Spectroscopic studies of the stability of zeolitic deNOx catalysts

The State of the Art in Selective Catalytic Reduction of NOxby Ammonia Using Metal‐Exchanged Zeolite Catalysts

“…It seems that the stabilizing effect of rare earth metals varies inversely with their ion size (180). Rokosz et al (191) showed that the hydrothermal stability of M-ZSM-5 (M ¼ metal) increases in the order: Fe, Na , Ga , Co, Ni, Al , Pd , Ce , La, and that Cu doped with La is less stable than La only to dealumination by steaming (10% H 2 O at 6508C).…”

SCR of NOx by C3H6: comparison between Cu/Cr/CeO2 and Cu/Ag/CeO2 catalysts

“…The bimetal catalyst concept was introduced in the SCR-HC to improve the performance of the supported Cu catalyst by adding certain promoters [19][20][21][22]. The cocationpromoted copper catalysts have been extensively zeolitebased catalytic systems in NO x abatement [23][24][25][26].…”

“…The cocationpromoted copper catalysts have been extensively zeolitebased catalytic systems in NO x abatement [23][24][25][26]. The addition of transition metal cocations (Fe, Co, Ni, V, Mn, W, Mo, and Cr) onto zeolite-supported copper catalyst has been reported to tremendously increase the conversion of NO x under lean conditions [19].…”

Influence of Synthesis Conditions for ZSM-5 on the Hydrothermal Stability of Cu-ZSM-5

“…A period of large efforts to understand the properties of this catalytic system followed, but the material was found to be insufficiently stable for automotive applications [3]. The catalytic activity was lost as a result of Cu-ion migration while the zeolite framework remained less affected [3][4][5][6][7][8][9][10][11]. Hence, ways to increase the bonding strength of the Cu-ions to the ZSM-5 framework are of interest to improve stability of Cu-ZSM-5.…”

“…Attempts to improve the stability by introduction of other cations, ionexchanged into Cu-ZSM-5 have resulted in small or negligible improvements using, e.g. Sm, Pd, Sn, La, Ce, Ag and Co ions [9,[12][13][14][15][16][17][18]. In situ synthesis of ZSM-5 onto cordierite monoliths has been reported to improve zeolite crystal stability [19].…”