Chemical deactivation of Cu-SSZ-13 ammonia selective catalytic reduction (NH3-SCR) systems

Potassium poisoning on Cu-SAPO-34 catalyst for selective catalytic reduction of NOx with ammonia

“…Three main bands at 220, 280-340, and 800 nm occur in the fresh and potassium poisoned Cu-SAPO-34 catalysts. The band at 220 nm is attributed to oxygen-to-metal charge-transfer (CT) related to the isolated Cu + /Cu 2+ bound on the framework of zeolite [33,34]. Bands at 280-340 nm are assigned to square-planar copper oxide clusters, which are the precursors of the highly dispersed CuO phase [35,36].…”

Recent Progress in Atomic-Level Understanding of Cu/SSZ-13 Selective Catalytic Reduction Catalysts

“…In contrast, hydrothermal degradation is typically irreversible due to permanent structural changes in the zeolite that result in, for example, loss of Brønsted acid sites and changes to the chemical or physical structure of Cu active centers. This explains why hydrothermal aging effects have been so extensively studied [39][40][41][52][53][54]. Prior studies have suggested that Cu/SSZ-13 durability enhancement can be achieved in a number of ways: (1) composition optimization, that is, choosing optimized Si/Al and Cu/Al ratios [31]; (2) zeolite particle size optimization [55]; (3) new synthesis methods development [30,[56][57][58][59]; and (4) introduction of stability enhancement additives.…”

MnO -CeO2 catalysts synthesized by solution combustion synthesis for the low-temperature NH3-SCR

“…The peak in the range 592.5-530.0 eV corresponded to lattice oxygen (O 2− ), whereas the one in the range 530.7-531.7 eV was associated with the surface-adsorbed oxygen (O ␣ ), also known as O 2 2− or O − [19]. It has been reported that O ␣ plays a key role in the SCR reaction and a high content of labile oxygen (expressed in Table 2 by the O ␣ /O ␤ ratio) can enhance the catalytic performance [20].…”

“…In recent years, several catalysts among those working at low temperatures have received a particular attention, as for instance: noble metals [1], zeolites [2] and manganese oxides [3]. In particular, the latter system seems to be the most interesting since it conjugates the property of good activity without the presence of macroscopic drawbacks, such as the high costs of noble metals and the poor hydrothermal resistance of zeolites.…”