Mild-condition methane conversion with oxygen by an ultrasound-catalysis coupling process

Mild-condition methane (CH 4 ) oxidation into valuable chemicals using earth-abundant oxygen (O 2 ) is a highly desirable yet challenging process due to the chemical inertness of CH 4 and the low reactivity of O 2 . Herein, we report an ultrasound-catalysis coupling strategy for highly efficient conversion of CH 4 into high-value oxygenates under mild conditions, using O 2 as an oxidant and carbon nanotube-supported platinum nanoparticles (Pt/CNT) as a catalyst. It achieves a superior formation rate of 3727 μmol g cat. −1 h −1 and a selectivity of 92% for C 1-2 oxygenates at 5 o C and 0.1 MPa, significantly surpassing both previously reported thermo-catalytic and ultrasound-driven processes under low-temperature conditions. We find that ultrasound-driven surface cleaning effect enhances the exposure of active Pt sites, thereby facilitating the adsorption of CH 4 and O 2 . Furthermore, the localized and instantaneous high-temperature and high-pressure microenvironment generated by ultrasonic cavitation not only promotes the activation of CH 4 and O 2 for C−H cleavage and C−O coupling, but also accelerates the mass transfer of reactants and products.