Shielded bifunctional nanoreactor enabled tandem catalysis for plasma methane coupling

Abstract

Abstract The direct conversion of methane into valuable unsaturated C2 hydrocarbons (C2H2 and C2H4) attracts growing attention. Non-thermal plasma offers a promising approach for this process under mild conditions. However, the competing formation of C2H6 and excessive dehydrogenation limit the selectivity toward C2H2 and C2H4. Herein, we develop a promising shielded bifunctional nanoreactor with a hollow structure and mesoporous channels (Na2WO4-Mn3O4/m-SiO2) that effectively limits CH4 overactivation and promotes selective coupling to form C2H2 and C2H4 under plasma activation, achieving 39% CH4 conversion with 42.3% C2H2 and C2H4 fraction. This nanoreactor features isolated Na2WO4 embedded within the channels and Mn3O4 confined in the cavity of the SiO2 hollow nanospheres, enabling internal tandem catalysis at co-located active sites. Na2WO4 induces the conversion of diffused CH4 and CH3 into reactive intermediates (*CH and *CH2), which subsequently couple on the Mn3O4 surface to form C2H2 and C2H4. Furthermore, the mesoporous channels inhibit the plasma discharge within the nanoreactor, preventing deep dehydrogenation of CHx species to solid carbon. This nanoreactor demonstrates a highly selective route for the nonoxidative conversion of methane to valuable C2 hydrocarbons, offering a new paradigm for the rational design of catalysts for plasma-driven chemical processes.