Kinetics of ammonia consumption during the selective catalytic reduction of NO x over an iron zeolite catalyst

Fe-Beta zeolite for selective catalytic reduction of NOx with NH3: Influence of Fe content

“…Zeolite catalysts have a large specific surface area and plentiful acid sites that adsorb NO and NH3, leading to their outstanding catalytic performance for de-NOx in the NH3-SCR process. Many kinds of zeolite are used for the NH3-SCR reaction, such as ZSM-5, Beta, MOR, SAPO-34 and SSZ-13 [8][9][10][11], and transition metals, such as Cu [12][13][14][15], Fe [15][16][17][18], Mn [1,19] and Co [20] are used as the main active component in the modified zeolites. Among these, Cu-ZSM-5 and Fe-ZSM-5 catalysts are the most extensive researched.…”

Promoted Decomposition of NOx in Automotive Diesel-like Exhausts by Electro-Catalytic Honeycombs

“…If reaction does not occur instantly, which is the case shown in Figure , the rate of deNO x by reactions and should be lower than that by reaction alone. Thus, additional formation of NO 2 should decrease the overall deNO x rate, a situation opposite to that observed in ammonia-based SCR, noting that the fast SCR with a much higher reaction rate prevails in the presence of NO 2 . Since NO can be oxidized homogeneously in the gas phase to form NO 2 , being especially faster when the gas phase is cooler, , the overall deNO x rate can then be considerably lower.…”

“…Thus, additional formation of NO 2 should decrease the overall deNO x rate, a situation opposite to that observed in ammonia-based SCR, noting that the fast SCR with a much higher reaction rate prevails in the presence of NO 2 . 21 Since NO can be oxidized homogeneously in the gas phase to form NO 2 , being especially faster when the gas phase is cooler, 22,23 the overall deNO x rate can then be considerably lower. Thus, deNO x is better performed before the exhaust is cooled in order to avoid, or at least to reduce, the oxidation of NO in the gas phase to NO 2 .…”

Polycyclic Aromatic Hydrocarbons (PAHs) and nitrated analogs associated to particulate matter emission from a Euro V-SCR engine fuelled with diesel/biodiesel blends

“…The SCR system is still the most widely used in many countries, due to its selectivity to reduce NO x emissions (Tadano et al, 2014). The injection of urea and a catalyst ensures reductions of up to 90% in NO x emissions, through a reduction reaction of NO x and NH 3 resulting in nitrogen and water (Amanatidis et al, 2014;Bacher et al, 2015). Nevertheless, SCR technology is not without its challenges, such as the emission of NH 3 , stoichiometric disproportion of urea consumption, cost, and deactivation of the catalyst by deposition (Cheruiyot et al, 2017).…”