Abstract
In this study the effects of adding alkaline-earth (IIA) metal oxides to NiZr-loaded Zeolite Y catalysts were investigated on hydrogen rich production by ethanol steam reforming (ESR). Four kinds of alkaline-earth metal (Mg, Ca, Sr, or Ba) oxides of 3.0% by weight were loaded between the <TEX>$Ni_6Zr_4O_{14}$</TEX> main catalytic species and the microporous Zeolite Y support. The characterizations of these catalysts were examined by XRD, TEM, <TEX>$H_2$</TEX>-TPR, <TEX>$NH_3$</TEX>-TPD, and XPS. Catalytic performances during ESR were found to depend on the basicity of the added alkaline-earth metal oxides and <TEX>$H_2$</TEX> production and ethanol conversion were maximized to 82% and 98% respectively in 27(<TEX>$Ni_6Zr_4O_{14}$</TEX>)3MgO/70Zeolite Y catalyst at <TEX>$600^{\circ}C$</TEX>. Many carbon deposits and carbon nano fibers were seen on the surface of <TEX>$30Ni_6Zr_4O_{14}$</TEX>/70Zeolite Y catalyst but lesser amounts were observed on alkaline-earth metal oxide-loaded 27(<TEX>$Ni_6Zr_4O_{14}$</TEX>)3MO/70Zeolite Y catalysts in TEM photos after ESR. This study demonstrates that hydrogen yields from ESR are closely related to the acidities of catalysts and that alkaline-earth metal oxides reduce the acidities of 27(<TEX>$Ni_6Zr_4O_{14}$</TEX>)3MO/70Zeolite Y catalysts and promote hydrogen evolution by preventing progression to hydrocarbons.
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