Hydrogen-rich gas production by steam and oxidative steam reforming of crude glycerol over Ni-La-Me mixed oxide catalysts (Me = Ce and/or Zr)

摘要

The production of H-2-rich gaseous mixtures from steam and oxidative steam reforming of crude glycerol was investigated on catalysts with general formula Ni(12 wt.%)-La-2(Ce1-xZrx)(2)O-7 (x= 0, 0.5, 1). The catalysts were prepared by the polymerized complex method based on the Pechini-type reaction route and characterized by a variety of physical and spectroscopic techniques. Samples were calcined in air at 850 degrees C for 4 h. All catalysts showed a well-defined NiO phase and a mixed oxide with a general formula A(2)B(2)O(7) (A: La; B: Ce and/or Zr). NiO was completely reduced to metallic Ni on all catalysts under pure H-2 at 650 degrees C. Ni reducibility is favored by the presence of Ce. Redox properties of Ce can also explain a synergetic effect leading to the higher basicity of the catalyst containing Ce and Zr (x= 0.5). Catalytic tests were performed at 650 degrees C by feeding the fixed-bed tubular reactor with a crude glycerol:water solution containing 30 wt% glycerol. The best results were achieved on the catalyst displaying the highest basicity (Ni-La-2(Ce0.5Zr0.5)(2)O-7 both under steam and oxidative reforming conditions. Removal of carbon and alkali metals by simple procedures allows to a significant recovery of the initial catalytic activity without changes in their chemical and phase structure.