Open AccessIn situ Ni K ‐edge XANES study of the reducibility of Ni in f.c.c. catalysts
Author(s) -
Bare S.R.,
Modica F. S.,
Ringwelski A. Z.
Publication year - 1999
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049599001089
Subject(s) - xanes , catalysis , in situ , k edge , nickel , materials science , enhanced data rates for gsm evolution , chemistry , crystallography , physics , metallurgy , computer science , spectroscopy , absorption spectroscopy , organic chemistry , quantum mechanics , telecommunications
The majority of the Ni in an aged equilibrated catalyst (ECAT) from the resid UOP fluid catalytic cracking (FCC) unit in the Pertamina EXOR-1 refinery (with 12,000 ppm Ni) is present primarily as a NiAI204 phase. No appreciable Ni reduction occurs below 500°C in a flow of H2. In situ Ni K-edge XANES has been used to follow the reduction kinetics of this NiA1204 phase. Reduction in H2 is described by pseudo-second-order kinetics. An apparent activation energy is estimated to be 26 kcal/mol. This value is compared to that of 4.3 kcal/mol for NiO reduction and 32 kcal/mol for NiAI204 reduction. Less than 10% of the Ni is estimated to go through a redox cycle in an FCC unit, resulting in a negligible impact on the hydrogen in coke calculation.