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Published September 1995 | public
Journal Article

Arrested Formation of Carbon Oxides in Programmed Oxidation of Methane on Nonstoichiometric Samaria

Abstract

CO_x species evolved during transient exposure of Sm_2O_3 catalysts to very low pressure CH_4/O_2 mixtures are monitored in real time by molecular beam mass spectrometry at 1100 K. The rise of m/z = 28 and 44 signals is significantly delayed relative to the onset of CH_4 decay only on substoichiometric Sm_2O_(3-γ) samples. This observation rules out CO and CO_2 as primary products of methane heterogeneous oxidation and implies that their immediate precursor, most probably CH_3(g), is slowly oxidized during the initial stages of Sm_2O_(3-γ) surface reconstruction. Present results suggest the possibility of suppressing carbon oxides in the oxidative dimerization of methane by dynamic control of selective site populations.

Additional Information

© 1995 American Chemical Society. Received: February 24, 1995; In Final Form: June 5, 1995. This project was financially supported by CONICET-Argentina, under grant PID-1131/91.

Additional details

Created:
August 20, 2023
Modified:
October 23, 2023