Diffuse Reflectance UV–visible spectra of (A) Cu-H-MOR (Cu/Al = 0.20, Na/Al = 0.03), (B) Cu-Na-MOR (Cu/Al = 0.22, Na/Al = 0.63), and (C) Cu-Na-MOR (Cu/Al = 0.36, Na/Al = 0.37).Zeolites were dried under argon at 823 K for 3 h (pink), calcined under oxygen at 823 K for 5 h (dashed gold), and reacted under CH4 at 473 K for 2 h (navy).Difference spectra (calcined–argon, dash-dot orange; calcined– CH4, dotted green) are shown.