Abstract
The direct conversion of methane into valuable unsaturated C(2) hydrocarbons (C(2)H(2) and C(2)H(4)) attracts growing attention. Non-thermal plasma offers a promising approach for this process under mild conditions. However, the competing formation of C(2)H(6) and excessive dehydrogenation limit the selectivity toward C(2)H(2) and C(2)H(4). Herein, we develop a promising shielded bifunctional nanoreactor with a hollow structure and mesoporous channels (Na(2)WO(4)-Mn(3)O(4)/m-SiO(2)) that effectively limits CH(4) overactivation and promotes selective coupling to form C(2)H(2) and C(2)H(4) under plasma activation, achieving 39% CH(4) conversion with 42.3% C(2)H(2) and C(2)H(4) fraction. This nanoreactor features isolated Na(2)WO(4) embedded within the channels and Mn(3)O(4) confined in the cavity of the SiO(2) hollow nanospheres, enabling internal tandem catalysis at co-located active sites. Na(2)WO(4) induces the conversion of diffused CH(4) and CH(3) into reactive intermediates ((*)CH and (*)CH(2)), which subsequently couple on the Mn(3)O(4) surface to form C(2)H(2) and C(2)H(4). Furthermore, the mesoporous channels inhibit the plasma discharge within the nanoreactor, preventing deep dehydrogenation of CH(x) species to solid carbon. This nanoreactor demonstrates a highly selective route for the nonoxidative conversion of methane to valuable C(2) hydrocarbons, offering a new paradigm for the rational design of catalysts for plasma-driven chemical processes.