Understanding the electronic metal-support interactions of the supported Ni cluster for the catalytic hydrogenation of ethylene

Abstract

• The influences of electronic metal-support interactions (EMSI) on the catalytic hydrogenation of ethylene on three supported Ni catalysts (i.e. Ni 4 /TiO 2 , Ni 4 /CeO 2 and Ni 4 /BNO) have been studied systematically via DFT simulations. • When Ni cluster is loaded on the three substrates, the Ni cluster exhibits positive charge state with different charge density due to the EMSI. • The charges on Ni clusters are almost linearly correlated to both the adsorption energy of ethylene and the charge transfer from Ni to ethylene. • The charges on Ni could further affect the performance of the catalyst during the hydrogenation process of ethylene, where the Ni cluster with more electrons is beneficial for the hydrogenation reaction. • The coverage effect of hydrogen is also evaluated. At high H coverage, both the kinetics and thermodynamics of the hydrogenation reaction would be significantly promoted. The electronic metal-support interaction (EMSI) has a very profound impact on the catalytic activity of supported catalysts. In this paper, density functional theory calculations were utilized to understand the effect of EMSI between Ni cluster (Ni 4 ) and three substrates (CeO 2 , TiO 2 , and BNO) on the catalytic hydrogenation of ethylene. When Ni cluster was anchored on the surface of support, visibly electron transfer from Ni to substrate was observed, leading to positively charged Ni clusters with the sequence of Ni 4 /TiO 2 > Ni 4 /CeO 2 > Ni 4 /BNO. During the ethylene hydrogenation reaction, the electron rich Ni 4 /BNO exhibits superior performance in activating of both H 2 and ethylene molecules, while the electron deficient Ni 4 /TiO 2 shows the worst activation among the three catalysts. As a consequence, the activation energies of ethylene hydrogenation follow the same sequence of the charge state on the supported Ni clusters at both low and high H coverages. Our results suggest that the EMSI between metal nanoparticles and support materials is capable of tuning the charge state and electron density of supported metals, which further determines the activity of the catalyst. This work provides a potential approach for design new catalysts with desired activity by utilizing appropriate support materials.