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

Abstract

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 Pt-40 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 N-2 selectivity is attained more than 85% at 400 degrees 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.