Synthesis of spherical and size-controlled Pt dendrimer-encapsulated nanoparticles for SCR of NOx

Highly active and selective alumina-supported Pt dendrimer-encapsulated nanocomposite materials were successfully prepared and evaluated for the selective catalytic reduction (SCR) of NOx using methane as reductant. The physicochemical properties of the prepared samples were investigated with X-ray diffraction (XRD), Brunauer Emmett Teller (BET) surface area, inductively coupled plasma mass spectrometry (ICP-MS), and transmission electron microscopy-energy-dispersive X-ray analysis (EDX) techniques. The resulted metallic Pt40 particles are spherical and well separated from each other. As derived from the transmission electron microscopy images, the average particle diameter of dendrimer-encapsulated nanoparticles (DENs) is 2.4 nm. The diffraction profiles of fresh and used catalysts indicated that the prepared materials are highly stable after 40 h of time-on-stream reaction. For DENs Pt/Al2O3 sample, the distribution of platinum particle size ranged between 2 and 20 nm. In the present investigation, the N2 selectivity is attained more than 85% at 400 °C. In addition, the time-on-stream results revealed that the DENs Pt/Al2O3 catalysts are very effective on the reduction of NOx under wide temperature window.