A comparison between hexaaluminates and perovskites for catalytic combustion applications

Hexaaluminates and perovskites are two promising candidates for use in catalytic combustion applications. In the present study two hexaaluminates, LaMnAl 11O 19 and LaCoAl 11O 19, were compared with two perovskites, LaMnO 3 and LaCoO 3, with respect to their thermal stability and catalytic activity for combustion of methane and gasified biomass. The results showed that the hexaaluminates retained a much higher surface area even after calcination at 1200 °C compared to the perovskites. LaMnAl 11O 19 showed the highest catalytic activity of all catalysts. LaCoAl 11O 19 generally showed low activity. Of the two perovskites, LaCoO 3 was the most active, and the initial test run the activity for biomass combustion were close to that one of LaMnAl 11O 19 even though its surface area was only one tenth of the hexaaluminate's. However, it was severely deactivated in the second test run. Similar deactivation but less severe was also found for the other catalyst.