Hydrogen production from steam reforming ethanol over Ni/attapulgite catalysts - Part I: Effect of nickel content

Hydrogen production by stream reforming ethanol (SRE) derived from biomass is a promising method. Thus, utilizing cut-price mineral clays to exploit an efficient and stable catalyst is of great significance. In this work, attapulgite (ATP)-supported nickel species catalysts with different Ni contents (denoted as xNi/ATP, x = 5-40 wt %) are manufactured by conventional and home precipitation methods. Many tests such as N-2 adsorption-desorption, XRD, TEM, H-2-TPR and XPS are utilized to characterize the structural and surface properties of as prepared catalysts. It is found that the metal-support interaction and reducibility of xNi/ATP catalysts presented volcano-shaped trends in terms of Ni content, and the Ni-O-Si/Al species formed through the interplay of nickel species with the ATP framework play a key role in determining catalytic performance. The superior balance of Ni-O-Si/Al species in the 20Ni/ATP catalyst gave it the highest reductive degree and metal-support interaction. Consequently, 20Ni/ATP exhibited the uppermost hydrogen production and ethanol conversion and the most catalytic stability during the SRE reaction. In addition, the conversion and H-2 yield obviously decreased with the weight hourly space velocity (WHSV, h(-1)), whereas they presented volcanic-type curves with increasing steam/carbon (S/C) molar ratios during SRE.