title: Quasi in situ Ni K-edge EXAFS investigation of the spent NiMo catalyst from ultra-deep hydrodesulfurization of gas oil in a commercial plant.
abstract: Ni species on the spent NiMo catalyst from ultra-deep hydrodesulfurization of gas oil in a commercial plant were studied by Ni K-edge EXAFS and TEM measurement without contact of the catalysts with air. The Ni-Mo coordination shell related to the Ni-Mo-S phase was observed in the spent catalyst by quasi in situ Ni K-edge EXAFS measurement with a newly constructed high-pressure chamber. The coordination number of this shell was almost identical to that obtained by in situ Ni K-edge EXAFS measurement of the fresh catalyst sulfided at 1.1 MPa. On the other hand, large agglomerates of Ni(3)S(2) were observed only in the spent catalyst by quasi in situ TEM/EDX measurement. MoS(2)-like slabs were sintered slightly on the spent catalyst, where they were destacked to form monolayer slabs. These results suggest that the Ni-Mo-S phase is preserved on the spent catalyst and Ni(3)S(2) agglomerates are formed by sintering of Ni(3)S(2) species originally present on the fresh catalyst.
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Tohoku University, Aoba-ku, Sendai, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Hamabe
authors.forename: Sungbong
authors.initials: S
authors.lastname: Jung
authors.forename: Hikotaro
authors.initials: H
authors.lastname: Suzuki
authors.forename: Naoto
authors.initials: N
authors.lastname: Koizumi
authors.forename: Muneyoshi
authors.initials: M
authors.lastname: Yamada