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Main observation and conclusion: The catalytic properties of the CeO2 catalyst for propane dehydrogenation (PDH) are examined by employing the density functional theory calculations. Surface modifications and their effects on the surface reactivity are explored by creating the oxygen vacancy and single Pt atom doping. A comparative study between the binding energies of the different PDH reaction species reveals a considerable Lewis acid‐base interaction over the pristine and defective surfaces, which dominantly strengthens the bond formation between the adsorbates and the catalyst surface, resulting in the enhancement of surface reactivity. The creation of oxygen vacancy and doping the CeO2(111) surface with single Pt atoms changes the charge distribution over the surface on account of excess 4f electrons. This electronic change increases the bond formation abilities of the inactive Ce atom and hence increases the adsorption strength. Oxygen vacancy in the defective CeO2(111) surface migrates over the surface with the addition of an appropriate adsorbate. Moreover, it is revealed that the propylene is more strongly adsorbed on the single‐Pt‐atom‐doped CeO2(111) surface than the pristine and defective surfaces, which decreases the deep dehydrogenation energy barrier and ultimately results in the lowering of the selectivity. [ABSTRACT FROM AUTHOR]

Abstract: Ni catalysts are widely used to catalyze ammonia decomposition. In this study, first-principles calculations are performed to investigate the preferred adsorption sites and the adsorption energies of NHx (x=0–3) and H, and the transition states, activation energies and rate constants of NH3 stepwise dehydrogenation and associative desorption of N on the stepped Ni(211) and the close-packed Ni(111) surfaces. The results show that the barrier of associative desorption of N, which is higher than those of NH3 stepwise dehydrogenation, on Ni(211) are 1.10eV higher than that on Ni(111), indicating that the associative desorption of N on Ni(211) is difficult to take place. Hence the strongly adsorbed N atoms would block some of the step sites of Ni(211). The N-blocking Ni(211) surface is constructed, and then NH3 decomposition on 2N–Ni(211) is investigated. The results indicate that Ni catalysts with too many or too few step sites, which can be associated with Ni particle sizes, show low ammonia decomposition activities. Therefore, different sized Ni-based catalysts are employed to catalyze ammonia decomposition, and TOFH2 as a function of Ni particle size is correlated. Finally, the structure sensitivity of ammonia decomposition over Ni catalysts is rationally interpreted. [Copyright &y& Elsevier]

• High selectivity of core-shell alloy catalysts for propane dehydrogenation. • Linear scaling relations are established to identify the descriptor. • Microkinetic modeling is carried out to obtain turnover frequency. • Co@Pt is the best catalyst by making a compromise between activity and selectivity. Microkinetic analysis combined with the results obtained from density functional theory calculations has been performed to examine the catalytic activity and selectivity of Pt-based core-shell alloy catalysts for propane dehydrogenation. Calculated results indicate that substitution of 11 late transition metals for the core region of Pt nanoparticles would significantly modify the electronic structure of the surface Pt atoms through the strain effect and charge transfer. The core-shell catalysts are found to have less negative propylene adsorption energies and higher activation energies for the dehydrogenation reactions than Pt, thus giving rise to a lower catalytic activity and a higher selectivity toward propylene. Linear chemisorption energy and transition state energy scaling relations hold very well in the present work, and the adsorption energy of propylene is identified to be a good descriptor to represent the overall kinetics. The scaling relations also suggest that a higher catalyst selectivity toward propylene can only be achieved at the expense of a lower catalytic activity for propane dehydrogenation. If a compromise is made between catalytic activity and catalyst selectivity, Co@Pt is proposed to be the best core-shell catalyst for propane dehydrogenation. [ABSTRACT FROM AUTHOR]