Understanding Fischer-Tropsch Chemistry at Surfaces
The chemistry of the Fischer-Tropsch (FT) reaction is of particular interest due to the ability to convert syngas into various sized hydrocarbons (CxHyOz). Most FT catalysts produce hydrocarbon products based on the Anderson-Schultz-Flory distribution. A few catalysts have been shown to break this distribution, which opens the door for wider tailorability of products. Of these catalysts, a number utilize promoters such as Mn, Mg, Na, and K to enhance catalytic performance.
Our group collaborates with Prof. C. Buddie Mullins at UT Austin to study surface reactions related to the Fischer-Tropsch process. Using density functional theory, we studied Mn/Co models for the dissociation of CO. In agreement with experiments, we saw that Mn coverages on Co promoted the adsorption and dissociation of CO.
Selective Oxidation of Acetaldehyde to Acetic Acid on Pd-Au Bimetallic Model Catalysts
Acetic acid is a widely employed reactant in the chemical industry, and it is also used as a food ingredient. Here, we reported a catalytic reaction pathway for the gas-phase selective oxidation of acetaldehyde to acetic acid on a Pd-Au(111) heterogeneous moedel catalyst with different Pd coverages. Different size of Pd ensembles could change the binding energy of intermediates, and also affected the way of adsorption. We found that stabilization of CH2COO* as size of Pd ensemble increases, which can be directly connected to selectivity. This work is collaborated with Prof. C. Buddie Mullins at UT Austin.
S. Han, K. Shin, G. Henkelman, C. B. Mullins,
Selective Oxidation of Acetaldehyde to Acetic acid on Pd–Au Bimetallic Model Catalysts,
ACS Catal. 9, 4360-4368 (2019).
L. Xu, D. Mei, and G. Henkelman, Adaptive kinetic Monte Carlo simulation of methanol decomposition on Cu(100) J. Chem. Phys. 131, 244520 (2009).
R. A. Ojifinni, J. Gong, N. S. Froemming, D. Flaherty, M. Pan, G. Henkelman, and C. B. Mullins, Carbonate formation and decomposition on atomic oxygen precovered Au(111) J. Am. Chem. Soc. 130, 11250 (2008).
R. A. Ojifinni, N. S. Froemming, J. Gong, M. Pan, T. S. Kim, J. M. White, G. Henkelman, and C. B. Mullins, Water-enhanced low-temperature CO oxidation and isotope effects on atomic oxygen covered Au(111) J. Am. Chem. Soc. 130, 6801 (2008).
G. Henkelman, A. Arnaldsson, and H. Jónsson, Theoretical calculations of CH4 and H2 associative desorption from Ni(111): Could subsurface hydrogen play an important role?, J. Chem. Phys. 124, 044706 (2006).
G. Henkelman and H. Jónsson, Theoretical calculations of dissociative adsorption of CH4 on an Ir(111) Surface, Phys. Rev. Lett. 86, 664 (2001).