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

Abstract

Improving the selectivity and activity of C 2 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 C 2 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 CH x (x = 1−3) monomer, as well as the activity and selectivity of CH x monomer and C 2 species. Among these, only the Cu/WC−C catalyst is screened out to achieve outstanding activity and selectivity for C 2 H 2 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 CH x and C 2 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 C 2 species from syngas.

Enhanced Proximity of Rh1,2‐Rhn Ensembles Encaged in UiO‐67 Boosting Catalytic Conversion of Syngas to Oxygenates

“…The conversion of syngas to oxygenates is associated with the interface between Rh and the oxide support or promoter. [6][7][8][9][10] Monometallic Rh catalysts often provide poor selectivity for oxygenates, mainly producing undesired methane and light hydrocarbons. The selectivity can be significantly improved by constructing effective interfacial sites with promoters and supports, yielding unique surface Rh species of atomically adjacent Rh + /Rh 0 species that determine the abilities of CO dissociation and insertion, which affect the distribution of hydrocarbons and oxygenates.…”

“…The conversion of syngas to oxygenates is associated with the interface between Rh and the oxide support or promoter [6–10] . Monometallic Rh catalysts often provide poor selectivity for oxygenates, mainly producing undesired methane and light hydrocarbons.…”