3.2. Catalytic activity
The results of the measurements on the catalytic combustion of
the three studied hydrocarbons over SrMnO3 perovskite heat treated
at 1000 C for 10 h are presented in Figs. 3 and 4. In Fig. 3 the
gas conversion over the catalyst is plotted as a function of reaction
temperature for the three gases. It has been found that the catalytic
combustion of the three hydrocarbons is complete, and the gases at
the reactor outlet only contain CO2 and H2O. The complete combustion
(in air) in the LPG case can be expressed as complete oxidation
of the two component gases (propane and butane):
C3H8 þ 5O2 ! 3CO2 þ 4H2O ð8Þ
2C4H10 þ 13O2 ! 8CO2 þ 10H2O ð9Þ
In the case of the two studied aromatic hydrocarbons, toluene
and benzene, the catalytic combustion starts at 100 C, but the conversion
factor does not exceed 60%. For the mixture of aliphatic
hydrocarbons, LPG, the catalytic combustion starts at a temperature
by about 50 C higher than for benzene and toluene, and it
reaches a much higher conversion factor for temperatures over
350 C. The sample exhibited the best catalytic activity (conversion)
for LPG combustion (92% at 400 C and 95% at 550 C) and
proved poor performances in catalytic combustion of toluene and
benzene (50% conversion and 54% conversion respectively over
400 C).