An Investigation of the NO/H2/O2 (Lean De-NOx) Reaction on a Highly Active and Selective Pt/La0.7Sr0.2Ce0.1FeO3 Catalyst at Low Temperatures

Pt/Mg-Ce-O catalyst for NO/H2/O2 lean de-No x reaction

“…The flow-system used for conducting catalytic measurements at 1 atm total pressure consisted of a mass flow measuring and control system (MKS, Model 247C), mixing chambers, a quartz fixed-bed micro-reactor (2 mL nominal volume), and a gas chromatograph/mass spectrometer (GC/MS) (Hewlett Packard 5890, Series II Plus/Omnistar-Balzers) analysis system. The flow system, the micro-reactor and the analysis system used have been recently described in detail (Costa et al 2001). The feed stream consisting of 0.25% NO, 1.0% H 2 , 5% O 2 and He as balance gas was used in all experiments.…”

“…The amount of supported-Pt catalyst sample used for catalytic experiments was 0.15 g and the total flow rate was 100 NmL/min, resulting in a gas hourly space velocity (GHSV) of about 80.000 h -1 . For the experiments to study the effects of H 2 O in the feed stream on the NO conversion and N 2 selectivity, a feed gas mixture containing about 5 mol% H 2 O was prepared as previously described (Costa et al 2001).…”

“…However, the actual concerns about increasing emissions of carbon dioxide and the problems faced by the use of NH 3 as reducing agent lead to a demand to find appropriate non-carbon-containing reducing agents for the catalytic removal of NO from combustion exhaust streams, preferably at low temperatures, e.g., below 250 C. Hydrogen is one of the gases present in the exhaust stream of vehicles and has been reported to be very effective as a reducing agent for the NO/H 2 reaction (Hecker and Bell 1984). However, few studies have been reported for the reduction of NO by H 2 in oxygen-rich conditions (Burch and Coleman 1999;Costa et al 2001). This is likely due to the fact that hydrogen can be easily consumed in a combustion reaction with O 2 .…”

“…On the other hand, one of the drawbacks of the Pt-Mo-Na/SiO 2 catalyst is its relatively low stability under lean-burn conditions in the presence of water (Yokota et al 1997). A remarkable catalytic behaviour towards NO/H 2 /O 2 reaction has recently been reported over Pt/perovskite catalysts (Costa et al 2001). In particular, N 2 selectivities higher than 80% in the presence of 5% (v/v) H 2 O in the feed stream were reported.…”

Nitric Oxide Reduction Using Hydrogen Over Perovskite Catalysts with Promotional Effect of Platinum on Catalytic Activity

“…Costa et al studied 0.1 wt.% Pt supported on La 0.5 Ce 0.5 MnO 3 perovskite type material for the NO/H 2 /O 2 reaction in the 100-400°C range [24]. In another report 0.1 wt.% Pt supported La 0.7 Sr 0.2 Ce 0.1 FeO 3 perovskite catalyst has been studied for the same reaction [25]. In fact, it has been shown that the Pd/LaCoO 3 exhibits better activity as compared to Pd/Al 2 O 3 .…”