Insight into the CC chain growth in Fischer-Tropsch synthesis on HCP Co(10-10) surface: The effect of crystal facets on the preferred mechanism

Abstract Spin-polarized DFT calculations are performed to probe into the preferred mechanism of C C chain growth in Fischer-Tropsch synthesis on HCP Co(10-10) with the higher surface area exposed. The effect of HCP Co crystal facets on the preferred mechanism of C C chain growth is identified among carbide mechanism and C(H)O mechanism in the processes of C 1 to C 4 hydrocarbons. CH 2 is the most favored CH x monomer. The C 2 hydrocarbon is dominantly formed via carbide mechanism, and CH 3 CH 2 is the most favored C 2 hydrocarbon. Subsequently, the most favored C 3 hydrocarbon, CH 3 CH 2 CH 2 , is formed via carbide mechanism of CH 3 CH 2 coupling with CH 2 . Further, the most favored C 4 hydrocarbon, CH 3 CH 2 CH 2 CH 2 , is formed via carbide mechanism of CH 3 CH 2 CH 2 coupling with CH 2 . Thus, the preferred mechanism of C C chain growth on Co(10-10) mainly focus on carbide mechanism instead of C(H)O insertion mechanism. The carbide mechanism is that RCH 2 coupling with CH 2 to R'CH 2 (R' RCH 2 ), followed by coupling with CH 2 to R''CH 2 (R'' R'CH 2 ) can realized the C C chain growth cycle to form higher hydrocarbons. Finally, the crystal facet of HCP Co catalyst affects the preferred mechanism of C C chain growth, and Co(10-10) via carbide mechanism is more favorable than Co(0 0 0 1) via CHO insertion mechanism.