Effect of CaO–ZrO2 addition to Ni supported on γ-Al2O3 by sequential impregnation in steam methane reforming (original) (raw)
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Fuel Processing Technology, 2012
In this study, catalysts containing 5 wt.% Ni deposited on a support composed of a CeO 2-ZrO 2 solid solution deposited on alumina were tested in the steam reforming of methane. The supports, with various ratios of Ce to Zr, were prepared by co-precipitation of the oxide precursors, followed by calcination in synthetic air. The catalysts were then prepared by Ni impregnation of the supports. The prepared solids were characterized by temperature-programmed reduction with H 2 (TPR-H 2), in situ X-ray diffraction (XRD) and X-ray absorption near-edge structure (XANES) spectroscopy. The XRD analysis confirmed the formation of a solid solution between ZrO 2 and CeO 2. In the catalytic tests, it was found that catalysts with higher Ce content did not exhibit deactivation during 6 h of reaction. The catalyst with highest Ce content, Ni(0.8 Ce 0.2 Zr)Al, provided the best result, with the highest rate of conversion of methane and the lowest carbon deposition, which may be partly due to the smaller Ni 0 crystallites in this sample and also the segregated CeO 2 particles may have favored H 2 O adsorption which could lead to higher C gasification.
ASEAN Journal of Chemical Engineering, 2008
Catalytic performance and characterization of Ni/CeO2/ZrO2 and commercial catalyst from Indonesia were investigated in steam reforming of methane. Ni/CeO2/ZrO2 catalyst was prepared using co-impregnation of cerium nitrate and nickel nitrate onto zirconia support material. BET, SEM, EDS, XRD, TPD, TG, and ICP analyses were employed for the characterization of the catalysts. Remarkable catalytic performance of Ni/CeO2/ZrO2 catalyst at 600oC operating temperature and atmospheric pressure of about 74.9% methane conversion was obtained compared to 55.9% using the commercial catalyst. In addition, the presence of cerium in Ni/CeO2/ZrO2 was effective in improving the stability and resistance to coke formation. Less carbon formation was confirmed from the thermo-gravimetric analysis. These results showed that the prepared catalyst is promising in the industrial application which can be used at lower operation temperature for energy saving.
In the present work, the influences of H 2 S and CO 2 on hydrogen production from methane steam reforming reaction over Ni/CeO 2 and Ni/Al 2 O 3 were studied. According to the experiment, both H 2 S and CO 2 inhibited the methane steam reforming rate over both catalysts and consequently resulted in the decreasing of hydrogen production yield. In the presence of H 2 S (2-10 ppm), the rate dramatically decreased due to the sulphidation and cannot be fully recovery even though H 2 S is removed from the feed. At the same operating conditions, Ni/CeO 2 provided higher resistance toward the deactivation than Ni/Al 2 O 3 . CO 2 also presented negative effect on the production of hydrogen from methane steam reforming over both catalysts due to the inhibition of methane and steam adsorption by CO 2 . The adding of oxygen through the inlet feed along with methane and steam as the autothermal reforming is also carried out. Oxygen promoted methane steam reforming rate for both catalysts. However, H 2 production from methane steam reforming decreased with increasing oxygen partial pressure due to the inhibition of steam adsorption by this component and the oxidation of hydrogen production by oxygen atom.