A. Djaidja et al., Oxidative transformation of methane over nickel catalysts supported on rare-earth metal oxides, CATAL TODAY, 61(1-4), 2000, pp. 303-307
The oxidative transformation of methane over Ni catalysts supported on La,
Sm and Ce oxides was investigated at atmospheric pressure, T=723-923 K and
CH4/O-2=1-10. The BET surface areas were low (3-22 m(2) g(-1)) and decrease
d strongly after reaction (down to 0.5 m(2) g(-1)). Carbonate species, Ni2O
3 and supported oxides were identified by XRD or IR spectroscopy studies in
both the fresh and used catalysts. The Ni degrees phase was also probably
formed as amorphous phase. The oxidative coupling of methane route passed t
hrough a minimum as a function of the Ni percentage and was favored by the
Ce or Sm oxide support, Li additive and low reaction temperature. High sele
ctivities (60-90%) and good yields (about 15%) in C-2 hydrocarbons with low
carbon balance (0-10%) were obtained at 823 K, La supported oxide, Ba addi
tive and high reaction temperature favored the partial oxidation of methane
. The obtained results were discussed in the light of the reducibility and
acid-base properties of the catalysts. (C) 2000 Elsevier Science B.V. All r
ights reserved.