Syngas Conversion to C₂ Species over WC and M/WC (M = Cu or Rh) Catalysts: Identifying the Function of Surface Termination and Supported Metal Type
2022
Zhao, Wantong | Guan, Zun | Li, Debao | Wang, Baojun | Fan, Maohong | Zhang, Riguang
Improving the selectivity and activity of C₂ species from syngas is still a challenge. In this work, catalysts with monolayer Cu or Rh supported over WC with different surface terminations (M/WC (M = Cu or Rh)) are rationally designed to facilitate C₂ species generation. The complete reaction network is analyzed by DFT calculations. Microkinetics modeling is utilized to consider the experimental reaction temperature, pressure, and the coverage of the species. The thermal stabilities of the M/WC (M = Cu or Rh) catalysts are confirmed by AIMD simulations. The results show that the surface termination and supported metal types in the M/WC (M = Cu or Rh) catalysts can alter the existence form of abundant CHₓ (x = 1–3) monomer, as well as the activity and selectivity of CHₓ monomer and C₂ species. Among these, only the Cu/WC–C catalyst is screened out to achieve outstanding activity and selectivity for C₂H₂ generation, attributing to that the synergistic effect of the subsurface C atoms and the surface monolayer Cu atoms presents the noble-metal-like character to promote the generation of CHₓ and C₂ species. This work demonstrates a new possibility for rational construction of other catalysts with the non-noble metal supported by the metal carbide, adjusting the surface termination of metal carbide and the supported metal types can present the noble-metal-like character to tune catalytic performance of C₂ species from syngas.
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