(281b) Effect of Ammonia In Syngas On the Fischer–Tropsch Behavior of a Precipitated Iron Catalyst

Effect
of ammonia in syngas on the Fischer¨CTropsch behavior of a precipitated iron catalyst

Wenping
Ma, Gary Jacobs, Jungshik Kang, Dennis Sparks, and Burtron H. Davis^*

Center for Applied Energy Research, University of Kentucky, 2540
Research Park Drive, Lexington, Kentucky, 40511, USA

Abstract

The effect of
ammonia in syngas in the concentration range of 100 ppbw ¨C 200 ppmw on
Fischer¨CTropsch reaction over 100 Fe/5.1 Si/2.0 Cu/3.0 K catalyst was studied
at 260 ^oC, 175 psig, H₂/CO = 0.67 and 10 Nl/g-cat/h  in a 1-L slurry phase reactor. The
ammonia added in syngas originates from concentrated ammonia and ammonia
nitrate soution. Three concentrations of ammonia in syngas feed,  i.e. 100 ppbw, 20 ppmw and 200 ppmw, were
employed to examine the sensentivty of the iron catalyst to NH₃. The
examinion of the impact of each NH₃ concentration on the iron
catalyst FTS performance lasted for 144 or 168 h. The results indicated
that  the iron catalyst  was quite resistant to NH₃ poisoning
at the FTS conditions used. During 950 h of testing, no changes on the catalyst
selectivities to CH₄, C₅₊ , and CO₂, the
selectivities to C₄ olefin and paraffin,  and the selectivities to straight C₄
olefin and internal C₄ olefin was observed. The catalyst
displayed a slight increase in CO conversion while adding 100 ppbw solution in
the first 96 h, which might be partly due to a slight increase in the water-gas
shift activity for the catalyst. Afterwords, the iron catalyst  displayed a stable CO conversion (~56.3%)
regardless of the concentrations of NH₃ used.  

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* Corresponding author:  Burtron
H. Davis, davis@caer.uky.edu,
Tel: 859-257-0251.