(656b) Capturing the Restructuring of Co-Based Catalysts in Oxygenate-Driven Fischer-Tropsch Synthesis from First Principles
AIChE Annual Meeting
2020
2020 Virtual AIChE Annual Meeting
Catalysis and Reaction Engineering Division
Single Atom Catalysts: Synthesis, Characterization and Performance: I
Wednesday, November 18, 2020 - 8:15am to 8:30am
As seen in Figure 1A, a phase diagram (Figure 1A, graph) comparing a large number of possible CO/CoCu structures using the Cu/Co(755) surface, geminal Co tricarbonyl (Figure 1A.1) formation is predicted at ambient pressures while ruptured, diffusive Co(CO)3formation (Figure 1A.2) is predicted to occur above ~7.3 bar and FT-relevant pressures. Exergonic dimerization (~ -0.1 eV/dimer) to Co2(CO)5 (Figure 1A.3) was also shown and suggests a mechanism for Co nanoisland formation. We have subsequently shown this to occur on the vicinal-kinked Co(14 11 10) surface as well, suggesting that this reconstruction mechanism is relevant to FT in general.
With an eye specifically turned toward CO dissociation, we additionally examined the interaction between CO and metal-oxide-doped Co catalysts using small MOx nanoparticles (M = Ti, Zr, Mn) adsorbed on the Co(0001) facet. A linear trend was found between the amount of charge transfer from MOx to CO and the CO stretch frequency (Figure 1B.1). This is visualized via the differential charge density in Figure 1B.2. Overall these phenomena provide a framework for future studies on oxygenate-driven FT.