Passive SCR: The Effect of H $$_2$$ 2 to NO Ratio on the Formation of NH $$_3$$ 3 Over Alumina Supported Platinum and Palladium Catalysts

Abstract

We investigate the relationship between the H 2 :NO ratio and NH 3 formation over alumina supported Pt and Pd catalysts. By kinetic studies and in situ infrared spectroscopy, we report that NH 3 formation is not only sensitive to the catalyst formulation but equally dependent on the feed gas composition and temperature. Specifically, we identify that hydrogen plays an important role in the dissociation of NO at low temperature. We also show that the support material itself plays a vital role in the ammonia formation mechanism due to the redox behaviour of NO adsorption at low temperature. This was unexpected as the noble metal is generally considered to be the active phase for the reaction of NO and H 2 .

Why Nitrogen Oxide Inhibits Co Oxidation Over Highly Dispersed Platinum Ceria Catalysts

“…The peaks at 1930, 1750, and 1675 cm − 1 are assigned to species bound to Pt. The bands at 1750 and 1674 cm − 1 are assigned to NO bonded to Pt in linear (ν NO lin (Pt 0 ) and bridged (ν NO br (Pt 0 )) configuration, respectively [12]. The minor peak at 1930 cm − 1 could either be assigned to CO adsorbed on platinum-ceria boundary sites (ν CO lin (Pt-Ce 3+ ) or NO adsorbed on oxidic platinum (ν NO lin (Pt 2+ )) [13,14].…”