Effect of CaO–ZrO2 addition to Ni supported on γ-Al2O3 by sequential impregnation in steam methane reforming (original) (raw)

Abstract

Ni catalysts supported on (CaOeZrO 2 )-modified g-Al 2 O 3 were prepared by sequential impregnation. The effects of varied CaO to ZrO 2 mole ratios at 0, 0.20, 0.35, 0.45, and 0.55 on the activity and stability of the modified Ni catalysts were studied. As a result of using CaOeZrO 2 as a promoter, each catalyst contained CaOeZrO 2 at only 5%. g-Al 2 O 3 used as support was modified by CaOeZrO 2 before the deposition of nickel oxide. The addition of CaOeZrO 2 at an optimum ratio was expected to improve the stability of Ni catalysts due to the decrease of carbon formation resulting from carbon gasification. All the fresh catalysts were characterized by ICP, XRD, BET surface area, TGA in H 2 , and TPR before catalytic testing in steam methane reforming at 600 C. The spent catalysts were examined by TEM and TGA to observe the catalysts deactivation. The identification of CaOeZrO 2 phases indicated that CaO and ZrO 2 reacted with each other to be monoclinic solid solution ZrO 2 , CaZr 4 O 9 , CaZrO 3 , and CaO corresponding to the phase diagram of CaOeZrO 2 . The existence of CaZrO 3 for 0.55 mol ratio of CaO/ZrO 2 enhanced activity in steam methane reforming because oxygen vacancies in CaZrO 3 greatly preferred the water adsorption creating the favorable conditions for carbon gasification and, then, water gas shift. The prominence and continued existence of these two reactions on the Ni catalysts leads to the particular increase of H 2 yield. Moreover, the increasing amount of CaZrO 3 in the Ni catalysts significantly improved carbon gasification. However, the Ni catalysts with CaZrO 3 showed whisker carbon after catalytic testing; this carbon specie has not been tolerated in steam methane reforming. Therefore, these results significantly differed from the hypothesis.

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References (23)

  1. Ghenciu AF. Review of fuel processing catalysts for hydrogen production in PEM fuel cell systems. Curr Opin Solid State Mater Sci 2002;6:389e99.
  2. Pen ˜a NA, Go ´mez JP, Fierro JLG. New catalytic routes for syngas and hydrogen production. Appl Catal A 1996;144: 7e57.
  3. Armor JN. The multiple roles for catalysis in the production of H 2 . Appl Catal A 1999;176:159e76.
  4. Tsang SC, Claridge JB, Green MLH. Recent advances in the conversion of methane to synthesis gas. Catal Today 1995;23: 3e15.
  5. Fonseca A, Assaf EM. Production of the hydrogen by methane steam reforming over nickel catalysts prepared from hydrotalcite precursors. J Power Sources 2005;142:154e9.
  6. Kordesch K, Simader G. Fuel cells and their applications. Weinheim: Wiley-VCH; 1996.
  7. Bartholomew CH, Farrauto RJ. Fundamentals of industrial catalytic processes. 2nd ed. New Jersey: John Wiley & Sons, Inc; 2006.
  8. Pompeo F, Gazzoli D, Nichio NN. Stability improvements of Ni/a-Al 2 O 3 catalysts to obtain hydrogen from methane reforming. Int J Hydrogen Energy 2009;34:2260e8.
  9. Trimm DL. Catalysts for the control of coking during steam reforming. Catal Today 1999;49:3e10.
  10. Bharadwaj SS, Schmidt LD. Catalytic partial oxidation of natural gas to syngas. Fuel Process Technol 1995;42:109e27.
  11. Matsumura Y, Nakamori T. Steam reforming of methane over nickel catalysts at low reaction temperature. Appl Catal A 2004;258:107e14.
  12. Seo JG, Youn MH, Song IK. Hydrogen production by steam reforming of LNG over Ni/Al 2 O 3 eZrO 2 catalysts: effect of Al 2 O 3 eZrO 2 supports prepared by a grafting method. J Mol Catal A 2007;268:9e14.
  13. Urasaki K, Sekine Y, Kavabe S, Kikuchi E, Matsukata M. Catalytic activities and coking resistance of Ni/peroskites in steam reforming of methane. Appl Catal A 2005;286:23e9.
  14. Bellido JDA, Souza JED, M'Peko J-C, Assaf EM. Effect of adding CaO to ZrO 2 support on nickel catalyst activity in dry reforming of methane. Appl Catal A 2009;358:215e23.
  15. Kingery WD, Bowen HK, Uhlmann DR. Introduction to ceramics. 2nd ed. Singapore: John Wiley & Sons, Inc; 1976.
  16. Stubican VS, Ray SP. Phase equilibria and ordering in the system ZrO 2 eCaO. J Am Ceram Soc 1977;60:534e7.
  17. Pawelec B, Fierro JLG. Handbook of thermal analysis and calorimetry. In: Brown ME, Gallagher PK, editors. Applications of thermal analysis in the preparation of catalysts and in catalysis. Applications to inorganic and miscellaneous materials, vol. 2. Amsterdam: Elsevier B.V; 2003. p. 119e90.
  18. Seyfi B, Baghalha M, Kazemian H. Modified LaCoO 3 nano- perovskite catalysts for the environmental application of automotive CO oxidation. Chem Eng J 2009;148:306e11.
  19. Seo JG, Youn MH, Song IK. Hydrogen production by steam reforming of liquefied natural gas (LNG) over nickel catalyst supported on mesoporous alumina prepared by a non-ionic surfactant-templating method. Int J Hydrogen Energy 2009; 34:1809e17.
  20. Youn MH, Seo JG, Kim P, Song IK. Role and effect of molybdenum on the performance of Ni-Mo/g-Al 2 O 3 catalysts in the hydrogen production by auto-thermal reforming of ethanol. J Mol Catal A 2007;261:276e81.
  21. Snoeck J-W, Froment GF, Fowles M. Filamentous carbon formation and gasification: Thermodynamics, driving force, nucleation, and steady-state growth. J Catal 1997;169:240e9.
  22. Snoeck J-W, Froment GF, Fowles M. Kinetic study of the carbon filament formation by methane cracking on a nickel catalyst. J Catal 1997;169:250e62.
  23. Xiulan C, Yuan L. New methods to prepare ultrafine particles of some perovskite-type oxides. Chem Eng J 2000;78:205e9.