Effect of the calcination temperature on the performance of a CeMoOx catalyst in the selective catalytic reduction of NOx with ammonia

• Effect of calcination temperature on a CeMoOx catalyst in NH3-SCR reaction is examined.
• High temperature calcination leads to the enrichment of MoO3 on catalyst surface.
• Calcination at high temperature decreases the NO oxidation activity.
• High temperature calcination (700 °C) leads to the destruction of the acid sites.

The effect of the calcination temperature on the structure and the catalytic performance of a CeMoOx mixed oxide catalyst in the selective catalytic reduction (SCR) of NOx with NH3 has been investigated. Compared to the catalyst calcined at 400 °C, the one calcined at 500 °C shows a performance of a slightly lower NOx conversion in the reaction temperature range below 200 °C, and a higher NOx conversion above 350 °C. However, further increase of the calcination temperature to 600 and 700 °C leads to a drop of the NOx conversion and the N2 selectivity in both the low and high reaction temperature ranges. For the samples calcined at 600 and 700 °C, Mo significantly enriches on the surface. These samples also favor the formation of N2O, and show a poor redox ability in NO oxidation reaction. The low ratio and low mobility of the surface chemisorbed oxygen correlates to the poor redox ability of the samples calcined at high temperatures. Furthermore, an abrupt drop of the surface area for the sample calcined at 600 °C is observed and the destruction of acid sites during the high temperature calcination also recorded.

Figure optionsDownload high-quality image (121 K)Download as PowerPoint slide