(727e) Transient Kinetic Analysis of Acetone Hydrogenation to Isopropanol over Platinum Catalysts: A Combined Experimental and Theoretical Approach

Transient reaction kinetics experiments of heterogeneous catalytic systems are combined with density functional theory (DFT) electronic structure calculations and microkinetic models to quantify the reaction mechanism and catalytic activity of acetone hydrogenation over a platinum catalyst at 350 K. Transient response models based on a detailed DFT-based steady-state microkinetic analysis of the acetone hydrogenation mechanism on platinum predict minimal changes in the surface coverage of the most abundant reactive intermediate (MARI) upon removal of acetone from the reactant feed. In contrast, predictions for transients following a substitution of the reactant acetone species with another ketone (e.g., pentanone), as in the case of traditional steady state isotopic transient kinetic analysis (SSITKA) studies, show that full removal of the MARI from the catalyst surface can be achieved at 350 K. Experimental transient kinetic analyses of the acetone hydrogenation reaction over supported platinum catalysts are consistent with model predictions for surface residence times during desorption and reactive transients. Quantitative analysis of the experimental responses highlights the importance of coverage effects on surface reactivity for this system based on estimates of the number of active sites required for isopropanol product formation.