Hierarchical core-shell Ni@C-NCNTs nanocomposites tailored for microwave-induced dry reforming of methane process

The dry reforming of methane (DRM) is an important technology for syngas production, but its industrial application has been limited by the extremely high temperatures required to activate the thermodynamically stable CH4 and CO2 molecules. Herein, Ni-MOF-derived Ni@C-NCNTs nanomaterials with hierarchical core-shell structures and N-doped defects were elaborately designed and synthesized as bifunctional microwave absorbers and reforming catalysts by two-step pyrolysis processes. Efficient syngas production via the microwave-induced DRM (MW-DRM) process over Ni@C-NCNTs-5 was achieved. The double-hierarchical Ni@C-NCNTs with different loading amount of defective N-doped carbon nanotubes (NCNTs) on the Ni@C microstructures were rationally constructed by modulating the dosage of melamine in the secondary pyrolysis processes, which significantly improved the microwave absorption and conversion capacity and catalytic performance due to the synergistic effect of multiple loss mechanism of the incident microwave and the mitigation of active metal sintering. Density functional theory (DFT) calculations also indicated that surface engineering on the defects of the Ni@C-NCNTs catalysts could strongly promote the electron transfer and thus enhance the adsorption and catalytic activation of CH4 and CO2. More meaningfully, energy efficiency was significantly improved for the MW-DRM process by approximately 31 times than the conventional heating catalytic process owing to the direct, rapid, and highly effective energy transfer process under microwave irradiation. In conclusion, this dimensionally-designed core-shell catalyst demonstrated obvious superiority of catalytic performance and process intensification in the MW-DRM process. Hierarchical core-shell Ni@C-NCNTs nanomaterials and N-doped defects for microwave-induced CH4 dry reforming with excellent catalytic activity and energy efficiency.

Automated summary

This study presents the design and synthesis of hierarchical core-shell Ni@C-NCNTs nanomaterials with N-doped defects for microwave-induced dry reforming of methane. Efficient syngas production was achieved through the microwave-induced DRM process over Ni@C-NCNTs-5 catalyst. The material's structure and composition were optimized to enhance microwave absorption and conversion capacity, catalytic performance, and surface reactivity. The MW-DRM process demonstrated significantly improved energy efficiency compared to conventional heating catalytic processes.