C. Schinzer et al., HYDROGENATION OF TOLUENE OVER LA0.8SR0.2FE1-XCOXO3-Z PEROVSKITE CATALYSTS, Zeitschrift fur Naturforschung. B, A journal of chemical sciences, 52(8), 1997, pp. 927-934
The hydrogenation of toluene over perovskites of composition La0.8Sr0.
2Fe1-xCoxO3-z (x = 0.0, 0.2, 0.5, 0.8 and 1.0) is reported. The cataly
st material has been prepared by the coprecipitation method using male
ic acid as the complexing agent. The activity for the gas phase reacti
on of toluene and hydrogen at temperatures between 50 degrees C to 300
degrees C is reported for as-prepared and activated materials. The co
nversion has been found to be nearly temperature-independent over the
as-prepared perovskites with a maximum of 40% conversion found for a c
omposition La0.8Sr0.2Fe0.5Co0.5O2.86. Activation by an oxygen treatmen
t at 500 degrees C was successful to enhance the activity of the Co-ri
ch perovskites. All of these catalysts show a complete conversion of t
oluene at 100 degrees C, but activity decreases by time due to a reduc
tion of the catalyst material. Again, La0.8Sr0.2Fe0.5Co0.5O2.86 exhibi
ts the slowest loss of activity. A model for its special properties is
mainly attributed to the p-type conduction behaviour. The conversion
behaviour of the perovskite type catalysts investigated here is compar
ed to the results obtained with noble-metal supported catalysts and it
can be concluded, that the perovskites exhibit higher conversion rate
s, maximum temperatures and higher cracking onset temperatures than th
ese.