1. Catalyst Modification to Reduce Product Inhibition During High Temperature Water-Gas Shift, C. Lund (PI)
DFT models of unpromoted and Cu-promoted sites on iron oxide were created and used to predict changes in heats of adsorption of water-gas shift intermediates resulting from promotion - surface promotion causes 60 to 80 kJ/mol decrease - sub-surface promotion causes less than 20 kJ/mol decrease Mechanistic kinetic modeling was used to experimentally estimate the change in heats of adsorption of intermediates - decreased by 10 kJ/mol - consistent with sub-surface promotion - same for both redox and formate mechanisms Strongly suggests that metallic copper particles are not responsible for promotion Discovered that copper promotion lessens inhibition of the rate by the product CO2 (see figure)