Identification of Hydrogen Species on Pt/Al2O3 by in situ Inelastic Neutron Scattering and their Reactivity with Ethylene
S. Yamazoe, A. Yamamoto, S. Hosokawa, R. Fukuda, K. Hara, M. Nakamura, K. Kamazawa, T Tsukuda, H. Yoshida, T. Tanaka
Catal. Sci. Technol., Accepted.
Hydrogen (H) species adsorbed on catalyst surfaces are key intermediates in catalytic hydrogenation reactions over supported metal catalysts. However, individual identification of H species on the metal catalysts has not been established to date. Here, we elucidated the H species on Pt/Al2O3 by the combination of in situ inelastic neutron scattering (INS) and density functional theory (DFT). Several H species in the presence of H2 were successfully identified at different sites on the Pt surface and Al2O3 support. The in situ INS and FT-IR measurements revealed that the hydride/atop Pt‒H, bridged perimeter/terrace Pt-H-Pt, and threefold Pt3‒H are active intermediates in the C2H4 hydrogenation reaction, whereas the edge Pt-H-Pt is a rather inert species. In addition, the in situ measurements indicate that the Al2O3 itself acts as hydrogen storage material by mediating AlO-H and Al‒H‒Al species, which serve H species in the C2H4 hydrogenation reaction.