The Direct Partial Oxidation of Methane to Dimethyl Ether over Pt/Y2O3 Catalysts Using an NO/O2 Shuttle

• Published in: Angewandte Chemie International Edition 2020-09, Vol.59 (38), p.16644-16650
• Main Authors: Vargheese, Vibin, Kobayashi, Yasukazu, Oyama, S. Ted
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Catalysts; Dimethyl ether; Fixed bed reactors; Fixed beds; Hydrogen peroxide; Methane; methane partial oxidation; Nitrogen dioxide; Nitrous oxide; NO/O2 shuttle; Oxidants; Oxidation; Oxidizing agents; Pt/Y2O3; Yttrium oxide
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202006020

Using a mixture of NO + O2 as the oxidant enabled the direct selective oxidation of methane to dimethyl ether (DME) over Pt/Y2O3. The reaction was carried out in a fixed bed reactor at 0.1 MPa over a temperature range of 275–375 °C. During the activity tests, the only carbon‐containing products were DME and CO2. The DME productivity (μmol gcat−1 h−1) was comparable to oxygenate productivities reported in the literature for strong oxidants (N2O, H2O2, O3). The NO + O2 mixture formed NO2, which acted as the oxygen atom carrier for the ultimate oxidant O2. During the methane partial oxidation reaction, NO and NO2 were not reduced to N2. In situ FTIR showed the formation of surface nitrate species, which are considered to be key intermediate species for the selective oxidation. Via surface NOx species: Methane is oxidized directly to dimethyl ether (DME) on Pt/Y2O3 without the formation of methanol, when NO and NO2 serve as the oxygen transfer system. There is no formation of N2 and the ultimate oxidant is O2.