(513cb) Density Functional Theory Analysis of Trends in Propane Dehydrogenation on Palladium Alloys
AIChE Annual Meeting
2020
2020 Virtual AIChE Annual Meeting
Catalysis and Reaction Engineering Division
Hydrocarbon Conversion II: Light Alkane Dehydrogenation
Wednesday, November 18, 2020 - 8:30am to 8:45am
We performed an extensive thermodynamic and kinetic analysis on a series of steps and terraces on the Pd and PdIn surfaces. The results show that the barriers for dehydrogenation are 0.4-0.7 eV lower on the Pd-terminated step of PdIn as compared to the PdIn (110), suggesting that these are the active sites for the alloys. These energetics are then input into a microkinetic model, and a degree of rate control analysis has been performed to derive plausible activity, selectivity and stability descriptors. Further to test the validity of the computationally obtained selectivity descriptors, catalytic experiments were performed on a series of intermetallic Pd alloys (Pd3Fe, Pd3Mn, Pd2Ga, and PdZn). The comparisons with experiments show that the selectivity descriptor could qualitatively distinguish between the highly selective 1:1 alloys, with the partly less selective 3:1 alloys which have 3-fold Pd ensembles. Moreover, a detailed transition state structure analysis shows how the promoter/heteroatom influences the C-H and C-C bond breaking barriers, which has implications for rational design of dehydrogenation catalysts.