Abstract
The d-band center position of the metal catalyst is one of the most important factors for catalytic selective hydrogenation, e.g., the conversion of nitrostyrene to aminostyrene. In this work, we modulate the d-band center position of the Pt surface via H coverage manipulation in order to assess the highly efficient selective hydrogenation catalyst using density functional theory (DFT) calculation, which is validated experimentally. The optimal transition metal catalysts are first screened by comparing the adsorption energy values of two ideal models, nitrobenzene and styrene, and by correlating the adsorption energy with the d-band center positions. Among the ten transition metals, Pt nanoparticles have a good balance between selectivity and the conversion rate. Then, the surface hydrogen covering strategy is applied to modulate the d-band center position on the Pt (111) surface, with the increase of H coverage leading to a decline of the d-band center position, which can selectively enhance the adsorption of nitro groups. However, excessively high H coverage (e.g., 75% or 100%) with an insufficiently low d-band center position can switch the chemisorption of nitro groups to physisorption, significantly reducing the catalytic activity. Therefore, a moderate d-band center shift (ca. −2.14 eV) resulted in both high selectivity and catalytic conversion. In addition, the PtSn experimental results met the theoretical expectations. This work provides a new strategy for the design of highly efficient metal catalysts for selective hydrogenation via the modulation of the d-band center position.
Highlights
IntroductionRational catalyst design strategies generally need to be guided by theoretical calculations [1]
Rational catalyst design strategies generally need to be guided by theoretical calculations [1].By constructing adsorption competition strategies for initial configurations and key intermediates, potential advantageous catalysts can be screened and predicted, which can greatly reduce the costs involved in studying catalytic processes and industrial production [2]
Combining the adsorption energy values of –NO2 and –C=C groups and the change of reaction barriers, we found that the hydrogenation selectivity of nitrostyrene could be further improved by moderately changing the d-band center positions on the surfaces of Pt nanoparticles
Summary
Rational catalyst design strategies generally need to be guided by theoretical calculations [1]. There have been studies involving manipulation of the d-band center positions on solid catalyst surfaces to improve the selectivity of the catalytic reaction [16]. We compared the adsorption energies of –NO2 and –C=C on 10 transition metals using the DFT method and screened potential superior metals (i.e., Pt nanoparticles) through d-band center position changes. Combining the adsorption energy values of –NO2 and –C=C groups and the change of reaction barriers, we found that the hydrogenation selectivity of nitrostyrene could be further improved by moderately changing the d-band center positions on the surfaces of Pt nanoparticles
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