Toward catalyst design combining DFT, kinetic modeling and sensitivity analysis: Cu-based catalysts for CO2 hydrogenation to methanol
We carried out a combined DFT, KMC and sensitivity analysis to understand the effect of alloying on the catalyst activity and selectivity and screen the metal doped-Cu systems towards the CH3OH synthesis. Our DFT study showed that on Cu(111), CH3OH synthesis from CO2 and H2 through the formate pathway and the RWGS + CO-Hydro pathway, where the formate pathway is preferred according to the KMC simulation. The sensitivity analysis based on a KMC simulation identified two descriptors, which are key to promote the catalytic activity of Cu (Figure on the left). One is the activation barrier for H2COO hydrogenation. The other is the CO binding energy (Figure 3a). An ideal Cu-based catalyst towards CH3OH synthesis should be able to hydrogenate H2COO easily and bond CO moderately, being strong enough to favor the desired CO hydrogenation rather than CO desorption, but weak enough to prevent CO poisoning. In this way, the CH3OH yield via both the formate pathway and the RWGS+CO-Hydro pathway can be facilitated.
Our results show that doping Ni, Pt, Pd as well as Rh is able to promote the CH3OH synthesis reaction while Au deactivates the reaction (Figure on the right). On Pd, Rh, Pt and Ni doped Cu(111) surfaces, the optimal pathway is tuned from the formate pathway in the case of Cu(111) to the RWGS+CO-Hydro pathway, though both pathways contribute to the production of CH3OH. Doping these active metals stabilizes the surface intermediates, in particular, CO and HCO, and therefore promotes CH3OH synthesis via the RWGS + CO-Hydro pathway. Indeed, among the systems we studied, Ni-Cu(111) displays the highest activity to H2COO hydrogenation, the moderate binding to CO, and therefore the highest selectivity and activity to methanol synthesis.
Ref: Y. Yang, J. Evans, J.A. Rodriguez, M.G. White, P. Liu, Physical Chemistry Chemical Physics 12 (2010) 9909-9917; Y. Yang, M. G. White, P. Liu, Journal of Physical Chemistry C 116 (2012) 248-256.
Last Modified: October 25, 2013