current interest. Nowadays, it is focusing on alternative methods for the production of hydrogen from renewable energy sources. The production of hydrogen from biomass is receiving increased attention as a more feasible option due to its renewable and carbon-neutral nature. Particularly, alcohols have shown good features for hydrogen production. They are easily decomposed in the presence of water by steam reforming reaction generating a H2-rich mixture. Nowadays, the catalysts of hydrogen production by steam reforming ethanol were suggested to be the emphasis on reaserch.Hydrogen production from ethanol steam reforming over alumina-supported nickel-copper catalysts modified with La, Mg and Zn was studied. Characterization of catalysts by XRD, TPR, XPS ,TPD of NH3 and TG-DTA revealed changes in the acidity, nickel-copper dispersion and nickel-copper-support interaction with the type of the modifier added to Al2O3. The acidity of catalysts containing Mg, La, and Zn additives decreased with respect to that supported on bare Al2O3. The trend of metal dispersion derived from XRD followed the order:MgO–Al2O3 >ZnO–Al2O3 >La2O3–Al2O3 >γ–Al2O3.TPR and XPS analyses indicate the development of strong interactions between nickel-copper species and supports.The activity measurements indicated the different catalysts functionality that influences on their reforming activity.Thus, the higher reforming activity for Mg modified catalyst respect to bare Al2O3 was explained in terms of the lower acidity and better dispersion achieved in the former. On the other hand, the lower intrinsic activity of La-added catalyst was explained in terms of the Ni worse dispersion on the catalyst surfaces.Reaction temperature are investigated using NiCu/Al2O 3-MgO and NiCu/Al2O3-ZnO catalyst,which a complete conversion of ethanol and no ethylene or acetaldehyde was detected from 300-600℃, over 90% of selectivity to hydrogen could be obtained at 600℃.Characterization of catalysts after reaction showed the amount and type of coke deposited on catalysts surfaces. Zn and Mg additives were found to prevent the formation of carbon on catalyst surfaces.