Structural Characterization and Catalytic Activity of Pt Dendrimer Encapsulated Nanoparticles Supported Over Al₂O₃ for SCR of NO _x

Pt/Al₂O₃ and Pt–Mg/Al₂O₃ nano composites were successfully prepared by dendrimer templated synthesis route. The obtained dendritic nanoparticles were dispersed in alumina support and they were evaluated for SCR of NO _x using methane as reductant. Thermal analysis results of uncalcined samples revealed that the oxygen can accelerate the rate of dendrimer shell decomposition. X-ray diffractograms of 500 °C calcined samples disclosed the amorphous nature of materials, whereas 1000 °C air calcined samples showed enhanced crystallinity as well as diffraction pattern corresponding to Pt and PtO. HRTEM images of Pt₄₀–G4OH dendritic nanoparticles showed uniform particulate distribution with average particle size of 2.4 nm. The STEM results of 0.5 Pt/Al₂O₃ sample calcined at 500 °C exhibited a wide range of particles between 2 and 20 nm. This indicates the huge segregation of platinum metal particles during impregnation and subsequent calcination. Among the synthesized materials 0.5 wt% Pt/Al₂O₃ sample showed excellent conversion and selectivity for SCR of NO _x .