Residual chlorine ions on a Pt/Al2O3 catalyst surface prepared from ch
lorine-containing precursors appear to inhibit the total oxidation of
methane. At 450 degrees C, as chlorine is eliminated with time on stre
am, the reaction rate increases despite the sintering of the platinum
particles. The steady state reaction rate which is reached after 60 h
is identical to that obtained with a catalyst prepared from a precurso
r containing no chlorine. Whether chlorine is present or not in the in
itial state of the catalyst does not appear to have an influence on th
e evolution of the platinum particle size.