DFT Study of Pyrolysis Gasoline Hydrogenation on Pd(100), Pd(110) and Pd(111) Surfaces

摘要

Pyrolysis gasoline is applied to extract aromatics and to be gasoline blending stock, and its stabilization by catalytic hydrogenation under mild temperature is an important reaction in petrochemical field. Thereinto, styrene hydrogenation was considered as an example for the assessment of the catalysis performance for pyrolysis gasoline hydrogenation. In this work, the adsorption and diffusion of reactants (styrene and H) and the activation energy of styrene hydrogenation on Pd(111), Pd(100), and Pd(110) surfaces are discussed by density functional theory calculations. The adsorption energy of reactants (styrene and H) decreases in the order of Pd(110)>Pd(111)>Pd(100). The activation barriers with feasible intermediate products are investigated and the reaction activity based on the activation barriers follows the order of Pd(111)>Pd(100)>Pd(110). In addition, the diffusion barrier for styrene or H is smaller than the reaction barrier of styrene hydrogenation, indicating the true rate limiting step is the process of hydrogenation rather than the diffusion. Our results provide theoretical guide for the prepared catalyst with feasible surfaces by careful selection of preparation techniques in experiments.