Elsevier

Journal of Catalysis

Volume 173, Issue 2, 25 January 1998, Pages 247-256
Journal of Catalysis

Regular Article
Ni/Mg/Al Anionic Clay Derived Catalysts for the Catalytic Partial Oxidation of Methane: Residence Time Dependence of the Reactivity Features

https://doi.org/10.1006/jcat.1997.1942Get rights and content

Abstract

The catalytic partial oxidation (CPO) of methane was investigated with four Ni-based catalysts prepared through reduction of hydrotalcite-type precursors. The calcination of the precursors, generated materials in which the Ni species were differently distributed between NiO, (Ni, Mg)Al2O4phases and NiO–MgO periclase structures. The relative amount of the different phases depended on Ni content and affected the reactivity of the solids towards reduction and towards CPO step. Catalysts with high Ni-content required mild reduction conditions, but deactivated rapidly with time-on-stream due to carbon formation. Instead, catalysts with low Ni-content were activated only after a severe reduction treatment but showed high stability during the reaction. The effect of residence time was investigated with a particularly stabilized catalyst, in order to understand if selectivities and conversions could be kinetically controlled. Results were grouped considering three reactivity regions (τ  70 ms, 70 < τ < 150 ms, and 300 < τ <  720 ms). In the shorter residence time region, large chemical composition variations and large temperature gradients were observed along the catalytic bed and relevant differences between surface and gas temperatures were determined. These differences, not observed in the other two residence time regions, are discussed and related to heat transfer limitation, occurrence of direct oxidation routes and hot spot phenomenon effects.

References (41)

  • D.A. Hickman et al.

    J. Catal.

    (1992)
  • V.R. Choudhary et al.

    J. Catal.

    (1993)
  • D. Dissanayake et al.

    J. Catal.

    (1991)
  • O. Clause et al.

    Appl. Clay Sci.

    (1993)
  • G. Fornasari et al.

    Appl. Clay Sci.

    (1995)
  • O. Clause et al.

    Appl. Catal.

    (1991)
  • F. Cavani et al.

    Catal. Today

    (1991)
  • W.T. Reichle et al.

    J. Catal.

    (1986)
  • C.A. Bernardo et al.

    J. Catal.

    (1985)
  • P.K. de Bokx et al.

    J. Catal.

    (1985)
  • J.R. Rostrup-Nielsen

    J. Catal.

    (1984)
  • A.M. Gadalla et al.

    Chem. Eng. Sci.

    (1988)
  • J.R. Rostrup-Nielsen et al.

    J. Catal.

    (1993)
  • J.G. McCarty

    Catal. Today

    (1995)
  • M. Huff et al.

    J. Phys. Chem.

    (1993)
  • D.A. Hickman et al.

    Science

    (1993)
  • V.R. Choudhary et al.

    Angew. Chem. Int. Ed. Engl.

    (1992)
  • V.R. Choudhary et al.

    J. Phys. Chem.

    (1992)
  • M. Prettre et al.

    Trans. Faraday Soc.

    (1946)
  • L. Basini et al.

    Catal. Lett.

    (1996)
  • Cited by (135)

    • Production of hydrogen by ethanol steam reforming using Ni–Co-ex-hydrotalcite catalysts stabilized with tungsten oxides

      2021, International Journal of Hydrogen Energy
      Citation Excerpt :

      In our study, we have chosen the calcined hydrotalcites (ex-hydrotalcites) since they provide excellent support of Mg and Al resistant to temperature and with specific basicity provided by the MgO. The studies of Ni and Co with ex-hydrotalcites have gathered a good number of the required qualities, so for example for the catalyst of Ni-ex-hydrotalcite [13–20] high conversions of ethanol and selectivities to H2 have been found. These same catalysts have been prepared by coprecipitation adjusting the concentration of Ni to obtain a formula of the type NixMg2AlOy [14].

    • Study of LPG steam reform using Ni/Mg/Al hydrotalcite-type precursors

      2019, International Journal of Hydrogen Energy
    View all citing articles on Scopus

    J. L. AtwoodJ. E. D. DaviesD. D. MacNicolF. Vögtle

    1

    E-mail: [email protected].

    View full text