Fig. 2: In-depth understanding of APE.
From: Ammonia pools in zeolites for direct fabrication of catalytic centers
a DTA results of NH4-MOR and NH4–Cu(X)-MOR samples with different copper contents. Note: I: desorption of physically adsorbed H2O; II: H2O + Cu2+→CuO + 2H+; III: NH4-MOR → H-MOR + NH3; IV: NH3 + Cu2+/CuO→Cu+ + Cu0 + N2 + H+; V: Cu+/Cu2O → CuO or Cu0 → Cu2O/CuO. The exothermic and endothermic behaviors are abbreviated as exo and endo, respectively. b XPS depth profile of H–Cu(3.41 wt%)-MOR(APE). D represents the etching depth. c The relationship between Cu2+ proportion and nominal depth from the catalyst surface. d The H2-TPR profiles of different Cu-MOR samples. Note: I: H–Cu(3.27 wt%)-MOR(Air); II: H–Cu(5.72 wt%)-MOR(APE); III: H–Cu(3.41 wt%)-MOR(APE); IV: H–Cu(2.52 wt%)-MOR(APE); V: H–Cu(1.14 wt%)-MOR(APE); VI: H–Cu(3.27 wt%)-MOR(H2). The H–Cu(X)-MOR(APE) samples, with decreasing Cu contents, showed lower reduction temperature for the low-temperature peaks, indicating easy reduction of the copper species.
