TITLE: Iron-Induced Deactivation of Raney and Supported Nickel Methanation Catalysts. Semi-Annual Progress Report, September 15, 1978-September 15,1980.

AUTHOR: J. A. Dumesic.

INST.  AUTHOR: Wisconsin Univ.-Madison. Dept. of Chemical Engineering.

SPONSOR: Department of Energy, Washington, DC.


PUB.  TYPE: Technical Report

PUB.  COUNTRY: United States

SOURCE: Department of Energy [DE],  May 80,  74p.


It was concluded that: (1) the deactivation of Ni/Al sub 2 O sub 3 methanation catalysts is caused by particle size growth and surface site blockage (probably by carbon deposition); (2) the particle size growth in Ni/Al sub 2 O sub 3 methanation catalysts results from the formation of volatile Ni(CO) sub 4 , vapor phase transport and subsequent decomposition of Ni(CO) sub 4 ; (3) a region of safe operation conditions is found, and justified by thermodynamic equilibrium calculations, the proposed criterion is in terms of the equilibrium Ni(CO) sub 4 partial pressure, it can also be applied to other Ni/Al sub 2 O sub 3 systems with different loading and/or geometry; (4) the mechanism of methanation in the unsafe region may be different from that in the safe region; and (5) in-situ Moessbauer spectroscopy has been performed for the first time on a working iron catalyst at high pressure Fischer-Tropsch reaction conditions. In our brief studies, it was clearly shown that under these reactions conditions: (A) the top layer of a precipitated iron catalyst bed is present as a chi-carbide phase, and (B) the bottom layer of a precipitated iron catalyst bed may contain appreciable amounts of magnetite, depending on the CO conversion. (ERA citation 06:001808)