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)

Abstract

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 (Ce 1-x Zr x ) 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 °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 °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 °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 (Ce 0.5 Zr 0.5 ) 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.