Observation of induction period and oxygenated intermediates in methane oxidation over Pt catalyst

Selective oxidation of methane is one of the most attractive routes for methane to chemicals. However, mechanistic understanding and avoiding over-oxidation have great challenges because of its very rapid reaction rate. Herein, a capillary micro-reaction system was introduced to monitor the initial stage of methane oxidation over platinum. For the first time, an induction period is observed, dur-ing which oxygenated intermediates, such as methanol, acetone, methyl methoxy acetate, etc., are detected. Induction period can be shortened by methane pre-treatment at 600 degrees C, which generates highly active species containing unsatu-rated bonds. Combined these findings and observations of in situ characteriza-tions, the evolution route of methane oxidation over Pt is prosed, i.e., the reaction starts from the formation of initial species containing Pt-C bond, fol-lowed by the generation of oxygenated intermediates, and ended with the over-oxidation of the intermediates to CO/CO2.

Automated summary

A capillary micro-reaction system was used to monitor the initial stage of methane oxidation over platinum catalyst, revealing the presence of oxygenated intermediates. Methane pre-treatment at 600 degrees C was found to shorten the induction period by generating highly active species. Based on these findings and in situ characterizations, a reaction pathway for methane oxidation over Pt was proposed.