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Alumina-supported Ni catalysts modified with silver for the steam reforming of methane: Effect of Ag on the control of coke formation

Paper ID Volume ID Publish Year Pages File Format Full-Text
43442 45970 2007 11 PDF Available
Title
Alumina-supported Ni catalysts modified with silver for the steam reforming of methane: Effect of Ag on the control of coke formation
Abstract

The effect of Ag loading (0.1–0.6 wt.%) on the physicochemical properties and catalytic behavior of Al2O3-supported Ni catalysts on steam reforming of methane was studied. The surface properties of catalysts were evaluated by applying FTIR of adsorbed CO. Additional information was obtained by SBET, XRD, TPR, XANES, XPS and TEM characterizations. Ag caused a strong modification at the surface properties of the samples related to the CO adsorption and the stability to graphitic carbon deposition. The FTIR spectra of adsorbed CO on Ni/Al2O3 catalyst showed bands in two regions: (i) high frequency region (HF) with bands at 2075 cm−1 (HF1) and 2037 cm−1 (HF2), and (ii) low frequency region (LF) with bands at 1946 cm−1 (LF1) and 1902 cm−1 (LF2). The spectra of TPD-CO revealed that the HF2 species were favored with increasing the Ag loading, while the LF species were strongly suppressed. The kinetics parameters Eaapp versus ln A showed a compensation effect. The catalysts with Ag loading ≥0.3 wt.% submitted to stability tests showed high resistance to coke deposition. The high stability of the Ni catalysts promoted with Ag was attributed to changes in the superficial structure of Ni sites as result of the combination of different effects: (i) the decrease of Ni ensemble by geometric effect of Ag, (ii) changes of Ni sites involved in the nucleation of the graphite structure and (iii) equilibration of different steps of reaction rate decreasing the C* formation rate.

Graphical abstractA series of xAg-15%Ni/Al2O3 catalysts with Ag loading x between 0 and 0.6 wt.% was studied in the steam reforming of methane. The Ni catalysts promoted with Ag show high resistance to coke deposition. It was attempted to find a correlation between the surface and catalytic properties. Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Nickel catalyst; Silver; Steam reforming of methane; FT-IR; CO adsorption; XANES
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Alumina-supported Ni catalysts modified with silver for the steam reforming of methane: Effect of Ag on the control of coke formation
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 330, 10 October 2007, Pages 12–22
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
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Any Questions? feel free to contact us