Fuel effects on the activity of silver hydrocarbon-SCR catalysts

Environmentally-benign catalysts for the selective catalytic reduction of NOxfrom diesel engines: structure–activity relationship and reaction mechanism aspects

“…The past several years have witnessed a growth in research in NO x reduction by fuel-component hydrocarbons over Ag/Al 2 O 3 , while the light-off temperature for NO x reduction is still too high to be used for commercial application in diesel vehicles, even though it has been reported that low temperature activity can be promoted by the addition of H 2 . 24,[32][33][34][35][36][37][38][39][40] More importantly, aromatic hydrocarbons, typically present in diesel fuel, exhibit low activity for NO x reduction even in the presence of H 2 . 41 Indeed, when using diesel fuel (ultra-low sulfur diesel, US06) as the reductant, 34 Ag/Al 2 O 3 showed high initial activity for NO x reduction in the presence of 3200 ppm H 2 , while its activity gradually decayed with time, reaching a final conversion level similar to that observed in the absence of H 2 .…”

“…24,[32][33][34][35][36][37][38][39][40] More importantly, aromatic hydrocarbons, typically present in diesel fuel, exhibit low activity for NO x reduction even in the presence of H 2 . 41 Indeed, when using diesel fuel (ultra-low sulfur diesel, US06) as the reductant, 34 Ag/Al 2 O 3 showed high initial activity for NO x reduction in the presence of 3200 ppm H 2 , while its activity gradually decayed with time, reaching a final conversion level similar to that observed in the absence of H 2 . These results indicate that the issue of catalyst deactivation by hydrocarbon poisoning still needs to be resolved for the commercial application of HC-SCR.…”

Studies on H2-Assisted Liquefied Petroleum Gas Reduction of NO over Ag/Al2O3 Catalyst

“…However, urea-SCR technology has serious drawbacks, such as an additional urea tank to be refilled periodically, heated to avoid freezing of the urea solution (urea-SCR) [1], and formation of high molecular weight products. Ergo, now a day hydrocarbons (HC) like those typically present in fuel mixtures are used as a reductant, such as: octane, decane, dodecane and propane [2][3][4], etc. Among the catalyst for NOx reduction most extensively researched HC-SCR of NOx catalysts are Ag/Al2O3.…”

Fuel reforming over Ni-based catalysts coupled with selective catalytic reduction of NOx

“…Among them, alumina-supported silver (Ag/Al2O3) is a particularly promising catalyst for practical application [1,[7][8][9]. The NOx abatement efficiency of HC-SCR not only depends on the nature of the catalysts but also on the structure and composition of the reductants used [8][9][10][11][12]. Generally, the efficiency of reductants for NOx removal over Ag/Al2O3 drops in the sequence of oxygenated HCs (alcohols, aldehydes, ketones etc.)…”

“…When n-C16H34 or diesel was applied as a reductant directly, the highest NOx conversion over 1.9% Ag/Al2O3 was only 50% (HC/NOx = 6, GHSV = 60000 h -1 ) [16]. Rapid deactivation of Ag/Al2O3 because of serious carbon deposition was observed when diesel such as gas-to-liquid (GTL, negligible sulphur and only 0.3 wt% aromatics) and US06 (ultra-low sulphur but 24 wt% aromatics) were used directly as a reductant for NOx conversion and the catalyst even failed to reach a steady state [10]. In contrast, when using small molecular weight HCs as reductants (e.g., C3H6), up to 90% NOx conversion was achieved using a Ag/Al2O3 catalyst over a wide temperature range (700-850 K) [17].…”