Sl. Gonzalez-cortes et al., Oxidative transformation of methane on 1.5 mol% Sr2+/La2O3-supported nickel catalysts, APP CATAL A, 213(2), 2001, pp. 259-271
This work examines oxidative transformation of methane on 1.5 mol% Sr2+/La2
O3 catalyst with nickel loadings up to 55 mol% nickel, prepared by wetness
impregnation. The solids were characterized by X-ray diffraction, infrared
spectroscopy, temperature-programmed reduction, BET surface area measuremen
ts, and thermogravimetric analysis. The NiO/Sr2+-La2O3 catalysts show a str
ong nickel oxide interaction with La2O3, involving anionic vacancies or str
uctural defects that induce LaSrNiOx solid solutions with island-like struc
ture formation. Two different reaction mechanisms are suggested depending o
n nickel loading. The 1.5 mol% Sr2+/La2O3 catalysts (0% Ni) favor oxidative
coupling of methane (OCM) to C-2 hydrocarbons, whereas the Ni-modified one
s favor syngas formation through partial oxidation of methane (POM). Anioni
c vacancies and coordinatively-unsaturated oxygen atoms (O-CUS) leading to
hydroxycarbonate phase formation are proposed. Nickel carbide and hydroxyca
rbonate phases influence on syngas formation is analyzed. (C) 2001 Elsevier
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