Density functional theory (DFT) calculations were performed to investigate the effect of Ni doping on C1 and C2 hydrocarbons production from CO2 hydrogenation on the Fe catalyst. The CH* species was found to be the most favorable monomeric CHx* species leading to both CH4 and C2H4 formation on Fe(110) and Ni-Fe(110) surfaces. The plausible pathway went through CO2→ HCOO*→HCO*→CH*. Although CO* formation from direct dissociation of CO2 was kinetically more favorable than CO2 hydrogenation to HCOO* and COOH* intermediates on the two surfaces, the subsequent hydrogenation of CO* to HCO* was energetically detrimental, resulting in the reverse conversion of HCO* to CO* preferred. Further conversion of CH* species led to either CH4 via several hydrogenation steps or C2H4 through C-C coupling followed by two hydrogenation steps. On monometallic Fe(110), the barrier difference associated with the selectivity determining step was only 0.10 eV, suggesting similar selectivity to CH4 and C2H4. In contrast, when a Ni atom was doped onto Fe(110), the selectivity difference became more pronounced, leading to an enhanced C2H4 production on Ni-Fe(110). These results revealed that adding a small amount of Ni could promote CH* formation from CO2 hydrogenation, C-C coupling of two CH* species and the further hydrogenation of C2 intermediates to ethylene.
|Translated title of the contribution||DFT Insight into the Effect of Ni Doping on Hydrocarbons Synthesis from CO2 Hydrogenation over Fe Catalyst|
|Number of pages||11|
|Journal||Journal of Molecular Catalysis|
|State||Published - Aug 1 2020|
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