Caracterizacio´n por SEM, EDS y micro-Raman de la influencia de la relacio´n molar SiO₂/Al₂O₃ y temperatura de reduccio´n sobre el sistema CuZSM5

The morphological and spectroscopic changes caused by reduction of ion-exchanged CuZSM5 samples with SiO₂/Al₂O₃ molar ratios (MR) of 30 and 70 in H₂ flow at 150 and 350°C are discussed. The nominal copper loading was of 1% by weight. SEM microscopy of CuZSM5 sample set showed that the treatment in reducing atmosphere at 350°C produces particle agglomeration and smoother surface texture that treatment at 150°C; this effect was more pronounced for the sample with RM 30. Furthermore, the particles corresponding to the sample with RM 30 are of irregular shape and have rough texture (cubic or rectangular crystals, protrusions) while the particles of the sample with RM 70 are in the majority of spherical smooth texture (leaf-shaped crystals/platelet, reclining). EDS elemental analysis reveals a heterogeneous distribution of copper as well other elements in each sample. The micro-Raman spectroscopy shows some changes in the vibrational modes for the studied samples.